Yanmar losing coolant
- Thread starter Tim R.
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Except the head gasket should have no passages for the intake. Air goes in the side of the head from the intake manifold directly to the intake valve. In fact, the only way coolant should be able to get into the intake would be if there is a crack in the head which could be the culprit.
Although, some automotive engine do have a coolant passage in the intake manifold for preheating, this engine does not.
Thanks for all your thoughts Rich. They have certainly gotten me thinking about other causes.
Doesn't the head have coolant passages, intake passages, and exhaust passages? Every liquid cooled engine I have seen has this configuration.
I wasn't thinking about coolant passages in the intake manifold, only in the head itself.
I wasn't thinking about coolant passages in the intake manifold, only in the head itself.
Yes it does and a leak there would indicate a cracked head. but there are no passages for intake through the head gasket. Therefore, coolant could not be getting to the low pressure intake from a failed head gasket.
The only passages through a head gasket on this engine(and most others) are for coolant, oil, push rods, head bolts and the cylinder itself.
Keep the ideas coming.
Rich, I do not need you yelling that my diagnoses is not certain. That is exactly the reason why I used the word "could" in the descriptions. Please read more carefully next time before breaking out the caps and bold. And be sure you understand the design of the system.
If the AF is leaking into the raw water via the HE, AF gets to the exhaust via injection in the riser.
The HE on this engine is integrated into the exhaust manifold. Water in the cylinder could be from the exhaust manifold. A leak from the HE housing/exhaust manifold could allow water to back fill any cylinder via open exhaust valve.
My troubleshooting(my profession for 20+ years now) skills always start with the simplest solution first. The HE was the easiest part to check and verify and for the record the serviceman at Mack Boring agreed to start with this.
If the AF is leaking into the raw water via the HE, AF gets to the exhaust via injection in the riser.
The HE on this engine is integrated into the exhaust manifold. Water in the cylinder could be from the exhaust manifold. A leak from the HE housing/exhaust manifold could allow water to back fill any cylinder via open exhaust valve.
My troubleshooting(my profession for 20+ years now) skills always start with the simplest solution first. The HE was the easiest part to check and verify and for the record the serviceman at Mack Boring agreed to start with this.
Tim, I didnt shout, I was just too damn lazy to split your discussion into equal parts and simply what I 'thought' by increasing the font size would give a better 'read'. Sorry, If my explanation offended you, just ignore my response. I'll delete it.
Removed the exhaust riser and manifold. The manifold looks fine but the exhaust port on cylinder #4 shows moisture in it. All the rest appear dry. I then removed the intake manifold and the head. No obvious breaks in the head gasket. I will take the head to a machine shop to get magnifluxed and ensure the mating surface is true.
Taking a break from the engine now. Enjoying some beers lakeside.
Taking a break from the engine now. Enjoying some beers lakeside.
Tim,
Coolant leaking into a cylinder will vaporize by the high heat and should show up as smoky exhaust. Did you notice any change in the exhaust like white smoke or something? A real shame if the head is cracked. I guess at that point it becomes a decision to replace the head or the whole motor. 2000 hours suggests the rest of it should still have a lot of good life.
Coolant leaking into a cylinder will vaporize by the high heat and should show up as smoky exhaust. Did you notice any change in the exhaust like white smoke or something? A real shame if the head is cracked. I guess at that point it becomes a decision to replace the head or the whole motor. 2000 hours suggests the rest of it should still have a lot of good life.
Just a couple of things to look for if the head gasket blew.
The coolant leaking in and the pressurized gasses not leaking out can happen. I know that does not make sense but I have seen it happen. Seen it happen the other way and also a two way flow.
If coolant is making it to the combustion chamber it is VERY easy to tell. Seems that the steam produced does an excellent job at cleaning the cylinder head and piston on the leaking cylinder. They will be spotless. The exhaust port for that cylinder will also be less dirty than the others. It will not be spotless though.
