Go Back   MBWorld.org Forums > Mercedes-Benz Sedans > S-Class (W126)
Sign in using an external account
Register Forgot Password?


S-Class (W126) 1979-1991: 300 SE, 300 SEL, 380 SE, 380 SEL, 420 SEL, 500 SEL, 560 SEL, 360 SEC, 500 SEC, 580 SEC, 300 SD TURBODIESEL, 300 SDL TURBO, 350 SD TURBO, 350 SDL TURBO

Welcome to MBWorld.org!
Welcome to MBWorld,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
 
 
 
LinkBack Thread Tools Search this Thread Rate Thread Display Modes
Old 08-07-2011, 11:06 AM   #1
Newbie
 
Join Date: Aug 2011
Posts: 1
Drives: 1985 500 SEL; 1990 Mercedes 300SL
1985 500 SEL questions and input needed...

I just bought a Mercedes Benz 1985 SEL, Its seems to have a miss in the engine when it first starts and while slowly driving, once you get on the highway it does 75/80 MPH with ease, and feels like it did in 1985. I do not know when the last tune up was performed but I am planning on putting new wires, plugs, and distributor on it. Is there anything else that you would think I need to place on it.

The exhaust also has a small hole in it, so as the car is idling it has a "throbbing" feel and sound to it. Are there any concerns, should I not be driving a few miles a day until I have this all fixed. I want to keep the car OEM stock entirely, and bring it back to the showroom condition. However, has there ever been any success with a dual exhaust in these cars or is that a bad idea?

I am just driving it now to get a feel for the car and find any issues before I start tearing it apart.

Lastly, my climate control and radio does not work. However, when you turn the key on to the first position to give the car electricity my defrost comes on, has anyone ever experience this issue. I put a new (old) fuse into the climate control position and it immediatley blew when I turned the key, so I thought it could be a relay. If anyone has any thoughts I would love to hear them.

At 190Mi the car still runs like a dream, I bought it from the second owner in Columbus Ohio who owned the car since 1991. He was an older guy that maintained it well, for the 20 years he owned it. Please give me your thoughts on the car and what you think.
To remove this ad, register today or login if you already are registered!

ccstout is offline   Reply With Quote
Old 09-11-2011, 01:38 AM   #2
Newbie
 
unomas's Avatar
 
Join Date: May 2011
Location: USA
Posts: 8
Drives: 1985 MB 500SEL
Hi ccstout,

I am new to this forum, but I also drive an '85 500 SEL. Mine has 254k miles on the odo. I respect you very much for opting to keep yours stock. Mine is, and I can't tell you how much that means in the long run. My most sincere apologies if I go on telling you stuff you already know. I'm trying to break it down for everyone else's benefit.

As a general statement, this particular model and year has certain advantages over a 1986 or newer, second-generation W126. For starters, the systems were very refined and streamlined. There were few to none of the problems typical for first-model-year cars.

The M117 engines are really, really well engineered for a car from 1985. The Bosch Jet-Tronic F.I. system is really sturdy and durable. The main things that need to have attention given to them in this engine series are the following:

* Timing Chain replacement -- Very Important!!! I change mine every 70k miles now. These are "interference" engines and you will have to rebuild the cylinder heads if the chains slack or break ($$$$). The previous owner of mine broke the factory-installed chains at 171k miles and had to rebuild.

* Filter replacement -- I use the Severe duty cycle from the manual and new BOSCH filters.

* Tune-up with new plugs every 20k miles. I use Champion Single Platinums for cost-efficiency.

* New Wires when needed. I'm on my second set in 50k miles.

* My MB Mechanic said there is a 3mm allen-wrench slot in the air cleaner assembly that can be used as an adjustment for correcting rough idle. I haven't needed to do this myself. I can ask him more about this if you need the info.

* Belts every 50k miles.

This series of engines has been known to last for a very, very long time if maintained well. You will save $$$$ in the long run by putting $ into it every little while. I have personally seen a W126 with the 5.0L going strong at 420k miles, on the original motor.

No, I haven't seen any W126 5.0's with an aftermarket dual exhaust that looked good or sounded good. Keep the Euro look by going with something like this: 500SEL AMG Exhaust


One big thing to consider replacing would be the shocks and some brake components. These parts are, of course, designed to wear out and need replacing. I chose the OE Spectrum series from MONROE for my shocks. I replaced the calipers and the master cylinder with Centric brand parts I got on RockAuto.com.


I have run into similar issues as you have with the climate control, but not the radio. I am still having fun with the electrical systems, as the previous owner didn't hesitate to splice, chop and solder 'til kingdom come....

