New GPs, Blows 80A Fuse
 

I made a new post since I could not find this particular glow plug system issue by searching.

The glow plugs are in and I finally feel well enough to work on putting everything back together. (I took out the intake manifold since my car is a 1987 300D, 603 engine...)3

I'm at the point where I need the photos I took before I started to make sure I get everything back where it is supposed to go. My camera is taking for ever to download...so to keep moving I decided to put the new 80A fuse in, turn on my dome light, and try the plugs to see if they work. I turned the key, the light dimmed, and two seconds later the fuse blew.

Cleaned all connections
checked for continuity on all 6 wires with each wire by itself, one at a time.
installed 6 new glow plugs
Connected up all 6 glow plugs
reattached the 6 pin connector to the relay
put in new fuse then tried as above.

Where do I go now? Is my relay shot?

-Jim

I found something to check
 

In another thread a guy posted that if the ring lug on one or more of the glow plugs is touching the block you will blow the fuse.

This gives me something to look for on my car.

I had been searching the forum for info on how to see if the relay was bad. I finally found something when I searched for my actual symptom. :o
I searched for "Blow Fuse Glow." Much better results...

http://www.peachparts.com/shopforum/diesel-discussion/133598-replaced-glow-plugs.html?highlight=blow+fuse+glow

-Jim

You need a meter with a full scale of 10 ohms for resistance.

Pull the plug to the relay and measure the resistance of each glow plug to ground. Report back with the numbers.

You're looking for a circuit with zero resistance.........continuity to ground.

The normal reading will be near 1 ohm.........hence the need for a very accurate meter to separate the two.

The glow plug relay is fine.

Not sure if it'll help, but if you need a GP harness I think I have an extra you can have... :)

I can see clearly now...
 

If you know what to look for it is much easier to find what is wrong.

OK, here is the question on the fix. The wiring harnes has several brackets that I assumed went under the intake manifold (between the intake and the block). There are two or three of them. Then hold the wiring harness in place. Are they supposed to go there? If not, then where?

The brace that I put under the bottom bolt is touching the #5 glow plug nut.

Where is the glow plug wiring harness supposed to be attached at? (Bolted down at?)

-Jim

It goes under the intake manifold bolts, NOT between the manifold and the head!

Hummm...I'm going to blame the cough medicine on that one...:D

It says do not operate heavy machinery. I guess that includes wrenches...

Good stuff...:silly:

I'll fix it in the morning.

Thanks,

Jim

I moved the bracets a few minutes ago. Everything works as it should now. I think my timer went 36 seconds.

How long should it be?

I'm basing my 36 seconds off of the dome light dimming and coming back on bright, and on the clicking of the relay. I did not even look at the dash light to see what it did.

-Jim

Just checked it again. The light stayed on about 5-6 seconds. The timer went 36 seconds.

Sweet!

Now if I can just figure out where all of the other brackets and bolts go...

35.223 seconds.;)

My GP relay fuse just blew due to my own negligence, so I went to my local MB shop to get some replacements (I wanted extras). They gave me 30A fuse strips. I was a little surprised and asked him about it, but he assured me it was the correct rating.

Is my favorite local shop right or wrong?

That's the 'strip fuse' on Phil's parts side. The 80a fuse is what you want, not the 30.

Wrong, I think...:)

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1YK1CBA9Q1YK1CDOW7&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1987&product=P2015-11766&application=001029523

The part for my 1987 300Dt shows as an 80A fuse.
The strip fuses for the 1987 300TDt do not identify one for the Preglow system.

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1YK1CBA9Q1YK1CDOW7&year=1987&make=MB&model=300-TDT-002&category=All&part=Strip+Fuse

Did they really make two different systems in the same model year for essentially the same engine? I bet not.

-Jim

Damn, well at least it works and I have two extras. Will be picking up the proper fuse tomorrow.

Thanks for the quick reply.