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1980 450sl - My "learn how to work on cars" car
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Discussion Starter #1
So here's the 411:

My 1980 450sl has been running pretty poorly lately, with the following symptoms:
  • Running sluggish
  • Poor MPG
  • Rough Idle
  • White smoke and gas smell out of exhaust
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:

  1. Can it be repaired?
    Is there any way that the particular problem that it's having can be repaired without having to replace it with a new distributor? I don't know the full functionality of it yet (i'm researching it), but is it possible that the fact that it's only dumping fuel into one cylinder mean that the whole thing isn't busted and can be fixed?
  2. Experience with re-manufactured units
    So I've also started researching what my best option is for replacing it, if that is what I need to do. Instead of $1,800 for a new one, I've seen re-manufactured units offered for the $400 - $500 range. Has anyone had any experience with these, or give me any advice for things to check out to make sure it's in good shape?
  3. Can I do the replacement myself?
    My mechanic also told me that it would be about a 2 1/2 job to replace the distributor with the new one. Is this a job I can do myself at home, or does it require skill beyond those of your evening mechanic?
Thanks for your help!
 

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1986 560 SL
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2001 SLK320, 2001 C320
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Perhaps you should check around here for a 2nd opinion. The fuel distributor gets blamed for EVERYTHING, correct or not! To me, it sounds like a messed up fuel injector on cylinder #8.
 

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-88 250D, -93 280TE-24 Sportline and -00 E270T CDI
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898 Posts
Perhaps you should check around here for a 2nd opinion. The fuel distributor gets blamed for EVERYTHING, correct or not! To me, it sounds like a messed up fuel injector on cylinder #8.
I agree, check the fuel injector nozzles first.. blowing the injectors and injector pipes clean with compressed air can help. :)
 

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It Is What It Is, Dude
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22,839 Posts
Check the spark plug to confirm fuel wetness in the suspect cylinder. Swap that injector with one from a different cylinder. Run the car. Check both spark plugs for the wet fuel condition. If the wet plug follows the injector, the injector is at fault. If the wet cylinder stays at number eight, the fuel distributor is suspect.
 

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Administratoris Emeritus
2021 SL770
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46,416 Posts
If your mechanic is correct about the problem, the fuel distributor is a likely culprit. There are many rebuilders out there, most do a rather poor job of it, Python being at the bottom of the rung. The best product out there, bar none, is our CIS Flowtech units. The job is not that difficult, you should be able to do it yourself. Afterward, at some point in the not too distant future, you should have the car scoped to make sure the CO is properly adjusted. Good luck!

Mercedes Fuel Distributors
 

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1998 SL500, 1959 220S, 1970 280SL
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I have installed two or three CIS Flowtech units and have been very pleased with the results. Core returns have been w/o problems.

The replacement is a bit tedious, but not difficult. While you are at it, you might consider doing the injector seals. You start the engine by jumping the fuel pump relay and richening the mixture until you just get some gas from a loosened fitting on the FD.

Since you have an '80, you can fine-tune the mixture with a dwell meter or a DMM with a duty cycle function.
 

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1980 450sl - My "learn how to work on cars" car
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Discussion Starter #9
Thanks for all of the advice.

If I were to try to remove the plug and swap injectors...how does one go about removing the injectors? I'm not familiar with that process, but I imagine there's plenty of resources on here for that?

Thanks!
 

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1980 450sl - My "learn how to work on cars" car
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Discussion Starter #10
So I just got off the phone with the mechanic who worked on the car, who, for the record, was the opposite of helpful.

In our 45 seconds of gleeful conversation in which he made it seem like every word annoyed him more than the one before, I was able to confirm that he did not, in fact, check the WUR like I had been told.

All he kept saying was that it needed a new FD. I asked him about the WUR and if that could have anything to do with it, and he just said that the FD was missing on #8 and that had to be replaced before it would do any good to test the WUR.

Based on y'alls experience, is it possible that the WUR could be the cause of the #8 missing, or is what he saying make sense?
 

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It Is What It Is, Dude
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22,839 Posts
If the #8 cylinder is fuel wet the FD is the most likely culprit. It certainly not a WUR issue. The WUR does control how much fuel the FD distributes, but the FD determines how fuel goes to each cylinder.
 

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2021 SL770
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^ What he said. If the problem is confined to one or two cylinders, warm-up reg is definitely not the culprit.
 

