83 240D Oil Pressure Question - Page 2 - PeachParts Mercedes-Benz Forum

shertex · #16 11-19-2012, 08:53 PM

Quote:

Originally Posted by barry12345

Could be a higher than normal viscosity of oil was used or a viscosity increaser. Give him a call and ask perhaps. If not he may have some background information to add.

He used Mobil 1 0w40....so, if anything, it's less viscous than you'd want.

vstech · #17 11-20-2012, 08:21 AM

0w40 is incorrect for the 240.
did he change the oil filter?
I would dump that and put in some 5w40 rotella. the 240 really can't justify using more expensive oils. not that incorrect oil would peg the gauge, but it's bad on the motor to use that thin, lack of additive oil on a solid lifter engine.
also, I'd pull the filter and install a new one, and lower the idle. the only reason your oil pressure would be at 3 with 80C on the stat is too high an idle. unless you are in north alaska...

Air&Road · #18 11-20-2012, 08:22 AM

Quote:

Originally Posted by shertex

Yes.

What do you mean by "tight?"

Meaning the bearings are not worn. The added clearance of worn bearings is typically what causes low oil pressure.

charmalu · #19 11-20-2012, 11:16 AM

Quote:

Originally Posted by vstech

0w40 is incorrect for the 240.
did he change the oil filter?
I would dump that and put in some 5w40 rotella. the 240 really can't justify using more expensive oils. not that incorrect oil would peg the gauge, but it's bad on the motor to use that thin, lack of additive oil on a solid lifter engine.
also, I'd pull the filter and install a new one, and lower the idle. the only reason your oil pressure would be at 3 with 80C on the stat is too high an idle. unless you are in north alaska...

What did you mean by this line....

"the 240 really can't justify using more expensive oils."

Charlie

Air&Road · #20 11-20-2012, 11:41 AM

I agree with vs' line.

A 616 or 617 even in really good shape, will be sooting the oil quite quickly. You are MUCH better served to use an inexpensive diesel specific type dino oil and changing it more frequently, than putting the extra money into a synthetic oil and trying to run it longer between changes. Synthetic or not, the additives that deal with soot will be used up quickly, probably at the same rate. That is the weakest link in the chain.

barry12345 · #21 11-20-2012, 11:52 AM

Quote:

Originally Posted by charmalu

What did you mean by this line....

"the 240 really can't justify using more expensive oils."

Charlie

Guys with hundreds of years of combined experience used to wonder if wear patterns are changed if oil types are. I was present during many of the discussions years ago. Sythetics have improved since them though.

It hinges on the operational viscosities remaining the same I suppose. Viscosity provides the oil barrier between moving parts. On a diesel the pressures are more signifigant as well than gas engines.

Even as far north as we are in eastern Canada. Conventional 15-40 diesel rated oil on older diesels is the convention. Newer direct injection diesels seem to be a different kettle of fish. I have absolutly no ideal if the additional cost of synthetic would buy a longer engine lifespan. It very well might.

The strong point is synthetic does aid cold starts though and this may be signifigant on starter wear. Perhaps on engines as well. It is thought and proven that most engine wear or the rate of wear is much higher actually on cold startups. Synthetic oil is quoted as better in this regard as well. Using a block heater in colder weather is worthwhile in my opinion. Even if an engine will start without it. Simply based on reduction of wear.

shertex · #22 11-20-2012, 12:42 PM

I guess I have a hard time dumping 7 quarts of Mobil 1 0w40 that's only been in there a few hundred miles. Granted, it's not the ideal oil, but....

vstech · #23 11-20-2012, 12:48 PM

dump it and use it in your 124's... still not the right oil for those cars, but at least it's closer.

the 240 is a really heavy soot producer, and synthetics are just too expensive to waste on them. also, the 0w40 oil has ZERO wear protection for the cam/followers... ya GOTA have wear protection on the solid lifter engines. stick with rotella.
and change the filter and see if it makes a difference.

shertex · #24 11-20-2012, 01:42 PM

I don't understand the relationship between changing the filter and the pressure. If a filter were clogged, wouldn't that DECREASE pressure if anything?

