Author Topic: help with glow plug issue. (Read 9568 times)

veedubcanuck · « **on:** January 29, 2009, 01:21:03 pm »

1985 golf with 1.6na motor. When I turn on the ignition when engine is cold, the glow plugs will not shut off. The light just stays on. If I start the car then the light goes out. I changed the relay and sensor but it still does it. When engine is hot then it works normal, ie. the light does not come on. Anyone have this happen??

arb · « **Reply #1 on:** January 29, 2009, 01:23:43 pm »

There are 2 GP sensors. Did you replace both ? Did you verify the new one is good ?

Vincent Waldon · « **Reply #2 on:** January 29, 2009, 01:47:32 pm »

My understanding is that there are two identical coolant temp sensors, yes, one is for the glow plugs and one for the temperature gauge.

The glowplug light can stay on for 20-30 seconds when the engine is really cold (or if there is a problem with the temp sensor connected to the glow plug relay).

When you say "will not shut off"... this is for sure past 30 seconds ?

zukgod1 · « **Reply #3 on:** January 29, 2009, 01:57:06 pm »

Quote from: "arb"

There are 2 GP sensors. Did you replace both ? Did you verify the new one is good ?

Um nope.

1 sensor for the GP's

**Edit**
Oops, vince beat me to it.

veedubcanuck · « **Reply #4 on:** January 29, 2009, 07:24:29 pm »

Yes it will stay on for more than 30 seconds. It does not shut off until car is started.....

Vincent Waldon · « **Reply #5 on:** January 29, 2009, 07:55:22 pm »

Quote from: "veedubcanuck"

Yes it will stay on for more than 30 seconds. It does not shut off until car is started.....

Weird.

The relay listens for a signal from the starter telling it to shut off... so that part is working as it should.

Ordinarily I'd say "replace the relay" since it shouldn't be possible to go for longer than 30 seconds... but you've done that already.

Do you have a test light or multimeter ? If so, perhaps the next step is to see if power is actually being applied to the glowplugs themselves... and if so, for how long? The yellow light actually has very little to do with glowplug power... so this additional info might help us figure it out.

veedubcanuck · « **Reply #6 on:** January 29, 2009, 09:20:53 pm »

I'll give that a try and let you know. I'm just working on fixing this rust bucket up. So I don't know the history of the car.

regcheeseman · « **Reply #7 on:** January 30, 2009, 05:51:33 am »

blue/white wire is the critical one - if it is broken (O.C.) then the plugs will glow for full cycle - as if the engine was cold.

This is always how I use my glow plugs anyway, you can controll the cycle length with the starter switch and a short glow on a part warm engine saves from excessive cranking with the starter.

There are two senders/sensors - they may be seperate or amalgamated into one unit. But there are still two distinct thermo resistive elements.

arb · « **Reply #8 on:** January 30, 2009, 10:11:30 am »

I had a similar problem on one of my MK1's - the GP relay was bad and the fuse block had some corrosion as well.

CaddyWVO · « **Reply #9 on:** February 28, 2009, 02:21:03 am »

I am having a similar problem except that after the engine starts the light stays on and when I am stopped at a traffic light with the head lights on, they dim and when I shut down, the battery is dead.

We had a ton of rain the other night and somehow the water got into the cabin and I believe soaked the fuse panel. I have pulled the fuse panel out and tried unplugging some of the fuses and larger relays, but I'm really not seeing anything out of the ordinary.

This is an 81' Rabbit Caddy and until the rain, the glow plugs worked normally (i.e. light comes one, then goes off, start the engine, light stays off). Now, when I turn on the ignition sometimes it comes on bright and other times it comes on in a diminished, and much lower intensity. I have been having to get a jump start for the past 24 hours. I also sprayed all of the fuse panel with WD40 to make sure there was no water on the terminals, but perhaps I need to replace some relays since they got wet.

Anyone have some thoughts?

Thanks for responding, Charlie

Vincent Waldon · « **Reply #10 on:** March 01, 2009, 08:08:58 pm »

Quote from: "veedubcanuck"

Even if I pull out the relay, the light says on but obviously the glow plugs do not have voltage on them.

