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Discussion Starter #1
Hey Gang.
OK, so the head gasket replacement went by the book, followed the Bently and everything seemed to go well. While the head was off I cleaned up the injectors and the glow plugs.

Now it turns over but doesn't fire. Started fine before (except bad head gasket so ran horrible).
Seems like not enough power getting to the glow plugs, they're not getting hot at all.

Now here's the deal with this caddy. PO scrapped the whole system that connects the key to the glow plugs. In its place is just a normal 12v three-post solenoid that goes to a buss with fuses and then out to the glow plugs. The solenoid is flipped by a momentary button on the dash. That all seems to work, EXCEPT for some reason the buss is only getting around 11v of power. I'm not smart enough to know if the glow plugs need a good 12v plus to get hot.

I did take the 3 and 4 plugs out and jumped them direct to the battery and they got super hot super fast.

I know this is a strange (but simple) setup, but anyone got any thoughts? I figured I would keep at this route until I can get heat to the glow plugs before I started down the road of checking the timing.

1981 diesel rabbit with new head gasket. Until the head gasket blew and subsequently overheated it has run fine for over two years.
 

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If your Glow plugs aren't getting hot in the engine, then I would suspect that therein lies your issue.
Individually the Glow plugs work.
Together they don't.

So you are looking at the Solenoid / Relay that is powering the Glow Plugs.

If it is a Ford Starter Relay, Very similar to the one I used for a heat soak issue on my automatic Cabriolet, then I would look at the input to the Relay from the battery, Your Push Button should supply 12V to the smaller terminal to the relay to "PICK" it, which in turn allows the connection from the Battery side across the side that is connected to the glow plugs.

If you have 11V that is saying that you are dropping voltage, and that isn't a good thing because Voltage is the quick test that you have good current flow.
E=IR Ohms law.

Secondary issue is if there is air in your clear line.
Third issue is the starter spinning fast enough.

Charge your battery or test it.
If you have 11V between the lead from the relay to the starter then you have either a battery issue or a connectivity
issue between the two.

see: HOW-TO: Pimp your glowplug wiring

Now then the last question is do you have 7 second glow plugs or the 30-60 or wait forever type, as that would depend on how long you have to press the glow plug button to get good heat to the pre-cylinders to sustain combustion.

Lastly do you pull out the Cold Start button on the dash to allow the IP to advance the injection point on first start.
 

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Don't forget that the relay is probably mounted to some part of the fender and that is where it will be getting the ground from. We all know VW does not do grounds well. So be sure to check that connection and bolt for good contact.
Any corrosion at that point will induce a resistance and thus a voltage drop from the relay to the main buss for the GPs.
 

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Discussion Starter #4
Hey guys, took some time off wrenching, crazy dayz these!

Thanks for getting back to me!
Now then the last question is do you have 7 second glow plugs or the 30-60 or wait forever type, as that would depend on how long you have to press the glow plug button to get good heat to the pre-cylinders to sustain combustion.
I must have the 7-second variety, because I've never had to hold the button for more than 10 seconds. And when I took #3 and #4 out and hooked to battery they got red in just a few seconds.

Lastly do you pull out the Cold Start button on the dash to allow the IP to advance the injection point on first start.
I don't have a cold-start button, but I live in Hawaii so may not need it.

Was out there today, messing with it. What's strange is that I can't seem to get the glowplugs to heat up when they're in the engine. I even hooked a wire directly from the batter, no fire.
 

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Discussion Starter #5
Don't forget that the relay is probably mounted to some part of the fender and that is where it will be getting the ground from. We all know VW does not do grounds well. So be sure to check that connection and bolt for good contact.
Any corrosion at that point will induce a resistance and thus a voltage drop from the relay to the main buss for the GPs.
Yeah, great tip. I went out today and scrubbed/sanded/filed the grounds as best I could. Will try some more here in a bit, am charging the battery after trying for a while.
-r
 

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Was out there today, messing with it. What's strange is that I can't seem to get the glow plugs to heat up when they're in the engine. I even hooked a wire directly from the batter, no fire.

??? What the What ???
You mean you jumped a wire from the battery to the buss bar and get NADA????
That my friend is unheard of. Especially since you pulled 3 and 4 and know they glow.
So did you hook the battery lead to something else? There is a fuse in those red wires that go up to the block on the firewall. Since yours is converted over to a relay then perhaps the wire that used to feed the fuse block now feeds the relay and the internal fuse, in the plastic parts is fried?

Check it with a multi meter to see if it has continuity across the ends. If not you can install an aftermarket fuse that may be easier to maintain in the future. I added one to each of the Rabbits I own. 40 amp fuse in a water tight case. Works well.
 

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Discussion Starter #7
Yeah, drivin' me nuts. But, now I think I killed the battery. Will go get another one tomorrow.

Also maybe what I am thinking is not possible? I am thinking that if I jump the glowplug directly to the battery I will be able to feel it get hot on the outside. Is this true?
 

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Discussion Starter #8
Especially since you pulled 3 and 4 and know they glow.
So did you hook the battery lead to something else? There is a fuse in those red wires that go up to the block on the firewall. Since yours is converted over to a relay then perhaps the wire that used to feed the fuse block now feeds the relay and the internal fuse, in the plastic parts is fried?

Check it with a multi meter to see if it has continuity across the ends. If not you can install an aftermarket fuse that may be easier to maintain in the future. I added one to each of the Rabbits I own. 40 amp fuse in a water tight case. Works well.
Great stuff, thanks. Gave up for the day, but will be at it again tomorrow. Don't have anywhere to go, heh.

Stay safe everyone!
 

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Replace your Battery to frame and frame engine grounds. or Verify that your grounds are good. Take a set of jumper cables and attach them from the negative post of the battery to the frame and the Negative post of the battery to the engine. Start with the Basics.

Then measure the voltage on teh bus bar... (there is the Fuse on the firewall that I have had crack not blow) make sure that you are getting 12V to it. Ford Starter Relays do go bad, and or the grounding point goes bad.
A bad ground will make you think your battery is dead.

If you have an infrared temp tester you should see them get warm.....
 

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If you clamp a jumper cable on the neg side of the battery and then to the engine block you will have the best ground you can get. Then clamping a cable from the positive post on the battery to the buss bar where the GPs are attached you should be able to feel the #4 one get warm. Count to ten and remove the Post clamp on the Battery.
 

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Yes, that jumper test is a good test of Crappy grounds which on a 30+ year old car is probably one of the cheapest and best upgrades that you can do to your car to keep electrical gremlins away.... most of the ground wires are brown on a VW....even westy's but you have to be mindful of the differences between a Westy, and a Euro....Rabbits are USA Golfs are Euro of the same years up until they moved production from Westmoreland and the earlier Rabbits were euro versions up to about 78....before they were "Mericanized"...
 
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