W126, BENZ AID - COMMON QUESTIONS AND ANSWERS

'83 300D, Knock: injector, rod or what?

Just bought a one-owner '83 300D with 116k verified miles. Service book was regularly stamped. Car starts instantly, idles perfectly runs great. Has 2.5 bar oil pressure at idle. But it has a definite knock. Took it to the local independent MB repair facility. Diesel mechanic has three 300D's himself. I used my infrared remote thermometer and showed him that the injector body of #1 cylinder was showing just 120-degrees. Other four 170-175.
Injector was removed and replaced. Good compression--in the 300's. Haven't had chance to recheck temp. Knock is still there.
Now I am told it is most likely a rod knock! I don't have the money to start rebuilding the bottom end of this engine. Plus I am surprised that a rod bearing would go with this low mileage.

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85 300SD w/ Trap Oxidizer vacuum presure reading

I followed Kent's instructions the best I could in his Vacuum Diagnostic manual. Here is what I did and what readings I got: following the main black plastic line to the firewall, there are several lines that split off. 5 in total, I believe. I unplugged the four smaller, colored lines and plugged them with golf tees. The remaining line is actually some sort of plastic housing unit with a curved rubber hose attached. I took my measurements from this point and with the engine on, I got a measurement of 10 psi from my mityvac. I think this means something is up with my vacuum pump, unless I performed my measurements incorrectly.

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