Fuse Strip ? Glow plug timer ? - PeachParts Mercedes-Benz Forum

Beastie · #1 07-05-2010, 01:30 PM

Here goes. An 85 300SD I recently inherited from my Dad. It has sat for awhile and I am getting reacquainted with this excellent car. As I go through and bring all the services up to date I am gonna have more than a few questions and have been doing searches in the archives of other sites as well.
Here goes my latest ???.
1. My Dad had a new set of Bosch glow plugs in a bag in the trunk along with a
notched metallic strip in a small parts bag.
2. The bag says Fuse strip and has a few different part numbers on it
178 3186 N17 125 3
3. The plugs are Bosch 80006
4. Currently the dash light for the plugs does not light and I do not hear a click
as in from the timer. The car starts immediately though ( I wait 30-40 seconds after the dash lights up anyway though).
5. There is a spot under the hood on the drivers side inner fenderwell that looks like something was mounted there at some point but is no longer there.

So what is this Fuse strip, where does it go, does this car have a timer for the plugs and where is it what does it look like ?
The ARS light in the dash came on while driving this to my home and as I thought all the belts were very loose so I am replacing them. The battery is 2 weeks old. I am hoping that with the belts done the ARS will go out and the dash glow plug light will come on. Any thoughts while I putter with this are appreciated.

toomany MBZ · #2 07-05-2010, 01:58 PM

There is a strip fuse on the relay, it's probably an 80 amp. Yet your plugs seem to be working, in that case, so would the fuse. Check the glow plugs with an ohm meter. Not hearing a click after 30-40 seconds doesn't fit in tho. It does have a timer, that is the four prong part, the five are for the glow plugs.
Inspect the pad sensor wires on the front wheel hubs, this may be causing the ARS (ABS?) light to stay on. It may be broken or the pads need replacing.

Beastie · #3 07-05-2010, 02:27 PM

Thanks for the quick response and the photo. Where is this relay located I had read somewhere it is on an inner fender well ? I am going to replace the glow plugs anyway since I have them. Also going to rebuild the injectors and am not certain when the valves were last adjusted. My Dad had some declining health issues and is not too helpful as to when these were done. This car was meticulously maintained until 5-7 years ago and has been garage kept. It was his pride and joy and special gift he bought after retiring from the USMC after
31 years. I may pick your brain from time to time if that is okay. I noticed you live in central VA. Where ? I live in Ashburn near Dulles airport.
Alan

micalk · #4 07-05-2010, 02:51 PM

Generally, located on the front of the driver's fenderwell, but you should be able to follow the wiring harness back from the glow plugs to the relay.

First, when you find the relay, there's a wire that goes to the dash light. Apply +12V to pin #3 on the four-pin plug and make sure the light works. It probably does. You may have only a single glow plug out. The relay module has a comparator circuit in it that measures the #1 glow plug against the sum of the rest of the plugs. Check #1 first, and if it isn't right, replace it and see if the light comes on then. If it does then save the rest of the glow plugs for issues further down the road. If it doesn't, replace them all. They're probably due.

Also remove the fuse, inspect it for a crack in the middle (it happens) and re-install it if it looks good. Keep the strip fuse in the glove box just in case.

My regards to your father for his service.

Beastie · #5 07-05-2010, 03:05 PM

Again , it is always great to get fast responses from the members here. I went back before reading your post and found the relay ( cheated and went to Peachparts site and looked for the relay and used there pics plus the one sent by toomanybnzs and found it. The relay does not appear to be broken however it does appear bent in the middle so I will remove an check ( it might be a small hairline break) also the one plug cap does not appear to be seated fully so I will clean and recheck once I have all the belts back on. As a long time owner of german cars using the bullet fuses I know they can look fine but are corroded where you can not see and thus to not allow proper operation. I will be changing all the fuses out. As for my Dad. He is still kicking but has dimentia with a touch of alzheimers thrown in. He has moments of great clarity at the most unexpected times. On the 4th at my parents home he thanked me for getting his Mercedes squared away for him since he wanted to take a drive and
see some of his friends ( all buried at Arlington National Cemetery)
I will update and add more questions as I proceed thanks again.
Alan

Beastie · #6 07-05-2010, 03:15 PM

Along the same line. Just below the ABS pump and to the left of the timer relay is a flat preformed mount with a bolt hole on the middle. It shows a slight ring of rust where possibly a washer rubbed. There is nothing mounted there but it sure seems as though something is missing. My Mom had this at a shop that was not specifically one that works on MB's let alone a Diesel. I did not feel comfortable with them but they were polite to Mom so she used them. I am
suspicious. Any thoughts as to what was mounted there. I try to take a photo
here later.
Again thanks
Alan

Diesel911 · #7 07-06-2010, 12:58 AM

The Glow Plug Relay Fuse is supposed to have that bent down dished area. That Bend helps keep it from breaking due to expansion and contraction.

The new Strip Fuse is flat. When you instll the new Strip Fuse leave the screws a little loose and use one of your Fingers to apply just enough pressure to slighly bend the Strip Fuse. Hold it there and tighten the Strip Fuse Retaining Fuse.

toomany MBZ · #8 07-06-2010, 09:10 AM

Just out of the other pic is a bracket of some sort, doesn't seem anything was ever attached on mine.

