OzVMX Forum
Clubroom => Tech Talk => Topic started by: Kenneth S (222) on May 07, 2012, 05:48:00 pm
-
Hi Guys,
I have been working on my CR250RE, the Steam Train, and have fitted a brand new 1.4 radiator cap. I refilled the radiator right to the top, fitted the cap and started the bike. For the first 5 minutes of running, the coolant dribbled out of the overflow tube when I revved the engine. In total about 40-50ml of coolant came out and then it seemed to settle down. I imagine the coolant expands when it is heated so this is normal and there will always be an area of unfilled radiator at the top. Is this correct?
-
Yes. (don't you love the short answers)
-
I'll elaborate a bit. ;)
Exactly as you suggested, the liquid needs space to expand when hot, so you'll never keep the radiator completely full when cold. Unless the system has an expansion tank which is supposed to allow the coolant to escape into the tank when hot, then be drawn back into the radiator when it cools down. (Although the one on any of my Husky's never worked.... ::) )
In short, keep an eye on the level, but I'd be confident that your cooling system is working correctly.
-
Thanks guys. Fingers crossed for this weekend. I have pulled the clutch case off this thing at least 5 times in the last 7 weeks since I received the bike!
-
Kenneth. I had the same issue with one of my CR250RE's a year or so ago, would spit coolant out when revved. Simply put mate you've probably got a head gasket leak. In my case the head was warped and allowed a small amount of blow-by on the head gasket. Removed, checked and confirmed it was concave (they tend to do this due to the studs that hold the head on puloing it down on the outside and warping the head), resurfaced it, new gasket and no more problem.
Hope this helps.
Cheers
Craig
-
Kenneth. I had the same issue with one of my CR250RE's a year or so ago, would spit coolant out when revved. Simply put mate you've probably got a head gasket leak. In my case the head was warped and allowed a small amount of blow-by on the head gasket. Removed, checked and confirmed it was concave (they tend to do this due to the studs that hold the head on puloing it down on the outside and warping the head), resurfaced it, new gasket and no more problem.
Hope this helps.
Cheers
Craig
Thanks Craig, much appreciated. The case works fine thanks. Thanks for getting it to me so quickly.
-
Hi Craig,
The steam train reemerged at the recent Canberra race meet. On the Sunday morning before the racing, at 0 forking degrees, I took the head off and had a look at the head gasket. I think you were right. As a quick fix, I put some gasket goo in around the lip of the gasket, nipped it up to set, then tightened it down just before the racing and while it still leaked, it was not nearly as bad and I was able to get through the races. Thanks for the tip. Will resurface top and bottom and replace the head gasket.
Cheers
-
check the top of the cylinder to they tend to sink around the exhaust port
-
The plot thickens. I saw a photo of a head for sale on eBay and noticed the coolant intake fittings looked to be larger in diameter to my head. This caused me to question my head. On closer inspection, I realised that a previous owner had crossthreaded and glued the wrong size brass inlet fittings to my head. As this bike is a new model to me, I was not familiar with what the stock head looked like. BigK was good enough to send me an old head he had kicking around for this bike and yes, I think this is the source of all the issues over the last 4 months. Surely this massive restriction in coolant flow would result in a huge increase in pressure, especially when I rev the engine, and the coolant was forced out at the weakest point. Fingers crossed, things might now settle down.
Thanks guys for all the tips. I have taken all the advice and along with BigKs head, surely I am close to solving this one.
Sorry Hardo but I think the Steam Train might soon be dead.
Old head on left, BigKs head on right
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/CR250REHeads.jpg)
-
Yep that shiny head is certainly BigK's .
-
The plot thickens. I saw a photo of a head for sale on eBay and noticed the coolant intake fittings looked to be larger in diameter to my head. This caused me to question my head. On closer inspection, I realised that a previous owner had crossthreaded and glued the wrong size brass inlet fittings to my head. As this bike is a new model to me, I was not familiar with what the stock head looked like. BigK was good enough to send me an old head he had kicking around for this bike and yes, I think this is the source of all the issues over the last 4 months. Surely this massive restriction in coolant flow would result in a huge increase in pressure, especially when I rev the engine, and the coolant was forced out at the weakest point. Fingers crossed, things might now settle down.
