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

[PEZBerq]

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?

[Montynut]

The cooling system is pressurising and blowing coolant out the radiator overflow. The discharge hits the exhaust header pipe.

[Lozza]

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,

[Mike52]

Drag a fine file across the top of the cylinder .
You should see what's happening real quick.

[Kenneth S (222)]

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

[Mike52]

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.

[Kenneth S (222)]

Got it. Thanks, I'll try that and see what I find.

[mainline]

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

[Kenneth S (222)]

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)........

[evo550]

Yeah that corroded magnesium is nasty stuff, keeps popping up as a fine white powder for ages.

[Kenneth S (222)]

Started it up the other night. Absolutely nothing coming out of the radiator overflow. The test will be next week at the Lakes.

[Bitten]

and the outcome was?

[Hoony]

and the outcome was?

yeah wondering that too.

[Kenneth S (222)]

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.

[Simo63]

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