Hi all,

I have a 1972 280SE 4.5 (M117). The oil pressure normally pegs the gauge at full pressure within a second or two of firing up. It usually stays there even when warm.

Today I started it up and got zero pressure on the gauge. I tried a few times with the same problem. I pulled the feed for the gauge and tested the guage with compressed air and it seems to be working fine. I fired it up again with the tube still disconnected and no oil came out of the fitting on the head.

This is the first time the car has been started in a month. The oil filter is still fresh (only a few hours of running time on it). Looking for some words of wisdom before I pull the pan off to have a visual look at the pump and pick-up. Could a relief valve problem cause this?

Thanks in advance,
Allan

start your engine and turn off the oil filler cap on the valvecover.
there you should see a thick jet of oil on the cams.

edit: if you don´t have oil on the cams your oilpump is gone sick...

__________________
´64 W111 220seb coupé
´66 W113 230sl pagode
´67 W110 230 6cyl
´69 W111 280sec coupé
´71 W115 250ce coupé
´72 W108 280se 4.5
´73 W108 280se 4.5
´79 W123 300d auto
´80 W123 230ce 4cyl

I wouldn't perform that check with the engine running, I'd do it while cranking. If you can crank for 30 seconds and see no oil pressure, something's terribly amiss. My 4.5 will put up oil pressure within 5-10 seconds MAX of cranking. To check this, unplug the D-Jet harness on the distributor and the cold start valve, that will ensure that no gas gets shot into the engine and you can crank without fear of flooding or diluting your oil with gasoline. If no pressure builds within a reasonable amount of crank time, first pull your filter and ensure it's installed correctly, then if you still get no pressure it's time to drain and pull the pan.

Of course, you have done the obvious and checked the oil level I assume

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

The M108 chassis should have a direct reading oil gage, that is, the actual pressure runs to the gage, no electrical sender/gage.

Great idea, until the line ruptures and spray oil all over the dash and floor....

Not certain of the pickup point on the M117 iron block, but it's usually at the oil filter housing.

If you had oil pressure, and have performed NO work in the engine compartment, nothing disturbed or incorrectly installed, be very careful when testing.

This scenario strongly suggests a true no oil pressure condition. Certainly do not start the engine, disconnect as suggested earlier.

In addition to verifying oil on the cams, you can also disconnect the oil line at the instrument cluster, and route it to a bottle. Cranking should reveal oil flow, and then your gage is the problem. If not, you need to go further back toward the engine and verify that the sensing line is clear.

After that, as suggested, it's time to pull the pan and verify the pump.

Jim

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95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Thanks for the great replies guys!

I did pull the pan and found the source of my problem...frozen sludge!

First look in the pan revealed over half an inch of a thick black paste. It had covered the oil pick-up end as there was a clear impression in the paste from the oil pick-up. Another glob of the paste came out of the pick-up end when I poked in there.

I initially feared the worse, some sort of catastrophic failure that resulted in the bits being deposited in the pan as this paste. When I began scooping the paste out of the pan with a putty knife, I noticed that it had no metallic content. Below the paste I also found a layer of ice (it's been well below freezing up here the last few days).

I placed the paste in a container and put it out in the sun. What was initially a solid scoopable paste turned into a pure liquid (oil) in about 20 minutes.

The car had to be stored outside this winter, and every time I had to start it, I did let it get to operating temperature before shutting it off. It appears this was not enough to prevent condesation from forming in the wildly fluctuating Ontario climate.

I need to get fresh oil and an oil pan gasket before I can test the car (I've already put a fresh oil filter in). Hopefully the few times I did start it without pressure did not cause any damage (6 or 7 second bursts).

I'll follow up with some hopefully good news tomorrow.