Thanks guys for all the tips. I have taken all the advice and along with BigKs head, surely I am close to solving this one.
Sorry Hardo but I think the Steam Train might soon be dead.
I don't think that would result in a 'massive' increase in pressure, there would be passages that would be mich tighter than that in the cylinder. Compacting and slowing the water in the cylinder head is a good thing anyway. Most heads have a single 19mm or 3/4in outlet in them. Top of the cylinder not being flat has given me the most head gasket/o ring issues over the years.
-
hahahah good one Hoony
-
Sorry Hardo but I think the Steam Train might soon be dead.
:'(
I sure will miss following that Steam Train... it has been my guiding light for 2 meetings !! :P
-
A quick update on this one. I reassembled the bike the other night and took the time to use my torque wrench to tighten the head nuts. It took no extra time at all really, up until this reassembly I didn't have an original owners manual to tell me what the torque should be but I picked up a beauty recently so I had all the info at hand. After hand tightening them, I was surprised how much tighter I had to tighten the nuts with the torque wrench and realised that my 'mechanics feel' might have been a little too careful and I am quite sure that I didn't have enough torque on the head nuts prior to now. As these bikes are so old, I worry about over tightening things and I think this could have been one of the contributors to my steam train problems. Doh ::)
-
Lozza, it seems you were spot on.
Blew 'another' head gasket on the weekend and did my best to keep it on the track with a makeshift trackside gasket courtesy of James Boags, Bob's gasket goo and the kind assistance of my old Manly clubmate from the 70s, Geoff. A stretch I know, but with only 3 lap races you don't know unless you try. No joy though as it blew on lap 2. The good news is that thanks to Ando & Middo, we might have finally got to the bottom of this. The barrel has been sleeved and it seems that after you sleeve them the sleeve settles and the outer barrel distorts just slightly. In some places, there is the faintest lip just barely noticeable between the sleeve and barrel itself. Not enough to cause such problems I would have throught but I am told this will interfere with how the inner rim of the gasket seals.
Off to the machine shop to have it shaved. Fingers crossed!
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/Bulahdelah2012/BoagsGasket.jpg)
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/Bulahdelah2012/482.jpg)
-
Glad you seem to have gotton to the bottom of the problem Kenny, your persistance is impressive and hopefully after hacing the cylinder top skimmed, might be rewarded with a reliable Honda.
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/Bulahdelah2012/482.jpg)
Mate I couldn't let the opportunity pass to comment on this fantastic picture. A great one to remind you of the drama you have had to endure with the bike. Now I know why you have said it turned into a steam train, I've never seen one produce anywhere near this much steam before.
Cheers
Craig
-
Well the plot thickens. So far I have replaced the hoses, the radiators & radiator cap (with new ones), the head gasket, had the head and cylinder decked, and on the weekend, when I started it up, as I revved it the coolant STILL pissed out the overflow tube. >:( At this stage, I recon if I changed the engine it would still do it. :-\ All I can think of now is there must be a fault in the cylinder allowing combustion on induction pressure to leak into the cooling jacket. It can't be anything else! Can it! ???
-
I would've eBayed the thing by now. ???
-
I would've eBayed the thing by now. ???
Yes, it has occurred to me but I am a stubborn bugger who doesn't like to give up.
-
I would get somone to pressure test it and see if it leaks down, and if so you may see where its leaking from.
I do feel your pain.
-
These things can sure be frustrating to solve.
Assuming everything else is done correctly, (head sealing etc.)
Then I would suspect a cracked head.
A crack in the head will let combustion pressure into the water jacket which will overheat the water and push it out the overflow.
There could possibly be a crack in the cylinder but it’s most likely the head.
Take the head off once more and study it carefully under a good light with a magnifying glass.
Cracks can be hard to detect sometimes as they will close up when cold and open up when at operating temperature.
You can get crack detecting sprays from engineering shops that may help find something but it may be easier to give it to someone experienced in testing for cracks
-
This might sound a little too simplistic and tell me of fork off if you must but could the lugs that hold the radiator cap not be bent correctly
I had a real issue on a modern 4 stroke with it boiling over at the drop of a hat until a 'bush mechanic' mate I was riding with had a quick look at my cap on the side of the track, took out some pliers and nipped them up a bit to ensure a real tight seal and voila no more issues and that was 2000km of off road riding ago
Best of luck with it
-
My guess would be when they pressed sleeve in they have cracked the barrel case or not cleaned it before pressing in.Put a pressure tester on radiator and see if it drops off.You will need to warm motor first
-
Had similar problems on a CR 250 some how the barrel got broken where it bolts to the crank case got it welded put it back together started it and would start to piss coolant out overflow ended up being a crack in the transfer port that was not able to be welded. Named it the 2 minute noodle that's how long it took to cook.
