So I've got a 1976 300d, that was mistreated and is requiring a lot of attention. I've got most of the major mechanical problems sorted out now, but the next big thing is electrical- and I need help.

Instead of being able to warm the glow plugs with the ignition switch, someone installed a cheap hardware-store switch/button under my dash on the drivers left hand side. So I have to hold the button in (the glow plug light still works) to warm the plugs. This would all be well and good but the switch heats up to the point where I have to hold it with hot pads and it burns holes through them. This is getting worse and worse (as things do). What was this guy thinking and how do I fix it?

Thanks in advance!

__________________
1976 300D 217k...an old car needin some love. (GONE OFF TO RUSTY CAR HEAVEN)

1982 240D probably something like 190,000 miles...was Old Yeller, but I changed the name to Buttercup

This was probably done initially because the necessary circuit in/on the "ignition" switch that works the glow plug system failed. So, the first task will likely involve determining if the above assumption is true. If it is, then the "ignition" switch will need to be replaced with a new one or a good one from a junk yard car.

__________________
1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

There's too much current going thru that switch if it's too hot to hold. You could simply install a relay in the circuit and avoid putting a heavy load thru that switch.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'd rather have it be the ignition switch then anything else, since that's a bit easier to repair, but:

Do you know how to test it? I haven't been able to find any way to do this.

Is it possible that part of the problem could be the preglow time relay? According to all sources, it's supposed to be on the front drivers side fender, which it isn't. However, with all this ghetto electrical work, it looks like it may be installed under the dash. Is this even possible?

Electrical work is new for me...I'm just hoping it's not in need of an ignition switch and a preglow time relay.j

d

__________________
1976 300D 217k...an old car needin some love. (GONE OFF TO RUSTY CAR HEAVEN)

1982 240D probably something like 190,000 miles...was Old Yeller, but I changed the name to Buttercup

I used a 15 amp switch with that sort of system but when I switched to the new style GPs requiring a 80 amp fuse I ran the wires through a solenoid. You can get a 15 amp push button switch at any auto supply and use a solenoid just to be sure. Or you can look under the driver side "knee" panel and check out the GP relay. I was too cheap too buy a new relay, that was several years ago and i like my push button. I dont need no relay too tell me how long too glow those plugs

__________________


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"

Greetings! I am the idiot that you speak of. Towards the end of my time driving that 300d I had to jerry rig that button due to a faulty relay. The relay is still under the dash and maybe you can troubleshoot it. What I did with the button was to hold it against the underside of the dash so it wouldn't burn my fingers. Also I wasn't really thinking at all when I did it, It was a matter of necessity. I just needed to get the car to run for a week more. It is good to see that car wound up with someone from this forum. I don't know its story of recent, but I assume it's seen several owners between me and you, (about 3 months). I did the valves, replaced the shocks and sway bar bushings (front) before I sold it. Did someone replace the vacuum pump diaphragm yet?

__________________
"spreading a trail of obnoxious where ever we go"
1981 300sd w/ 341,500 miles

http://www.wecrash.com/pics/ddda_banner.gif