19 replies to this topic

[Captain Mainwaring]

I agree with you that if the fluid is dropping down to where you can see the top of the core, you have an issue to sort out.

 

You have done a compression test which is good.  If you have access to compressed air, I think you should carry out a leak-down test to rule out a leak of coolant into the combustion chambers.  A compression test may only show that type of failure when it is extreme.

 

Hmm, I'm not sure....if he's running with no stat he could have localized boiling on number 1 that would be enough to cause his issues, I have a big diesel 4x4 that does the same thing, always drops it's water down to the level of the top of the cores, but if I look, with the engine cold, the top hose is under vacuum, but the vacuum isn't enough to draw water back through the rad cap to top itself up again. This vehicle gets really heavily abused in real tropical conditions and never gets close to overheating, it also never uses any coolant after it's sorted itself out and found it's own level.

[BradleyRogerson]

if it was leaking into the chambers wouldnt it run terrible though? i thought it was due to blowing out of the overflow but dont understand why its doing this and not boiling over, maybe it just needs a flush after i did that water pump as i didnt flush it after i ran the engine then added the water hoping it would circulate pushing the air round and out the radiator. 

[Captain Mainwaring]

What you can do is disconnect the overflow and connect a bike foot pump to the overflow stub - pressurize it to say 25 psi after you have checked the level of the water in the rad - leave it under pressure for an hour or so and come back and take a look at the level.

If it drops you've got a leak - could be head gasket. If it does drop and there is no obvious external leak the suspect the head giblet - take the plugs out and spin it over before you start it though to prevent bending a rod.

[Italianjob]

I had the same issue on my audi, blowing water out of the header tank.

 

Thought i had a leak somewhere, took me over a month to find out what it was messing about with things, ended up being the head gasket.

 

Im not saying it is but if nothing else is pointing to it id get it checked before you do more damage driving it.

[dklawson]

Hmm, I'm not sure....if he's running with no stat he could have localized boiling on number 1 that would be enough to cause his issues,

 

 

Sorry, I missed that he was running without a thermostat.  My mistake.  If there is no thermostat and no blanking sleeve to keep "normal" flow through the head I can offer no suggestions for what is going on.  I have not worked on A-series engines without either.

 

Bradley, you are correct that generally when there is leakage between the cooling jacket and chambers the engine runs poorly.  However, if the leak is small and only opens when the engine is hot this can be missed.  A leak down test is typically carried out with the air cleaner off and radiator cap removed so you can look and listen for where air is gettting that it shouldn't be.  A tiny head gasket leak that may pass a compression test will sometimes be revealed as bubbles in the radiator during a leak down test.