Thanks again,
Allan

* spitfireal, interesting post. The only time I've ever heard of anything like sludge blocking an oil pump pickup screen was once when someone used several cans of the old STP, reasoning that if one can was good, several cans must be better. The additive wasn't run in/mixed. And the car was parked for a while. The weather was frigid. And the STP got thick and effectively blocked the oil pickup the next time it started.
* It would be interesting to have a sample of the sludge analyzed to determine if it is just (very) high mileage oil or some additive.
* I believe that the oil pressure line connects to a fitting on the back of the left cylinder head.

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Mercedes Svc. & Restoration
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Sounds like more than condensation to me. I would venture to say that you have a head gasket problem, or worse yet the coolant was under strength and you had a freeze crack problem. If the coolant was at the proper strength then it should not have frozen in the pan. I would check the gravity of the coolant that is still in the system. I just don't see that much condensation being a problem.

Thanks for the additional replies,

Just to clarify a couple of points, perhaps "frozen sludge" was the wrong term to use for what I found in the bottom of the pan. Perhaps "Oil Slurpee" would be more descriptive. There was a layer of clear ice below a layer of this "Slurpee" below the actual oil. The thickness of the first two layers (ice/slurpee) was thick enough to cut of the liquid oil from the pick-up.

As I knew the car would be outside this winter it received a fresh mix of antifreeze in the fall. What was in the pan was pure water and had separated from the oil and was not the white sludge that I normally associate with moisture contamination. The car had sat for a month prior to this incident - perhaps that contributed to the situation. The oil was also fresh from the end of the summer with no miles, but a few hours of running time on it (from me letting it warm up every time I moved the car).

For those not familiar with Southern/Central Ontario, it is extremely damp here and we do experience many wild temperature fluctuations over the winter. Condensation is even a problem for the cars inside of my garage if I have to open one of the doors during one of these temperature flips.

My oil slurpee turned to liquid in the sun yesterday. This morning it has refrozen to a hard paste again. I'm still assuming that I caused the heavy condensation due to not allowing the car to warm up enough on the frigid days I had to start and move it. Next year it will definitly be parked in the garage for the winter.

I'll follow-up when I get the fresh oil in.

Thanks again,
Allan

Proceed with caution. Something does not sound right here,

Tom W

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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.

If you pull the forth fuse(I think) from the front it will kill power to the ECU so the fuel pump will not operate. It's also a way to possibly keep your car from being stolen. It's easier than unplugging the D-Jet harness.

__________________
Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT

I think Tomguy was suggesting pulling the connector from the distributor trigger points under the hood not the ECU harness. The Cold Start Valve will still fire without the ECU being connected so pulling the fuse is not enough on its own to prevent starting.

Hi all,

Again, thanks for all of the input. One final (I hope) follow-up. With the pan back on and fresh oil, my oil pressure has returned to normal, just as it was prior to the "incident".

With the warmer weather arriving, and me avoiding running the car for short periods as I was before, I doubt the situation that caused so much ice to end up at the bottom of my oil pan will be replicated. I will keep a close eye out for any sludge formation to make sure there is not another source of moisture contaminating the oil.

Thanks again,
Allan

Spit,

I think what the other members are trying to say is that an engine SHOULD be a sealed environment.

Failure to be a sealed environment then humidity can cause condensation inside your engine.

You need to ask yourself how did that water get in the engine.

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72 250 M130 W114

Hi Gary,
Disabling the ECU will prevent any fuel from being dispensed as the fuel pump will not run. Fairly sure this is the case but it's been a few years since I have done this. It's easy to test though. Just pull the ECU fuse, turn on the ignition and see if you can hear the fuel pump run.

__________________
Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT

Hi all,

Im hoping someone can help with my problem. I have a 1971 290 SE (W108) and the instrument cluster wont light up. I have taken it out, replaced all the globes, cleaned all fittings etc but it didn't light up before and wont now. I have also checked all the wires connecting it with my circuit tester, they seem to be fine. I have even checked the fuse tablet under the dash, and replced all fuses (I'm sure they needed doing anyway) This is my first Mercedes Restoration, and I would really appreciate any advice or hints.

Cheers,
Luke