Just had a starter motor and oil pressure sender unit put in. Now the glow plug relay 80 amp fuse link gets blown every time I turn on the car. Gone through three already. Have a wire in there now to start the car. Have a feeling something's no longer grounded properly? Any one ever have this issue? Any ideas appreciated. Would love to get the proper fuse back in there.

Not sure but I'd recommend that you remove the piece of wire before you have a fire. If the 80 amp fuse blows right away you must have a serious short circuit. Check the glow plug wires to make sure one is not pinched/shorted and try disconnecting glow plugs to see if the short goes away, maybe one of them is shorted. Check the ends where the wires screw on to the glow plugs to be sure the metal eye is not grounding out on anything.

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Brian
87 300Dturbo 180K #14 head still running R-12 SOLD 12/2017
02 F350 Powerstroke 180K
05 Chevy Express 1 ton w/Royal Utility box 120K
08 Infiniti FX-35 40K
15 Golf Sportwagen TDI 35K
10 Sprinter 3500 chassis with a Class A Winnebago on it. 56K

I know it's tight visibility in there, but you have to follow the glow plug harness from the relay to each and every plug and find the one that the starter mechanic pinched.
one is grounded, and killing the plug. using a wire will cause a fire and destroy your car... don't do it.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Good thinking in the last post and probably very accurate in your case.


Another reason for not using a wire as a as a temporary fuse is you might flow more current through the glow plug relays contacts than they can tollerate. The weakest link in the glow plug circuit is going to suffer the most stress.

A dead shorted glow plug. That is one showing zero resistance is a not unknown cause as well as a feeder wire to a glow plug being shorted out somewhere. Keep this in mind for future issues if any.

thanks guys, will take the wire out right away and start testing the plugs/wires to see what I find.

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1987 300td 240k #14 head

If somewhere on the Wiring Harness there is a Steel Bracket with a Rubber sleeve or coating on it the rubber typically deteriorates and can rub through the Insulation on the Wire.

Someone in another thread mentioned that if you disconnect the Connector going to the Glow Plugs themselves and you try to Preglow and the Fues Burns you have an issue in your Relay.

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84 300D, 82 Volvo 244Gl Diesel

Ohm meter on each connection in the plug at the relay should find it. But I don't *think* the glow plug wires are anywhere near starter so i'm not sure what that person did when replacing starter. Maybe just a coincidence.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

Before I undertook looking into the glow plugs and wiring, I bought a handful of 80amp fuse strips from the dealer. Hard to do because they're $5 a piece compared to 50 cents online (the three I blew bought online). Wanted it done soon because of the fire issue everyone's mentioned, stuck it in, and voila. So far no problems. The dealer fuse seemed quite a bit more robust, doesn't bend as easily, etc. I guess there are some things that have an economy to the premium, especially since this can be such a fail part that can strand you anytime.

Anyway, thanks again all for your help.

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1987 300td 240k #14 head

I think there are two different amperage rating fuse links for the glow circuits. Some cars take the lighter and some the heavier one. Fifty and eighty amp varients come to mind but not in anyway sure.

You're right, the same strip fuse comes in both 50 and 80 amp. The ones I got that kept blowing had 80 A printed on them so I assumed they were right, though very possible they were a misprinted strip or some such error. A noticeable difference in thickness between the ones I got from the dealer. I think the 50's are for a heater maybe? Wouldn't be a big deal except that little fuse had the unfortunate side effect of disabling the car. Good to point out though that there ate two different amperages out there. Thanks.

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1987 300td 240k #14 head

I believe some of the mercedes glow plug systems use the lighter fuse. It really sounds like that is what you got from ebay no matter what the markings on them where.

Heater fuses and their holders are a problem as well on some of their cars. But they are not fifty amps. The cure is to add an external fuse and holder for the heater circuit. Seems the fuse contacts in the fuse panel are not up to the job.