W201 2.0d oil pump replacement - PeachParts Mercedes-Benz Forum

vandeo · #1 11-30-2017, 08:05 AM

I bought new oil pump form my 190D 2.0, and whaat lies ahead is replacement of the pump. Did anyone did this and is there some instruction? What to do first, What to replace also while replacing pump etc.
Thanks a lot!

sixto · #2 11-30-2017, 10:28 AM

You should have asked the question first. There are few pleasant shortcuts to removing the engine to replace the oil pump. With the engine out or at least clear of the crossmember, remove the oil pan, unbolt the oil pump from its attachments and the drive sprocket, replace.

It would be nice to replace the oil pump chain and tensioner but that requires removing the front cover. Consider a new main timing chain tensioner guide rail if you go that far.

Sixto
98 E320s sedan and wagon

vandeo · #3 11-30-2017, 12:19 PM

Does this mean that I need to remove the engine? I thought that i could just remove the oil pan?

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sixto · #4 11-30-2017, 12:49 PM

The oil pan has to clear the fixed crossmember that goes under the oil pan. It should be possible to raise rather than remove the engine but still a lot of things have to be disconnected and the engine has to be secure while you’re working on it from below. With a short engine like the 601 it might be sufficient to put ~6” blocks in place of the engine mounts. Probably have to disconnect exhaust pipe and front flex disc, fuel and radiator hoses, ...

Sixto
98 E320s sedan and wagon

vandeo · #5 11-30-2017, 01:35 PM

Thank you. I will try soon

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ah-kay · #6 11-30-2017, 05:48 PM

BTDT. It is a short engine so the oil pump is in the way if you want to remove the oil pan. Basically, you need to lift the engine with a hoist. Drop the pan, remove the oil pump, fish the pump out with the oil pan hanging. Put new one in, bolt it all up. Replace pan gasket then bolt up the oil pan. Fill up oil pump with Vaseline before installing to help oil pick up. It's above average DIY job.

Btw: Why you suspect oil pump is faulty? They don't go wrong often.

vandeo · #7 12-01-2017, 02:49 AM

Well, engine has almost 400000km on it. Oil pressure is droping a bit below 1 on summer hot days (on idle). I changed the oil pressure sender but all things indicate that engine is slowly giving up. Since I'm not yet ready for rebulding engine and I found new oil pump on ebay for 25€ I thought to give it a try. I once read somewhere that oil pump should be changed on 350000km on 601 engine....
Why vaseline? Where to fill it up? Through suction part screen?
Oh, I do a diagnostic computer maintenance to a friend who owns a mechanic workshop so in return, he alows me to use one of his auto cranes and tools, and helps me if I need a hand, but I try to do it all by my self, and not to bother him or his employes much, and I like to do maintenance of my mercedes, so I don't mind a bit harder DIY job as long it is doable.

ah-kay · #8 12-01-2017, 02:37 PM

All oil pump are gear pump and they last a long time. I wouldn't suspect problem with oil pump but who knows. Basically you need to prime the pump with Vaseline to pick up the oil as gear pump does not self prime well and you need oil! Open up the pump and fill it with Vaseline, to help it self prime.

Diseasel300 · #9 12-01-2017, 03:09 PM

I wouldn't be suspecting the oil pump unless it's been fed a steady diet of sand and engine shrapnel. As said above, they're gear pumps and last a very long time, typically the service life of the engine.

Make sure you're using the correct weight of engine oil. Original spec was 15W-40, if you're using 30 weight oil, you can expect the oil pressure to be low.

Normal hot idle oil pressure on the OM60x engines is ~1bar. Depending on the sensor and the electrical integrity of your vehicle, the gauge may not reflect that properly. Does the oil pressure build quickly when the engine is revved? You should have the gauge pegged by 2K RPM. If it does, the oil pump is fine.

mbolton1990 · #10 12-01-2017, 04:39 PM

Yea, highly doubtful the pump is indeed bad.
I've never seen one fail, not like it couldn't happen but extremely rare..

sixto · #11 12-01-2017, 04:44 PM

The only 60x oil pump failure I heard of was the seizing from vacuum pump bearing debris years after vacuum pump failure. The symptom was instant engine seizure, not low oil pressure

Sixto
98 E320s sedan and wagon

ah-kay · #12 12-01-2017, 04:47 PM

Quote:

Originally Posted by Diseasel300

Make sure you're using the correct weight of engine oil. Original spec was 15W-40, if you're using 30 weight oil, you can expect the oil pressure to be low.

.

Oil spec has nothing to do with pressure. Liquid is uncompressible so even water would give the same pressure.

Diseasel300 · #13 12-01-2017, 09:37 PM

Quote:

Originally Posted by ah-kay

Oil spec has nothing to do with pressure. Liquid is uncompressible so even water would give the same pressure.

It has nothing to do with the compression, it has to do with viscosity. Thinner oil slings out of the bearings, journals, and any "wear" areas in the engine, higher leakage rate results in lowered system pressure. The oil weight corresponds to a given viscosity, shear rate, and film thickness. Thinner oil in a worn engine will result in lowered oil pressure compared to a higher viscosity. It isn't a huge amount, but it does produce a change in the overall system pressure.

sixto · #14 12-01-2017, 09:41 PM

Oil pressure changes with temperature which suggests viscosity is a variable. Or is it the oil pump that tightens and loosens with temperature? Likely both but I imagine viscosity change with temperature plays a bigger role.

Sixto
98 E330s sedan and wagon

Diseasel300 · #15 12-01-2017, 09:58 PM

Quote:

Originally Posted by sixto

Oil pressure changes with temperature which suggests viscosity is a variable. Or is it the oil pump that tightens and loosens with temperature? Likely both but I imagine viscosity change with temperature plays a bigger role.

Sixto
98 E330s sedan and wagon

Oil viscosity changes (oil thins as it heats) as do the tolerances in the engine. It's not uncommon for an old worn out tired engine to have horrible idling oil pressure simply due to wear. The more worn the bearings and journals are, the more oil leaks out and the lower the system pressure.

The oil pump is a fixed displacement. At a given RPM, it moves a fixed volume of fluid. The pressure in the system is regulated by a valve to prevent overpressure, and anything below that is a function of leakage for the volume of oil moved. More leakage per unit volume = lower system pressure.