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#1
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1980 450SL - Mechanic says I need new fuel distributor - advice appreciated
So here's the 411:
My 1980 450sl has been running pretty poorly lately, with the following symptoms:
So I gave in and took it to my local mechanic. After an hour inspection, they diagnosed it as the fuel distributor dumping too much fuel into the #8 cylinder, and told me that I need to get a new fuel distributor. Before I do that, I wanted to get some feedback on a couple of questions I have:
Thanks for your help! |
#2
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When was the last time the O2 sensor was replaced? Try adjusting the air/fuel mixture a bit richer.
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Question Authority before it Questions you. |
#3
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if you send me a PM I can snag one from the yards around here, they are plentiful, and in rather good shape. Cost+shipping (actual). . .
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". . .back before accountants designed cars" -Current Stable- '78 MB 450SL-C 107.024.12.020783 #3840 <Kayleen> '85 FORD F250 6.9L Diesel <Allison> '98 Lexus ES300 <Rachel> Long Gone... '74 Chevy G10...........................'99 GMC Yukon 4X4 '83 Chevy Suburban 6.2 diesel .....'99 SAAB 9-5 '90 Mitsubishi Eclipse GS............. '01 Chevy Tahoe '98 Nissan Altima .......................'02 MB ML320 '88 Chevy Suburban V2500 4X4 6.2 diesel |
#4
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Quote:
Say it does need to be replaced...is that potentially something that could make the fuel distributor 'appear' to be faulty? Thanks! |
#5
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My guess is this is a job you can do yourself--IF you can get the two screws that hold the FD to the throttle body busted loose. Get you a wide/thick blade screw-driver and see if you can break the screws loose. I watched my experienced MB mechanic wrestle the screws on mine for over a half hour before getting them broken loose. You'll learn what you need to install it by removing same.
However, the FD may not be the problem. On my car, the FD only does what it is told to do by the warm-up regulator (WUR). Don't know if yours has a warm-up regulator on it or not, but after replacing the FD, injectors, warm up regulator, fuel pump, fuel accumulator it turns out the rebuilt WUR that was put on the car was not holding pressure. Thus, causing the rich mixture. Have another WUR that was shipped today and hope that will finally put this problem to rest. It has been close to a year that we have been chasing the problem. But, boy have I learned a lot about this car!!! I recommend John Hervey at http://www.specialtauto.com to you. His is a one-man operation, so you need to stay abreast of the transaction. Finally, don't just take a FD or WUR off of any car. The FD has a number on the plate on the back of it and the WUR has a number stamped on the top of it. Try to replace the one on yours with the same number. You'll see the various part numbers on the SpecialTAuto website. Good luck.
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Don '85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000 '95 C280 - 174,000 |
#6
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Quote:
The O2 sensor can make a big difference. Bosch make one for $22 bucks.
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Question Authority before it Questions you. |
#7
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Hi supercanuck
I would be a little wary of this one. generally speaking the FD will put out the same amount of fuel to all of the lines, so saying they are adjustable individually but generally if no one has messed with them the same amount goes to all. the injectors can let different amounts past if they are worn differently. the WUR is generally the biggest problem as it (mainly) controls the pressure that the FD runs at. personally at this point I would however suspect other things as white smoke is not a indication of fuel burning but of either coolant in the combustion chamber or transmission fluid being sucked out of the transmission into the engine through a bad modulator. I would pull all of my plugs and report back on the colours and condition cheers Barri
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61 Austin mini 67 Lotus 7 74 450sl 76 Cadillac 8.2l (501 ci) some new cars megasquirt conversion on: djet 74 450sl http://www.mercdjetmegasquirt.britautorepair.com/ cis 76 450sl http://www.merccismegasquirt.britautorepair.com/ the best view is always from the point of no return |
#8
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Quote:
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#9
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Since I'm relatively unfamiliar with the FI systems on these cars all I can give is a general observation here. White smoke can be fuel boiling rather than burning. How's the ignition? Is it running on all 8? I'm sure the mech. thought about that though...
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-Evan Benz Fleet: 1968 UNIMOG 404.114 1998 E300 2008 E63 Non-Benz Fleet: 1992 Aerostar 1993 MR2 2000 F250 |
#10
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That does not mean you don't ever have to replace the O2 sensor. If the car has over 70,000 miles replace it. It's a major component for lambda control.
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Question Authority before it Questions you. |
#11
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got to agree with 450slcguy the o2 sensor is a major part of the system and controls enrichment feedback when normal running. if your o2 sensor is bad it will slowly enrichen the mixture to defaults. most o2 sensors last about 60k miles and then start to be very slow to respond. all narrow band sensors work the same way and so long as you are able to splice wires you can replace them. I just bought 2, 4 wire o2 sensors for $10 off ebay, gm sensors for a suburban as i remember. put one in my jag and one in my mercedes 450sl (I have djet but use it to run an air fuel mix meter). they work just fine
cheers Barri
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61 Austin mini 67 Lotus 7 74 450sl 76 Cadillac 8.2l (501 ci) some new cars megasquirt conversion on: djet 74 450sl http://www.mercdjetmegasquirt.britautorepair.com/ cis 76 450sl http://www.merccismegasquirt.britautorepair.com/ the best view is always from the point of no return |
#12
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Not to discount all the 'replace the O2 sensor' advice...but in this particular case, according to his post the number eight cylinder is wet. This would not be a sensor issue.
Check the the spark plug at the suspect cylinder and confirm the fuel wet condition. Swap that injector to another cylinder. Run the engine. Check both spark plugs for fuel wet condition. If the wet plug follows the injector, replace the injector. If the wet plug remains at the number eight cylinder, the fuel distributor is suspect.
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1978 450 SLC |
#13
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Thanks everyone for all of the advice.
Before I took the car into him, I had been told that the WUR was the most likely culprit, but I had also been told to have the cooling system pressure tested as well, to maybe account for the white smoke. When I took it in I told him these things and specifically told him about the WUR - when they were done with all of the tests, he said it was only the FD and that everything else, even the WUR were working just fine. But that's the reason I wanted to put this post up, to check and see what others thought. While I'm trying to get this worked out, I may go ahead and replace the 02 sensor AND WUR, just incase, and see what happens. Now, another question. With all of this in mind, how bad is it to drive the car for a little while? I realize I'll be getting horrible MPG, but is that pretty much the only major problem, or will doing so cause more damage? |
#14
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Will this one fit??
Another question...
Fellow forum Member Lexxani has offered to pull a Fuel Distributor from another car and send it to me, however it's from an earlier 450SL with a 117.982 engine. Will this fit my 1980 450SL with the 117.985 engine, or is the FD specific to this engine? |
#15
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FD is specific to this engine.
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Question Authority before it Questions you. |
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