Strange glow plug issue want to go manual
 

I have a strange issue with my glow plugs on my 85 300 SD 617. It seems that when my light is out in my dash that tells me a glow plug is burned out. Well it seems when I change 1 at a time because I only believe in fixing whats broke the light on dash works for about 2 weeks and then another g.p. goes it seems it never ends. I would like to go to a manual set up with switch. I have read some posts on this but I am not clear on it. If I go manual will my current still be going thru my relay box? I do like when my light in dash tells me when a plug is blown. Will I still have this if I go manual? I think someone said you need a special solinoid that can take constant 12 volts all the time . Can someone tell me exactly what parts I would need and how to do this? I think if I go to manual set up my glow plugs will last longer as I will only use them when I need to. Tired of changing g.p.'s every 2 weeks. Even though I even ream out the holes before install.

There are probably dozens of manual solutions, all variations on a theme.

I use a Ford starter solenoid and connect it to a gutted glow plug relay. This allows me to use the stock harness and fuse and keep everything looking nice and tidy.

http://www.peachparts.com/shopforum/...glowrelay1.jpg

Post 8 in the following thread shows the mods I did.

http://www.peachparts.com/shopforum/diesel-discussion/322389-glow-plug-relay-1982-300d-turbo.html

I don't use a glow light in the dash as the click of the solenoid provides positive indication of the glows working.

Be sure to use a momentary switch so you can't forget it and burn up your glows.

What brand of glowplugs are you installing?

If Bosch, where are you buying them?

Back a few pages in my build thread is my manual installation. It's about as simple as it can get. Just the glow plug harness (I had lost mine so I made a new one), a Ford-style starter solenoid (you might want the constant-duty one), and a push button in the car. At the recommendation of the guys on here I also added a warning light from the glow plug side of the relay back into the truck - it lights when I push the button but more importantly it will stay lit if the solenoid sticks in the "ON" position - not good. Anyhow, dead simple.

I'm sure you could fix the stock system but it might take a lot of troubleshooting and maybe lots of expensive parts.

Good luck!

Dan

The only way the Glow Plug Relay can kill Glow Plugs if if it stays on all the time. If that was so you would be having charging and dead Battery issues.

Are you using only Bosch or Beru Glow Plutg?

This is my own opinion based on the fact that the Glow Plugs pull a high amperage till they get hot then the amperaged drops to around 16 amps and stays there.
If Carbon surrounds most of the Glow Plug tip I believe most the heat gets conducted into the Cylinder head and the Coolant and that heat conduction keeps the Glow PLugs cooler longer and keeps the Glow Plugs pulling higher amps for a longer time.

Cleaning out the Carbon from the Glow Plug Holes when the Plugs are out should fix that part of the issue.

The condition of your Injectors and essentialy anthing out of spec going on in the Precombustion Chamber can shorten the life of Glow Plugs.

The pic is part of the Mercedes Manual. I crossed off the part about Filiment/Loope type Glow Plugs as you do not have those.

I have the Ford type Starter Solenoid and Push Button on My Volvo Diesel and have had Zero issues with it. The Starter Solsnoid is make to pull way higher amps then the Glow Plug Relay does.

This is on a W123 and the square Connector on the Glow Plug Relay.

Glow Plug Wire colors on the square Connector and where they go.
Here is a description of the numberd sockets:

1) rd/bk (Black) ignition switch (Voltage goes thorugh this to turn on the Glow Plug Relay, if you cut the Wire and wired a push button Switch to it and your GP realy is still good you could use the button Switch to turn the Glow Plugs on and retain the feature that tuns the Glow Plugs on while the Engine is cranking bay way of the Purple Wire on a W123. I also believe the Glow Plug Light would still work if you do this.)

2) vi (Violet/Purple) On turbo models goes to a Wire Terminal/Junction block and mates with a White Wire coming up from the Starter Solenoid. When you Crank the Starter + Voltages goes through the White Wire to the Violet one and turns the Glow Plug Relay On. (You could disconnect this wire at the Terminal Block or the small Terminal at the Starter Solenoid and wire it to a push button Switch.)

3) blu/wt (Blue with white strip)glow indicator Light

4) br (Brown)ground

I did the Ford starter solenoid as well, but went with a toggle instead of a momentary button. Sometimes it's necessary to glow for 30+ seconds and I didn't want to have to sit there with my finger on a button the whole time. Open the door, flip the switch, climb in, buckle seatbelt, adjust mirrors, etc while the GP's are doing their thing. Then turn key, start engine, turn off GP's.

A nice addition is a 50 or 60C temp switch in a coolant line to short out the ground to the relay when the car gets warm. This will give you a nice few minute afterglow and be a safety shutoff in case you forget to flip the switch off. You could also just use the ignition switch as the glow switch this way. The plugs wouldn't come on at all with a warm engine though so you could add manual override button for when the car is warm so you can glow a few seconds when the car is hot if you want. Personally i like the mb relays and they are pretty cheap and the new ones have afterglow.

Even when I was in my 20s My memory was too bad to reilably remember to turn off something like the Glow Plugs.

I have at lest twice on on other cars managed to get out of the Car and ignoring the Buzzer telling me the Head Light were on and came back to a dead Battery.

Part of one of our Members pic showing the differance between the shorter Glow Plug used in where the Afterglow is used. I am guessing that the afterglow Plugs are shorter to keep the away from the burning Fuel sice they are going to remain on longer and are already hot longer.

glow plug issue
 

Thanks for replys as for right now with temps. in the 30-40's the car has no trouble starting. I think all the g.ps. are working but have not checked them yet. I think when this happened about 2 weeks ago the light in the dash would work and then not work and eventually not go on all at which time I did find a bad glow plug replaced it and now 2 weeks later same problem. I am useing bosch g.ps. from A.Z. I read from a post today the light on dash is controled by a temp. sensor which on an 85 300 SD is located in the relay is this correct? Because if so maybe this is my problem if my glow plugs check out ok but yet the light on the dash is not coming on.

I used to change only the bad glows, but it is pretty time consuming and they are a part with a definite life. Now if one goes bad I generally change all of them.

I have the A.Z. Bosch Plugs in mine. All of the ones I have bought from them have been made in France and the last lot I bought as spares had the Holigraphic sticker on the Box.

After installing the Bosch Plugs over 5 years I go I have had no failures.

However, it is warm here so the Plugs don't get much of a workout and If I have the Fuel Injection Lines as I did when I re-timed the Fuel Injection pump (X2) and after I did the compression check I pulled the GPs (I also checked the opening/pop pressure on the Injectors) and reamed the holes.

This is definitely a valid concern. I have pretty bright indicator light that turns on with the GP's, hard to miss. 10k miles on the swap, haven't forgotten and left it on yet, knock on wood...........;)

I have an 84 & 85SD. The glow system works flawlessly at 200,000 and ~250,000. It would be more productive to repair your system than to put the effort into rigging something that generally works. Look into a glow plug reamer if yours are burning out and you installed Bosh plugs. Changing how the system turns on and off will not fix the problem of the plugs themselves burning out.