(My) Problem 2/3 : Oil pressure

[dogan124]

Hello again to everybody,

I have an oil pressure problem on my 1991 w124 300d.

The display of the oil pressure rise up 7-8 second after the engine start.
The sound of the engine also changes after full oil pressure is observed. I was given the ideas of :
*changing the oil pump : Had it changed with a new item : no improvement at all.
*use thin oil : even worse.

My theory is that, the box where oil filter is placed is losing the oil in it through the valves back to the oil container at the bottom, when engine is stoped. Then when the engine is started again, the pump fills the box before it forces the oil pressure gauge.

With this theory I had the valves of that box (sorry for my limited dictionary about the name of this item). The valves looked OK but the mechanic had the springs even rougher, but no change was observed again. But I was insisting on my theory and changed the whole box with another one (used). Again nothing...The stick that goes through the oil filter box ! Yes a great idea, change the two little seals (although not available even in MB), but again nothing.

Then comes the winter time when I noticed things are better down to 5-6 seconds. Also noticed that the problem is some what the engine (or oil) temperature dependent. When a hot engine is stopped and wait more than two minutes the problem can be observed clearly. But if the engine is cold, and you stop it, and start again after -even- 40 minutes the oil pressure can rises as soon as engine turns.

Now, what bothers me is that I feel engine is worned every time I start it. The normal pressure readins are fine : top for cool engine, and 1.8 for normal operating temperatures.

The other theary -that I dont like- is the wear or gap onthe crank or other engine bearings. (The compression of the engine is quite good though)

Any comment on this ? I would also appreciate your engines delay until the oil pressure is visible

Kind regards,

Dogan

 

[lookskyward1]

I would suspect the main engine bearings are worn resulting in the slow pressure build up.

If the engine is in otherwise good condition I would put up with it for now but use a heavier (thicker) oil, bearing in mind the higher temperatures your car works in compared with the UK. If you are going to put up with it like this for now, it may be worth treating the engine with Slick 50 to help reduce the wear on start up.

Hope this helps, good luck.

 

[l5foye]

Hello
Have you a genuine MB oil filter fitted? Sometimes spurious or counterfeit filters will give the same thing that you are experiencing.

 

[dogan124]

I would suspect the main engine bearings are worn resulting in the slow pressure build up.


But if so, how could the oil pressure 1.8 at idle (I assume good) can be attained ? (and full pressure as soon as 1500-1700 rpm)

Mean while I use castrol gtx 20/50 which is preffered here, due higher temps as you said.

And I will check that slick 50 (initially I tried another one but gave up)

thanks

 

[Ian B Walker]

Is it realy safe to put in Slick 50 taking into consideration the valves are hydraulic?

 

[lookskyward1]

I've used Slick 50 in all of my recent cars, all of which has had hydraulic tappets. I've not had any problems, then again I've never noticed any benefits either?