In the fall of '02 I replaced all 5 glow plugs in my '81 300TD wagon with new ones. They weren't Bosch, they were either Champion, Autolite, or Motorcraft.

Well, I just checked today and 2 of the 5 are bad. I haven't pulled 'em yet because I'm waiting for new ones.

What causes them to give out early? Should I go ahead and replace all 5? With Bosch or doesn't it really matter?

Not looking to cause a brand debate, just want some guidance.

thanks!

If you do a search on this topic I think you'll find several posts about the early demise of non-Bosch glow plugs. I always use Bosch, so I've had no experience with other brands, but I'm sure you'll get responses from others who have used them.

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Mike

2000 SL500 22,000 miles
1981 300CD 188,000 miles
1979 450 SEL 266,000 miles
2005 Cadillac CTS 25,000 miles

My 1985 300d had ALL 5 glowplugs replaced 2 winters ago.
They are BOSCH plugs.
Last weekend was BITTER COLD......-5F. to -10F. (BELOW ZERO)
I was in the mountains of western Mass.
Unfortunately, my block heater cord developed an internal short in the wiring near the plug. ....damn!
Anyway, after much cranking and cranking etc.......she would NOT
fire.
While ATTEMPTING the starting process, the glow plug lamp on the dash was functioning CORRECTLY.........After many attempts, the dash lamp would NOT light.
Next, I located a replacement industrial 3 prong connector to attatch to the existing block heater wiring (after the shorted section of wire).....Then plugged the b-tch in for 3 hours.
When I touched the top of the valve cover, it was very warm to the touch.
The "Black Bomber" lit right up. We drove all day on the back roads with some stops and starts along the way.
Today, the weather is MUCH WARMER at 33F.....
After I got home from work, I checked for correct voltage at the input of the glow plug relay...OK!
Next, I checked for voltage at EACH of the output terminals of the G.P. relay....OK!
My flashlight began to dim... ...After ohming each of the leads to the actual glowplugs, 3 had infinite resistance, the other 2 appear good. Time to go in for the night. I will drive my company gas truck for work tomorrow.
My QUESTION being: similar to shawnster...ie: WHAT ACTUALLY WOULD CAUSE (a genuine set of BOSCH plugs) to GO BAD?
In an attempt to see if POSSIBLY any OTHER path for the electricity to bypass the plugs, I sprayed some electrical contact cleaner at EACH of the GPs.....still no go
I SUPPOSE that there is the slightest chance that thyere may be enough corrosion at the threaded celectrical contact points to cause resistance....HOWEVER, I do believe that I indeed need to replace the 3 bad GPs.
Any thoughts on this matter would be appreciated .
Best wishes always, and SORRY that I needed to play diesel mechanic instead of attending the "ICE BOWL N.E. GTG"
See 'ya,
spo out

ttt

Glow plugs are meant for intermittant use only. Leave them on too long and the burn out (the filament breaks off the weld at the tip) and they fail.

Cranking for extended periods of time and rapid cycling of the glowplugs can "use them up" pretty fast.

I know, I've fried quite a few in the Volvo. Use Bosch only, the rest of them fail faster.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!