Low oil pressure - '92/'93 500SL

[LeaUK]

Does anyone know what the minimum pressure should be, or what is 'normal'? Recently mine's dropped to less than 1/2 bar on idle in drive and on occasion (during hot weather) to 1/4bar.

This concerns me - and I'm sure I've seen web articles with details of fixing low oil pressure issues on the 500 SClass

Of course most docs point to minimum pressure at 3K RPM, but what about at idle and loaded.

Thanks
Lea

[LeaUK]

Jim's excellent web site does it again - http://pages.prodigy.net/jforgione/MB_lifter.html

Best I check my oil tubes!

[ctaylor738]

If you have a blown-out oil tube, you will hear the ticking hydraulic element.

Another fix is to replace the oil pressure sender.

[LeaUK]

No ticking appart from first started for around 3-8 seconds.

Still worth taking the cam covers off though I suspect. I wonder if there's a gasket needed?

[ctaylor738]

I haven't worked on an earlier M119, but I believe that you have the coil packs on top of the spark plugs. Both have to come out to take the covers off. Not a quick or fun job, and IMO the covers are best left undisturbed unless there is a real problem. I replaced the gaskets when I did the oil tubes on my coupe, and you need to pay attention or they will leak.

[LeaUK]

Hi Chuck

Only a single coil pack on the 119.72 LH engine so that should make things a little easier.

I've been told that this low oil pressure reading isn't an issue, but I often see people posting 1.5-2 Bar at min so hence my concern.

Am I being over concerned?

[LeaUK]

Any one with examples of oil pressure readings when in Drive and at stand still would be appreciated.

Thanks
Lea

[ctaylor738]

My coupe with 108K gets erratic readings, which I suspect are due to the sending unit. It will go as low as .5 bar when it's really hot. Lately it has been around 1 or a little less.

My SL, with 28K on the engine has never gone below maybe .8 bar.

[LeaUK]

Chuck

What's the viscosity rating of your Oil and also the outside temp when you've noticed the pressure?

I'm using 5:40 and it's around 20DegC here at the mo.

Thanks
Lea

[ctaylor738]

Both cars have 5 30. Outside temps have been as high as 32. If either car idles for a while on a hot day, the engine temps will go as high as 100.

I believe that the spec is .3 bar at 600-650 rpm.

[aam]

Originally Posted by LeaUK

Does anyone know what the minimum pressure should be, or what is 'normal'? Recently mine's dropped to less than 1/2 bar on idle in drive and on occasion (during hot weather) to 1/4bar.

This concerns me - and I'm sure I've seen web articles with details of fixing low oil pressure issues on the 500 SClass

Of course most docs point to minimum pressure at 3K RPM, but what about at idle and loaded.

Thanks
Lea

Hi Lea long time no see.
How are you?
I thought you wanted to sell your car some time a go.
I have a psi of 1.5 at idle in drive with 20W50 oil.
If it gets very hot it goes a little less but never at 1.
Your oil is maybe thin, try to replace the filter and oil usually when
I do that the pressure goes a little up.
When it goes a little down I know the oil is contaminated and is time to replace the oil even if the millage is short.
Sometimes the oil sender is bad.
Oh, about the coils your 500 has two.
Regards.
aam.

[LeaUK]

Hi aam

Never wanted to sell my baby even though I spotted a SL500 '2000 plate in immaculate condition last weekend and for only 11K GBP - only 65K Miles too!

Can't believe the price fall here in the UK, but it wouldn't surprise me if that darn ever increasing fuel cost is putting people off.

Yeah, I haven't been about for quite sometime due to setting up a business - it zap you. And a as a result my SL needs some love as I've only taken her out a few time recently.

TBH, I can't remember if she's got 5/30 or 5/40 but I know I recently lowered it from 40 to 30 or 50 to 40 to help with oil pressure on hot days. She's regularly serviced and oil/filter never gets more than 2K Miles between changes

Ah, yeah, two coils - one for each V! Thanks for pointing this out.

I have a psi of 1.5 at idle in drive with 20W50 oil.

Am assuming you mean Bar or is your gauge in PSI? In the UK we're in Bar!

Lea

[johnathan1]

My oil gauge seems a little jumpy at times...and every once in a while the gauge will sit at 0 when in drive and idling, goes up slightly when put into park, and jumps up to 3 bar as soon as I touch the throttle...is this cause for concern?

[ctaylor738]

Here are the specs from alldata, no information on operating or ambient temp, though.

Oil Pressure at RPM

0.3 - 1.5 bar at 600 - 750 rpm
0.7 - 3.0 bar at 1000 rpm
1.6 - 5.0 bar at 2000 rpm
2.0 - 5.5 bar at 2500 rpm
2.5 - 5.5 bar at 3000 rpm
2.7 - 5.5 bar at 4000 rpm
2.8 - 5.5 bar at 5000 rpm

[deanyel]

Is that specifically for 119 motors, or all motors? My 119 motors have always been about 1.5.