Disappearing water.

[Tony Brooks]

 

Hi Daniel.

 

Oil is good, no sign of water or sludge.

 

This morning I undid the filler cap and got the usual "hiss" that I've been getting. The water level was down a bit so topped up to about 1/4" below filler neck as per the manual. I then started the engine with the cap off. After about a minute, foam started pouring out of the filler indicating that there was a lot of air (possibly exhaust gases) in the system. After 10-15 minutes of this purging it stopped, then returned to normal. As everything had settled down, I then topped up again with hot water. This brought about another round of foam purging (coincidence?) . Five minutes later all was well again so, replaced the cap and left it running.Still running an hour later and it seems ok.....until the next time maybe.

 

If the head gasket is on its way out and letting gases into the system, why would it stop doing so after a few minutes?

 

Rob....

 

If this is a skin tank cooled boat then that 1/4 inch is almost certainly wrong. Heat exchangers systems hold a set amount of coolant and the engine mariniser knows exactly how much so can calculate the expansion and then say how much gap to leave below the filler neck. On skin tank cooled boats no one knows how much coolant an individual system will hold until they measure it and the boat builders do not seem to do that. The upshot is that a number of people believe the manual and in effect constantly overfill the system only to loose coolant each time the engine warms up and the coolant expands. The easiest way to get the correct level is to fill to the brim, go for a good run, let the engine cool and then check the level - that will be the correct level for that boat.

 

The extra coolant volume is also why the "normal" manifold header tanks may need augmenting by a larger separate tank.

 

Actually I doubt the above is the cause of the OP's problems when he talks about foam and pressure escaping from a cold engine.

[ROBDEN]

 

If it is combustion chamber to coolant channel head gasket failure it may be stopping after a short while due to gasses clearing the coolant channel of coolant. The pressure would be enough to keep the channel full of air and not allow the regress of the coolant.

 

You could check this by letting it foam till it settles, switching off for 5 minutes allowing the coolant to settle back into all the cooling system chambers (don't top-up the system at all) and then restarting. If you get a fresh lot of foaming then I think you've found your culprit unfortunately.

 

Lee.

 

Just tried it. Engine run 3 hours ago. Just took the cap off, "hissss" started engine. within a minute it started foaming.

So it's starting to look like it's the head gasket.

 

You can buy a kit that will test the coolant for combustion products.

 

http://www.amazon.com/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76

Hi Chalky.

 

Yeah I've been reading about them and from what I've read they seem to be a bit hit and miss. Not really a definitive answer.

 

Rob....

 

 

If this is a skin tank cooled boat then that 1/4 inch is almost certainly wrong. Heat exchangers systems hold a set amount of coolant and the engine mariniser knows exactly how much so can calculate the expansion and then say how much gap to leave below the filler neck. On skin tank cooled boats no one knows how much coolant an individual system will hold until they measure it and the boat builders do not seem to do that. The upshot is that a number of people believe the manual and in effect constantly overfill the system only to loose coolant each time the engine warms up and the coolant expands. The easiest way to get the correct level is to fill to the brim, go for a good run, let the engine cool and then check the level - that will be the correct level for that boat.

 

The extra coolant volume is also why the "normal" manifold header tanks may need augmenting by a larger separate tank.

 

Actually I doubt the above is the cause of the OP's problems when he talks about foam and pressure escaping from a cold engine.

 

Hello Tony.

 

Yes, two skin tanks.

 

I did wonder about this as the coolant level always seemed to be more constant when it was 1/2" -3/4" below the filler neck.

 

Now it's looking more and more like the head gasket but none of the usual blown gasket signs like constant boiling up, white exhaust, water in the oil or a sludgy mess.

Could there be a problem with exhaust header tank? I've never heard of one before, just clutching at straws I think.

 

Rob....

[Chalky]

 

Now it's looking more and more like the head gasket but none of the usual blown gasket signs like constant boiling up, white exhaust, water in the oil or a sludgy mess.

Could there be a problem with exhaust header tank? I've never heard of one before, just clutching at straws I think.

 

 

Having blown head gaskets on a number of engines during vehicle development I've never had the "classic" signs of boiling and oil in water. I've had blows between cylinders and also the one I described earlier. Not all failed head gaskets are spectacular. On the K series the coolant disappears slowly over time till the engine over heats and the liners move.

[Tony Brooks]

 

Just tried it. Engine run 3 hours ago. Just took the cap off, "hissss" started engine. within a minute it started foaming.

So it's starting to look like it's the head gasket.

 

Hi Chalky.

 

Yeah I've been reading about them and from what I've read they seem to be a bit hit and miss. Not really a definitive answer.

 

Rob....

 

 

Hello Tony.

 

Yes, two skin tanks.

 

I did wonder about this as the coolant level always seemed to be more constant when it was 1/2" -3/4" below the filler neck.

 

Now it's looking more and more like the head gasket but none of the usual blown gasket signs like constant boiling up, white exhaust, water in the oil or a sludgy mess.

Could there be a problem with exhaust header tank? I've never heard of one before, just clutching at straws I think.

 

Rob....

 

I will stick my neck out and say that most marinised engines use the wtaer jacket around the exhaust manifold as the header tank. They have a "radiator" pressure cap on them. The the problem I described reared its head on the more modern engines that really needed a pressurised system so may hire fleets fitted an additional plastic type expansion tank to allow for the greater expansion.

 

Since the 1970s most heat exchanger cores on the engines we deal with on here tend to be inside the exhaust manifold water jacker although tank cooled boats do not need the core. It is/was simpler to keep the manifold with or without the core and use that as the expansion/header tank just like they do on heat exchanger boats.

 

No, I do not think its a manifold problem because if it was you would have probably filled a cylinder with coolant and bent a connecting rod. On what I have read I suspect the head gasket.

[ROBDEN]

Thanks everyone for your time and input.

 

Unfortunately is does look like it's the head gasket.

 

I'm out in the sticks at the moment so I'll have to work my way back to civilisation where I can get transport, deliveries, etc.

 

Rob....

[Black Country Lee]

Thanks everyone for your time and input.

 

Unfortunately is does look like it's the head gasket.

 

I'm out in the sticks at the moment so I'll have to work my way back to civilisation where I can get transport, deliveries, etc.

 

Rob....

 

If you're anywhere near me (Dudley No.2 Coombeswood Arm (the old way to Lapal Tunnel)) I've a full tool box, a few chilled beers and enthusiusm

[ROBDEN]

 

If you're anywhere near me (Dudley No.2 Coombeswood Arm (the old way to Lapal Tunnel)) I've a full tool box, a few chilled beers and enthusiusm

 

Oh thanks very much but no I'm in the middle of the Shroppie.

 

I have a friend not too far away annnnnd he has a car.

 

But many thanks anyway.

 

 

Rob....

[Black Country Lee]

Damn, foiled by a horseless carriage lol

 

Lee.