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1980 450sl - My "learn how to work on cars" car
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Discussion Starter #13
Great, thanks for the feedback. I was able to locate the FD from a 78 W116 which has the 117.985 engine...assuming that fits my engine, I'll get that installed and see how it goes.
 

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2021 SL770
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It will not fit, 1980 V8's use their own fuel distributor, different from pre-1980, and different from post-1980.
 

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removing the fuel injectors: using a small open wrench, turn clockwise the 4 fuel line connectors attached to the butt end of the injectors carefully. get a t-handle socket wrench 14mm size. remove the two nuts holding down the rubber seals of the injectors, the hold down piece is oval shaped flat metal. wiggle the injectors free. check the rubber seal if they're aged and hardened. if still pliable enough, take it to a fueltek injector pump shop. have it attached to the nozzle of a hand operated pump and crank the handle a few times to unseat the spring and observe the spray pattern, the spray should be atomized and should look like a small cloud. if even one of them sprays like a pee stream, replace the four with new ones. if the rubber seals have hardened, buy new injectors too, or use a thin coat of silicon rubber sealant.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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9,762 Posts
So I just got off the phone with the mechanic who worked on the car, who, for the record, was the opposite of helpful.

In our 45 seconds of gleeful conversation in which he made it seem like every word annoyed him more than the one before, I was able to confirm that he did not, in fact, check the WUR like I had been told.

All he kept saying was that it needed a new FD. I asked him about the WUR and if that could have anything to do with it, and he just said that the FD was missing on #8 and that had to be replaced before it would do any good to test the WUR.

Based on y'alls experience, is it possible that the WUR could be the cause of the #8 missing, or is what he saying make sense?
No WUR will effect all cylinders
 

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one of the major causes of poor engine performance and lack of power is the fouling up of the hairline-thin clearance between the plunger and the hole it snuggles up in inside the center of the fuel distributor. somehow, even with filters, sludge and minute rusty things end up up there. even if your fuel tank is plastic, the brackets inside the fuel tank holding the potentiometer of the fuel gauge gets really rusty. and if you have a metal fuel tank and if your car is about 15 yrs old, expect sludge, rust and varnish (from foul fuel) inside. better clean everything. including the inside of the fuel tank. put a meter long heavy chain inside and swirl it around in there for a couple of days, have the inside of the tank carwashed with hi-pressure water and dry it. apply rust converter too. and while you are doing this, never let the FD dry up without gas. or else,it will get stuck.
 

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500SLC #2624. Black on Black.
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removing the fuel injectors: using a small open wrench, turn clockwise the 4 fuel line connectors attached to the butt end of the injectors carefully. get a t-handle socket wrench 14mm size. remove the two nuts holding down the rubber seals of the injectors, the hold down piece is oval shaped flat metal. wiggle the injectors free. check the rubber seal if they're aged and hardened. if still pliable enough, take it to a fueltek injector pump shop. have it attached to the nozzle of a hand operated pump and crank the handle a few times to unseat the spring and observe the spray pattern, the spray should be atomized and should look like a small cloud. if even one of them sprays like a pee stream, replace the four with new ones. if the rubber seals have hardened, buy new injectors too, or use a thin coat of silicon rubber sealant.
Rogue1man, please follow the correct protocol for new posters. For your first post, you are meant to breeze in, and ask a question that has been answered in at least 15 previous threads. You should then complain when you don't get an immediate response, then you will get useful information at which point you will follow that info and leave without re-appearing again.

When people like you come along with helpful information, that is well written, for their first post, it ruins the balance.

Please go back and start again!

By now, I'm sure you know I'm yanking your chain! So welcome! Here's hoping you stick around!
 

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2008 E320 Bluetec, 1988 560SL totalled unto death). 1997 Dodge Ram 1500, 1983 300CD
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The original post

... is a year old. Has supercanuck fixed his problem? If so please tell us the method and result.
 

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2012 CLS 550 sedan
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212 Posts
Don't you just really not like it when someone asks a technical question and gets some good responses and never responds whether it worked for them or not? Man I really don't like that. Drives me nuts. I wanna know what worked and what didn't.
Maybe there could be a way of baring them from asking their next three questions, or something like that. How about imposing a fine? Or give them a black mark next to their name so we all know or something like that. And tell them why their questions aren't being posted. Maybe they will learn proper forum protocol, if there is any such thing.
To ask a good question and then fall off the face of the earth, just ain't right.

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