converting a 77 240D to pencil style glow plugs, questions
 

OK, I looked at the DIY sticky and I even searched for "glow plug replacement" but I still have a couple of questions.

I'm putting the new pencil style glow plugs into a 77 240D. Do I need to ream the glow plug holes somehow? There is a little loose carbon laying on the threads now that I've pulled the old ones out, and I figured I would just crank the engine over to blow that out before I put the new ones in. Also, what gauge of wire should I use to connect them? Looks like 8 is what is coming from the old relay plug, is that right?

Also, I have a push button switch and relay and I am thinking of converting the new plugs to manual control, but can I use the old relay if I decide to try that, or do the different plugs need a different relay? I noticed that the new fuse is 80 amp as opposed to the 50 amp that the old plugs used.

I already know to leave the ground strap off of the front plug when I get that far.

Thanks!

plugs
 

Just use as big of wire as you want with heat tolerant insulation....bigger wire equals less voltage drop....and crimped soldered copper lugs....
I used a couple of ford fender mount solenoids to the plugs direct from battery with a 100 amp fuse....2 pencil plugs on each solenoid.....and a spring loaded toggle so I cant leave them glowing when I forget to flip it back.....
I completely bypassed the relay unless you want to use the fuse .....you will be extremely happy with the results...no timer needed...just count....or estimate glow time ....experiment and you will find the best times for the temperatures .....
I even put an ammeter in the glow plug circuit to measure current during glow time.....lets you know when a plug is bad or battery getting weak....post back if more info needed ....lots of good material on the forum on this job.....

If you go to the Auto Part store and look at the Wire I believe it tells you on the Package what amperage the wire is rated for.
On the package it should have the amperage rating for the crimped on type eye or forked connectors you might be using.

might not be a bad idea to use #8 on the main feed wire, but 10 from the first GP on is fine.
80 amp fuse is for when there's a short, 4gp's rarely pull over 40A

As vs suggests 8 and 10 should handle it, but it's such a short run, going a size bigger(smaller numbers) would not be expensive or a bad thing.

In the last years of my 84 240D's life I set up a Ford starter relay to feed the glow plugs and added a spring loaded rocker switch to the panel to pick the starter relay. It worked great. Doesn't take long to get the hang of just how long to glow before starting.

thanks for the replies! I have a coil of nice, marine grade 10 gauge, so I'll just use that.

If the glow plugs aren't going to draw 80 amps, do I need a big relay like a ford starter relay, or can I use a 40 or 60 amp bosch relay (little square ones)? I have a drawer full of miscellaneous bosch relays already. I was thinking of mounting a manually controlled relay under the dash near where the old one came out and tapping into the existing plug wiring to connect to the glow plugs and the dash light.

Wire size chart: http://www.rbeelectronics.com/wtable.htm

Sounds like you've got a good handle on it. Remember to fuse you system to the weakest link; wire, relays or what have you. Don't want to have a fire.

Question
 

Did you read these threads?


glow plug conversion kit thread links (Loop to Pencil)
http://www.peachparts.com/shopforum/diy-links-parts-category/151959-glow-plug-conversion-kit-thread-links.html#post1155675

I never found that link. Thanks!