Premature Glow Plug Failure | Electrical Problem

If it is happening on a regular basis it probably is not bad glow plugs

We receive reports from time to time from Mercedes diesel owners that all their glow plugs have burned out. We also have received emails from customers who are having problems with one or more glow plugs burning out on a regular basis.

Problem & Solution

Common among these chassis:

W110 W111 W112 Sedan

W115

W116

W123

W124

W126

W140

W201

We have sold hundreds of sets of glow plugs over the past 15 years and have found premature glow plug burnout can be caused by one or more of the following:

1. Glow relay is sticking and staying on too long

2. If using manual button it is held on too long each morning

3. Carbon in the pre-chambers

4. Poor spray pattern of the injectors thus flooding the tips during high heat leading to premature failure

5. Injection pump timing set to far in advance

6. Failure of alternator voltage regulator creating a charge voltage over 14 volts.

7. Continuing to start the car with one or two bad plugs- this puts strain on the other good plugs due to a higher voltage

We have never found a set to just fail under normal operations with all of the above correct.