'03 Jetta: Replace Glow Plugs?

Mass. Wine Guy

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'01 Golf: Replace Glow Plugs?

My 2001 Golf has about 131,000 miles on it. For a few months I've had a CEL on it. A friend ran VAGCOM and it looked like it was some weird voltage in the glowplug/harness region. The car starts and runs fine, so I don't know if the glow plugs are at fault.

I'm going to bring the car in to my local independent mechanic on Tuesday for routine maintenance, and have him change out the harness. Should I also replace the glow plugs?

Thank you.
 
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Chemboy

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Nov 22, 2003
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Kenmore, WA
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2012 Jetta Sportwagen DSG
Mass. Wine Guy said:
My 2001 Golf has about 131,000 miles on it. For a few months I've had a CEL on it. A friend ran VAGCOM and it looked like it was some weird voltage in the glowplug/harness region. The car starts and runs fine, so I don't know if the glow plugs are at fault.

I'm going to bring the car in to my local independent mechanic on Tuesday for routine maintenance, and have him change out the harness. Should I also replace the glow plugs?

Thank you.
Why not have the resistance through each glow pug checked and look for faults? OR, you can replace the glow plugs (not a bad idea at your age and mileage) and if the problem persists, then look at the harness. No point in throwing out parts that aren't broken...unless you hate having excess cash.

--Andy
 

Mass. Wine Guy

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Sorry for the inaccurate title. I tried correcting it.

I thought the glow plug harness was a known issue. I already have the harness and new glow plugs. Should I start by just changing the glow plugs?
 

TurbineWhine

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Jetta, 2003, Platinum Grey
Mass. Wine Guy said:
Sorry for the inaccurate title. I tried correcting it.

I thought the glow plug harness was a known issue. I already have the harness and new glow plugs. Should I start by just changing the glow plugs?
Yes, start by just changing the Glow Plugs (less labor) but before you change out a glow plug have the shop measure the resistance of the glow plug tip to the engine block. That resistance should be between .6 and .9 Ohms and they should all be within that range. Now his meter may be off a little so what you are really looking for is very close reading between all 4 plugs ( .6 to 1.0 Ohms). The harness is an issue only because VW chose to use a 50KV system (spark plug style) on a 12V application. That connection of the harness to the glow plug should have been a bolted or soldered connection. The resistance of a good plug vs. a bad plug is so small that any little issue of harness to plug connection can cause a CEL, even if the glow plug is perfectly fine. Save the harness replacement as a last ditch effort.

TW
 

Mass. Wine Guy

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Does this mean to just uncouple each of the four harness leads going to each plug and spray the stuff inside the rubber contact housing?

whitedog said:
And have the shop use some Deoxit to clean the harness first.
 

whitedog

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2004 Jetta that I fill by myself
Mass. Wine Guy said:
Does this mean to just uncouple each of the four harness leads going to each plug and spray the stuff inside the rubber contact housing?
You can even turn the openings up, spray a bunch in there and use an old glowplug to try to get the metal pieces moving around in there. There is one sleeve inside another and it's between the two sleeves that the corrosion builds. Working the old glowplug in and out should give a bit better results than just sparying the Deoxit in there. After removing the glowplug, turn the opening down and rinse with a bit more cleaner.
 

Mass. Wine Guy

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Maybe I'll do that to the harness myself. I don't want to tell my mechanic how to do it step by step.
 

whitedog

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It's easy-peasy, but it certainly helps if you unbolt that black, vacuum ball first.
 

ymz

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First, find out what the problem is...

You can measure the resistance of the 4 glow plugs using any cheapo digital volt-ohm-meter (multimeter)... Harbor Freight just had some real cheapos on sale for $1.99 this weekend... now the cheapest they have is about double that...

If all 4 check out more or less the same (within about 0.3 ohm of each other), then suspect the harness - and rather than replacing it, just give it a good scrubbing with DeOxit D5 or equivalent... sometimes, just the act of removing and replacing the harness will clean enough corrosion to eliminate any future CEL's - for a while...

This certainly isn't a job that calls for profe$$ional help unless you really have no time or inclination... the trouble with most regular mechanics is that they'll just fix it by replacing parts that may not need replacing... (and charge you for the priviledge...)

