|Topic Review (Newest First)|
|08-22-2007 02:45 AM|
Hydrolock generally speaking will only blow a head gasket between the cylinder and the water jacket and will not always maifest itself in water/oil mixing. Also this would, even if it doesn't result in serious internal damage (bent conrods, cracked pistons), always result in a noticeable misfiire because such a blown gasket will reduce compression which is essential to ignition on a diesel engine.
More likely is a serious overheat which causes a little distortion in the head/block joint and create a leak between the water jacket and an oil gallery. This will not cause any other signs of failure than the creamy oil and will not result in a misfire unless it goes to a cylinder.
The second situation is way more sinister because an oil flush/change could mask the condition (for a while) with no other symptoms evident.
Hope this helps.
|08-21-2007 11:30 AM|
Water in the lube oil is more likely the result of a blown headgasket which can be caused by filling the cylinders with water as described above, but a blown headgasket can also be caused by overheating the engine. If the engine really was hydrolocked, there is likely to be damage to the valves, injectors, main crank and bearings, and perhaps pistons and connecting rods, and maybe the starter motor and flywheel. In other words the engine would not appear to run normally.
The heat exchanger is probably a separate issue. I can't see how the heat exchanger would allow water into the crankcase unless that model also has an oil cooler.
I would agree with the suggestion that you plan on walking away from this particular boat, or else come to an agreement that reduces the price of the boat by the cost of a new engine in place. I say in place because pulling an engine out of a boat and then installing and realigning an engine is a pretty big line item.
|08-21-2007 11:15 AM|
|eherlihy||Finally (and I promise to shut up after this), a "new engine with all the trimmings may be ~15K, but the installation will add to that. The guy that runs my sailing club has told me that he spends about ~$12K on a complete *rebuild* for his fleet of 30-40 foot boats.|
|08-21-2007 11:10 AM|
Oh yeah, pulling the valve covers should NOT show if there is any damage related to this problem, but it will cost (somebody) money.
Also changing the oil, while usually a good thing, could, in this case, mask the problem.
|08-21-2007 10:50 AM|
Given that you are still inclined to go aheard with this boat and you and the seller compromise on a selling price based upon currently known damage, I'd suggest you consider two options, the first being the riskier of the two:
1. Stipulate in the contract that the seller be responsible for an agreed-upon amount of repair costs beyond that which you and the seller agree to for the actual selling price, or
2. Escrow a portion of the agreed selling price pending a reasonable trial period during which you can be assurred the engine damage is known.
The latter option would minimize you litigation risk
|08-21-2007 10:49 AM|
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.
|08-21-2007 10:04 AM|
I am the C400 Tech editor. I will PM you.
|08-21-2007 09:02 AM|
Moisture detected in the core may or may not be a serious issue. It is an issue that needs to be addressed, in that the incursion at least needs to be stopped. If there was too much moisture for too long, rot will begin and then more serious repairs may become necessary. It sounds like you have at least one such spot on the boat you're considering. Our boat had no soft spots, but the entire aft 1/3 of the cockpit sole had very high moisture readings. High enough that the surveyor was confident that, tho it wasn't soft now, it certainly would be before too much longer. So, before we repaint the decks, we'll be having that torn up, re-cored and re-glassed.
To me, the bigger issue is the engine. Water in the oil is a Very Bad Thing. I suspect a blown head gasket. You need a thorough engine inspection by a qualified marine mechanic, to include engine oil analysis and compression test.
|08-21-2007 01:57 AM|
The info on the water in oil siuation seems a little vague. I don't know of any situation where a compromised heat exchanger will put water
in the oil unless there is a specific heat exchanger to cool the oil (unlikely). This sounds like a head gasket blown beteen an oil gallery and the cooling system.
Walk away? Well, maybe you can discuss a price reduction that sees an economical repowering of the boat remembering that there will be an element of betterment that you shouldn't be too reluctant to participate in financially. If there is a partial contribution from your side, evaluate the benefit of having a new engine.
If there is no contribution from the seller or if this is not the only serious defect then I agree with several other posts - walk away.
|08-21-2007 01:31 AM|
Get an estimate on the deck repair.
Price out a new engine.
Compare the boat's price to others for sale.
Consider what "the rest of the survey" may show.
If your price point is tight and you buy this particular boat, how do you plan to deal with the fact that you may not be sailing until you raise the money to get this boat fixed? Not that this boat will be just sitting not costing you money in the meantime.
I am no expert, but I generally consider 1000 hours about the time that you will have to start putting money into a diesel engine, in $2-300 chunks. Alts, pumps, etc.. start to show wear.
I would be approaching this boat as an immediate canidate for plan B, and that ain't the sailin' plan. Plan A includes the engine ok, the deck is fixed for less than 2 grand, nothing else is seriously wrong, and you got an accurate survey. If you can deal with Plan B-buying a motor, fixing the deck correctly, waiting to sail for a year or so, and anything else that comes to light-I might buy the boat. If you are counting on Plan A, don't buy it.
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