Stretch · #25 11-20-2012, 01:58 PM

Quote:

Originally Posted by shertex

I don't understand the relationship between changing the filter and the pressure. If a filter were clogged, wouldn't that DECREASE pressure if anything?

Have a look at the FSM - chapter 18-005.

It shows how the oil lubrication system works. If the filter is clogged the oil should be by passed directly to the main parts of the engine to "save them".

I wouldn't be too concerned about the gauge reading - I however would not trust anyone else to have done an oil change properly. I'm sorry to be so negative but it is the first thing I always do to a new car.

Diesel911 · #26 11-20-2012, 03:14 PM

I think that you started this thread because you knew your Gaguge reading was not typical/abnormal.

Without a special Fitting and another suitable Pressure Guage there is no way to verify it the Instrument Cluster Gauge is correct of not.

Changing the Oil Filter and seeing and seeing if that effects the pressure is the easiest thing to do.

Slighly harder is to check that Valve that is in the Stem/Tube of the Oil Filter.
I don't know how to take that apart but on mine the Tube is pressed into the Cap. I was able to pull it out and shove an Air Gun into the Tube and blow Air out pasted the Valve.

I don't think this would be possible unless the Car sat a long time but the Pressure Relief Valve in the Oil Pump could be stuck.

If you don't want to remove the Tube from the Oil Filter Cap there is an about 1/16" diameter Hole at the top of the Tube for the filtered bypass Oil to pass through. It might be possible to shoot some Air pressure through that hole.

shertex · #27 11-26-2012, 02:06 PM

Changed the oil filter...no change in gauge behavior.

Stretch · #28 11-27-2012, 03:53 AM

In that case you have a sticky choice to make.

The by-pass valve could be malfunctioning. But this is just a "could"...

...I don't want to make more work for you. But if you are up for a bit of a fiddle then perhaps this is worth trying =>

In chapter 18-005 (in the OM616 manual) at the end of the chapter on page 13 it talks about applying excessive force and pushing a seal out of position (seal numbered 24) which then LOWERS the oil pressure. You can reach this seal by removing the oil filter (again). Now this isn't a fix it is a test.

I reckon that if you remove that seal and run the engine for a short time (with out the seal but with the filter etc) and you don't see a reduction in oil pressure that that means that the oil isn't getting to the filter "enough" - it is being by-passed by the by-pass valve.

This isn't a Mercedes FSM test - this is a made up by me test (based on my understanding of the system). It might not work. Read through that chapter and see what you think.

Are there any comments from anyone else on this idea?

EDIT:-

This is assuming the gauge is correct. If it swings from zero to max I would expect that to be the case - well it isn't a calibrated thing anyway is it - but it does indicate that it is working.

Just an FYI - if you look just in front of the IP you'll see a little cap that can be undone for a special tool that is a mechanical tachometer. This cap could also be used to gain access to the oil pump pressure as the oil flows through the intermediate shaft to the IP at this point. This might be worth considering - but we're getting into the realms of difficult to make measuring solutions now...

shertex · #29 11-27-2012, 04:10 AM

My inclination is not to worry about it....unless there's some clear reason why I should.

Army, I will say that your point about not trusting others with oil changes is well taken. When I removed the filter, the o-ring seemed to be more compressed than I would have expected....suggesting to me that PO did not change the filter (though he says he THINKS he did).

Also, FWIW, I asked one of the techs at the outfit that does my oil analysis about the M1 0w40....he said "I would let it go for awhile. The VI improvers are very good and the additive package is aggressive on the Mobil 1 products. Since it is a gasoline engine oil, I would probably drain at 7500 miles though."

t walgamuth · #30 11-27-2012, 06:25 AM

I certainly would not run a 240 7500 miles on any oil let alone one which is really not correct for the engine.