I finally got around to upgrading my glow plugs. I put in the new style plugs, with all new, marine grade, 8AWG wire and a new fuse holder and 80 amp fuse.

I also switched them over to manual control, since my relay quit working right. I took the relay apart first to see if I could fix it, but the points were really badly burned and pitted, and I couldn't get a point file in there without bending the contacts around.

So I went and got a push button momentary switch, and went on ebay and found a Bosch style 80 amp relay for under $10, and went to work. My goal was to set this up without cutting anywhere in the wiring harness, and without drilling any new holes in the body or dash.

I used a bullet connector to get switched power to the switch out of the old glow plug relay wiring plug.



I took out the broken idle speed adjustment cable, and used that hole to mount the switch. I plugged the hole left behind in the rubber boot in the firewall with a bolt.



New 8 gauge wire everywhere.



I mounted the relay in the little relay box on the driver's side inner fender.

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1976 Mercedes 240D, unknown mileage
1977 Mercedes 240D, 225k
1992 Dodge/Cummins 4WD, 284k
1990 Subaru Legacy wagon, 330k
1991 Subaru Legacy wagon, 225k

Is that the new style pencil type GP's? If so they should be wired in parallel, not series.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

They are wired in parallel; I removed the ground strap on the end. My understanding is that they are individually grounded through their connection to the head.

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1976 Mercedes 240D, unknown mileage
1977 Mercedes 240D, 225k
1992 Dodge/Cummins 4WD, 284k
1990 Subaru Legacy wagon, 330k
1991 Subaru Legacy wagon, 225k

I'm pretty sure they are grounded to the block. and the a wire feeds each glow plug separately.

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92 300D 2.5L OM602 OBK #59

There is nothing wrong with they way they are presently wired. If one Glow Plug goes bad the rest will still be getting their Voltage.

However, It will be harder to locate which one of the Glow plugs is bad then if would if each Glow Plug had a separate wire going to it.

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84 300D, 82 Volvo 244Gl Diesel

Nope, not the new style. Hes good

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

8AWG is a little overkill. I use #10. you could have used a little #8 to the relay, then several #14's to each plug. but what you did is fine.

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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!

A lot of folks dont realize the coil of the relay does not draw alot of current. For most of the relays we have in MB's, 16g is overkill for the coil. The load side or the switched side is the place we need the heavy duty wiring usually.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

well, to activate the coil I just used 14 gauge....

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1976 Mercedes 240D, unknown mileage
1977 Mercedes 240D, 225k
1992 Dodge/Cummins 4WD, 284k
1990 Subaru Legacy wagon, 330k
1991 Subaru Legacy wagon, 225k