Replacing the Warm-up regulator

[AMD'd]

My mechanic recommended replacing my warm-up regulator (82-380SL). The retail price for these units is very high. In Canada the cheapest I've found so far is $1,000 Cdn for new. The prices are less from on-line stores in the US ($550-600US).

I have recently found a couple of places (such as http://www.specialtauto.com/mercedes-parts/index.html) that refurbish them for less than half the price of new ($190US). Does anyone have experience using refurbished regulators? Or any experience with any of the companies that do refurbish them?

[ctaylor738]

How about some background on the problem, and why the tech thinks you need a new one? This is an expensive part that does not seem to fail very often and there are very specific tests to determine if there is a problem.

[AMD'd]

As some background, I am not mechanically inclined and rely on my mechanic for advise. He worked for MB for many years and currently runs a private shop fixing Mercedes cars.

That being said, the problem I was experiencing was in the summer. Car was getting very poor gas mileage and there was a gas odour when driving.

My mechanic did a pressure test on the regulator and indicated that although it was getting the right voltage it would not regulate the pressure. When the engine was warm the pressure was too high (above specifications). He indicated that all of the components up to the regulator are working.

[AusMBtech]

If the fuel pressure out of the warmup regulator is too high the the engine will run leaner, more so on acceleration...........high system pressure will make it run richer (but this is adjustable).

You'd better check the diagnosis again.

[ctaylor738]

I always thought the WUC kept control pressure higher at colder engine temperatures, thus richening the mixture. Do I have this wrong?

But I do agree that I would try to adjust the hot engine control pressure by changing the shims on the valve before buying a new WUC.

[AusMBtech]

The control pressure is lower when cold and acceleration (if vacuum controled as well).

An example control pressure for your engine (reg 056, 101) at 0degC/32degF control pressure should be 0.5-0.9bar. At 20DegC it should be 1.2-1.6bar. Once fully warmed up it should be 3.4-3.8 bar (without manifold vacuum control). Manifold vacuum only further changes control pressure by 0.2-0.3 bar.

These are just examples. I need your engine number (first 6 digits) and control pressure reg number for the exact specs.

If system pressure is out then it'll effect running of the system even if control pressure is in spec.

If the faults are occuring when the engine is warm, control pressure AND system pressure is in spec then i'd be looking elsewhere for your problem (ignition, injectors, tune, leaks)