Learning the HARD way...
Join Date: Jan 2007
Location: Boston / Ft Myers Area
Thanked 142 Times in 139 Posts
Rep Power: 10
I have to weigh in on this... If it was my money, I would walk away, unless the seller were to spring for a COMPLETE engine rebuild. The fact that you had to ask about the water in the oil shows that there is smoke here, and it's not just comming from the engine... How did the current owner suddenly forget to preheat the glow plugs after 800+ hours?
While the heat exchanger may have needed to be changed, it alone is not the cause of water in the oil. The lubrication and cooling systems are supposed to be seperate. Actually there are TWO cooling systems in most modern diesels; raw water and fresh water. The heat exchanger is where the raw water and fresh water cooling systems meet. Heat is drawn off the engine into the fresh water system, and it passes through the heat exchanger to, you guessed it, exchange it with the raw water system. The now cooled fresh water is returned to the engine to be heated again, and start the cycle all over. The raw water system runs this now warm water into the exhaust elbow, which cools the hot exhaust gasses, and then falls into the water-lift muffler. As exhaust continues to enter the muffler it blows bubbles of water, and exhaust out the transom exhaust pipe.
Hydrolocking can occour if the engine is cranked over too long (like +1min.) without the engine starting. What happens is that the waterlift muffler gets full of water, which then backs up the exhaust to where it can enter a cylinder when the exhaust valve opens. When this happens, because water does not compress, water is forced to take the path of least resistance, and the engine experiences tremendous wear. The path of least resistance can be bypassing the rings (doubtful), pushing out the head gasket, or cracking the block. Any of these would inject coolant water into the engine oil. All of these are expensive to fix. In addition there is a tremendous strain on the connecting rod, the bearings, even the crankshaft, which may manifest themselves over time in drastically shortened engine life.
It seems more likely that this engine has had an overheating problem that resulted in a warped (possibly cracked) engine block. The replacement of the heat exchanger treated the first problem, but not before the second problem manifested itself. I would be very curious about the status of the fresh water system. Is there any oil mixed in there (this would appear milky, or foamy)? If so, you have a leak between the fresh water system and not the raw water system. You could do a compression test on each cylinder, which would help localize the problem... but why?
Walk away, or get a complete engine rebuild at the seller's expense.
Last edited by eherlihy; 08-22-2007 at 01:37 PM.
Reason: Confused author: Raw water .NE. Coolant