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Old 03-08-2000, 02:39 PM
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Just bought a 1986 300E about a month ago, and the engine appears to be in distress when its idling (its fine once it gets moving, although there's a slight pause when I first hit the gas). I noticed last night that when the engine is stuttering, the oil gauge is at mid-level. When the car gets moving, the gauge goes up to the top (and runs great). Can anybody give me a diagnosis? Cost to repair?

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Old 03-08-2000, 02:54 PM
akry's Avatar
W140 Maniac
Join Date: May 1999
Location: Burnaby, BC, Canada
Posts: 960
When you hit the gas, does the engine vibrates, and hesitates a little? Do you feel the engine is loosing power?? Maybe it's the spark plugs and coils?? Just a thought....

P.S. One more thing, do you see dark exhaust when you accelerate hard???

Andy Kuo

<LI>1992 Mercedes-Benz 400SE
<LI>Moonstone Grey/Black Leather

Mercedes Owners ICQ ActiveList ID#61730549
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Old 03-08-2000, 02:59 PM
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I just had the sparkplugs replaced. Don't see any dark smoke when I accelerate hard. The tech that I took it to adjusted the fuel mixture in hopes of fixing the problem, but to no avail.
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Old 03-08-2000, 08:34 PM
Registered User
Join Date: Jan 2000
Location: New Bedford, MA USA
Posts: 1,583
Sounds like fuel starvation, or low fuel pressure. Start with the fuel filters, make sure the fuel pressure regulatior vacuum line is connected and not leaking. Oil pressure you describe is fine. Go chase the fuel gremlin, but don't rule out spark entirely. BTW, how did the tech adjust the fuel mixture? Or at least how did he tell you what he did and, what did he charge for doing that. Good luck

Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 03-08-2000).]

[This message has been edited by jeffsr (edited 03-08-2000).]
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Old 03-08-2000, 09:30 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Be sure to have the engine looked at on a scope. Have a Mercedes tech do this for they look a little differnt than some. The engine has solid wires with resistor tips...they can be replaced individually.

1981 280GE SWB
1987 16V

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Old 03-08-2000, 09:41 PM
Aaron's Avatar
Join Date: Aug 1999
Location: Cincinnati, Ohio
Posts: 1,935

I had a 126 chassis 300SE in today with similar problems. It turned out to be a weak fuel pump. Just my $0.02

Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'89 420SEL
'93 300E 2.8
'72 Alfa Romeo 2000GTV
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
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Old 03-08-2000, 09:44 PM
Join Date: Jan 2000
Location: Indpls.,IN. USA
Posts: 84
One common problem on 300e's is a blown fuse on the overvoltage relay. This still allows the engine to run but none of the normal enrichments will occur. To properly set the fuel mixture you need an instrument that shows the intergrater correction. A substitute would be to monitor the oxygen sensor voltage. If your mechanic did neither of these things he's just guessing. Another problem that I've seen repeatedly is a split vacuum hose on the idle control hose where it connects to the bottom side of the fuel distibutor housing. This is probably easier to see from under the car. One eazy way to detect vacuum leaks is to poor a heavy stream of water over the intake manifold and related plumbing. If you do this of course you need to avoid putting water into the flap of the mixture control unit, assuming you might best test with the air filter removed. Good luck! A properly running 300e is one fine automobile.
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Old 03-09-2000, 08:45 AM
Posts: n/a
The tech said that the engine was being and starved, changed the fuel mixture, and charged me an hour of labor. It seems like I'm going to have to bite the bullet and take it to the dealer. Since I paid less than $5K for the car, I guess I can handle it. Other than this minor problem, the car runs like a champ.
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Old 02-26-2001, 05:42 PM
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Join Date: Jan 2001
Location: Santa Clara, CA
Posts: 413
I have the same problem as you did. Did you ever get your problem fixed? What was the ultimate cause.
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet
'86 560SL 124K Miles
'94 320E Wagon, 74K Miles
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