Former VWDieselParts.com Forum

I'd go with the 20A fuse panel instead of the 15. The 15A should work, but just in case you ever pulles more amperage than what you were supposed to, the 20A won't smoke as easily on you.

Fatmobile - The factory original fuse between GP relay and GPs melted a few years ago. There is no fuse now - just two eyelet terminals bolted together (not my doing!). I'm leaving the factory GP relay in place, and using the original red/white wire from the relay to click the solenoid on. If the control circuit of a solenoid draws a fraction of an amp, I'll probably just throw a 5A fuse in line.

Vincent - thanks for the tip. Some the pics I've seen had 15A fuses, now I know better!

None of the solenoids I looked at were continuous duty, but they WERE small and cheap. I'll see if I can dig a cont. duty solenoid out of a store in town, hopefully for less than $30.

some of the "Ford" starter relays have 6 ohm coils... using Ohm's Law, amperage = volts/ohms or 12/6 = 2amps. this is supported by the 'spark' test and you can tell there's some current flowing in the winding of the coil. a 5 amp fuse should be fine but just realize the current draw isn't 'fractions of an amp'.

there's no reason to find a continuous duty relay... you ain't keeping the GPs on continuously!

-dan

agreed, you can also use electric snowplow solenoids ( for trucks , ATV's etc )

Princess Auto up here stocks them fairly cheaply....

or start solenoids from ..... outboards with electric start... ATV's .... motorcycles....riding lawnmowers....tractors

I ended up buying a starter solenoid from a 1985 F150 - model F492 from Autozone. It has worked just fine. Even on the coldest days I've experienced no issues.

The generic small engine starter solenoids from NAPA cost more than the cheapo that I bought from AutoZone.

no surprise there

more units built = lower cost per unit.

they were just other options in case you had one floating around.

So is the idea to totally bypass the original relay?

You could bypass the original relay by using a pushbutton and solenoid (like the Ford starter solenoid) but the only mod I did on mine was to eliminate the bus bar across the plugs and run individual 10 gauge wiring. That has made troubleshooting and replacement a million times easier.

I also did a mod on my old 79 (now sold) pulled the glow plug relay and wired in a big pushbutton rated for about 80 amps (old industrial control button) and just pushed the button n for 30 seconds to heat the plugs. I did that one because the glow plug relay was toast and the control lines at the socket were in bad shape.

So it all depends what you want to modify. If you want to eliminate the whole factory setup including relay the solenoid and pushbutton method works pretty well

or as an alternative, leave the original relay in AND add a manual pushbutton. that's what i did and it allows the normal timer system to work when people borrow my car. if i want to give it extra glow time, i just hold the manual button in and the original relay is over ridden.

running separate wires to each GP is a sweet mod because not only can you trouble shoot which GP is dead, but you can also remove individual glow plugs without removing the buss strip from the whole string.

-dan

Good idea. I just unplugged the temp sensor on mine to give it more glow plug time - it stays on as long as I have the key in the start position but I don't let anyone drive my car except my son who knows all those intricacies.

and don't forget, when running individual wires, to use an open lug terminal at the glowplug. i used a solid copper ring and then cut a notch in the loop to allow the wire to be lifted off the GP without taking the nut all the way off... just loosen it and no more dropped nuts!

since my GP wires sweep to the drivers side, i cut my notch so that the bottom of the ring is open. this way the wire can rest on the GP stud via gravity while the nut is tightened.

-dan

So I basically hook my new set up in place of where the buss bar is? What exactly is the buss bar and where is it located? I can't find much in the way of the glow plug system in my bentley manual.

The bus bar runs across and attaches to the glow plugs on the cylinder head - it's copper and held on to each glow plug by an 8mm nut and usually a washer. They can be a pain to get to and is easiest to do with the injector lines removed. At the passenger side of the bus bar is the heavy wire that puts power to the bus bar. So I made up 4 equal length 10 gauge wires to attach to each of the glow plugs and ran them over to the wire that is the power lead. I terminated both ends of the glow plug wires in ring tongue terminals and use a screw to tie the glow plug wire "power" end into the main power wire. I cheesed out and just did that and insulated the power end of things in electrical tape but you could do whatever works for you. Mine have been that way for about 6 years now with no issues. I ran equal length wires to the glow plugs just to provide the same voltage drop to each plug but you could tailor them to a length that dresses in nicely if you prefer. Doing that will result in slightly more power to the ones with shorter wires but that's probably not a big deal.

Just read this whole thread for a second time starting to understand it a bit better. What is the point in using the heavy duty tractor/ ford solenoid. How do I wire it up so the facotry glow plug engagement system is still what fires my plugs?

Putting the solenoid in the engine bay keeps the fat wires from being run through the firewall and plugged into the relay.
The long wire length and connections drop voltage,
the fat wires would cause alot of trouble if they ever shorted under the dash
the solenoid takes the load off the stock relay,
the wire going to the glow plugs can be used to fire up the solenoid so the stock relay operates it.