Could one quart low do this? (long) - PeachParts Mercedes-Benz Forum

Terry240d · #1 12-24-2005, 03:59 PM

First of all, Merry Christmas or Happy Hanukkah to all here, and thanks for any thoughts on this...
A search of the symptoms I experienced yielded good info, but the symptoms are gone, and I want to know your suggestions for next steps.

1982 240d, 273k.

I have a slow oil leak (golf ball size puddle nightly) and I usually add about a half quart overy 10 days or so. That's about 600 miles of driving for me. The car has started well in any conditions, and has ran well. There is a good amount of blowby, enough to make the cap dance lively.

Anyway, after getting the car back from body work that took two weeks, I noticed lower oil pressure while driving- a bit over 2 on the gauge. At idle (I pulled into a gas station) it was lower, and I heard increased clatter. I turned up the idle adjust, and the clatter went away, but the pressure wouldn't go up to 3. I checked oil, and it was just over a quart low. After putting a quart in, the car required lots of cranking time before starting.

However, after getting home, all of the above symptoms disappeared- it starts immediately again, and pressure is normal. Santa is bringing valve adjust wrenches, and I know that I need to chase the leaks down... any other thoughts?

83mercedes · #2 12-24-2005, 04:47 PM

Quote:

Originally Posted by Terry240d

After putting a quart in, the car required lots of cranking time before starting.

However, after getting home, all of the above symptoms disappeared- it starts immediately again, and pressure is normal.

So are you saying that the pressure was low on the drive home after you filled it, and then it went back to normal the next time you started it, or did it return to normal right after filling and on the drive home?

Terry240d · #3 12-24-2005, 04:50 PM

but the first few warm starts were loooong (Christmas shopping errands)!

Starts were immediate about an hour later

thanks
Tr

83mercedes · #4 12-24-2005, 04:55 PM

Given that, I'd say that the low oil was definitely the culprit for the low oil pressure.....I'm not quick to say that your starts would be so drastically affected by slightly less oil circulation, however.

For now, I'd say just keep your oil topped off, find and repair the leak, and don't worry about it unless you experience the symptoms again with normal oil level. Good luck, oil leaks are nasty...

Stevo · #5 12-24-2005, 08:41 PM

"a bit over 2 on the gauge"

Being a qt low would not cause this. There was something else going on. I bought a 240D once that had a BIG dent in the oil pan. When I pulled the oil pan the oil pump was broken off (hanging on by a thread) above the sump screen meaning it was picking up suction real high and a qt low mighta been a problem. You'd normally have to be WAY more than a qt low to affect oil pressure.

#6 12-24-2005, 09:11 PM

Quote:

Originally Posted by Stevo

"a bit over 2 on the gauge"

Being a qt low would not cause this. There was something else going on. I bought a 240D once that had a BIG dent in the oil pan. When I pulled the oil pan the oil pump was broken off (hanging on by a thread) above the sump screen meaning it was picking up suction real high and a qt low mighta been a problem. You'd normally have to be WAY more than a qt low to affect oil pressure.

I agree, I don't see how being a quart low would cause either low oil pressure or hard starting. How long since your last oil/filter change? A dirty oil filter may be more likely to cause low pressure. I have no idea about the hard starting issue, if the engine was cranking at normal speed there should be no relationship between oil level and starting.

Terry240d · #7 12-24-2005, 10:06 PM

Craig- I have changed oil & filter frequently; 2k since last change at this point.

Question, Stevo- my pan has some healthy dents- in itself, should that be replaced? Also, from the info I've given, is the oil pump your first suspect?

Stevo · #8 12-25-2005, 02:24 AM

"Question, Stevo- my pan has some healthy dents- in itself, should that be replaced? Also, from the info I've given, is the oil pump your first suspect? "

I wouldn't replace a lower pan just because it is dented, most are to some extent. The pick up for the pump is close to the bottom of the pan so if the dent was a good size one I would pull the pan and take a look. You'de have to replace the gasket, thats it. There are a couple of O rings on the oil filter stem that may cause low oil pressure, if they are bad (turned to stone) and are cheap to do. I would sure keep my eye on it and keep plenty of oil in the trunk. I think my broken off oil pump was pretty unusual but if you have a big dent it coulda happened. Swapping out the pump was an easy fix.

Terry240d · #9 12-25-2005, 10:25 AM

Quote:

Originally Posted by Stevo

There are a couple of O rings on the oil filter stem that may cause low oil pressure, if they are bad (turned to stone) and are cheap to do. I would sure keep my eye on it and keep plenty of oil in the trunk.

Will do- thanks again!

P.E.Haiges · #10 12-25-2005, 10:54 AM

Terry,

I was merrily driving my '80 300Sd last summer when suddenly the oil pressure gage started to fluctuate. I stopped immidately and checked the oil lever. It wasn't full but it was always OK at this lever before.

So I added another quart of Mobil 1 and everything seemed OK.

Recently I got a new oil pan because the original one was dented. When I took off the pan, the rubber end on the oil pump was broken off thus the oil level had to be higher than before. It looked like the dented oil pan pushed up the rubber part until it broke from being old and the rubber was not as pliable as the new part.

So maybe you want to check the rubber part on the oil pump. New part cost about $20 which is high for a simple moulded part. But I was glad it was still available for a car 25 years old.

I go for parts for my Chevy truck and have been told sorry, we don't have that part anymore because your truck is over 10 years old and we aren't required to supply parts for vehicles over 10 years old. Why don't you buy a
new one?

They can KMA if they think they will get my to buy a new vehicle from them because they won't supply parts for my older vehicle.

P E H

Terry240d · #11 12-26-2005, 09:08 PM

Will update if I find anything...

Stevo · #12 12-26-2005, 10:46 PM

Yah, It would be great to hear if you find any answers.
Sometimes MBs have been known to heal themselves