Mercedes 601 602 603 Diesel Engine Glow Plug Removal and Repair - by Kent Bergsma

Burned out glow plugs are becoming an increasing problem in the 60x. engines produced from the mid 1980s to the mid 1990s. This 60x. group in question includes the four cylinder (601) engine that came in the 1984-1986 190D 2.2, the five cylinder (602) engine that came in the 190D 2.5 and 300D 2.5 from 1986 to 1993, and the 6 cylinder (603) engine installed in the 124, 126, and 140 chassis 300D / TD (1987 only), 300SDL and 350SDL.

These were Mercedes new class of diesel engines with aluminum cylinder heads. All turbo models can be easily recognized by the flat intake manifold that goes from the turbo side of the engine over the middle center of the engine valve cover. We get emails all the time from people asking where the glow plugs are located. On these engines it is very difficult to even see them let alone get them replaced without some major surgery. The process looks a little daunting at first, but with the right instructions and tools you can do this job in an afternoon.

This manual will take you through the step-by-step process of removing the intake manifold, replacing the plugs and re-installing the manifold. Sure not as easy as replacing the glow plugs in the earlier diesels - but with these instructions it is very doable for the home mechanic.

SPECIAL NOTE: If you plan to change your glow plugs you will need a replacement intake manifold gasket. CLICK HERE to order. We can also supply you with new glow plugs. Just type glow plugs in the search box on the right to find the correct ones for your model.

Here is a recent testimony from one of our customers:

Dear Kent,
Thank you, Thank you, Thank you,
I have a 1992 300D 2.5 Turbo Diesel with 160,000 miles that was a very
very sick. It had serious difficulty starting unless the block heater had
been on for an hour. When it started, there was a lot of smoke initially.
Then I found the Mercedes Source website and was intrigued by the glow plug
reamer and the glow plug removal instruction booklet especially for the
602. That engine design is so difficult to access the glow plugs. Yet
your 602 instruction booklet made it all understandable. You really did a
great job explaining in words and photos the steps required. I know that
to write understandable instructions is difficult and you are to really be
commended for doing a superb job. And then best of all, that Pencil Glow
Plug Reamer was amazing !!!! I used a mirror to look at the chambers before
and after and I was sure impressed. Now the engine, starts immediately
without using the block heater and there's no smoke. It's as if it was
brand new.
Thank you so much !!!
Erik A.
Redmond, WA