-
Old head on left, BigKs head on right
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/CR250REHeads.jpg)
Hi, I think I know what your problem is…
…as the bloody E-bay help would frustratingly say as it becomes obvious that your last e-mail and the 10 before that were never actually read by a human.
Hopefully I can be a bit more help than that.
I have just gone over your posts as your problem now has me intrigued and I still reckon it’s the head.
Hands up those who have ever changed a fouled plug with a new plug and then spent countless hours trying to find why the bike won’t run only to eventually find that the new plug you put in was a dud.
Well I reckon your replacement head my not be up to scratch.
The head on the right looks like it has had a weld repair around the spark plug hole.
This weld may be good enough to hold the combustion pressures inside the motor but there is a good chance that there is still a crack between the combustion chamber and the water jacket.
I doubt the smaller brass water spigots were the problem with the old head, I reckon there was a crack there somewhere.
Your barrel may be the culprit but I read that it has been resleeved with a steel liner. For the barrel to be the problem then it must have a crack in the upper part of the liner or its not sealing around the top at the barrel / liner junction.
Problems with barrels cracking are rare, cracked heads are common, especially with a head brace. Make sure the head brace stays have oval holes where they meet the head. If there is no ‘give’ at this junction then any flex in the frame will transfer all stress to the head.
-
Thanks Geoff,
You make some very valid points. I do not have oval holes in the head braces so that could definitely be a contributing factor. I have parked it for the past month as it has been giving me the s*#ts and spent time on my trailer. I have a couple of tests I plan to do which hopefully will narrow down what the problem is.
One person on the forum suggested the coolant I am using could be foaming up and creating the extra pressure. I have bought some clear hose to run from the top of the radiator each side down to the head and I am going to hook that up, start up the bike and watch for foaming and confirm to myself I have a good flow of fluid through the pipes.
As hardhaacker suggested, next I am going to do a pressure test. I am going to remove the barrel & head intact, run a hose from one head intake to the other and I have bought from Enzed a fitting to fit into the open end of the larger outtake pipe and the other side fitting our airlines at work. I am then going to put up to 6-7 Bar of pressure into the cooling system and submerge the barrel in a bucket of water.
It better leak because if it doesn't I will be completely baffled.
-
6 to7 bar is 87to 100psi. That is way to much pressure to subject any part of your cooling system to. Your cap blows of at about 14 psi to protect your cooling system. They usually pressure test at about 20 psi. I would not be surprised if it blows your head gasket in the water jacket sections. You will see a leak but it will be one you just caused and you will be no better off. Do your test, but do it at 20 psi as your system only ever gets to 10 to 14 psi. You don't want to go down wrong path again. That head does look suspicious with the welded up plug hole.
-
I am not suggesting you are wrong Head as I am no cooling system expert. Kenneth is trying to find a leak between the combustion chamber and cooling system not a leak in the cooling system to atmosphere. The 20psi pressure relief in the radiator cap is to protect the radiators, hoses and pump not the cylinder itself I would have thought.
The pressure within the combustion chamber is, naturally, far greater than the cooling system so the test pressure needs to be higher, remembering that the cylinder is isolated (removed) from the more delicate cooling system components. I am still not sure Kenneth’s test will locate the leak as he will be pressurising the cooling system and checking for leaks to the combustion chamber when the leak is the other way (it should expose the leak but not necessarily). The cylinder will also be at ambient temperature which may not expose the leak as it may need to be at operating temperature for the leak to open up.
Kenneth the coolant you are using is the Toyota long life recommended for magnesium engines (I suggested it :-[) have you tried running pure water as a test to eliminate the coolant as a potential cause? Possibly going back to the original head would also be a possibility as the only reason you changed was the incorrect hose connectors (I seem to remember that you may have already tried this).
