W126, BENZ AID - COMMON QUESTIONS AND ANSWERS

Year: 1987
Model: 190D (Turbo)
Engine: OM602
Mileage: 225,000

Problem: bad "metallic sound" - sounds like injectors knocking.

Overview:

This knocking exists at low RPM. The engine also idles very rough. It goes away when you rev the motor or place a load on the motor. If I run a thicker fuel (like clean motor oil or power steering fluid - bypassing the main tank), the knocking also almost completely goes away.

I have bled the lines. I purchased the entire injector rebuild kit (w/ new nozzles). I balanced each within 50psi. I have changed air and both fuel filters. I have removed and cleaned the main tank. I have blasted out supply and return lines (to and from) the fuel tank.

It may be worth noting that:

-> The previous owner *may* have run veggie fuel

At ca. 154,000 miles I have been slowly bringing the engine performance back to snuff. I recently rebuilt my turbo using your excellent kit. The compressor and turbine blades and shaft were in excellent condition so I opted not to purchase the replacement set.

Prior to the rebuild my boost pressure at 4000 rpm was 9 psi. Following the rebuild, there was no improvement in boost pressure. Per your instructions, I tested the waste gate (with a bicycle pump) and it appears to work.

The ALDA tube and Banjo bolt are clean; I've installed a new air filter, adjusted the valves following your instructions, installed rebuilt Monarch fuel injectors, and did a diesel engine purge (which was clean) and replaced the fuel filters.

A while back I purchased a 560sl to join my mercedes fleet. I thought it was a good deal, but it has white smoke upon start up. I am currently doing the repair/replace analysis I began thinking that while I was at it, it would be nice to get a little more horse power out of it. In researching the internet, I found that the sl 560 was de-tuned for the US market, that the SEL/SEC has more horsepower. Also when investigating, it appears that used sel/sec engines are less expensive than the sl motors.

Found a disconnected blue wire near my battery. Can't figure out what it goes to. The previous owners installed an aftermarket radio so I'm wondering if it is from that or if this wire was disconnected from somewhere else. I'm having difficulty tracing it to figure where it is going. Any help is much appreciated. The wire comes through the firewall into the area near the battery and is blue.