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Discussion Starter #22
The cruise control thing indeed. I unplugged it for now as I still need to get it running before I worry about fixing “luxuries” lol.

Yesterday, I wanted to do a smoke test so I freed the line from the brake booster and blew in cigar smoke. Leaks coming from either the air distribution hoses, injector seals, or injector holders. Putting those on order. That was the only place I saw smoke come out. It doesn’t seem like that much to cause the vacuum leak that It seems like it has. I know only the defroster works, blows hot and cold but the dash vents do not. Could a bad check valve and bad pods contribute to a vacuum leak or are the vacuum systems separate?
Went to change the fuel filter last night to find all of the steel lines pretty well rusted. I don’t know whether the filter is original or not but it is factory Mercedes and looks as old as the ugly-ducking fuel pump. I cannot free the fuel line going out from the filter. Though when I let the filter drain from the inlet side, it was rusty. Soaking it in pb blaster now, hoping for better luck tonight. Will probably have to pull the whole assy. From the car and the fuel tank and just completely recondition. What are the chances this is the cause of my idle problems? Crossing my fingers I can just do the back end fuel system, clean injectors, and get it roadworthy. I don’t want to rebuild a distributor but I rebuilt the power seat switches... and that’s pretty much the same thing ;)
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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Now that the cruise actuator is disconnected there is no more of that nasty scraping clacking?

M.
 

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Discussion Starter #24
Now that the cruise actuator is disconnected there is no more of that nasty scraping clacking?

M.
Yes, no more scraping. It looks like the motor inside is worn, but it also doesn’t shut off and drains the battery. I removed it and expect maybe a cruise control relay is bad? Regardless, ordered whole new back end fuel system last night, pumps, accumulator, strainer, check valve, all new lines except from rear to front of car, little 2 sided “filter” nut thing from fuel line to FD, steel fittings, and crush washers. I should pull the tank to clean it and try to rebuild the sender (stuck on half). Truth be told, the plan for this car was to fix, enjoy, and hopefully sell for a profit. I don’t believe it’s going to go this way and while the diagnosis is a pain in the ass, it’s easy to work on, the hood goes 90 degrees, and it looks very nice. Hopefully she’ll get sorted before I bury myself in it
 

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Discussion Starter #25
Hey guys,

Finally got some time to put some work in on the benz. Today i'm in the process of replacing the fuel pumps, filter, accumulator, fuel tank vent valve, and a couple of fuel lines that are pretty shot looking. There was a fair bit of rust in the filter and a little sludge in one of the fuel pumps. The hard line that I had purchased from PelicanParts that connected the filter, pump, and accumulator had the wrong thread size for the accumulator, that was annoying, so back for return and reusing the ugly, rusty line. I bought a tank screen but am having trouble finding a tool that will actually get it off. When I bought the car I was told the tank was empty, the sender is stuck in half position, and I had only added a couple if gallons to see if it would run. Disconnected the fuel pump and.... easily 10+ gallons in the tank. Thank god I had empty 5 gallon buckets next to me. I assumed there would be more rust in the tank due to what came out of the filter but the fuel really didn't look all that bad. Some sediment came out of the fuel pumps, one definitely looks original. I'm crossing my fingers and praying that my issue is mechanical and not electrical in nature as that's not exactly my forte, but then again, working on anything this old isn't. I bought pretty much every hose from the tank up to the line that takes the fuel to the distributor but once under the car I see only a few need replacing, the rest are still quite supple and in good shape.

Additionally, I took off the line to the brake booster and blew a cigar in there to try and find any leaks. Looks like it was leaking from 4 injectors/the air distribution hoses so I'm going to change all of the injector holders, seals, air distribution hoses, and I got a single new injector just to compare spray patterns.

My question is this: Are these symptoms consistent with my issues? Car fires immediately when cold, but won't stay running without constant gas application. When warm, it will run on its own for an indeterminate amount of time, sometimes stumbling and catching itself, shooting revs up to around 1k, and then falling back down to below idle, but generally catches itself and stays around 600-700. Can rev up to 2k+ (haven't pushed it) and sometimes it dies whilst the revs fall. It will generally run on its own, dying sporadically (sometimes 3 minutes, other times 15 minutes) but total about 20-30 minutes at which point it will start again but won't stay running more than a few seconds. Wait an hour, come back, and will fire right up, but with same symptoms as before. I guess i'll have my answer in a few hours, but if this isn't it what COULD it be? I'm tackling my fear of electrical today and buying instead of borrowing a multimeter to test electronics. Green wire, passenger footwell, what is this? A mouse chewed the sheathing off, I ET'd it back up but thought it may be important?

LASTLY, could the O2 sensor still be faulty even if the O2 sensor light is NOT on?

I would have never bought this car if I hadn't found this forum first, so thank you guys for providing a valuable resource to a wannabe like me :)
 

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Discussion Starter #26
Well this isn't going as planned... Cut the fuel line from the filter to the feed line and whilst trying to disconnect it I twisted and pinched the metal line that I believe goes to the front of the car. Was going smoothly up until that... Can anyone point me in the right direction on what I do from here? The new line is $200+ and I don't know if you can purchase the hard line section by itself or how it goes back together. 😓 Maybe I should have bought a chevy LOL
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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What a pain that fuel line too!

If you don't want to do the whole line, how about sectioning in some new joined with a compression fitting?
 

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Discussion Starter #29
What a pain that fuel line too!

