Volvo MD17C blew a rod? - Page 2 - SailNet Community
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post #11 of 22 Old 01-02-2011
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The mechanic will receive less than half the $85/hour because of shop overhead and usually the $85/hour does not bring in a profit for the shop owner. The owner makes the profit from the difference between the wholesale cost of parts and the retail cost that they charge the customer. Have the mechanic check for compression in the cylinder. If nothing, then pull the cylinder head. It's not much labor and you will have some idea of what you are going to have to do. You cannot make a final decision until you know how much cylinder and bearing wear there is plus the cost of parts and labor. The machanic can put a micrometer on the cylinder bore where the head is removed to determine the need for new oversize pistons and/or new sleaves, but bearings and engine cracks have to be determined with a complete tear down.
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post #12 of 22 Old 01-02-2011
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I think it's more likely that you had ring failure followed by excessive crankcase pressure and poor combustion which caused the oil to puke out and the motor to slow down and stop. A good thing about the MD17 is that you can pull individual cylinders. I don't recall however if there are access panels through the side of the block to get at the connecting rods if it's necessary to pull the pistons without removing the engine.

If it were me and the damage was limited to the top end, I would probably patch it up and keep running it. If a connecting rod went out, I would probably replace the motor.

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post #13 of 22 Old 01-02-2011 Thread Starter
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I do have a torque wrench. Your idea is a good one. I did provide a lot of information. If I had any more info, I would not have had to ask. Thanks
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post #14 of 22 Old 01-02-2011 Thread Starter
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There was no bang, the engine rpm went down and it stopped. In the last hour I have taken off the valve cover for pectin # 3 and there was emulsified oil (ie water in the cover area). Under number 2 valve cover no water or emulsion.

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post #15 of 22 Old 01-02-2011
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Are you low on coolant now? Sounds like a head gasket blew.

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post #16 of 22 Old 01-02-2011
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Emulsion

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In the last hour I have taken off the valve cover for pectin # 3 and there was emulsified oil (ie water in the cover area). Under number 2 valve cover no water or emulsion.
Maybe no condensation on the #2 valve cover is because of the crankcase ventilation connection location. Let us know what you find that caused the engine to quit as it really is hard to diagnose a problem, especially when not actually being present.
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post #17 of 22 Old 01-02-2011
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Turn the engine so that the rocker arms stop moving that happens on the compression stroke and occurs for a full revolution. Now, If the valve head has broken off from the stem inside the engine, then if you loosen the rocker adjustment for valve lash, and if no gap appears between rocker arm where it moves against the top of the valve stem (the area just above the top of the valve spring) then we know the engine has "swallowed a valve" and will probably need to be pulled as there will probably be a hole in the piston where the valve went through it. Since there are hydraulic valve lifters, you will have to back of the adjustment several turns, but if no gap appears, well that tells there is this major problem. If you see a broken valve spring with a big gap already there, you also have the same major problem, a broken head, or piston or both.
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post #18 of 22 Old 01-03-2011
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No Bang

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There was no bang, the engine rpm went down and it stopped.
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In that case, I wonder if it is water in the fuel
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post #19 of 22 Old 01-03-2011 Thread Starter
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Racor water separator should preclude that.

Update: all three jugs are out and # 3 sleeve has been pressed out has been sent for magna flux, but no obvious crack. No obvious gasket or ring seal leak. Next measuring rings ... keep those ideas coming, if you are familiar with the hardware at this level.

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Keith
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post #20 of 22 Old 01-04-2011
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Trouble Shooting

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Have the mechanic check for compression in the cylinder. If nothing, then pull the cylinder head. It's not much labor and you will have some idea of what you are going to have to do. You cannot make a final decision until you know how much cylinder and bearing wear there is plus the cost of parts and labor. The mechanic can put a micrometer on the cylinder bore where the head is removed to determine the need for new oversize pistons and/or new sleeves.
Not sure if the compression check was done before the disassembly as the disassembly may not have been needed and the compression check would have ruled out catastrophic failure. On the other hand you never know what will be found on a disassembly, maybe something major unrelated to the engine quitting might be found. At this point the mechanic should check for cylinder wear. Wear takes place at the top of the cylinder because this is where all the heat and pressure is when diesel is injected at the beginning of the power cycle. If less than five or six thousandths of an inch, then wear on the piston ring groves on the piston should not be excessive and all that is needed is cleaning carbon out of the groves. If there is wear, then the piston grove can be cut a little wider and a spacer inserted alongside the new piston rings. This is probably what the mechanic meant when he said he would measure the rings. You must have new rings as the old ones will not seat. The cylinder wear can be as much as ten or twelve thousandths, and an overhaul done without new oversize pistons and/or new liners, but unless you are not going to run the engine many more hours, I would go with new pistons and/or liners at five or six thousandths cylinder wear. If there is some wear at the top of the cylinder, there will be a ridge above where the rings run in the cylinder. This will have to be cut out with a ridge reamer as the new rings will hit the ridge and damage them. Diesel engines have much less cylinder wear than gasoline engines because the diesel is a light oil and lubricates the cylinder walls while the engine runs. Another thing that should be done is a valve job as these will wear out twice as fast as the cylinder walls so that a valve job will be needed half way through the life of the engine. If a diesel becomes hard starting over time, it is most likely valves. Do you have any idea how many hours are on the engine? Why did the engine quit? We still do not know why.
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