Relays and GP's

[flowmastergfunk]

of course you post as I am writing about you! lol

That WAS one thing I was curios about! Having one of these solenoids fail and get stuck on! The first drive after I finished adding my little fusebox and all that, I started overheating on the freeway and didn't understand why! Somehow my car had gotten to boiling and pushing water past the cap....and it made me wonder if my plugs got stuck on. Freeway speed air should keep me plenty cool...

I filled my car back up and it was fine after that(although inspiring me to change my coolant and upper hose setup), but it was another variable that occurred to me...and I am happy you mentioned this. Unless you hear the CLACK, you can't be sure that your glow plugs stopped getting power! Thank you for reminding me...because I was interested in figuring a wiring solution to having the LED get it's signal POST hd relay! Just more proof that modifying the glow system increases the chance for potential problems!

(still not  converting back )

[8v-of-fury]

I am against what Toby said, this does in FACT help starting over a stock system.

The stock system keeps the plugs pulling 40-50A after the light has gone off and while you are cranking the starter. That 50A is 50A that could be better spent in cranking the starter over and not firing the plugs that are still red hot after glowing for 10 seconds.

When my car was IDI and I needed plugs, I would burn for like 3-5 seconds for almost any weather and then turn them off and engage the starter. When it was super cold, and I burned the plugs while I was cranking (this helped tons on super cold days) it could be heard that the starter was significantly slower spinning with the plugs on as opposed to off.

Another thing I like about the toggle switch manual setup I had was that I could After-Burn the plugs for as long as I wanted. Like until the smoke cleared, the engine idle steadied, or I was happy with its running status. The AAZ's stock system (which used duraterms from day 1) has an after-burn feature of up to three minutes after the key has been let go of the "start" position.

[92EcoDiesel Jetta]

...


If anything, (for some of us control freaks) perhaps adding a switch to manual override switch in place of the stock relay would be a more appropriate mod to add to the list (in conjunction with the HD mod). Perhaps a plug-n-play unit that fits directly into the stock relay spot, and has a certain length of wire coming out of it to mount a remote on-off or tog 8)gle switch. I know not everyone is interested in manually controlling such a function, but this would give you the chance to revert to the timed relay, if desired, without molesting the stock harness. Fully reversible (minus whatever hole you would drill to mount the switch).

That's what I did, took the stock VW relay (very robust and well made relay BTW, much better than the Ford starter junk solenoid) and added wires to it to a push button switch so that it is manually controlled. I also added a piezo buzzer that sounds when the glow plugs are on which alerts you in case of the relay hanging and applying constant power to the glow plugs (very small chance of that happening). On top of that, I added a mechanical push button on the relay to manually close the contacts if the relay coil fails. On top of that, I carry a heavy duty jumper cable to manually jump the glow plugs in case all of the above fails. I think I have all the bases covered.

Oh, I also got rid of the 8 mm nuts on the glow plugs and replaced them with quick disconnects. Imagine changing glow plugs in the middle of winter and dropping those nuts into the snow with no replacements? You're screwed! This won't happen with quick disconnects plus you can get the wires on/off in seconds.

[ORCoaster]

Great discussion guys.  And Civil no less.  We sure this is the VW GTD forum? 

Love the thoughts from 92EDJ.  I think they go in the box labelled OVERKILL/well thought out for doomsday. 

I am with the thought that if GPs on and starter turning the battery is really having to deliver there.  Cutting off the GPs then hitting the starter can be heard on a cold  day.  I don't think it is just the cold doing it either.

Four wires, 10 amps that if the way I look at it.  Some have asked me why the spark plug wires are so small in my car.  Some day I will explain it to you. 

Something about a 40 amp fuse just makes me shudder about that load inside the car but then I don't have a honking amp in the back either. 

[92EcoDiesel Jetta]

I once had a manual system fail on me, where the starter solenoid I had used failed in the "glow" position. Leaving my glow plugs on for my 35 minute drive, and subsequent 20+ minutes afterwords that it took to drain my battery completely flat.

This was 3 years ago, and those glow-plugs are still in a daily driven diesel to this date.. They would have at the time been getting 14v for 35 minutes and then the full battery voltage after I shut it off. Roughly an hour of straight glowing.

Duraterm FTMFW.

That's because the Ford starter solenoid is a bad design. I've had one hang also. If you take one of them apart, you will see the solenoid pushes a copper shorting bar onto 2 studs, shorting them out. That bar can hang with the onset of corrosion.

