Liquid cooled motors, discharging some fluid after a refill. Normal?

[Simo63]

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.

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

[Kenneth S (222)]

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!

[maico police]

I would've eBayed the thing by now.

[Kenneth S (222)]

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.

[hardhaacker]

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.

[GMC]

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

[Bitten]

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

[DR500]

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

[mitch75]

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.

[GMC]

Old head on left, BigKs head on right

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.

[Kenneth S (222)]

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.

[head]

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.

[Montynut]

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 instead of making cappuccinos .

[head]

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.

[Montynut]

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