Just food for thought as the amusement has gone out of watching Ken pull his hair out. I want to see him take that CR up to challenge Hardo ;D instead of making cappuccinos ::).
-
The combustion chamber its self is designed to handle high pressure by the design of the gasket with its metal ring around the cylinder. the water jacket sealing is not. That test may work, but all I am saying there is a good chance that that pressure will blow out the gasket to atmosphere, then you will think you have found the problem only to be no better off. Do the test but not at those pressures or gradually increase the pressure. From what I have read I do not think any kind of pressure test has been done. You need to start from scratch and test the cooling system as a whole, cap included. Far to expensive to just continue to change out parts.
-
Very good points Head and I can see your logic. Another reason that Ken could be mislead by the test and may need to rethink it. I do not believe that he has been loosing coolant other than the radiator cap lifting and discharging the lot after a short period.
The last problem at Lakes seemed different than previous times in that you didn't even get the bike on the track it lifted the radiator cap while warming up while previously it took 3-4 laps.
You must have the world biggest collection of used head gaskets for '84 CR250s by now. I'd have burnt the whole thing by now and I have noted that everyone keeps the fuel drum and matches well away from you at meetings recently ;)
-
Thanks guys,
Yes that make a lot of sense, the head gasket is designed to hold combustion pressure in, not cooling system pressure out, so I will gradually increase the pressure as you suggest.
I haven't added here that after I had the same problem with the head BigK sent me, the welded one, I figured that eliminated the head as the problem, so when I had Greg Ball bore my cylinder and skim the top of it, I also had him skim the original head and put the original fittings back in it for me, so I am now using the original.
Yes Monty, I have a good collection now of blown head gaskets and others that were ruined each time I have had to pull the bloody thing apart, well over 10 times this season >:(. I will never need any more of the other gaskets though as I have had to buy sets each time :-\
One other variable which has occurred to me recently. The bike was in such bad shape when I got it, I decided to replace the hoses just so I knew they were OK. I did not buy a set made for the bike, at the time I couldn't find one and I have not since found one. I went to the local Pirtek shop and bought standard radiator hose. One of the reasons I want to run the clear hose test is to make sure that none of the hoses going around bends have closed off the flow.
And yes, it has crossed my mind I'd like to give Mr Hardo a bit of a hurry up ;D
I'll keep you posted.
-
What bore size are you on ? I don't know alot about Honda oversizes, but generally Honda will do a genuine piston to about .5mm o/s then some aftermarket manufacturers continue up to about 2mm o/s maybe even bigger, those big pistons may require an aftermarket gasket to go with them and not the standard Honda gasket. Had this problem with an oversized fourstroke piston, blew 2 genuine headgaskets until I found out you could get oversized gaskets to suit.
-
What bore size are you on ? I don't know alot about Honda oversizes, but generally Honda will do a genuine piston to about .5mm o/s then some aftermarket manufacturers continue up to about 2mm o/s maybe even bigger, those big pistons may require an aftermarket gasket to go with them and not the standard Honda gasket. Had this problem with an oversized fourstroke piston, blew 2 genuine headgaskets until I found out you could get oversized gaskets to suit.
That makes sense as well. I'm on 67.44mm and the gasket measures 68.5mm. I did the flow test through the clear tubes and I am getting very good circulation of coolant on both sides. Being the softer clear plastic tubing the pressure in the system was more noticeable as the tubes began to balloon up until the coolant shot out the overflow. I also did the pressure test on the barrel and head intact as described above and there was no leak fully submerged under water until the pressure was high enough to leak through the head gasket.
I am stumped. :-\
I inspected the top of the barrel closely and even through I sent it away with the head to be skimmed and matched, there still seems to be faint pitting where the gaskets is supposed to seal. I am beginning to think that it wasn't skimmed enough and that could be it.
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/CR250RECylinderArrows.jpg)
(http://i1213.photobucket.com/albums/cc468/24HourMerchMan/ClearHoses.jpg)
-
I also did the pressure test on the barrel and head intact as described above and there was no leak fully submerged under water until the pressure was high enough to leak through the head gasket.
Say What?
The normal running pressure of an engine would be more than your average compressor puts out.
It shouldn’t have leaked at all during your test.
-
I also did the pressure test on the barrel and head intact as described above and there was no leak fully submerged under water until the pressure was high enough to leak through the head gasket.
Say What?
