Club 80-90 Forums

Thanks - that all makes more sense.

BTW, I tried another fuse - blew instantly.

When you say remove the wire connection from the fuse to the busbar, if the fuse is blown then isn't that the same? Or do I have to remove the connection we see in the centre of this photo? Anyway I read between these points ...



With a good bit of scratching I was able to get the multimeter to read zero. Have we definitely ruled out the relay and are getting into glowplug/busbar issues?

Looking at that pic you are going to have to have a very close look at all of that wiring and the busbar. There is corrosion at the connection to the busbar and the busbar looks twisted and the insulation is hanging off. The glow plug looks like it was fitted at the time of the ark! (Well overdue for replacement I should say). You are going to have to remove the busbar to check each plug individually if you cannot find any evidence of a short on the wire or busbar. Changing the glow plugs get progressively harder as you move on after that first one. The one by the injector pump is the hardest but can be done with a lot of patience and care.



E D I T - forgot to say: if you remove the wire from the busbar you can then tell whether the short is in the wire or the busbar/glow plugs. Just a process of elimination that we take for granted after years of head scratching over engines.

Oldiebut goodie wrote:Surely the fuse will not blow on an open circuit - did you mean to say short circuit ie no resistance?

Yep. That's what I meant to say.

Looking at those photos you're going to have a bugger of a job getting then glow plugs out!
Start applying the plus gas now!

You'll probably have to remove the injection pump and attack them with a six point deep socket.

Hello everyone, new dawn etc...

In trying to disconnect the bus bar, the head of the first glow plug sheared off. So now the bus bar feeds 3 glow plugs, which incidentally look in way better condition than the first one!

I phoned a friend who is nor a VW expert but general mechanic and he said that I should now be wary of the top of the glow plug shearing off and the rest then being stuck in the engine block. I guess that is where the plus gas rather than WD40 comes in?

WD40 had not helped loosen that first nut so, so far, I've not been able to test the wiring between the bus bar and the relay - but the ohmmeter still seems to read zero at the start of the bus bar. So I assume a new fuse will blow again, but maybe for 80p (with three left) I should try.

This is becoming a bigger job.... but in the short term I dearly want to get it to the MOT retest tomorrow - but I could wait until Tuesday (final day) when the temp should get up to 25 degrees, I'd be able to let that engine block bask in the sun, and even get out a hairdryer. Perhaps I will test that technique this afternoon but should it work?

I have read about a direct connection battery to bus bar but that sounds scary!

Hair dryer treatment for 10 minutes. Cranked 6 times or so and then it started firing.
What a relief, I should be able to get it to the MOT retest tomorrow!

Of course I still have a little issue with those glow plugs (any other words of wisdom appreciated) but the acute pressure is off.

You could try and connect a jumper lead to the bus bar and the positive terminal of the battery, that would get the glow plugs working.

I think that was the solution that scared me!
But you are perhaps suggesting that this is done for, say, 30 secs ahead of actually starting, but remove them just before ignition?

Yes, about 20 to 30 seconds would be fine.
When the glow plug led goes out the glow plugs are still connected and work for about 20 seconds.
Listen to the relay, it'll clunk as it drops out after about that time.

Wrong advice at present state of play!
Sparks will fly doing that without sorting out the short circuit which hasn't been found yet - all that is certain is that it still shorts somewhere after the first glow plug at present.

I think OBG is right to inject some caution. The risk of putting an un-fused 12v feed on the busbar directly, with a probable short circuit in the system, is that you could end up effectively 'welding' the defective glow plug(s) to the block, and then you'd really have a BIG problem.

Thanks - all taken in and for now I'll stick with the hair dryer, and I know it works!

There really is such a difference between the state of that first plug and the others. I've had it suggested to me that the other three have been replaced at some stage but the other was rusted in when the others were swapped. If that's the case I'm tempted to replace the other three as one of them is the likely culprit. I think the fuel gubbins will have to come off though.

Anyway it's easy enough to get a relay (just in case) and glow plugs but the bus bar is trickier - I think it should be replace and there are none listed at JK or VW Heritage, my usual ports of call. Any suggestions for where else I look?

Unless it is really badly corroded (i.e. holed or paperthin) you should be able to clean the busbar up. It is just a copper strip.

If it is fubarred then you could run a high voltage/current silicon wire glow plugs 2,3 and 4 and then connect the leads to glow plug 1.

Brickwerks stock the bus bar - https://www.brickwerks.co.uk/index.php/ ... iesel.html

Thanks. Brickwerks was the next place I looked and I have one on order with 4 plugs and relay. I figure that I will probably be sending back some of these bits.

I have the MOT pass document in my hands!

The nut is not coming off the bus bar so I cut the cable. The ohmmeter tells me that there is no resistance between the bar and the head so I presume that one of the 3 remaining plugs is defective. But trying to educate myself on this, I find articles on defective plugs having a large resistance, way over 1-2 ohms.

Final thought is that it could be very useful to have some spare 8mm nuts!