64 oz per hour would not show up as a white cloud in the exhaust. It takes a VERY big leak to make a antifreeze cloud in a water cooled exhaust system. The water absorbs/condenses/washes out the anti smoke before it can leave the tail pipe. Cars are a little different.
Leaks into the intake manifold in diesels are accompanied by hard starting ALWAYS so I'm thinking intake mani and head ports are ok (yes there are no coolant passages in the intake but there are in the head.
Leaks into the exhaust CAN/MAY be accompanied by hard starting but not always. Unfortunately you can't pressurize a raw water cooled engine with the exhaust mani off to check it.
Since she runs good, starts good, and just leaks anti I'm thinking a bad head gasket given the HE checked out.
The coolant leaking in and the pressurized gasses not leaking out can happen. I know that does not make sense but I have seen it happen. Seen it happen the other way and also a two way flow.
If coolant is making it to the combustion chamber it is VERY easy to tell. Seems that the steam produced does an excellent job at cleaning the cylinder head and piston on the leaking cylinder. They will be spotless. The exhaust port for that cylinder will also be less dirty than the others. It will not be spotless though.
64 oz per hour would not show up as a white cloud in the exhaust. It takes a VERY big leak to make a antifreeze cloud in a water cooled exhaust system. The water absorbs/condenses/washes out the anti smoke before it can leave the tail pipe. Cars are a little different.
Leaks into the intake manifold in diesels are accompanied by hard starting ALWAYS so I'm thinking intake mani and head ports are ok (yes there are no coolant passages in the intake but there are in the head.
Leaks into the exhaust CAN/MAY be accompanied by hard starting but not always. Unfortunately you can't pressurize a raw water cooled engine with the exhaust mani off to check it.
Since she runs good, starts good, and just leaks anti I'm thinking a bad head gasket given the HE checked out.
Finally found time to properly test the heat exchanger housing/exhaust manifold. I sealed up the fresh water side and filled. Pressurized and then I heard it. Leakage. I turned it over and found a steady stream of water coming from just inside the area where the exhaust riser bolts on. There is a fresh water jacket to aid in pre-cooling the exhaust gases.
The only similar issue I found on the internet that somewhat matched my symptoms had the exact same failure.
Guess I will be ordering a new HE/exhaust manifold tomorrow. That is gonna hurt!
The only similar issue I found on the internet that somewhat matched my symptoms had the exact same failure.
Guess I will be ordering a new HE/exhaust manifold tomorrow. That is gonna hurt!
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Glad you found it..
Tim, since that part does not see compression/combustion stresses, ya might consider talking to a good welder about repair of that pinhole.. Probably a casting defect but no good way of knowing if that is the only place in the casting where it was too thin or had inclusions.(also the brand new one may have defects). But .. worth a talk to a good shop .. they can sand/bead blast to better see the defect and ya may save a lot of dollars.. again.. this only sees low water pressure and some thermal transients.. but not very high temperatures.. Just something to consider..
have it bead blasted and cleaned as Kloudie suggested...then have a good tig welder weld it up with silacon bronze rod...we used to do this to the cylender heads back in the early 70's on the XR750 engines to reduce the dome in order to balance out the intake flow...it held up great and in your case not being a high compression problem it will do fine..and a hell of a lot cheaper than a new part.....just my thoughts.....use um or not ....
regards
woody
regards
woody
Yup.. too thin .. that is probably why it holed through.. a problem with the mold moving or something when it was poured, and then the wall for the water jacket gets offset and thin.. too bad, Tim.. but the thing is ya found it and it will be (or should be) less than a new head..
- Dec 30, 2009
- 680
Tim, the heat ex looks exactly like a miniature water tube steam boiler. That is what u see when you swing open the 2 ends of a 500 hp steam water tube boiler. Only it works the opposite, flames heat the water.When the service is done in the spring they look for leaking tubes.One of the ways they deal with a leaking tube is to plug it. I believe they have a # they factor b-4 they will no longer get proper heat exchange in relation to the # of plugged tubes. Can u weld or solder the bad tube on each end? Just a guess ...... Red
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