The normal running pressure of an engine would be more than your average compressor puts out.
It shouldn’t have leaked at all during your test.
Geoff I pressurized the cooling system hoping it would show me a leak in the head or cylinder. I gradually increased the pressure until the head gasket leaked bubbles into the combustion chamber. Backwards so to speak.
-
I also did the pressure test on the barrel and head intact as described above and there was no leak fully submerged under water until the pressure was high enough to leak through the head gasket.
Say What?
The normal running pressure of an engine would be more than your average compressor puts out.
It shouldn’t have leaked at all during your test.
Geoff I pressurized the cooling system hoping it would show me a leak in the head or cylinder. I gradually increased the pressure until the head gasket leaked bubbles into the combustion chamber. Backwards so to speak.
Well that’s your problem then.
The head gasket should have held more pressure than what you should have been able to give it.
So…
# Still has warped head or barrel.
# Head not tensioned correctly.
# Head bolts stretching
# Studs in head pulling through head
# Dodgy head gasket
-
If you tested the cooling system at 6 - 7 bar as mentioned earlier in this thread then that is way more pressure than the normal operating pressure with 1.4 bar radiator cap. What pressure did the gasket start leaking?
-
Kenneth indicated that the head gasket leaked into the combustion chamber. The normal pressure differential between the combustion chamber and cooling system is usually very high when the engine is running i.e. Compustion pressure less cooling system pressure which would be many many BAR of pressure.
The only question is that the gasket is designed to seal high pressure in the combustion chamber from getting into the cooling system not the other way round. Kenneth had high pressure in the cooling system. The head gasket may not hold pressure in that direction so to speak nearly as well as it does in its designed 'normal' pressure differential although given the test was at ambient temperature I would have thought that it should have held full air compressor pressure easly as GMC says.
GMC may be onto something regarding the head studs maybe they have been stretched beyound their working tension at some point meaning that they no longer do their job when tensioned up correctly. High temperature fasteners at work for example have a relatively short life of only two tension cycles before they are replaced.
That cylinder does not look like it has been skimmed at all.
-
If you tested the cooling system at 6 - 7 bar as mentioned earlier in this thread then that is way more pressure than the normal operating pressure with 1.4 bar radiator cap. What pressure did the gasket start leaking?
Its hard to say as I manually let in a little more pressure in stages, at a guess I think it was up around 5-6 Bar before it leaked.
I had the studs at the specified tension but they do look worn. I did notice though when I pulled it down, they did not seem as tight as they did when I put it together. That could be my imagination though.
-
I see what you guys are saying about the water jacket being meant for low pressure, but that is only as far as the hoses and radiator is concerned.
I stick rubber plugs in exhausts and pump them up to 50 Psi without problems so I don’t see why 2 flat surfaces (head & barrel) bolted firmly together can’t hold at least 100 Psi. The gasket sits firmly between these surfaces and cannot work as a one way valve.
I knew a guy with an old 202 that couldn’t keep the head screwed down tight. It had been cooked a few too many times and the head bolts kept pulling through the block. He had to helicoil all the head bolts in the end. That was a cast iron block but your barrel may have suffered some odd fatigue at some point.
A doctor once over dosed my son when he got milliliters and milligrams mixed up.
Are you sure you have the correct tension for the head bolts.
Do you use a torque wrench?
With so many different figures thrown around it is easy to get confused. Just look at this thread, some of us talk in Bar and others in Psi.
Bolts stretching under load isn’t that uncommon.
I think from memory KLX head bolts suffer from stretching, especially when big bore kits are fitted.
-
That cylinder does not look like it has been skimmed at all.
Just had another look at that picture and I reckon your could be right.
An easy check is to use some valve grinding paste on a thick sheet of glass.
Work the barrel around in a circular motion. It will change the texture of the surface, if the whole surface changes at once then it should be flat but if it only changes the texture in some spots and not others then it is not flat.
-
as gmc said ;)
But If you dont have any valve grinding paste you could try a sheet of 1000grit or so wet and dry on a sheet off glass draging the barrell back and forth to find any low points ;)
-
Can you post a pic of the gaskets. Said a long time ago the cylinder top sinking over the exhaust port is common. Has the head been machined much? As heads can flex from combustion pressures
-
I can post a pic of the latest gasket but I don't think it will show much. It was brand new and all I had done is start the bike in the pits at a race meet when the fluid started to come out the overflow, I didn't even get a chance to ride it this time. These gaskets self destruct as you take the head off because the soft waffle type sealing surface around the coolant ports sticks to the surfaces and tears apart when you take the head off.