If you don't want to do the whole line, how about sectioning in some new joined with a compression fitting?
This! Any idea what specific tools I may need to accomplish this? Moreso connecting the hose with threaded fitting from the filter to the metal lines in question? Forgive me if this is a noob question lol. So far, the only downside to working on an old car is RUST... being from upstate NY I should probably get used to it :)
 

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1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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You'd need to get some steel line the same size as the twisted section.
Cutting out the damaged & remake that section, mate it to the existing good line with compression fittings.

Properly sized metal line

Small tubing cutter

Properly sized compression fittings

Metric Flare Wrenches will prove invaluable. Harbor Freight has a nice selection for about $15.

A metric tubing bubble flaring kit (a loaner from AutoZone) OEMTOOLS Metric Double Flaring Tool Kit

Safety glasses, yellow ones are great for under the car. I found some the other day that have reader lenses too!

Those are the bare facts, I guess..

Good luck man

M
 

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Discussion Starter #31
You'd need to get some steel line the same size as the twisted section.
Cutting out the damaged & remake that section, mate it to the existing good line with compression fittings.

Properly sized line

Small tubing cutter

Properly sized compression fittings

A metric tubing bubble flaring kit (a loaner from AutoZone)

Safety glasses

Those are the bare facts, I guess..

Good luck man

M
You rock dude, thank you! This is my new weekend project I guess
 

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Hey! I drive a Chevy too! :-D - a dead reliable stripped out '91 S-10 with a T5 and Iron Duke (psst - don't tell anyone but - I like it).

Regarding the filter in the tank, did you manage to change it? After much trial and woe I ended up using a large pair of tonge and groove pliers. You could almost certainly use an offset box end wrench (I didn't have one that large).

Pete
 

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Discussion Starter #33
Hey! I drive a Chevy too! :-D - a dead reliable stripped out '91 S-10 with a T5 and Iron Duke (psst - don't tell anyone but - I like it).

Regarding the filter in the tank, did you manage to change it? After much trial and woe I ended up using a large pair of tonge and groove pliers. You could almost certainly use an offset box end wrench (I didn't have one that large).

Pete
I frustrated myself in trying to find a way to connect the rubber hose from the filter to the feed line and raged out for the weekend LOL. Im going to take a crack at it again when I have time (for those of you who understand the real estate market right now in Upstate New York, that could be October, not that I'm complaining :)) I did find a bicycle fork tool that others on the forum say will suffice, so I may be ordering that. Truthfully, i'd really be balls to the walls on this project if I felt this was actually the fix for the car but I'm very pessimistic after my extensive forum research. I want this thing on the road but i'm still deciding at what point I want to cut my losses.
 

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Discussion Starter #34
The car seems to have a lifter tick that wasn't present when purchased, rises and falls with RPMs. I have not taken the covers off to check the condition of the chain and guides but I'm assuming at 92k miles and 33yrs (don't think it's been done), it is overdue. I haven't been rough with it, though maybe I gave it too much gas to keep her running whilst cold? Maybe the fuel system cleaner just removed the sediments and plugged it up even more? It seems to be on the cylinder that I think has a misfire. The oil seems thin, no scent of gasoline or any coolant, but it just doesn't seem right to me. No smoke from the exhaust. It doesn't sound like the chain slapping and it sometimes goes away. Dunno. Lucasoil and shut my mouth? Close to giving up but I just can't walk away.
 

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Discussion Starter #36
Alright guys, going for the gold here. After numerous trips to autozone, I’m not sure how to proceed. I was going to simply tap into the supply line where it runs straight with 3 other lines under the driver side of the car and connect it to the hose coming from the fuel filter but I don’t know the thread size. Anyone have this info? Should I just cut it and barb fitting a rubber hose and fit it to the metal line with a compression fitting?
 

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Discussion Starter #37
Okay, yesterdays post was dumb, fuel lines fixed, car is back together and now it DOESNT STALL! It was, im pretty positive, the tank vent valve. New one i could blow through but not suck, the one i pulled from the car had some resistance but a pop. Replaced in under 2 minutes and no more audible whoosh when pulling the cap off the tank.

Heres where i'm at: My cold start issue is the same, cranks a while, runs stupid rough and gas is needed to keep it running. Warmed, it still misses at idle, but smooths out when under acceleration. Have never driven a "good" example so i don't know what she's supposed to feel like but she felt strong. I replaced the air distribution hoses and found the stems to be cracked on all 8 injector cup ports. Didn't notice a huge difference, but the economy gauge sits a little closer to where it should.

Replaced:
Cap and Rotor
Plugs (NGK Non-Resistor)
Fuel Accumulator
Fuel Tank Vent Valve
Fuel Pumps
Fuel Filter
Metal fuel lines connecting pump/filter/accumulator assy
Fuel Accumulator
Various old fuel lines
Air Distribution hoses

I felt confident enough to insure it and ill be heading out tomorrow to register it and hoping a little driving will help diagnose/bring back the beast. Plug wires weren't replaced by me... they appear to be beru, the rubber is still quite supple. I did notice another small crack in a rubber piece on the top of the ICV, rubber that has a smaller, very thin clear and red line running to it and the stem it plugs in to has a small crack. I plan to replace, but what else could I be looking at here? Cold start valve? Coolant temp sensor? Thermo time valves? o2 sensor? Are there any other areas I should be checking for possible vacuum leaks? I figured I got the big ones with the air distribution hoses but the economy gauge tells a different story. At least now my project is drivable!
 
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