Ah... that's the classic sign of a water separator issue... the other thing that can turn on your glow plug light on an MK2.

They're a "feature" of early MK2s and can be found under the car, passenger side, near the axle beam.

If you have one, it may:

- be full of water and need to be drained
- have corroded sensors and/or wiring

If you don't have one, but used to, the person who deleted it may have just cut the wiring and wrapped it with electrical tape... which then gets coated in road salt and starts to cause all kinds of bizzare glow plug behavior. BTDT. :roll:

CaddyWVO · « **Reply #11 on:** March 01, 2009, 09:34:14 pm »

Hey Vince,

Thanks for the pic and post. Who would ever think of something like that on a diesel. I thought that's why they have a drain on the fuel filter?!

I have been all under my caddy and there is no water separator. The problem really only started after the vast amount of rain water got into the cab and ran across the fuse panel (there was a puddle a half inch deep in the driver rubber floor mat). Tomorrow I will get into my book and looking for the section in the elec. diagram for the relays. I plan to pull them, inspect them, then douse with WD40 internally and then plug them back in to see what happens. Also, having the relay engaged is the only way the battery would be dead too because it's also shorting out all of the electrical from the alternator to the battery. It might be more complicated than that, but I know it's not a water separator or open ended wire. That's just too much electricity being drained.

jtanguay · « **Reply #12 on:** March 01, 2009, 10:36:48 pm »

Quote from: "CaddyWVO"

Who would ever think of something like that on a diesel. I thought that's why they have a drain on the fuel filter?!

the fuel quality back then was probably terrible :wink:

ldeikis · « **Reply #13 on:** March 21, 2009, 05:52:54 pm »

I'm hoping to piggyback onto this thread, but I can start a new one if need be.

The PO of my 81 rabbit didn't consider the leaky windshield worth fixing. This lead to water leaking directly onto the fuse/relay panel, causing hell. The glowplug relay has been doing this thing where it works normally (light comes on for some period of time when engine is cold, goes out as soon as you twist key or after maybe 10 seconds if engine is totally cold, car starts fine even in very cold weather) but ALSO sometimes freaks out and sporadically glows the plugs on its own. This sounds like a tap tap tap tap (one friend said it sounded like an angry mouse in the dashboard on an old fashioned type writer) really quick and erratic. I could reach under the dash and feel that it was, in fact, the GP relay triggering. It wasn't lighting the dash light, but I believe WAS briefly powering the GPs since the lights would dim/flicker as it happened. This usually happened within ten or fifteen minutes of starting the car; would happen erratically for a few minutes, then go away and stay gone for the rest of the ride.

I replaced the windshield seal and ordered a new quick-glow relay (PO told me he'd replaced relay and plugs with quick glows) which I installed today. Lo and behold, the light comes on (and multimeter confirms GPs are powered) but won't turn off until I twist the key. I left the key in "on", waiting, for a good minute and a half, but the plugs stay powered til I twist the key no matter what. Once the engine is started, the dash light and the GPs themselves are off. I also tried shorting the temperature sensor wires to ground to simulate a warm engine--the new relay behaved correctly then, too--no glow plug action at all. It's just if I let it glow with a "cold" engine and wait patiently for it to turn off that it leaves me hanging.

I know that, so long as it turns off when I start the engine, I can go ahead and drive it anyway, but since I just paid a bunch of money for this relay and my girlfriend also drives the car, I'd like the thing to function as intended.

So the question is: When the engine is totally cold, other than me turning the key is there any signal from the car that tells the relay when to switch off, or is totally internal to the relay? Therefore, if the relay isn't shutting off, is there any possibility other than a faulty brand new relay?

Thanks.

Luke

PS If it matters, the old relay (that tap-tap-taps) is Bosch 0 281 003 099 and the new relay is mysteriously unbranded, W. German Gluhzeit-automatik 51 233 001. The part I ordered and am invoiced for is p/n 171911261.

veedubcanuck · « **Reply #14 on:** March 21, 2009, 08:05:57 pm »

I forgot about this, never did update. In my case it was indeed the connection of the water separator. I just got rid of it. =)