Glow Plug Re-Wiring

Vincent Waldon · Post by **Vincent Waldon** » Wed Jan 20, 2010 1:33 am

Yeah, depending on the solenoid it can:

(a) draw a fair bit of current all on its own
(b) overheat... some starter solenoids are designed for duty cycles of 30 seconds or less... on an AAZ the glow plugs run for several minutes of afterglow

For both those reasons and the most important reason of all (c) Vince is a cheap you-know-what I picked a commonly-available garden tractor starter solenoid stocked by NAPA.... rated for continuous duty, designed to run off a garden tractor battery so low current, and pretty cheap at around 10 bucks.

Having said that... any starter solenoid should work... and the best one is the one you've already got in your hands!

coke · Post by **coke** » Wed Jan 20, 2010 1:37 am

The solenoid I'm using is supposedly rated at 100 amps, and while its probably not constant duty rated, the load going through it is probably much less than cranking an old V8 over.

Vincent Waldon · Post by **Vincent Waldon** » Wed Jan 20, 2010 1:46 am

coke wrote:the load going through it is probably much less than cranking an old V8 over.

On a cold Maine day a V8 can be a bear for sure. But with the right pipes she sure sounds purdy once she starts!!

surfcam · Post by **surfcam** » Wed Jan 20, 2010 1:46 am

I forgot to mention to fuse the wire before the solenoid. I have never had the issues that fatmobile had but then again I am running a separate circuits.

coke · Post by **coke** » Wed Jan 20, 2010 1:52 am

Yeah I'll admit I skipped the fuse part, and I really need to add one in there.

Post by **Fatmobile** » Wed Jan 20, 2010 1:52 am

Are garden tractor solenoids smaller?

Vincent Waldon · Post by **Vincent Waldon** » Wed Jan 20, 2010 2:25 am

Yup... a wee bit overall... and it definitely has a smaller footprint since the big terminals are on the top rather than to the sides.

Can't find any pictures on my hard-drive... the HOW-TO on my site has a couple that might give you a better idea.

From the NAPA site:

http://catalog2.genpt.com/catviewer15/% ... ShowPics=1

You can get a feel for the size based on the spade-lug terminals.

Again... don't get me wrong... I got no religion on solenoids...NAPA wanted 45 bucks for a "Ford" version and 10 for the garden tractor version... made the decision easy!!

Of course I had just cleaned the garage that spring and thrown out the old Ford solenoid I used back in the day to bridge in the second battery in my old VW van for starting during the winter.

surfcam · Post by **surfcam** » Wed Jan 20, 2010 1:49 pm

I bought mine from Parts Plus. They said, "they had two different ones". One had a long duty cycle (continuous use) and could be use on golf carts with lots of batteries. I don't believe it was that much more.

rabbit_man · Post by **rabbit_man** » Thu Jan 21, 2010 6:19 pm

Fatmobile wrote:I have used the glow plug relay to control the ford starter relay.

Sometimes the ford starter solenoid allows so much current flow that the voltage will drop,
enough to shut off the glow plug relay,
then the voltage will rise again and the ford starter solenoid will be triggered again.

BztBztBzt

I've had this happen on both cars I've tried this with.
Doesn't happen every time, hasn't happened on my car in weeks.
But the ford starter solenoid is loud when it chatters on and off, a bit embarassing.
This could probably be solved by hunting down voltage drops in the wire supplying the glow plug relay. Might be a bad ignition switch.

THAT'S AWESOME, I'VE ALWAYS WONDERED WHAT THAT WAS!!!!!!!!

Yeah it started happening, um.....the day I pimped my plugs with a big starter solenoid.

The difference with mine is it does it after the GP light is off and the "afterglow" is done then it chatters when trying to shut off.

What's the fix for it? Just a continuous duty one or a smaller/less heavy duty one? Thanks, I might be able to get rid of that embarassing clatter now

Post by **Fatmobile** » Fri Jan 22, 2010 12:34 am

I haven't found a cure.
It basically stopped doing it on it's own, with my Rabbit. At least it hasn't happened in a long time.
On the GTI Rabbit diesel; I have a manual glowplug button she can push that stops the chatter until the relay times out.
I am going to try another glow plug relay on hers,.. and maybe a better ignition switch.
I made sure the glow plug relay was grounded good but that didn't help.

the vegenator · Post by **the vegenator** » Fri Jan 22, 2010 9:41 am

Fatmobile- you say the voltage drop that causes the BztBztBzt could likely be caused by a faulty ignition switch, eh?

I'm sure I have a bad ignition switch... it wasn't a dealer switch but a cheapo replacement that I bought four years ago. You have to jiggle the key or the wiring harness the right way to get it to start. I'd like to install a push button ignition switch (cheapest alternative)... But would this solution prevent any potential issues like what you're dealing with?

Post by **Fatmobile** » Fri Jan 22, 2010 10:37 pm

There must be a voltage drop somewhere.
I think the ignition switch provides the 12V signal that turns the relay on so the drop could be as it goes through the switch.
I know the switch in the GTI diesel is weird. Sometimes the buzzer doesn't shut off when the key is removed.
She also has a manual switch, so when it starts oscilating she pushes that; the noise stops and the glow plugs get solid power.

rabbit_man · Post by **rabbit_man** » Sun Jan 24, 2010 2:43 am

My ignition switch is the same as my '80 gasser parts bunny........

TylerDurden · Post by **TylerDurden** » Sun Jan 24, 2010 12:26 pm

Many thanks for the tips on GP rewiring.

I just discovered all four of my caddy's GPs were toast.

I suspect it happened when the typical rabbit water-leak killed my relay under the dash... I had an event last summer when the battery died and the car would not start. I jumped the battery and the truck started, but the glow indicator stayed on. I pulled the relay and replaced with a spare, I also installed a voltage indicator LED to the GP bussbar; but the damage to the GPs may have already been done.

A postmortem revealed the original relay full of water. I rekon the GPs were energized the entire time when the truck was last operated and even after shutdown; killing the battery and the GPs.

So, now I am replacing all the GPs using the individual fuseblock method (AWG 12 to each) and keeping the single LED to verify voltage at the block.

The individual LEDs for each GP may come later... Maybe two-color LEDs that indicate an energized state and an open state. Still pondering that one.

the vegenator · Post by **the vegenator** » Thu Jan 28, 2010 11:33 pm

I forgot to mention to fuse the wire before the solenoid. I have never had the issues that fatmobile had but then again I am running a separate circuits.

You're talking about fusing the wire that comes from the glow plug harness to the solenoid, right?

I assumed this would already be low current since there's not much of a draw.