Glow plug light flashes after car started, poor MPG - PeachParts Mercedes-Benz Forum

1981_300sd · #1 10-08-2009, 02:24 PM

Hello,

Having another strange issue on my 1982 240D

Car starts fine in the morning, but does "stutter" more than it used to.

Then while driving the glow plug light will turn on for a couple of seconds, and turn back off. This will happen several times on my 15 mile commute - so even when my car is warmed up and going down the freeway.

I also used to get 330 miles per tank in the car, now im down to about 270.

Does the glowplug symptoms and the car being sluggish have anything to do with each other? Biggest question I have is why the glowplug light comes on and off when the car is already started and warmed up.

I know the car being sluggish is usually plugged fuel filter, dirty injectors, things like that (does have new fuel filters in the last 200 miles and going to check my injectors soon) but not sure if the glowplug light turning on when it does has anything to do with the other issues.

Thanks for any help in advance.

Graplr · #2 10-08-2009, 02:40 PM

My glow plug light used to flicker on and off while I was driving. I attributed it to a faulty glow plug relay. Even though mine would test good most of the time, I was still leary. I bought the upgrade after-glow kit from fastlane (with 4 new Bosch duratherms) for ~$100. My glow plug light no longer flickers.

I don't see a correlation with the gp light and the sluggishness.

1981_300sd · #3 10-08-2009, 02:49 PM

ok cool.

One thing I want to clarify, is that the glowplug light does not flicker. It turns on, says on for maybe 4-5 seconds, then turns off.

ts not like faulty equipment where if I make a sharp turn the light will flicker or something like that.

Diesel911 · #4 10-08-2009, 02:52 PM

Have you been haveing any smoke and if so what color?

I first would check the Glow Plugs; you can use that Diesel Giant website pictorial on how to do it. You will need a Digital Volt/Ohm meter; Harbor Freight sells them for $4.
I do not know what year it changed but the Older models had a Coolant Temp sensor connected to the Glow Plug Relay. If yours has one perhaps the wire is loose of there is a problem with the Sensor.

If there is enough crap in your Fuel a new Filter might last a matter of hours; I have seen this. So when you changed the Filter may not matter.

Just to rule the Filters out as a source I would change them and Keep the Old Filters in a Plastic Bag so if it turned out they were OK I could reuse them.

Then there are the Fuel Tank Screen that can get restricted and the Fuel Tank Vent also (drive without the Fuel Fill Cap and see; if performance improves your tank vent is restricted).

It could also be time for a Valve Adjustment.

Graplr · #5 10-08-2009, 03:03 PM

Quote:

Originally Posted by 1981_300sd

ok cool.

One thing I want to clarify, is that the glowplug light does not flicker. It turns on, says on for maybe 4-5 seconds, then turns off.

ts not like faulty equipment where if I make a sharp turn the light will flicker or something like that.

Yes, that is what I meant by flicker. It would turn on for a few seconds, then off.

Here is the new glow plug relay-
http://catalog.peachparts.com/ShopByVehicle.epc?q=&yearid=1982@@1982&makeid=63@@MERCEDES+BENZ@@X&modelid=6142%3AMBC%7C1489%3AED%7C10000129@@240D&catid=241959@@Body+Electrical&subcatid=242005@@Preglow+Time+Relay&applicationid=W0133-1606169&mode=PA

$116.45 with 4 gps worth about $40-50 just themselves. Plus I believe you get free shipping for an order of that much.

But, I would definitely follow Diesel911's advice and check everything out first.

winmutt · #6 10-08-2009, 03:09 PM

Valve adjustment is in order if its over due. Certainly test the GP.

1981_300sd · #7 10-09-2009, 06:54 PM

Thanks for the responses everyone, will start investigating this weekend!