Glow plug relay issue

Glow plugs are about $12.00 each. First get an ohm meter and find out any are open. You can get a decent one at Harbor Freight for less that $8.00 sometimes much less than that if they're on sale. After you find out how many are open you can replace those or all. If none are open then it could be the relay or wiring, but first check continuity on the GPs. You can do this yourself. Whenk is the last time your tappets/valves were set?

The symptoms you previously described were of an engine whose glow plugs are dead. That implies the glow plug relay is suspect rather than individual glow plugs.

But to confirm that hypothesis, as the starting problem developed did it manifest itself as you describe - long cranking until the engine finally ran or that the engine started immediately but had misfires - didn't run smoothly - for the first 20 seconds of running? If the former then the glow plug relay is the probable culprit, glow plugs if the latter.

The glow plug relay is located on the driver's side fender. Look for a 3 x 5 black box with wires attached. It has a plastic cove that you can remove by sliding it UP. Under that cover is the glow plug relay fuse, a/k/a fusable link. It should be intact, not burned through. This is the first place to check and the most probable cause of your car's starting problem. The link is held in place by two screws, remove them and the link is free. A replacement link costs about $1 at a M-B dealer, buy a spare for "next time".

Replacing the individual glow plugs is not hard but a few cylinders are nasty on one's hands. Each glow plug has a wire attached to it by a small nut that's very easily dropped. The glow plug itself is unscrewed with a wrench. If you undertake to replace the glow plugs buy only Bosch or Beru glow plugs - they cost about $8 to $10 each. Use a 1/4 inch metal drill to cut the carbon from the cavity before installing each new glow plug - just twirl it inside the hole with your fingers, the drill will do the rest. Then install each new GP and tighten it with a wrench. They don't have to be torqued very tight but should be as tight as you can reasonably pull the wrench in that cramped space. Reattach the wire and snugly tighten its little nut. Done.

Hope this helps you keep the car on the road, Happy New Year!

disconect batt before replacing 80AMP fuse on mine the shaft of the screwdriver grounds it if touched on the side

the case, minus a few cans!