Beastie · #9 08-08-2010, 09:46 PM

Took a while to get back to this issue with the car ( had to replace a window regulator) however today I finally put my meter on the plugs and they are all good and the voltage climbs. I did finally hear the GP timer come on it was fairly quiet. I have brand new GP's in the trunk so I am going to install them anyway
the dash light still does not come on. I will take the advice from an earlier reply to this thread and trace it back to the dash and hope it is a wire. Otherwise
how bad is it to remove the dash on this and replace the bulb or can it be reached from below.
Thanks
Alan

Beastie · #10 10-17-2010, 05:47 PM

I finally had a few minutes and started to change out the glow plugs this afternoon. I quickly realized that I had all the tools I needed.........at my parents home. So I started into it anyway and as I removed the first one it did not look bad at all except for a thin coat of black almost crystalline like substance at the tip. I changed it out and promptly dropped the nut for the power lead and down it went. Looked and looked etc. finally sprayed some brake cleaner in the area that it fell and then shot some compressed air as well
( after placing a large SS catch tray under the car and ping there it fell.
I placed the lead on and tightened everything down. by now I saw it was going to take longer than expected without the proper tools so I started putting my tools away. When done I thought I would go ahead and see if it had affected the non functioning dashpod GP timer light. As I turned the key it flashed on and quickly went out. I tried again but no go. I pulled the key and did it again and bang the light came on and promptly went out. Anyway I will change the remaining plugs Monday and see what happens. The GP's get power and the timer gets power and you can hear the relay click and it has a brand new correct battery ( another thread). The only issue is no GP light and having to cycle the GP's 4-5 times when the temp drops below 69 degrees or so. I will update.
Alan

Diesel911 · #11 10-17-2010, 08:45 PM

Quote:

Originally Posted by Beastie

I finally had a few minutes and started to change out the glow plugs this afternoon. I quickly realized that I had all the tools I needed.........at my parents home. So I started into it anyway and as I removed the first one it did not look bad at all except for a thin coat of black almost crystalline like substance at the tip. I changed it out and promptly dropped the nut for the power lead and down it went. Looked and looked etc. finally sprayed some brake cleaner in the area that it fell and then shot some compressed air as well
( after placing a large SS catch tray under the car and ping there it fell.
I placed the lead on and tightened everything down. by now I saw it was going to take longer than expected without the proper tools so I started putting my tools away. When done I thought I would go ahead and see if it had affected the non functioning dashpod GP timer light. As I turned the key it flashed on and quickly went out. I tried again but no go. I pulled the key and did it again and bang the light came on and promptly went out. Anyway I will change the remaining plugs Monday and see what happens. The GP's get power and the timer gets power and you can hear the relay click and it has a brand new correct battery ( another thread). The only issue is no GP light and having to cycle the GP's 4-5 times when the temp drops below 69 degrees or so. I will update.
Alan

If you want to get a longer life out of the new Glow Plugs you should clean the Carbon out of the Glow Plug Holes.
There is a Glow Plug Reamer made for that our you can used one of the other methods from the DIY Section.
DIY Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82

http://www.peachparts.com/Wikka/DoItYourSelf

E_S · #12 10-17-2010, 08:00 PM

The GP timer needs a working temperature sensor. Have you measured the sensor? It looks a bit like the GP timer/relay thinks the engine is at operating temperature all the time..

toomany MBZ · #13 10-18-2010, 01:26 PM

I don't know about the sensor, but if your plugs need changing, go ahead and do so.

I have swapped out glow plugs both with the metal fuel lines off and on. Off is much easier, but it can be done either way.

Beastie · #14 10-18-2010, 01:55 PM

Hey Bob ! How are things going. I was going to PM you with a few questions but have gotten busy getting my 03 Suburban ready for Winter. My wife works at a Hospital in Washington D.C. and also at National aka Reagan National Airport. Both jobs the only excuse for not making it in to work even with bad weather is Death. Anyway as I posted before I got no light at all but I do hear the relay click. I checked before and was getting 11+ volts at each plug while the timer cycled. The light came on for the first time in many years. If you turn the key to the preglow position it comes on and promptly goes off in a split second. I am going to do the other plugs regardless ( what a pain to get to,
those crazy Krauts. First they give the world Lederhosen and then barely accessible recurring maintenance parts) But ES had a good comment earlier.
Where does the GP relay get the information to glow or not and for how long.
It is hard to start in the a.m. when it gets a little cool but is pretty much okay when it is hot out. I know the valves need adjusting ( still have not gotten around to it) and it has gotten slower as well. When it starts in the a.m. there is a large cloud of white smoke ( fuel unburnt ?) and very rough idle so much that i have to feather the pedal to keep it running and then it smooths out some. I also believe I need new injector nozzles( in a few weeks)
Also the mileage is down. I did find fuel weeping from around the banjo bolt on the valve cover side of the IP. It is the clear line that goes from the spin on fuel filter top ( return line ?) I snugged it up and will watch it to see if it stops. Ideas ?
Thanks
Alan

E_S · #15 10-18-2010, 06:59 PM

I don't know where the sensor is located on the OM617 engine (despite having one myself..), but I guess there isn't that many on the engine. I guess there is two - one for the temperature gauge in the instrument cluster and one for the glow plug system. Just pull one and see if the dash gauge reacts, maybe? If so, then it's the other one..