190DT 602 questions

[jdzl]

Howdy all!

Was looking for a good commuter and a local gent had a 87 190D 2.5TD for sale - as luck would have it, we got on like a house on fire and I ended up taking the beauty home.

I'm fairly handy but have more experience with VW diesels than the Mercedes at present...

The car came with a huge stack of receipts (all the way back to 1990 or thereabouts) and has been well cared for as far as I can tell. It does however, exhibit an annoying behavior that I would relish the opportunity to vanquish.

A previous owner (but not the fellow I bought her from) installed a boost gauge, which may provide a clue (possibly trying to track down this behavior)? Basically the turbo is behaving like an on / off switch at the moment, with a very fine threshold based on throttle input. On partial throttle (35-50% maybe) it will make about 5-7psi, anymore than that and it will immediately go to 13-15psi. Once you're in to the boost it will stay there until you cross back over the threshold whereupon it immediately drops back down to 5-7psi. Unfortunately this magical threshold occurs right where your foot is to cruise at 65mph or so- treating all onlookers to taking off like a rocket ship, only to slow down, and so on...

I'm planning on looking for vacuum leaks and hoping that will clear some things up. I've also read that I should clean the switchover valve and pressure sensor? Anything else that would be of use?

Otherwise the car drives pretty well. The glow plug light acts a bit weird where it doesn't always turn on when you turn the key on, but turns on after the engine is started and then goes out a minute or so later... I'm going to check resistance on glow plugs etc and see where that gets me.

Many thanks!