Glow plugs stay on
 

I have an intermittent, glow plug problem. The dash light comes on but doesn't always go off. The problems getting worse lately with light staying on for up to 30 minutes.

Last night when I got home (the light had been on the whole 30 minute drive), I turned off the car and noticed the lights got brighter, so there's definitely a drain.

During the last two years, the light would go off after the 1st couple of minutes after the car started (if it did'nt go off right away), but it's been getting progressively worse.

The car starts fine, it fires up when the seat belt light goes off (about 10-15sec).

Any thougths?

I've got similar issues with the 300SD, although not to your extent yet.

Sometimes the glow plug light will only stay on for two seconds even when the car is cold. But I can tell the glow plugs remain on by the current drain.

Then sometimes the glow plug light will just stay on for several minutes even after the car has started. I have not had the time to check for power at the glow plugs during this condition.

I'll be working on it over time and let you know what I find. First suspect though is the glow plug relay itself.

Ken300D

There's definitely a drain. The battery was dead this morning.

I'm thinking relay problem myself.

As the glow plug relays age the number failing to function properly have increased very rapidly. The majority of the relays for OM61x engines are 20+ years old and while 5 years ago, it was rare to hear of one or two relay failures in a year, I've heard of 20 or thirty this year alone. Most of the failures seem to be of electrolytic capacitors used in the timing circuits, but I'm sure there are OTHER elements that CAN/DO fail.

In several cases reported this year - the NEW replacement relay were found to be defective as well. It has been established that relays manufactured and then stored for more than two years have a high initial failure rate when put into service. Sometimes, if the failure is simply a very short timeout period before the dash light extinguishes, the relay can be "repaired" by cycling it repeatedly 10-15 times.

Old relays taken out of service and stored - and then returned to service have a VERY high failure rate as well.

Seems like the best thing you can do for a glow plug relay is use it every day!

Both Bosch and Beru make/sell conversion kits to retrofit "afterstart" glow function with much quicker initial heating to older 4-5 cylinder diesels and these "kits" (which includ 4 plugs and a relay - you buy one additional plug if you have a 5 cylinder engine) sell for about what a new Mercedes glow plug relay alone sells for (~$100-120). Worth considering!

Marshall

It was the relay, got the new one from FastLane today. Now I no longer have to use the seat belt light as a timer.

Yes, capacitors are the electronic components that will give up with age, not mileage.

With aged electronics it is often necessary to do a complete capacitor renovation. Electrolytics are particularly prone to failure due to age. All capacitor types are effected, however. The least effected components are semiconductors.

Good luck,

OK...As Leathermang is a crusader for the inspection of pre chambers , I advocate the throwing away of your troublesome relays and installing push buttons, therefore becoming the master of your own glow. Chances are nobody will be able to steal your car either:D

Well you could count to 10 or 20-30 on a cold day!

Marshall

We don't do cold days in Austin.

Got a new feature now, the wipers cycle on startup

That's not a feature! That's a flaw!

Marshall

A feature is a hightech "nice" way of discriping a problem.

ex. One of the features of windows is its ability to freeze up when it gets confused and let you restart the machine for a fresh start.

That's not a feature - that's a FLAW! A REAL BIG ONE!

Marshall