HELP! Diesel Vanagon won't start... Glow plugs won't turn on

[mg93108]

Hi
I have a stock 1982 Vanagon Westfalia with a 1.6 NA diesel

It was running perfectly...getting over 30MPG of the freeway.

I went to start it the other day and the glow plug "light" (indicator) on the dash, didn't come on like normal. I thought (hoped) it might just be the indicator bulb. Nope. It obviously wasn't energizing the glow plugs. It was a really hot day so I thought I would try to see if it would actually start if I cranked it for a bit and sure enough, it started. All that to say, it sure seems like it's something in the glow plug circuit since it will eventually start.

Any suggestions? I have no idea where to start...no pun intended. I replaced the ignition switch about 3 months ago so I doubt that is it.

Thanks for the help!!

[Mike Robinson]

The first thing to check is the fuse for the glow plugs. In the engine bay at the back and left, funny big metal fuse. They pass a lot of current through them and eventually just die from metal fatigue. Check the connectors too.

Second the big relay next to the fuse. Very rarely fails, but could. I have travelled with a spare for 12 years ...

Check battery wiring and earths - the obvious stuff.

Mike
'82 Westy Diesel AAZ

[mg93108]

[mg93108]

So I checked every terminal to ever other possible terminal with a volt/ohm meter. I get no continuity from any of them to any other. Not sure if that is good or bad

[skills@eurocarsplus]

all that green ashy shit is corrosion. I would replace the relay and clean the plug it went into for starters.

*IF* this happened all of a sudden, this may solve your problem...but either way, that relay probably has some ugly stuff happening on the inside
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[Jeffrey Lee]

A lot of good info here regarding the VW diesel glow system, including how to test & troubleshoot the relay: http://www.4crawler.com/Diesel/GlowPlug.shtml

It’s also important to note that the dash indicator light is NOT actually driven by the glow plugs, but by a parallel circuit. So the glow plugs can in fact be working fine while the light is not, or vice versa. It sounds like in your case the plugs are indeed not activating, but you can confirm their operation by connecting a test light between the glow-plug buss bar and a good ground.

I agree that a good place to start would be a thorough cleaning of the relay spades and their corresponding connectors, and perhaps having a look at the interior. or just replace it: https://www.partsplaceinc.com/vw-1-6l-glow-plug-relay-3420.html

Good luck!
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Camp Westfalia
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www.CampWestfalia.com

[mg93108]

THANKS GUYS
I really appreciate the help.
I'll replace the relay...even if it "might" be good, given that it is 35 years old, it deserves a new one.

[dobryan]

I would also replace that big fuse strip too. After many years of use they can heat cycle, get brittle, and develop cracks that are not obvious. It is a cheap part.....
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[MarkWard]

With the key on, ground pin L in the glow plug relay block. The glow plug light should light. If it does, you have checked the bulb circuit and need to look at the temp sensor in the head next. Should be Blue wire with white tracer. Unplug it from the engine and the glowplug relay should energize with the key on. I would have unplugged the temp sensor first only because that is easier than pulling a relay on an antique.

For the record, I don't know this off the top of my head. I am looking at the Bentley manual for you page 97.37 and 97.38

edit, if it is a hot enough day, the glowplugs won't light either. Perhaps it was hot enough out that day and there is nothing wrong.
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[mg93108]

Here's what ended up being the problem. I should've reported back earlier.

It was the ignition switch.

It wasn't too hard to replace. And it was less than $20. Just a bit time consuming.

Taking off the steering wheel was the one item that required a tool that isn't always readily lying around. It requires a large socket 24mm.
A few years ago I found an inexpensive (and inexpensively made) socket set with very large sockets. I picked up the whole set for $5. You can buy a single 24mm socket on ebay for about the same amount of money. No they aren't high quality but for just taking off the steering wheel, it worked just fine.

[vandoka]

I have a 1987 syncro doka which originally had a webasto heater. Just today I completed an AAZ swap to replace the old 1.6 td. Well before the swap the glow plug light and glow plugs did work.

After the swap the light did not come on. After reading this thread I got voltage at the bus bar so the plugs are getting juice. I then tried to ground out pole 87 in the relay.

That did not change the situation.

During the swap I took the old webasto out and disconnected the harness to that heater. Other than that nothing really changed with wiring on the engine or in the cab.

I am wondering how to go about checking the glow plug light, or what other steps I might take to try and get the problem figured out.

Luckily the plugs work so I can still start up the new (rebuilt) motor!
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[Gnarlodious]

The first thing to check is the ground strap terminals from the transmission to chassis. If they get rusty surfaces your glow plug system won’t work because the engine heat sensor sends a higher temperature than it really is.
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Vanagon ’83 diesel AAZ w/Giles injection, 5spd 4.57R&P+TBD and a '78 diesel Rabbit

[crazyvwvanman]

What did you do about the 2 coolant temp sensors the original engine had when you switched engines? One of those was for the glow plug relay. Did you move the sensors and wiring over to the new engine?

Mark

[vandoka]

Yes, all of the original coolant sensors and wiring were carried over onto the AAZ. I purchased a 1.9 long block and swapped everything over from the 1.6. So now I have the one sensor on the top part of the head (oil pressure I think) then the two that fit into the coolant flange off the head.

This flange has the blue wire with the white trace referred to earlier in the post. I removed this wire to try and see if the glow plug light came on and nothing changed.

The engine ground and transmission ground are clean and making good contact so I am not sure where to go next.

As I said though the plugs are lighting up, the glow plug fuse is in good shape and the relay looks relatively new.
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[MarkWard]

So the problem is the indicator light is not functioning?
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[vandoka]

Yes, the light is not turning on as it normally has in the past during cold start up.
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[MarkWard]

The heater you removed was also diesel? Mark would probably know if the heater harness had a common point with the indicator light. What year vanagon? If someone is not able to help, I can look at the wiring diagram and suggest an easy test point for the indicator.
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[vandoka]

Mark,

It is a 1987 syncro doka from Sweden.
It is possible that the glow plug circuit was somehow connected to the webasto system.

Say you are running the webasto to heat up the coolant and thus the block. It gets hot enough that the glow plugs are not necessary....so then something happens to the glow plug circuit.

But how my disconnecting the webasto harness affects the glow plug light I am not sure.
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ

[MarkWard]

That complicates it some. What style fusebox early or late. Ceramic fuses or H type? I wouldn't have those wiring diagrams on hand.
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[vandoka]

The heater is very similar to the BBW heater in the bentley section 82. Here is a picture of the webasto control panel. It is sealed so you can't do much in there. The relay to the left I believe works with the aux water pump on the 1.6td motors.

And then this box contains the glow plug relay and fuse. It is the metal or tin bit that seems common on the vw diesels

So all the fuses are newer metal style. Yeah, knowing more about how to test the glow plug light on the dash would be useful..
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1987 2wd Westy "Vanny" 2.5 RMW Subaru
1987 Syncro Doka 1.6 TD swapped to AAZ