In my case, I had two separate issues on the Climate Control (mine is the thermostat-based "little wheel" automatic climate control). The first problem to solve was getting power to the dash (control) unit, the second was getting power to the blower unit in an orderly way.

Now comes the troubleshooting guide for the electrical. You can use this for all of your electrical troubleshooting on the various systems.

If you aren't handy with electrical systems, are really afraid of getting shocked or don't have time for all of this, print this post off and take your car into a decent local mechanic with good electrical know-how.

My personal recommendation is to avoid the national branded places like pep boys and especially the car audio shops, because our cars are special. For instance, a young mechanic or car audio guy with minimal training and experience is likely to make things worse or, at best, just waste your time.

For a little basic information, your fuse panel is the best place to start, as it is the very easiest to access. I agree that it could be a relay, so let's start with the fuse panel to narrow it down to which relay it is.

Items needed:

1. #1 or #2 Phillips head screwdriver, plastic handle (usually less than $1.00 at a hardware store).

2. One or two packs of GBC 8A fuses -- white (about $3-$4 each at most places).

3. Digital multimeter (cheap at HF, expensive most other places)

4. Flashlight (preferably a small one or a head-mounted style)

Start by taking a look at fuse #10 (White), which according to the info card is the circuit for a host of things, including your reverse lights, your climate control dash unit and the little temperature display that's right above the steering column on the dash. As a side note, try this test: set your parking brake and put the trans shifter into reverse with the key in the "on" position and the engine off, see if your reverse lights come on.

You said this fuse (?) was blowing as soon as you gave it power -- if this is happening, you must have a short or a overload. Start out by checking the terminals under the fuse slot for #10. Remove the two Phillips-head screws securing the fuse panel to the plastic fuse-box case and lift the panel up and forward to pull it out. Do not hesitate to pull firmly, you won't hurt anything. Now, take a light and look closely at the wires hooked up to the screw terminals on #10. In my case, one of the screws vibrated loose over time and wasn't making a good connection. Make sure that each wire that is hooked up has the little factory sticker on it that says "10" (this is about 1 inch away from the end of the wire) or whatever number of fuse you're working with. If it doesn't please reply to this post immediately and put up a photo, please.

If all your wires are in the right places on the fuse terminals, we have eliminated the possibility of a problem in the fuse panel for this circuit. You can close the panel up and turn the ignition on to see if you are still having the problem, and if you are, we will go right back into the panel to test each wire individually.

If you have a Multimeter handy, then check the power coming in on the black power supply wire. You should get 13.8 volts. If this is checks out OK, we should look at each of the load wires individually, which requires connecting ONE OF THEM AT A TIME to the load side of the fuse terminal. You should have a pack or two of white (8 amp) GBC fuses handy for this troubleshooting, in case you blow a few of them. Fuses - 5 pack

Connect each load wire one at a time until you find the one that is blowing the fuse. If none of them do it, then start checking them in pairs. Once you find the one that is doing it, note what color it is and then cover the end of it up with electrician's tape. Reconnect the remaining wires and close the panel up for now. Go down the list of systems on the info card, testing each one to see which one that wire belongs to. Now we can find the appropriate relay to replace.

If replacing the relay(s) doesn't do it, we need to look at two things: 1) the wire runs to the device/system. 2) the connections to the system (i.e. the terminals on the back of the climate control unit in the dash.

This is all the time I have for now... I will try to follow-up as soon as possible. Please don't hesitate to reply to this post or send me a Private Message with any thoughts / observations / questions / grumblings....

Hope this helps!


UNO
unomas is offline   Reply With Quote
Old 03-11-2012, 03:04 PM   #3
Junior Member
 
Join Date: Mar 2012
Posts: 21
Drives: 85' 500 sel
Quote:
Originally Posted by unomas View Post
Hi ccstout,

I am new to this forum, but I also drive an '85 500 SEL. Mine has 254k miles on the odo. I respect you very much for opting to keep yours stock. Mine is, and I can't tell you how much that means in the long run. My most sincere apologies if I go on telling you stuff you already know. I'm trying to break it down for everyone else's benefit.

As a general statement, this particular model and year has certain advantages over a 1986 or newer, second-generation W126. For starters, the systems were very refined and streamlined. There were few to none of the problems typical for first-model-year cars.

The M117 engines are really, really well engineered for a car from 1985. The Bosch Jet-Tronic F.I. system is really sturdy and durable. The main things that need to have attention given to them in this engine series are the following:

* Timing Chain replacement -- Very Important!!! I change mine every 70k miles now. These are "interference" engines and you will have to rebuild the cylinder heads if the chains slack or break ($$$$). The previous owner of mine broke the factory-installed chains at 171k miles and had to rebuild.

* Filter replacement -- I use the Severe duty cycle from the manual and new BOSCH filters.