All the best,

Yuri.
 

Mass. Wine Guy

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I agree with you, Yuri. But the car has 130,000 or so miles on it, I've had the new wire harness for a while, so maybe it's just good preventive maintenance to replace the harness and plugs.
 

Chemboy

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Kenmore, WA
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Mass. Wine Guy said:
I agree with you, Yuri. But the car has 130,000 or so miles on it, I've had the new wire harness for a while, so maybe it's just good preventive maintenance to replace the harness and plugs.
Nope. It's good preventative maintenance to replace the glow plugs (a wear item). It's a waste of money to replace the harness if it's not damaged.

--Andy
 

POWERSTROKE

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Staten Island (The Dump)
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2002 Golf
Mass. Wine Guy said:
My 2001 Golf has about 131,000 miles on it. For a few months I've had a CEL on it. A friend ran VAGCOM and it looked like it was some weird voltage in the glowplug/harness region. The car starts and runs fine, so I don't know if the glow plugs are at fault.

I'm going to bring the car in to my local independent mechanic on Tuesday for routine maintenance, and have him change out the harness. Should I also replace the glow plugs?

Thank you.
You can do this yourself. I just had this problem on my wifes car. Buy a cheap multi-meter from sears ($25). Ground the black wire from the multi-meter and test each glow plug. Touch the red probe to the tip of each plug. They should all show the relative same reading. If I recall it is 1.5. The one that is off in one direction or other is the offending plug. Also you can test each "outlet" of the harness as well. They should all read near 12v I believe. Correct me if I am wrong. If they all read proper, then that is not your problem. It is really simple to do.
I would not replace any item that is still serviceable. Replace when it is broken. Find out what is causing your problems first. When you take the plugs out, be real carefull, they are in there nice and tight so take your time.
 
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puter

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Mass. Wine Guy said:
You don't know my ability (or lack of it) like me. I'm not touching it.
The glow plugs come out like a spark plug.

You just take the cover off the engine, unplug the wire harness, unscrew the plug.
 

ymz

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Mass. Wine Guy said:
I agree with you, Yuri. But the car has 130,000 or so miles on it, I've had the new wire harness for a while, so maybe it's just good preventive maintenance to replace the harness and plugs.
My 2003 has 273,000 miles on it... original harness... needed a DeOxit treatment about 2.5 years ago... One glow plug went back at 153,700 miles, so I replaced all four... I've recently bought a 2001 that had 3 dead glow plugs... I put in the ones I took out of the 2003...

Just FYI...

Yuri.
 

Mass. Wine Guy

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So I changed both the glow plugs and wire harness (call me crazy) and the CEL is still on. Is this just a matter of clearing it from memory with a VAGCOM?
 

ymz

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Glow plug error codes must be cleared with a scan tool...

Vag Com's the best for these cars, but any generic scanner will do for this...

Most Auto-Zones (PepBoyz, Advance Auto, etc.) will scan the car for free, and some of them will also clear the code if you ask nicely...

Yuri.
 

MikeS_18

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MassWine,

You need to contact JollyGreenGiant (Jon Hess) in Bradford/Haverhill. He is an excellent mechanic and has Vagcom and all that jazz. That's the closet you'll get and well worth it.

You will need to reset the light even if you have cleared the faulty item. GP errors don't go away on their own.
 

Mass. Wine Guy

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MikeS_18 said:
MassWine,

You need to contact JollyGreenGiant (Jon Hess) in Bradford/Haverhill.
I did, and I was puzzled with his reply. I asked if I could come over to have the oil and filter changed, tires rotated and to take a look at my rear springs and shocks. After two or three emails and two phone calls he wrote back saying how he is too specialized to do routine maintenance. So I'm just guessing that something as mundane as clearing a fault code with a VAGCOM would be downright insulting to him.
 

MikeS_18

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huh. okay. He doesn't do basic maintenance (oil changes, tires rotated) so I can see that. You could contact peterv as well. he has Vagcom but is a bit further in East Hampstead...or Dave S in Nashua although I think he is in Mass some..and tommyt is in Manchester NH but drives all over creation so that's an option too.
 
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