1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out

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Mon 25 Oct 2010 13:20
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Negger

(later type glow plug control unit (GPCU) mounted on L/H Inner Wing)

Further to a previous post:

www.honestjohn.co.uk/forum/post/index.htm?t=59250

I have now replaced the full set of glow plugs twice since Jan 08, and they now need replacing again!

I've replaced the temperature sensor in the heater flow pipe which appears to be connected to the GPCU, just in case.

The temperature gauge and glow plug warning light on the dash appear to be working normally. Relay appears to be working OK.

Can anyone suggest a reason why these plugs keep burning out, as I obviously need to correct this before another new set go west?

My Haynes manual (3498) is not much help as the wiring digram doesn't cover the later type GPCU. Can anyone direct me to a suitable wiring digram ?

Is there a way to test the GPCU ?

Many Thanks

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Mon 25 Oct 2010 15:16
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Peter.N.

I did not see your previous post but have you checked that the glowplugs are switching off at the appropriate time or not perhaps coming on again? If you place a voltmeter inside the car connected between the glow plug supply rail and earth you can moniter the supply to the plugs.

Are the plugs going completely open circuit?

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Mon 25 Oct 2010 20:12
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Peter D

Yes, check the turn on times and tell us what make of glowplugs you are purchasing and from where. Regards Peter

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Tue 24 May 2011 12:06
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Negger

As an update, a friendly auto-electrician suggested using only genuine VAG glow plugs rather than the supposedly OE parts I had been fitting (from a well known national distributor !) These cost about 4X the price, but since then no further problems despite exceptionally cold winter, and now starts instantly.

Clearly the genuine parts are superior quality ?

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Tue 24 May 2011 13:13
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Peter.N.

I have heard this about glow plugs before but I have very rarely had them fail and usually had some spares in another engine I can use.

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Tue 24 May 2011 15:52
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - injection doc

Very common for aftermarket glow plugs I'm afraid 1 as they say you get what you pay for. I always use genuine, as there have been many cases of the tips falling off into an engine and causing thousands of pounds of damage !

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Wed 25 May 2011 10:57
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Negger

Thank you both for your input-hopefully these wont need changing again for the remaining life expectancy of the motor! Would strongly advise anyone needing to replace any glow plugs to get the genuine VAG parts. By the time the cost of two sets of aftermarket plugs are deducted, they are not so expensive after all. If you can get access to a TPS branch (Trade Parts Specialists) then that will certainly help with regard to cost.

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Wed 25 May 2011 14:34
1995 Passat 1.9TD AAZ Engine No. - Glow Plugs Burning Out - Simoncelli58

There was a programme on TV last night night.

You name it,some one makes a perfect copy in China/India.(Other country's may also copy) !

Perfect in all but quality.

Even the legitimate shops and dealers don't know what they are selling !

Chemists are affected too ! Scary if your Heart drugs are made in a drug dealers kitchen !!!

Scary,but at least our EML's come on and tell us where t our cars are faulty..

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