* Tune-up with new plugs every 20k miles. I use Champion Single Platinums for cost-efficiency.

* New Wires when needed. I'm on my second set in 50k miles.

* My MB Mechanic said there is a 3mm allen-wrench slot in the air cleaner assembly that can be used as an adjustment for correcting rough idle. I haven't needed to do this myself. I can ask him more about this if you need the info.

* Belts every 50k miles.

This series of engines has been known to last for a very, very long time if maintained well. You will save $$$$ in the long run by putting $ into it every little while. I have personally seen a W126 with the 5.0L going strong at 420k miles, on the original motor.

No, I haven't seen any W126 5.0's with an aftermarket dual exhaust that looked good or sounded good. Keep the Euro look by going with something like this: 500SEL AMG Exhaust


One big thing to consider replacing would be the shocks and some brake components. These parts are, of course, designed to wear out and need replacing. I chose the OE Spectrum series from MONROE for my shocks. I replaced the calipers and the master cylinder with Centric brand parts I got on RockAuto.com.


I have run into similar issues as you have with the climate control, but not the radio. I am still having fun with the electrical systems, as the previous owner didn't hesitate to splice, chop and solder 'til kingdom come....

In my case, I had two separate issues on the Climate Control (mine is the thermostat-based "little wheel" automatic climate control). The first problem to solve was getting power to the dash (control) unit, the second was getting power to the blower unit in an orderly way.

Now comes the troubleshooting guide for the electrical. You can use this for all of your electrical troubleshooting on the various systems.

If you aren't handy with electrical systems, are really afraid of getting shocked or don't have time for all of this, print this post off and take your car into a decent local mechanic with good electrical know-how.

My personal recommendation is to avoid the national branded places like pep boys and especially the car audio shops, because our cars are special. For instance, a young mechanic or car audio guy with minimal training and experience is likely to make things worse or, at best, just waste your time.

For a little basic information, your fuse panel is the best place to start, as it is the very easiest to access. I agree that it could be a relay, so let's start with the fuse panel to narrow it down to which relay it is.

Items needed:

1. #1 or #2 Phillips head screwdriver, plastic handle (usually less than $1.00 at a hardware store).

2. One or two packs of GBC 8A fuses -- white (about $3-$4 each at most places).

3. Digital multimeter (cheap at HF, expensive most other places)

4. Flashlight (preferably a small one or a head-mounted style)

Start by taking a look at fuse #10 (White), which according to the info card is the circuit for a host of things, including your reverse lights, your climate control dash unit and the little temperature display that's right above the steering column on the dash. As a side note, try this test: set your parking brake and put the trans shifter into reverse with the key in the "on" position and the engine off, see if your reverse lights come on.

You said this fuse (?) was blowing as soon as you gave it power -- if this is happening, you must have a short or a overload. Start out by checking the terminals under the fuse slot for #10. Remove the two Phillips-head screws securing the fuse panel to the plastic fuse-box case and lift the panel up and forward to pull it out. Do not hesitate to pull firmly, you won't hurt anything. Now, take a light and look closely at the wires hooked up to the screw terminals on #10. In my case, one of the screws vibrated loose over time and wasn't making a good connection. Make sure that each wire that is hooked up has the little factory sticker on it that says "10" (this is about 1 inch away from the end of the wire) or whatever number of fuse you're working with. If it doesn't please reply to this post immediately and put up a photo, please.

If all your wires are in the right places on the fuse terminals, we have eliminated the possibility of a problem in the fuse panel for this circuit. You can close the panel up and turn the ignition on to see if you are still having the problem, and if you are, we will go right back into the panel to test each wire individually.

If you have a Multimeter handy, then check the power coming in on the black power supply wire. You should get 13.8 volts. If this is checks out OK, we should look at each of the load wires individually, which requires connecting ONE OF THEM AT A TIME to the load side of the fuse terminal. You should have a pack or two of white (8 amp) GBC fuses handy for this troubleshooting, in case you blow a few of them. Fuses - 5 pack

Connect each load wire one at a time until you find the one that is blowing the fuse. If none of them do it, then start checking them in pairs. Once you find the one that is doing it, note what color it is and then cover the end of it up with electrician's tape. Reconnect the remaining wires and close the panel up for now. Go down the list of systems on the info card, testing each one to see which one that wire belongs to. Now we can find the appropriate relay to replace.

If replacing the relay(s) doesn't do it, we need to look at two things: 1) the wire runs to the device/system. 2) the connections to the system (i.e. the terminals on the back of the climate control unit in the dash.

This is all the time I have for now... I will try to follow-up as soon as possible. Please don't hesitate to reply to this post or send me a Private Message with any thoughts / observations / questions / grumblings....

