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sailak 06-25-2010 01:43 PM

Oil in Heat Exchanger

Something tells me this isn't a good thing. <G>

Yanmar 3GM30F, 1752 hrs, starts easily, runs fine, exhaust not smoky. I have noticed a bit of oily residue on water at exhaust after starting.

After our last outing I checked the coolant level and noticed it about 1 inch lower than normal, stuck my finger in with the above result. Mechanic is thinking head gasket or cracked head...gasket on order from Japan with 2 week delivery.

Anyone have a good source for Yanmar engine parts so I can possibly get parts quicker? (It's June....sailing season...arrrgh!!)

If it's a cracked head he's saying I'll have to repower since replacement heads are not available. Any ideas for who/where to buy a Yanmar?

I will get an oil analysis done ASAP to check for water in the oil. IF no water in oil AND it's a cracked head I plan on running it for remainder of season....will keep an eye on coolant levels.

Anyone have a 3GM30F in the shed that was only used to take granny to church on Sundays?

RichH 06-25-2010 02:07 PM

Those symptoms do strongly indicate a cracked head.

Check around with your local automotive 'speed shops' and 'auto mechanic shops' who specialize in racing. There are entities that can repair cracked heads and other cast iron components ...but this is a difficult and exacting process that takes lots of experience and expertise and wont be 'cheap'. These local folks may be able to 'steer' you to such a source.

DwayneSpeer 06-25-2010 02:31 PM

Not good obviously. However, if you do decide to repower I will again recommend Beta. I changed out my engine 4 years ago and couldn't be happier. You probably already know but they are Kubota diesels that are refitted for boats and the folks there are a real pleasure to work with.

Capnblu 06-25-2010 03:44 PM

So the oil, which is not in a pressure situation, within the engine (other than when it passes through the galleries to the bearings etc.) is getting into the heat exchanger by what means through a head gasket, or cracked head? and the coolant which when at working temperature would create a pressure in the freshwater side of your system, isn't putting coolant into the crankcase? Sorry, I don't buy it.... My bet will be on what your mechanic finds when he thinks this through. Get him to show you how, before you sign the cheque. Of course my usual advice is to do a wet and dry compression test, and AFTER you have those results, go for the oil analysis. Good luck.

hellosailor 06-25-2010 07:11 PM

Classic symptom of a cracked head or blown headgasket, but since there is an inch of coolant missing, that means the engine has been sucking in coolant as well as blowing out oil into the cooling system.

There may be water, or at least excess moisture, in the cylinders now--and if so it will be rusting the cylinder rings into the cylinder walls.

I wouldn't wait for the new head gasket, I'd pull the head NOW since it has to be done in any case. Examine the head and gasket for damage, and if it looks like just a gasket problem, make sure the water is out of the cylinders NOW and avoid problems with rust and corrosion that may occur after 2-3 more weeks of waiting.

Cracked heads can often be welded, or replacements located from a breaker or a secondhand source (i.e. Sailorman in fort Lauderdale), so repowering may not be necessary if you spend some time on the phone looking for alternative solutions.

It would be unusual to find an engine that could put oil in the coolant (and suck coolant out) that didn't have a head/gasket problem. You'd need to look for any failure points between the lube/cooling systems, most engines just don't "cross" them over at ny other point, although I'm sure some have ways to make that happen.

Rockter 06-25-2010 08:40 PM

I am surprised that the cylinder head is "not available".

The motor is not that old, surely?

mitchbrown 06-25-2010 09:09 PM

Im with capnblu on this one, the coolant is under pressure and so the only way oil could enter the water is if its coming from an area of the engine where there is oil pressure or when the engine cools maybe a tiny bit of oil could be sucked in from a non pressure area but I wouldn't tear the engine apart just yet. The engine is running okay so compression test and oil analisys is appropriate and i would flush the cooling system and refill and then monitor for awhile


TQA 06-25-2010 09:18 PM

Any chance there is an OIL COOLER built in to the heat exchanger?

If so it could be leaking small amounts into the coolant without affecting anything else. Engine oil pressure is higher than coolant pressure.

In which case you need a new heat exchanger.

Capnblu 06-25-2010 09:33 PM

"Engine oil pressure is higher than coolant pressure. "

Only in the passageways to the bearings and lifters if so equipped. Not in the head.

I also suspect an oil cooler as the culprit.....
I am always amazed at how many people want to pull the head off their engine, without a compression test.

TQA 06-25-2010 10:05 PM

Most oil coolers run at engine oil pressure as they are located between the oil pump and the main oil gallery either before or after the filter.

There are exceptions but that is the usual set up.

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