Car is 1991 350SDL with 159K miles. My MB dealer is dropping my oil pan to inspect the oil pump due to a low oil pressure condition. Their head diesel tech says he has often found the mounting bolts loose on these oil pumps and has found baffles in the oil pan that have fallen off and obstructing the oil pump pick-up.

I have a new MB oil pump that I paid $173 for and a new oil pump chain, guide and tensioner spring, would you have them install these parts or rely on the old parts if they look OK. They also told me they would install new rod and main bearings for $7-800 while they had the pan off if that was indicated or I wanted them too. Would it be a good idea to have the bearings installed? Is there a reliable way for them to diagnose the condition of the bearings?

Thank you.

350SDL's have problems with RODS BENDING. Has your engine ever been rebuilt or replaced by the dealer? Its a design defect. New rods were made that are stronger. The problem occurs over time and by the times its caught its often a case of ovalled cylinders. I would strongly advise you to research this issue in more detail (more details on the list) and check to see if this engine has had such a repair. If not, I suggest replacing ALL the rods while the oil pan is out.

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Brian Toscano

Hi Brian,

I am aware of all the problems with the 603.970 engines. Apparently most of the failed engines were prior to 100K miles and those that have made it past that seem to do well. I don't have any rod knocking or other bottom end noise at this time. So I am for the time being proceeding along the path of the original questions I started in this thread.

I am the original owner of this car and it has been a terrific one prior to the current low oil pressure situation.

Thank you for your input.

EZ,

$700 to $800 for replacing the engine bearings is an absolute rip off. Once the oil pan is off and oil pump out, its just R&R 26 bolts on the rods and main bearing caps and the bearings. Shouldn't take more than an hour. Bearings ahouldn't be more than $100. You might consider replacing the rod bolts because they are stretch bolts and for the extra cost, its low price insurance.

Bearings can usually visually inspected to see if thay have been damaged but a reliable way to check the bearings is to measure the clearance with plasitgage and measure the crankshaft rod journals. But this is equivalent to replacing the bearings so will they want $700 for this job too?

P E H