Hope this helps!


UNO
Hey I am new to this forum and mb. I just bought a nice 85 500 that was mechanic owned. They told me something was wrong with the injectors. Like you it had a miss at idle and sometimes a high idle. While surveying the car I checked the fuse box and found a relay that had a 10 amp blade fuse. It was blown so I changed it. Boom injector prob fixed the car came to life and runs great now. Good for me cause the sold the car to me for 1k because of that problem.

I have no dash lights or console lights working. Any suggestions?
Mblifer is offline   Reply With Quote
Old 03-25-2012, 10:46 PM   #4
Junior Member
 
Join Date: Aug 2011
Posts: 22
Drives: 87 560SEC (Euro)
Vacuum leaks, blocked injectors or a fuel blockage in the fuel distributor will cause a miss at idle that is masked at higher speeds. Try honing in on the cylinder that's missing and clean the injectors then get back to us.
alabbasi is offline   Reply With Quote
Old 04-06-2012, 08:32 AM   #5
Newbie
 
unomas's Avatar
 
Join Date: May 2011
Location: USA
Posts: 8
Drives: 1985 MB 500SEL
Great to hear that that solved it! It's amazing how quickly you can fix things by knowing where to look!

UNO
unomas is offline   Reply With Quote
Old 04-06-2012, 08:47 AM   #6
Newbie
 
unomas's Avatar
 
Join Date: May 2011
Location: USA
Posts: 8
Drives: 1985 MB 500SEL
Thumbs up

Quote:
Originally Posted by Mblifer View Post
Hey I am new to this forum and mb. I just bought a nice 85 500 that was mechanic owned. They told me something was wrong with the injectors. Like you it had a miss at idle and sometimes a high idle. While surveying the car I checked the fuse box and found a relay that had a 10 amp blade fuse. It was blown so I changed it. Boom injector prob fixed the car came to life and runs great now. Good for me cause the sold the car to me for 1k because of that problem.

I have no dash lights or console lights working. Any suggestions?
These lights are run off of Fuse 1 in the panel. Might start there with the loose connection theory. I could not attach the entire electrical troubleshooting manual for an '85 500 SEL in PDF format because it is too large, but I will try to cut it down and re-post soon.

Hope it will help!

UNO
unomas is offline   Reply With Quote
Old 04-09-2012, 04:42 PM   #7
Super Member
 
Join Date: Aug 2005
Location: Mercerville New Jersey
Posts: 795
Drives: 1991 560SEC Teal 1989 420SEL Ice Blue 1984 500SEC White
I have a stock 84 500 euro I am taking apart. This is the same as your 85.

Most likely the heating problem is the control unit, itself. Replace or send out to be rebuilt.

Good Luck
Bruce
BENZITCH is offline   Reply With Quote
Old 03-27-2013, 01:54 PM   #8
Newbie
 
Join Date: Mar 2013
Posts: 1
Drives: mercedes benz 500sel 1985 w126
mercedes benz 500sel 1985 w126 5.0

I have a starting problem with my 1985 mercedes 500sel w126 5.0 engine. Im starting with the fuses which seem to be OK. There is one blown metal strip fuse in a glow plug box a few inches coming out of the large main fuse box that is blown. My question is should I replace that metal strip fuse and what is its main function. What would a glow plug fuse be doing in a gasoline engine? Does it have anything to do with the kick down fuel relay box that is in the fuse box. thanks
glendinning2 is offline   Reply With Quote
Old 03-27-2013, 02:24 PM   #9
Junior Member
 
Join Date: Aug 2011
Posts: 22
Drives: 87 560SEC (Euro)
On my 1991 560SEL that strip was used in the circuit for the electric fan in front of the radiator. Whatever it's for, If it's blown, replace it.
alabbasi is offline   Reply With Quote
Old 03-27-2013, 03:42 PM   #10
Junior Member
 
Join Date: Mar 2012
Posts: 21
Drives: 85' 500 sel
Fuse

If I understand correctly you have found a blade type fuse located on top of a relay in the fuse box under the hood.i think it is called the over voltage fuse, should be a 10amp.
Change it and see what happens. Might solve your problem. If not you are only out .25 cents. That's the cheapest part on the car.
Mblifer is offline   Reply With Quote
Old 03-27-2013, 03:42 PM
 
 
 
Reply

Tags
1985, 500, 500sel, 50l, drives, ece, forward, mercedes, put, rear, removing, reverse, revive, sel, shock, turbocharger, w126



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off




All times are GMT -4. The time now is 08:21 PM.


Copyright 2001-2012 InternetBrands, Inc. / MBWorld.org. All Rights Reserved.
Everyone's Personal Details