Oil pressure problem

[K-Jet]

Good evening!

My car is currently only reading 30 psi at cold idle. I am hesitant to drive it or even run the motor. When I first noticed the oil pressure, the car was fully warm and at highway speed. Then also it was 30 psi.

Background information- this is a newly rebuilt 2.8 installed in a 1971 280SE. The installation was completed the day before the movers arrived. Before first startup, we got full pressure (45 psi +) just from the starter. After startup, the car ran poorly, but with good oil pressure. The motor has about 400 miles on it now.

What has happened since then?
1. The car was shipped across the ocean (container shipping).
2. I removed and flushed the fuel injectors to improve running performance.
3. When jacked by the front suspension cradle, the jack slid forward, dishing the oil pan. The jack had a hockey puck on top, so there are no sharp creases, but the pan is dished at the center.


So, yes I feel really stupid. Assuming occurrence number 3 is causing this problem, would straightening the pan likely solve this, or is there likely oil pump damage as well? When I open it up, how would I evaluate what I am seeing?

Or should I look elsewhere first?

Many thanks.

Dru
1971 280SE
1990 250D
1995 220TE

[Pinder]

thats where oil pump is. its possble you cracked it hence the drop in oil pressure. worth removing oil pan and check damage.

[ja17]

Remove the oil filter and break it open. Check to see if you have any metal debris in the folds. If so remove the sub oil pan and check for metal debris in the pan and oil pump intake screen.

[K-Jet]

Will do.

If the oil filter is clean, what then?

[rwmastel]

I would still drop the pan and investigate.  Can anyone think of a way to confirm clearance between pan and pump?  And, what clearance would be appropriate?

[K-Jet]

Or is it possible to straighten the pan? If so, how?

What specifically am I looking for when I inspect the oil pump for damage?

[Vander]

If the oil pan is dented inwards, with it removed you would put a block of wood on the inside of the dent and use a large hammer to beat it outwards until smooth. A new oil pan can be purchased for $50, whether you fix the old one or replace don't forget to install a new oil pan gasket.

[rwmastel]

And you can search this site for discussions about oil pans.  MB used slightly different versions over time, but only sells one version now.  Get what's right for your car, or just make sure you know what you're getting.  Knowledge is power!

[K-Jet]

This thread, I think you mean.

https://www.sl113.org/forums/index.php?topic=7962.0

[ja17]

If your oil pan was damaged, you definitely need to repair and inspect for internal damage as suggested.

[rwmastel]

This thread, I think you mean.

Bingo!  Great info and pics.  Even shows the oil pump pickup.  Good luck, hope you don't have any serious issues.

[Kevkeller]

You could put a thin layer of grease on the bottom of the pump screen and put the oil pan back in position. After pulling it off again if there’s any grease on the pan you know it’s touching.

I’d inspect the entire pump assembly. Maybe you cracked the oil pump case. You can try moving it with your hands maybe.

[K-Jet]

I've been sick the last little while and haven't made much progress.

I now have an external oil pressure gauge and will briefly confirm the dash gauge idle pressure reading first.

[K-Jet]

Finally some progress tonight, as I was ready to spend a few hours in the garage. I was unable to use the external oil pressure gauge, as it did not have a 9 x 1.5 mm fitting. I did check and reroute the oil pressure gauge line and reseat the fitting on the end (I may have had the fitting in backwards before), but the gauge reading was no better.

After this I removed the pan, had a look at the oil pump, and removed the oil filter.

1. The oil pump-I'm not sure what I'm looking for, but there is no damage obvious to me. The body is solid without any deformation, dents or fractures.

[K-Jet]

2. The oil filter element- the special one for newly rebuilt motors.

Is there a lot here or a little? The motor spent the better part of two years getting built, so some airborne fluff wouldn't surprise me. I couldn't feel anything in the pleats. But again, I don't have long experience here.

The oil sample is on the way to Blackstone.

And I apologize. Evidently I once knew how to embed pictures, but now do not.

[K-Jet]

3. And the oil pan.

I am really hoping that mark on the inside of the oil pan means that oil's access to the pump was simplyimpeded and straightening the pan will straighten the problem.

What are the chances of that? Or where else should I be looking?

Many thanks for your help.

[ja17]

What does the pick up on the oil pump look like? Make sure it is not cracked, or bent. The oil filter looks normal for a recently rebuilt engine.

[K-Jet]

What does the pick up on the oil pump look like? Make sure it is not cracked, or bent. The oil filter looks normal for a recently rebuilt engine.

Pictures of the pickup are in post 13 as attachments (I evidently don't know how to make pictures in line with my posting). Is there a particular view that would show more than what I can see there?

[Peter van Es]

Pictures of the pickup are in post 13 as attachments (I evidently don't know how to make pictures in line with my posting). Is there a particular view that would show more than what I can see there?

Hi K-Jet,

you cannot take .heic photo's taken with an iPhone and then just change the name to ".jpeg" and upload them. The .heic image format is too new and is not recognised as a picture. You need to convert them to jpg format before uploading (and reduce their size somewhat), as you have clearly done correctly on your later posts!

I've done it for you... so scroll up/down and see pictures of the pick-up.

[ctaylor738]

With new pans available for under $50, I suggest you replace the pan.  Even if you can beat the dent out it's likely to leak and the cosmetics will be terrible.

Fingers crossed that fixing the pan solves the problem!

Cheers,

CT

[Benz Dr.]

The oil pump clearly bumped up against the bottom of the sub pan. I would get a new one if it's available.

[Pinder]

that big semi-circle could mean low flow, worth getting a new pan.

[MarkCan]

K-Jet
While rebuilding the engine I replaced my lower oil pan with the newest version. I replaced the oil pump as well and to find a proper clearance I measured the pump protrusion out of the upper oil pan, than check the depth of the new lower pan. I add few millimeters to allow for proper flow. Why did I go through all this trouble? Well, there are several different pickups. They all look very similar but their reach, angle and height are slightly different. I used the latest pump version (from M130) with the older pickup assembly. No rubber extension.
I’m not posting the measurements here as different parts combinations will very the final height/clearance. This step needs to be performed by you.

[MarkCan]

Here is the example of the earlier pickup with the rubber extension for deeper reach.
Please note, strainer assembly itself is way shallower.

[Cees Klumper]

I'd start with getting a new pan on and seeing what the oil pressure is after that. It does look like with that dent the flow was impeded which a new pan might solve for and no need for a new oil pump.
New oil pumps seem in short supply, at high prices ($1,675?).