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Old 03-21-2000, 11:07 PM
Sean Thom
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My 75' 280 is running better! But now the oil pressure falls to 0 after a few minutes. I have been told to try tranny fluid with my oil and run a few hundred miles and change back. Is this a good idea? I took it to a mechanic (non-Mercedes) and he told me I needed a new moter but he didn't mention anything about an oil pump, which is what I think the problem is. Any suggestions?
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Old 03-22-2000, 07:49 AM
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You brought back an old, sad memory. I hope you don't go through the same thing I did. I also hope one of the long time MB Techs can shed some light, just to satisfy my curiosity, and more importantly fix your car. I hope you don't end up going through what I went through. If I would've had mercedesshop back then, maybe I wouldn't have had the sad experience.

I bought a really nice, stick shift, '68 230 sedan, cheap. Cosmetically it was like new and the entire car minus the motor was near perfect. It was fun to drive. I bought it with the full understanding I would have to overhaul the engine, low oil pressure, high oil consumption.

I took it apart and things weren't that bad, cylinder wear, crankshaft wear, etc. I replaced rings, bearings, oil pump, valveguides, valvejob, the whole bit. The camshaft journals and lobes lubricated via a spray tube that ran the length of the camshaft. There was one journal of the camshaft with some clearance, but it was lubricated from the tube, not pressure from below.

I got it all back together and it ran really nice. And decent oil pressure when cold. But when it warmed up, the oil pressure would go near zero at idle and to zero when starting off. I replaced an oil pressure regulator, even put a second head gasket on it, because of an oil passage at the front of the head that I thought may be the problem. I talked to an old time MB mechanic, and he never could give me any suggestions.

Generally, low oil pressure indicates worn bearings. I've seen alot of people think they could cure it by replacing the oil pump, but I don't remember this ever curing the illness. Of course, there are alot of places in the engine that if not right could bleed off pressure, and every model engines lubrication system routes the oil differently in some way.

I think that your 280 engine is a close cousin to my old 230 six cylinder. I hope that we can generate some dialog with the experienced MB guys that have been around long enough to have a history with these engines. I would like to satisfy my curiosity and more importantly, not see you go down the same road I did. I ended up getting rid of an otherwise really neat Benz.

Good Luck,

Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles
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Old 03-22-2000, 07:55 AM
Posts: n/a

BTW. I think the ATF fire drill is a waste of time. Some people used to use ATF to clean crankcases, but modern engine oils have adequate cleaners. If the engine is so gunked up that you need to flush it out, use good oil, and drain it HOT, and preferrably overnight. The last drops that come out are the most sludgy. Change it every 500 or 1,000 miles until it is clean. If the sludge is so bad that it is part of your oil pressure problem, it's probably way too late to help.

Good Luck,
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Old 03-22-2000, 08:10 PM
Sean Thom
Posts: n/a
Thanks for your in-put! I hope it isn't that serious but I got the car to put some money into, I hadn't planned to put that much in it! I can't even find parts for it! I have put in a couple of parts inquary's in at the parts shop but am still waiting for a response. I know I need to replase the linkage and maybe the carb but I can't even get ball-park figures to think about. My mechanic wanted $15000 to fix it but he couldn't even tell me this with a straight face!! He also couldn't find ANY used or rebuilt parts! I saw a 73' for sale with a good moter but that guy hasen't responded either, and he is a member of Mercedes Shop! I guess I will try to contact him again but knowbody seems to be able to tell me if that moter will even work with my 75'! This car looks great but I don't know what to do with it!?!
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Old 03-22-2000, 08:33 PM
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
Larry has it right about oil pressure. The pump is rarely the problem. The pick-up could be though. I would remove the subpan for an inspection. I would be sure there is plenty of clearance between the pan bottom and the rubber pick-up foot. Be sure that the rubber foot is shaped properly; it can sag and set on the pan bottom. I would also inspect the state of number one rod bearing at the same time.

These engines also almost never have lower end problems so if its bearing related it should be obvious once your in.

As to parts they are totally available. They just cost more and may have to come from MB. The only parts I would imagine no longer available would be colored interior trim.

The answer to your carb problem is to find someone who can fix yours. If you had to buy a new carb you would have way too much into it, especially if you have engine problems.

Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
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Old 03-22-2000, 09:12 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Be SURE to have an experienced tech replace the oil pump drive gear BUSHING. It is still available and will allow the gears to shear and sieze the engine. These are strong, and I mean strong engines. I owned a 67 250SE with power everything. I bought it with 0 oil pressure. I replaced the gear for the oil pump and the bushing and drove it for a long time. (this is in reference to an m129-m130 engine, if you have a m110, disregaurd message.)

1981 280GE SWB
1987 16V

[This message has been edited by Benzmac (edited 03-22-2000).]
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