Possible Glow Plug Harness Cure

Wingnut · December 5th, 2003, 21:34

There have been LOTS of posts about glow plug problems. When the code is thrown, it could be caused by several different factors. A bad plug or plugs (usualy), a corroded harness (often), or a bad relay (not very often).

Luckily, the most expensive option is the last one, so glad its not very common. A simple test can confirm or rule out a bad glow plug. So if they pass the test, then the code was likely thrown by a slightly corroded harness.

I found this product that may be able to help those who have chronic glow plug codes. Its cheaper, easier, and less invasive than changing the harness and may eliminate the triggering of MIL's.

For a complete list of distributors, click on the distributor icon at the top of this page

I also found this product from the same manufacturer. Not sure which one would be better?

EDIT: While placing an order for these products, I also found this one. It looks like it might be even better than either of the other two? It claims:

Improves conductivity
Deoxidizes, cleans, preserves, and lubricates
Reduces intermittents
Reduces wear, abrasion, arcing and RFI
Stabilizes connections between similar and dissimilar metals

Exaclty whay we are looking for to cure the harness problems.

FlyTDI Guy · December 5th, 2003, 21:52

I would opt for the product behind curtain number two. For glow plugs, the heat rating is in it's favor. I've been telling people to use Ox-Gard but... I have it on good authority it doesn't like heat and will dry out. This looks to be a better alternative considering it's 200ºc rating.

blitzoid · December 5th, 2003, 21:52

I wonder - any chemicals in either which might react badly to the wide range of temperatures, humidity and other elements found inside an engine compartment? Just a thought... my TDI doesn't have enough mileage for the glowplugs to be an issue, so I will be the first to admit i'm not exactly an expert here. Haven't had to take one out yet, or test it, etc.

Birdman · December 5th, 2003, 23:26

For whatever the reason milage and or time does not seem to make a differance in the lasting of glow plugs. [ QUOTE ]
my TDI doesn't have enough mileage for the glowplugs to be an issue, so I will be the first to admit i'm not exactly an expert here. Haven't had to take one out yet, or test it, etc.

[/ QUOTE ] But as long as it starts good i would not worry about it. Now on the early rabbits 1 bad glow plug and you had a problem. I have started this 01 in 0% weather WITHOUT using the glow plugs ( took fuse out) and while it started slower it still started.

blitzoid · December 6th, 2003, 11:20

That's what i'm saying - I haven't had the joy of having a problematic glow plug yet. Mostly, since i don't know much about the way they connect to the car, how the harness is protected, etc, I have no idea if my question about chemicals and engine compartment conditions is a valid one or not. If it is, i'd love to hear the answer. If it isn't, then it would seem that either product would fit the bill.

Either way, thanks to wingnut for doing the research on this. Very useful info.

cheers.

Wingnut · December 6th, 2003, 19:03

A bit of preventative maintenance could save lots of future agrivation. There have been a rash of phantom glow plug codes thrown and since there is no way to test the harness, the only way to eliminate it as the cause is to either replace it or try to treat it. Checking the plugs themselves is easy. So is checking the relay. So if those check out ok, then the harness seems like a logical place. I took my old harness apart to see why it would be bad.

Here are the pics I took:

As you can see, the two center liners are severely oxidised and scorched. The scorching is probably as a result of arcing due to the poor contact caused by the oxidation. So treating it is a viable solution if you catch it early. But treating it early & regularly is also good preventative maintenance.

This harness caused my MIL to come on 4 times within a months time. Each time returning within from a few to 400km after having it cleared. I have not had a CEL in a year now & 40k km. So obviusly, the harness was my problem.

HUDF162049 · December 7th, 2003, 02:02

I read this whole discussion but I still posted the same question. Myself and the mechanic shot the whole harness and every connection while moving the entire harness and no shorts or jumps in voltage occurred. So do you think it could still be a harness problem?? [img]/images/graemlins/confused.gif[/img] HUD

Frank M · December 7th, 2003, 06:04

[ QUOTE ]
HUDF162049 said:
I read this whole discussion but I still posted the same question. Myself and the mechanic shot the whole harness and every connection while moving the entire harness and no shorts or jumps in voltage occurred. So do you think it could still be a harness problem?? [img]/images/graemlins/confused.gif[/img] HUD

[/ QUOTE ]

the GP have a very low resistance. A slight resistance in the harness will change the total resistance dramatically. (you may not be able to see it on a meter while wiggling the harness, try a scope)
this will set off the CEL.

I have been spraying WD40 in mine and thus far have the original harness.

HUDF162049 · December 7th, 2003, 08:49

Thanks I'll give it a shot. I'll let you know how it turns out.. [img]/images/graemlins/smile.gif[/img]

Wingnut · January 4th, 2004, 00:43

Found another product. Check original post for details.

Wingnut · January 9th, 2004, 12:05

Ok. I got my shipment in today. I got one each of the Deoxit D5 & the Super contact cleaner:

Here as what is written on each can:

Deoxit D5:
- Improves conductivity
- Deoxidises, cleans, lubricates & preserves
- Reduces connection failures
- Reduces wear & abrasion
- Reduces arcing & RFI
- Temerature range -34* C to 200*C
- Effective on similar & dissimmilar metals
- Use on stationary & moving connections

Super Cpontact Cleaner:
- Cleans, lubricates & protects
- Eliminates oxidation
- Improves conductivity
- Safe on most plastics
- Molecularly bonds to all metals.

So I would have to say that while both seem to have the characteristics we are looking for (contact cleaning, contact enhancing & deoxidising) it looks like the DeoxitD5 looks like the better product due to its temp rating. But it was also more expensive. I will have a chance to test these products on the weekend as I have someone with a GP fault coming over to clear his MIL.

But even if you don't have a glow plug fault, I would still recommend picking up one of these products to treat your harness and use it as preventative maintenance. There are way too many glow plug faults being reported. And many are not glow plug related, so instead of spending $25 to replace your harness, just spend $10 and treat it before it becomes a problem. I will bring these cans to all future GTG's if anyone local wants a squirt.

RichCA · January 19th, 2004, 09:20

Here's a little more info on deoxit:
http://www.intendedacceleration.com/html/tip_14.html
and also some info on Stabilant 22 that is said to be good to use after using deoxit:
http://www.stabilant.com/
Apparantly stabilant 22 can be bought at vw, napa, uap.. I'm going to check it out today and check out the price.

Rich

four_barrel · March 8th, 2004, 17:30

I use DC 4 compound From Dow Corning. This stuff is good, [img]/images/graemlins/laugh.gif[/img] I use it at my job often. The price is a little high but worth it. This is just one link I found to show what it is. One tube will last a long time.

Chief Aircraft Inc.

AndyK · March 8th, 2004, 19:34

Unfortunately DC-4 Compound is a di-electric compound. I think I want the most current I can get and the best conductance I can get at the connection to the glow plugs.

Another A&P...

danix · March 9th, 2004, 04:45

stabiliant 22a is cheapest when purchased from Motorola, but it's still in the $30-40/bottle range. I can dig up the info if there is serious interest. The Caig products are very good for their price.