Geoff maybe you have identified the cause. The more I think about it, the more the evidence is mounting up that supports your worn cylinder thread/tired stretched studs theory. When the cylinder was skimmed, the guy obviously took the studs out. When I received the cylinder back, the studs were loose and I had to adjust the height of them. I remember thinking how sloppy they felt in the thread, with no resistance at all. If you add to that how when I loosened the head nuts the other night that they felt unusually loose compared to how tight I had tightened them, the thread inside the cylinder could be on the way out. So even though I am doing all the right things, the old and tired studs combined with the sloppy loose thread inside the cylinder is not maintaining the tension. Another fact supporting this theory is when I received this bike, I noticed most of the bolts had been over tensioned and I had to replace most of the fasteners so chances are the past owner did not treat the head nuts correctly.
As a next step I will double check how flat the surfaces are first and provided they are flat as I suspect they will be, to eliminate this possibility of tired thread and studs creating the problem, perhaps I should helicoil the cylinder threads and replace all the studs. I have never had to use a helicoil but I am sure it can't be too hard to work out. Any tips on how I should go about it?
Before I do that though and waste more money on what might be a faulty cylinder or head, can someone recommend where I can send the cylinder & head to do a professional pressure test to rule out a mechanical fault with them?
-
As a next step I will double check how flat the surfaces are first and provided they are flat as I suspect they will be, to eliminate this possibility of tired thread and studs creating the problem, perhaps I should helicoil the cylinder threads and replace all the studs. I have never had to use a helicoil but I am sure it can't be too hard to work out. Any tips on how I should go about it?
Helicoils are a piece of cake, however it is really important that they are installed exactly perpendicular to the head surface. A whole new set of problems will arise if they are not...
-
Is the steam coming out the exhaust or out the radiator overflow? I thought it was the exhaust but might have it wrong. Combustion chamber pressure changes during every stroke of course. Water is probably leaking in when pressure is low in the cylinder not high. Does the radiator hose pass pass water due to over pressure or not?
-
The cooling system is pressurising and blowing coolant out the radiator overflow. The discharge hits the exhaust header pipe.
-
I can post a pic of the latest gasket but I don't think it will show much. It was brand new and all I had done is start the bike in the pits at a race meet when the fluid started to come out the overflow
I think your wrong there, If the overflow is starting as soon as the bike is started what happens with the radiator cap off and kicked over any bubbles present. Testing the cylinder will be hard but a basic crack test will be easy to do. You can also do away with the head gasket and silicone it on with copper RTV or Wurth 912 or so,
-
Drag a fine file across the top of the cylinder .
You should see what's happening real quick.
-
Drag a fine file across the top of the cylinder .
You should see what's happening real quick.
Hi Mike, Not sure what you mean with this. Can you give me more detail?
KJ
-
Hi Mike, Not sure what you mean with this. Can you give me more detail?
KJ
Yer KJ it's called draw filing and you pull the file across the cylinder at 90deg.
Trying to figure out how to explain it.
Put both arms straight out in front of you.
Hold the file in both hands so it's across your body.
Put the file face down on the top of the cylinder and draw it towards you keeping it across your body.
You can push it away from you on the back stroke if required.
No need for any great pressure as you are only looking to see what the top of the cylinder looks like.
You can wrap some fine sandpaper around your file if you don't have a fine one.
Watch your fingers as you can snip bits off going over the bolt /water jacket holes.
If your cylinder has pulled up at the studs or has any other type of problem then it will show.
This is an old engine rebuilders trick to check if a block or cylinder head needs refacing.
-
Got it. Thanks, I'll try that and see what I find.
-
if you've got the studs out, you may want to countersink the holes just a fraction in case they're pulling up at that point. Had it happening to me on a yz125 that kept leaking at the headgasket
-
Absorbing all the thoughts on this thread and from helpers in the club, now looking back this is what I think might have happened.
Bought a bike with a corroded water pump, cracked water pump cover and blocked radiator. Problem was I didn't know it had a blocked radiator.
