Glow Plug replacement

Hi,

How often should glow plugs be replaced on the ALH? Car is 391,000 on it, and it is cranking more now that cooler weather has hit.

I bought the car with 358,000 on it, and did not see anything in the records about GP replacement. My olf MB 300D, I replaced the GP's every 3 years.

Thanks!

When the MIL comes on and a DTC is set related to the glow system and diagnosis of that system shows a plug is bad.

The glow system is monitored by the ECU.

Long crank time could be a lot of things. But if there is no DTC stored for the glow system, it is not the glow system.

Even the older IDI MB diesels would alert you to a bad plug by means of turning the glow lamp on after the engine was running. This function was done all in the glow controller by means of comparing circuit draw on each of the 4, 5, or 6 circuits depending on which engine it was.

Unless the car is throwing a glow plug code you don't need to worry. A long crank can be a weak starter or battery.

It is throwing the GP MIL, according the VCDS. It is also due for a starter refresh, due the the after start whirring noise.

OK, so what is your question again?

Fix the glow system, if you think you need a starter (slow crank but battery is OK, which is a common failure mode for these) then replace that too.

Only use a genuine Bosch reman starter. Bosch or Beru plugs are fine, but I like to use all the same type. They often need a glow plug harness (bridge) too. Which is easy on the later ALHs like yours, as it has a plug in the wire harness holder near the firewall.