Hello. I have a 1985 CA 300TD with 227,000 miles on the clock. I have driven this car for 2 years with no major issues. However a month ago I changed the oil pan because the original was banged up and had been that way since I purchased the car. I changed the oil when I did this of course and as an added benefit added Lucius oil stabilizer to the mix. The car ran fine with no noticeable difference for a month and then last week I started the car cold and the oil pressure only climbed to 2 bar when idling. It normally shoots off the scale as the engine is cold and the oil is extremely thick. Well I thought that was weird but I know that the Mercedes manual says danger only occurs once the oil pressure drops below 0.5 bar. So I drove to class to take a test on the way there I noticed it took 2-3 thousand rps to get the oil pressure needle to peg. I pulled over and stopped, thinking I was low on oil. The oil level was normal. I started the engine and took the oil cap off the engine sounded normal but had a lot of blow by. I looked in to check on the oil rail above the cam and the oil was dribbling out (only intermittent drops). I stopped the engine and had the car towed back to my house.

So the problem is low oil pressure (yet it has some oil pressure)
The possible causes that I can tell are as follows.
Pick up boot falling off
Oil screen clogged
Oil filter clogged
Two small o rings on filter tube missing
Oil chain tensioner broken allowing the oil chain to slip off the oil pump gear
Something wrong with the oil pump
SO today I went out and did some investigating and here is what I found.
There was enough oil in it for normal operation
The pickup boot on the oil pump looked fine and was still being held in place (was a little challenge to get if off of the neck)
The pick up screen was clean
The oil filter was not collapsed
The oil chain tensioner was fine and doing its job properly.

Basically nothing I thought it could be seemed to me amiss. But there was two things that struck me as odd. The oil pan was new and I found a dark flakey substance at the bottom of it (not shiny bearing metal) but more of a paint like substance. Also there was some stiff plastic looking strips at the bottom as well. They look like they have been shredded off parts of a plastic component. Which component I don’t know.
There is also something else. The cam chain that is above the oil drive chain was easy to move with a wrench. It wasn’t very taught at all. I could get about an inch of play out of it. I took the head cover off to inspect the cam chain and found that from the cam gear down the chain is extremely taught. Every guide seemed to be doing its job.

Conclusion
If the lower part of the cam chain is lose and the upper part is taught I don’t know if that would actually do anything bad to the engine. The sprocket that it would be lose on is the crank shaft sprocket and if it slipped off that by just one tooth it would destroy the engine, and my engine is running fine. SO if the cam chain is doing its job and the oil chain is doing its job and the oil chain tensioner is doing its job. WHAT BROKE!!!??? I have no oil pressure to the upper cam rail! I confirmed this visually! Why can’t I get oil pressure and what does the pieces found in the bottom of the engine mean? (Note there were no metal particles or flakes in the oil thank god)
Please help. This is my daily driver.

Here are pictures of the issue. I saved them to drop box


https://www.dropbox.com/sh/ocg7vqgeqp3uv52/AAD5OohhYTChX1hLalaFmQuIa?dl=0

Could the gauge be bad?

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1973 220D ~135k Mi
1979 Ford F100 300 I6 - 225k Mi

If the gauge was bad it would still be getting oil to the cam rail but it only drips like a drip irrigation system.

Here is are all of the pictures of the oil pump/plastic flakes/ and chain and oil system.

https://www.dropbox.com/sh/ocg7vqgeqp3uv52/AAD5OohhYTChX1hLalaFmQuIa?dl=0

Shredded silicone caulk? I'd drop the pan and see if the screen on the oil pickup is plugged.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I've never been deep inside one of the engines but the only thing I know about that might be source of the plastic are the chain guides and chain tensioner guide.

I'd solve this problem before I started that engine again.

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84 300SD
85 380SE
83 528e
95 318ic

I would have to agree with you regarding the chain guide. In looking at some of the pictures from parts supply web pages, the color and shape of the plastic shown is the same color and configuration as the pictures provided by the original poster.

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96 E300d

The pick up screen was clear though. The plastic oil bits were found at the bottom of the pan and there are not enough of them to clog the screen. Also when I replaced the oil pan I used a fitted fiber gasket. So no silicone is in the engine at all.

The Seal on the Vacuum Pump piston is some sort of Plastic.

If you changed the Oil Filter since you had the low oil pressure issue I did not see that mentioned.

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84 300D, 82 Volvo 244Gl Diesel

Did you notice if the part that has the Screen on it up further was cracked or loose?

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84 300D, 82 Volvo 244Gl Diesel

The oil filter was changed a month ago with the pan. I will put the pan back on and fill the engine with fresh oil and a new german oil filter. The old oil filter has no sign of clogging though. There are no abnormal particulates and only one or two small slivers of that plastic.

After reading more I have discovered that there are two oil pressure relief valves in the 1985 CA 300D. Correct me if I am wrong!

1. A relief valve on the oil pump itself
2. A thermo relief valve in the oil filter housing

Can someone confirm this and pictures of there location? I cant find anything on them.

Also my vacuum door locks have lost there effectiveness over the last month and a half. The doors will only lock seconds after i shut my car off. This could me the vacuum pump failing or a leak somewhere in the system. In any cause I have yet to see an guide on how to replace the timing chain guides within the engine. Vacuum pump tutorials are much easier to find.

rc:

1. The primary pressure relief valve is in the oil pump. It is oriented laterally, and the cap may be accessible with the pump installed. A broken spring or the plunger stuck open are prime suspects.

2. There is a thermostatic valve in the filter base that controls oil flow to the cooler.
There is a filter by-pass pressure valve in the filter base that will direct oil around the filter in the event of filter clogging.