Head gasket?

[Brookelise]

Our Ericson 34, with a 23 hp fresh-water cooled Universal M25XP diesel, has a problem that the mechanic said (over the phone) is probably a blown head gasket.

We have a coolant header tank and an overflow tank added above the hot water heater to prevent air lock; the pressure cap on the heat exchanger is normally kept shut and coolant is accessed only at the overflow tank. Lately, we've noticed that the coolant in the overflow tank has been rising to the top and sometimes overflowing, both while running the engine and when the engine is turned off. The level does not sink to the previous level, and when we check the coolant in the manifold, it is low or nearly empty; at one point when it was empty, the engine began overheating. In other words, the coolant apparently is leaving the manifold, rising up to the overflow tank and not returning.

We are also getting white smoke when starting the engine and sometimes when running it -- something that's never happened before. Finally, we have noticed that the engine, which has never burned oil, is starting to use it up. We have been told that these could be symptoms of a blown head gasket.

The odd thing is that these problems only started after the mechanic replaced the propeller shaft and dripless shaft seal. The new seal required a new connection from the raw-water hose exiting the heat exchanger, so he cut into that hose. This work couldn't be connected to the new problems, because it was all in the raw-water system, and the coolant problem we have is in the fresh-water, sealed system.

 

[Shadowfax]

Blown Head Gasket

The quick way to see if you have a blown head gasket to look at the oil and the coolant. If the oil has coolant in it, it will sort of look like a chocolate milkshake not the usual black to brown color. If oil is entering the coolant system the coolant will have oil on the surface and be cloudy. Both conditions will be obvious. If neither condition exist and you still think you have a blown gasket, and then have a compression test on each cylinder done. This is the most positive test.

Though steam out the exhaust, overheating and loss of power are signs of a blown gasket, your problem may be that the expansion tank [reservoir] hose may have a problem and not be feeding coolant back into the system, or your thermostat may be not opening causing the engine to overheat. After the engine has cooled open the twist cap and add coolant directly into the system and see if that cures your problem. Next replace the thermostat.

Just make sure that you don’t have a simple overheating problem before getting your head gasket replaced.

Good Luck

 

[rwthomas1]

Paul pretty much covered it all quite well. I would also add that having an oil analysis performed is a much better way to check if there is coolant in the oil if the oil shows no visible signs. Check out www.blackstone-labs.com or google "oil analysis" Generally if you see oil that looks like a muddy milkshake the bearings are already dead and you need to rebuild. I hope you are feeling lucky... RT

 

[Brookelise]

Head gasket

Thanks, Paul and Rob,

We did replace the thermostat, and we also checked for any blockages or loose connections in the coolant hoses. We found one loose clamp at the header tank and tightened it. We bled the coolant system, too, releasing some air.

We started the engine and went out for about 20 minutes, and things seemed to be running fine. However, when we were back at the mooring and restarted the engine, there was a lot of white smoke this time and the coolant started to rise to the top of the overflow (expansion) tank again. Also the coolant was emptying out of the manifold again, and not returning, evidently because of air in the coolant system. Something was reducing the pressure in the coolant system -- air from somewhere (maybe a blown head gasket?). Anyway, the mechanic is doing some tests at the end of the week. He hasn't looked at the problem yet.

As for cloudy coolant and milky oil, it's hard to tell at this point. The oil seemed to appear OK. We didn't see any water in it. The coolant might be slightly cloudy, but we're not sure.

 

[footrope]

Head gaskets can fail in ways that will not cause coolant to get into the oil. Had this happen to me on an automobile engine. Plenty of white steam on morning startup, but not much of anything else except a steady drop in coolant level in the radiator. From everything you've reported, and the rest of the opinion in this thread, it sure sounds like a head gasket. Hope it isn't too expensive.