Running it hard with more fuel/boost... Anyone going through glow plugs?

[vwjunkie53]

Is anyone else having trouble with keeping glow plugs in there engine?  Mine keep burning out/going bad whatever.  I am using the good Bosch plugs (made in France) not some cheap autozone junk.  I'm wondering if it would have anything to do with the engine being run hard pretty often and the higher boost and fueling levels and of course the added combustion heat.  I never had to replace the plugs in my 85 TD Jetta after I rebuilt the engine, and I ran it decently hard, but not as much boost or as hard as the volvo.  I have replaced almost all the glow plugs twice and I have only had the car since June!  Any ideas?

Jason

[Vincent Waldon]

A couple of questions spring to mind:

- are they burning out internally, or do they look physically damaged when you remove 'em?

- is your glow plug relay turning them on and off properly, or is it leaving them on too long repeatedly?

- what voltage is your alternator putting out?  Anything else burning out quickly as well... headlights, etc?

[vwjunkie53]

No damage to the tips, they always look fine.  They don't even look erroded away at all.  They just burn out.

The relay is working correctly as far as I know, I can hear it turn on and then click off.  Since its firing six plugs its a big ass relay and pretty loud click when it turns on and off.

Good voltage from the alt, and I'm not having any other electrical problems with the car/buring out bulbs/etc.  The battery is new as well.

Jason

[burn_your_money]

What torque are you installing them to?

[weejimmy]

do you get them from a reputable suplier? or ebay specials etc?

http://www.boschautoparts.co.uk/pcGlow12.asp?c=2&d=1

[zukgod1]

No damage to the tips, they always look fine.  They don't even look erroded away at all.  They just burn out.

The relay is working correctly as far as I know, I can hear it turn on and then click off.  Since its firing six plugs its a big ass relay and pretty loud click when it turns on and off.

Good voltage from the alt, and I'm not having any other electrical problems with the car/buring out bulbs/etc.  The battery is new as well.

Jason

You need to elaborate a bit more on this.

Voltage; what is it?

Glow plug relay; Test it. Stick a Test light on the glow plug bar and start it up to actually see whats going on, watch the light for a good 5 min to make sure it's not turning back on after you get driving.

[vwjunkie53]

I'm buying the tips from the VW shop I work at. They are Genuine Bosch plugs not the offshore junk.  I did have a test light wired up into the car over the summer for a while to make sure it was staying off and it never did anything weird.  I had it dangling in the car for about a month and took it out after nothing ever happened!  As for voltage, I'm measuring the same voltage at the end of the power wire to the plugs from the relay as I get at the battery (a little over 12v).  I'm at a loss why they keep crapping out. I never had this problem with my jetta.  As for torque, I snug them in with a wrench.  Nothing crazy tight as I don't want to strip the head of course.  I doubt I'm getting them too tight but maybe not tight enough?  I've never had one come loose or back out.

Jason

[zukgod1]

Ok so it sounds like you have gone through the correct testing so your only other option is to get your glow plugs from another vendor.

You wont get an intermittent glow plug failure from boost/fueling, you'll get a physically burnt out plug like the end will be burnt off.

Try another vendor for your GP's..

[vwjunkie53]

I guess thats about my only recourse at this point.  I have examined the glow plugs closely and they are Bosch made in france plugs...  The boxes don't look old or like they have been laying around.  Kinda annoying!

Thanks for the suggestions.

Jason

[vanbcguy]

The only other thing is the torque used on installation - I know someone mentioned it earlier, but just so it doesn't slip away - overtightening the glow plugs will make them fail prematurely in exactly the way you are describing.

[macka]

I had slow relay installed by the DPO when I bought the car, I have the proper one now, I think Libby is on the right track with the relay. It also wouldn't hurt to pimp the plugs ala Vince. It makes a huge difference in the cold start.

[burn_your_money]

Doesn't burning oil also shorten the life of glowplugs?

[Rabbit on Roids]

Doesn't burning oil also shorten the life of glowplugs?

yes, badly. least my audi engine ate some good plugs up fast. it burned a quart every 100 mi.

[745 turbogreasel]

I believe EGT and glow life are inverse proportional.

[vwjunkie53]

Ya egts were my theory which is was i was asking about more fuel/boost.  My car uses some oil but nothing like a quart per 100miles!  They are fast plugs the relay is the original as far as I can tell.  I'll look up the torque spec in my manual and torque them all.  I really doubt I'm over tighting them but I suppose its possible.  I build engines for a living, I'm pretty good at feeling whats too tight!

Jason