Race Day 1/ While I rode it, fluid leaked from the cracked water pump cover and I kept topping it up. As I rode it though, it was probably over heating due to the blocked radiator and the head began to warp.
Race Day 2/ Once the head was warped, it began to blow head gaskets. First time this weekend
Race Day 3/ Second time this weekend.
Race Day 4/ Tried another head kindly donated by BigK, still blew another head gasket so decided to have it looked at. In hind sight I probably warped this head as well due to the blocked radiator. Had the head shaved and the cylinder put on a lap stone so they matched but still did not know the radiator was blocked.
Race Day 5/ Had gone back to the original, now machined head and blew a head gasket. Discovered the radiator was blocked. Thanks Scrivo for your input.
Race Day 6/ New radiators, new head gasket, full of anticipation, coolant began to pour out the overflow as I warmed the bike up. WTF!!!! ???
Race Day 7/ Didn't bother :-\
I now suspect that the blocked radiator caused both heads to warp. The first time when I blew 3 head gaskets and the second time when I blew another 2. The reason the bike didn't run on Race Day 6 was that the damage had been done on Race Day 5, before I replaced the radiators.
Race Day 8/ Well, The bike now has new radiators, I've checked the water pump is working and pumping fluid through both sides, I've had the head and barrel re-machined flat and pressure tested. The studs and the thread have been checked and are holding tension.
Thanks to all for your input. It is much appreciated. We will see what happens now....If it does run, I've learned a huge lesson. Check the DAMN radiators first before you do anything else. If it doesn't run, I'm going to (Censored)........
-
Yeah that corroded magnesium is nasty stuff, keeps popping up as a fine white powder for ages.
-
Started it up the other night. Absolutely nothing coming out of the radiator overflow.:) The test will be next week at the Lakes.
-
and the outcome was?
-
and the outcome was?
yeah wondering that too.
-
You don't want to know. Still more Steam after about 4 laps of practice ???. I'm checking the gear oil tonight to see if the coolant is leaking through the mechanical seal. If not, my next step has to be change the barrel. :-\
-
You don't want to know. Still more Steam after about 4 laps of practice ???. I'm checking the gear oil tonight to see if the coolant is leaking through the mechanical seal. If not, my next step has to be change the barrel. :-\
Shite Ken .. this is still giving you grief?? I would have burnt the bloody thing by now :)
-
You mentioned it originally had a corroded waterpump casing, What is the condition of your radiator cores? the magnesium will clog these in a heart beat and then set hard like calcium rendering your rads, and to a certain extent your waterjackets, useless until flushed (or replaced).
Worth a look.
Disregard this, just read an earlier post ::)
-
Thanks Evo I think you were spot on, that was part of the problem. Simo, I have considered it, believe me. I'ts a bloody nice bike to ride when it goes though. I was lucky enough to score today a complete top end which I am told by the seller is still on the standard bore. There was no coolant in the gear box oil so hopefully the new barrel and head will do the trick.
-
I received the replacement barrel I bought from a guy on Mark's Swapmeet. I sent it to Greg Ball to get it measured & checked over before I put it on the bike. Ben noticed it has been re-sleeved. The strange thing is that the original sleeve has not been completely removed so the barrel has a sleeve within a sleeve so to speak. I've never seen this but my experience with these old bikes is minimal. Ben said it could be because the original sleeve/casting had some locating keys so it could have been impossible to completely remove the original sleeve.
Has anyone experienced something like this?
-
All sleeves are done that way.
-
All sleeves are done that way.
Monties aren't. :)
-
Ok, most resleeves are done that way
-
Montesa bikes have a replacable sleeve as standard (up to 1983 when a few started with coated cylinders instead of sleeves) which allows a new sleeve to be shrunk in once you reach the last oversize. Sleeves are available for most models
-
Ben said it could be because the original sleeve/casting had some locating keys so it could have been impossible to completely remove the original sleeve.
Has anyone experienced something like this?
Nonsense.Someone has just been slack, lots of 'cast in' sleeves (ie the aluminium cylinder is cast around the iron liner) have 2 or more internal ribs. You have to find where the ribs are and machine the cylinder out down to the lowest rib, then machine the new liner to match.
The sleeve inside a sleeve will be a excellent barrier to removing heat from the cylinder walls