Duraterm glow plugs have 2 coils to limit current once it heats up. They typically draw 20 amps at cold start surge then slowly drop to around 9 amps  and that keeps them from burning out if left on extended periods. IMO, it is the initial surge that kills them if the voltage to them is higher than designed. If you look at the glow plug specs, there is a voltage rating to them. I think the Duraterms are 11 Volts. If you run very short length and very heavy gauge wires to the glow plugs, you can get them to run at higher voltage than designed (governed by the gauge and length of the stock wiring) and shorten their life. I have no proof of all this, just using logic and common sense.

[92EcoDiesel Jetta]

I am against what Toby said, this does in FACT help starting over a stock system.

The stock system keeps the plugs pulling 40-50A after the light has gone off and while you are cranking the starter. That 50A is 50A that could be better spent in cranking the starter over and not firing the plugs that are still red hot after glowing for 10 seconds.

When my car was IDI and I needed plugs, I would burn for like 3-5 seconds for almost any weather and then turn them off and engage the starter. When it was super cold, and I burned the plugs while I was cranking (this helped tons on super cold days) it could be heard that the starter was significantly slower spinning with the plugs on as opposed to off.

Another thing I like about the toggle switch manual setup I had was that I could After-Burn the plugs for as long as I wanted. Like until the smoke cleared, the engine idle steadied, or I was happy with its running status. The AAZ's stock system (which used duraterms from day 1) has an after-burn feature of up to three minutes after the key has been let go of the "start" position.

I always manually glow the plugs then remove power to the plugs when I crank so the starter will get full power and spin at the highest RPM instead of being dragged down by the glow plugs. Once the engine fires, I can always turn the glow plugs back on if I want. So far, I've never needed to do that.

[8v-of-fury]

It was not a ford solenoid, it was generic high amperage relay/solenoid. Different design. I've had OEM relay's stick on before too.

I have proof (from my own first hand experience) that higher voltage to the Duraterm plugs (which are 4 years old now) does not shorten their life any. They each had about a 24" total run of power, battery to starter lug, starter lug to solenoid, solenoid to fuse block and then to plugs. Literally zero voltage drop, they got full 12.30-12.61V of battery voltage.

I always manually glow the plugs then remove power to the plugs when I crank so the starter will get full power and spin at the highest RPM instead of being dragged down by the glow plugs. Once the engine fires, I can always turn the glow plugs back on if I want. So far, I've never needed to do that.

What is your ambient winter temperature though... lol

[92EcoDiesel Jetta]

I always manually glow the plugs then remove power to the plugs when I crank so the starter will get full power and spin at the highest RPM instead of being dragged down by the glow plugs. Once the engine fires, I can always turn the glow plugs back on if I want. So far, I've never needed to do that.

What is your ambient winter temperature though... lol

20 F sometimes single digit, rarely below 0 F.

[8v-of-fury]

Well, come on up and see how yours starts at -20 F

Last winter, we had a huge drop for a few days where the ambient was -40C/F (they cross over at this temperature). Not even the gas engines started, it was brutal.

[Gizmoman]

I'm amazed at how long this thread has kept going.

My initial attempt was simply to do what Vince Waldon suggested in a post on his site (and also here in the FAQ).
The question was if I could use two 40 amp relays (splitting to two GP's each) instead if one bigger one. The reason being is that I have four in a nice fuse box and I am only using two for the WAIC and oil cooler wiring.

Anyway, the original question has basically been answered with a yes.

As for starting, I'll stick with the stock system.
Turn key to on, yellow light comes on.
When it goes out, start. Has always worked for me, even if I'm camping in a cold climate area (I haven't tried it yet at -20 though ) .

If I take a quick run to the store, it won't turn on again for the second start.

[745 turbogreasel]

Hmm, I have 2-4 extra of every part of  the factory glow system, because no part of it has  needed replacement while I continue to cannibalize cars for other parts.  Still,  for those time I want glow, but the  stock system doesn't want to, I have a 6" #10 wire...Short across the stock relay terms, and rejoice in your glow!
Aside from that, I really do  prefer the MBZ glow harness connector, mainly from a diagnostics standpoint.

[TylerDurden]

One of the joys of VW ownership is the water leak that fills the GP relay...

Sometimes they fail to glow,
Sometimes they fail to shut off.

In the latter, the non-Duraterm GPs burn out.

A "truth light" LED added to the dash to indicate voltage at the GPs is cheap, simple verification that power is there when it's supposed to be.

[745 turbogreasel]

There was a guy on one of the truck forums  curious about the Duraterms, so he hooked up a power supply, and left it running 36 continuous hours.
Eventually turned it off because he had to leave the house unattended.

[Gizmoman]

Geeze - now I gotta run four wires to my dash and install four LEDs?
I gotta stop reading this site till I'm done. All I was going to do was rebuild my AAZ - I'm looking at over a year now.

I already have the wire and the LED's, oh what the he//

[745 turbogreasel]

Watching for the dome light to undim not good enough?