1981 300TD. I've got a major oil leak which my mechanic has traced to a bolt which appears to be about 17mm or so, which goes into the front of bhte block, between the crank pulley and vacuum pump.
Apparently there is some kind of speed sensor mounted on a bracket in front (over top) of this bolt.
Well, the bolt has backed out, is loose, and I'm losing a ton of oil.
My mechanic was able to tighten it using a screwdriver, of all things, but states that he doesn't think he can get at it with any kind of driver.
What is it?
How to get at it?

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shawnster,

I'm not exactly sure what they are called but I think they are plugs. My 240D had them loosen up and they leaked alot of oil.

I was able to get a wrench on mine and tighten them up. I'm surprised your guys couldn't figure out a way to get on it.

I think I tightened up the ones on my 300D when I had the vacuum pump off (to replace that gasket).

Good luck

240Joe

Shanster,

I think that is the oil pressure release valve. It lets oil from the oil pump flow back into the crankcase when the oil pressure gets to a pre set level.

That would explain why you lost so much oil when it came loose. Its not just a leak, its oil under pressure

If it comes loose again, I would remove what ever it takes to tighten it because if it comes out you could loose oil pressure and damage the engine.

P E H

Same place as my oil pressure relief valve, but I thought the newer engines have it on the oil filter bracket. If it is then you can pull it out and reinstall with some non-permanent locktite. But I'd wait until somebody with this engine chimes in.

__________________
daBenz - 1970 220D

Shawnster,

If the oil relief valve is somewhere else, the plug is in the end of the main oil passage of the engine. So it should be tightened properly so it doesn't come out and the loss of oil cause damage to the engine.

P E H

What part number is it?

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

many thanks for your help. i do not know the part # and the bolt is VERY difficult to get at- that's half the problem, how to tighten it down?

my mechanic says that it appears that this bolt is underneath a speed sensor which is mounted on a bracket...

how to get at it?

DO I NEED A SPECIAL TOOL TO GET AT IT?
OR DO I NEED TO REMOVE SOME EQUIPMENT?

Shaunster,

I'm not sure but all you should need is an open end wrench once you remove what is in the way. You might start by removing the radiator so you can see better.

P E H

Shaunster,


there are all kinds of things up on the front of the engine that need to sealed when the engine is assembled. There are 3 timing chain guide pins, one of which might be your leaker. What ever it is you have to be able to get to it to tighten it up. I would pull it out enough to get some thread sealer on MOST of the threads and tighten it back up. Like PEH said you might want to pull the radiator.

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

my mechanic is going to have it in next thursday AM, he'll probably pull the radiator and get at the $%8@ thing. Yes, we'll use some loc-tite or whatever it is. I think this will fix my oil leak and I'll get more miles out of the ole girl than I figured when I was thinking my main seals were leaking.
I'm a moderate DIY'er but I don't think I'm ready to pull the radiator... what do you guys think?
-shawn

Shanster,

I think R&R a radiator is a very simple job. MB radiators are much easier to remove than other makes because they just slip in and out instead of being bolted in.

You have to start somewhere to be a DIY guy. This is a good place to start. Once you get the radiator out, you may be able to slip a wrench in there and tighten the plug.

P E H

shawnster, absolutely a job you can do once you know what the part is. Why pay somebody else to do the lefty loosy righty tighty stuff? If nobody with this engine chimes in then you may need to make a good investment and buy the service CD (also helps keep this web site going). That CD is going to tell you where the oil pressure relief valve is. You may also get lucky and only have to pull the fan and shroud. For what it's worth, my CD says that's the first place you look if the engine front is leaking oil.

mplafleur, the part no. for mine is 114 180 02 15, as of 8/6/92 which is the date on the part bag tag (say that five times really fast). It's two inches long, of which the threads are about 1/4in deep. The wrench end looks like 17/32in across the flats by about 3/8in deep. The wrench end also has a hole about 3/16in diameter. The valve body itself looks like 25/32in diameter (it's snowing today and I'm too lazy to go out and get the metric wrenches - I don't know why I have this part in the house).

__________________
daBenz - 1970 220D