I own two 83 300's, a D and a CD. Both have the same OM617 turbo charged engine, one has 187,000 the other about 207,000. I was checking some vacuum lines and generally looking around under the hood. For whatever reason, I performed a sort of test with a very odd outcome and I think something is wrong with one of the motors. Here it is:
I took off the breather tube that leads from the valve cover to the air cleaner. I took it off at the air-cleaner end. On one engine while at idle I firmly plugged the end of the tube with my thumb. Pressure built up quickly and the engine very promptly stalled.
On the other engine I did the same. Again pressure built up quickly and quite strong BUT the engine never stalled or even indicated anything was going on.
As a further test, I disconnected the overboost switch on each engine, but the results were exactly the same.
Both engines have all vacuum lines and their EGR valves attached.
The engine that stalled has a little more smoke than the other but not excessive. Both cars are used regularly and perform pretty well, both use the same Sunoco diesel fuel, both have new air cleaners and fuel filters. Neither car needs engine oil added between changes (3~4K).
What is going on here?? Obviously something's not working right but I don't know which is OK. Any clues? Can some of you run a similar "test".
Thanks for your input.