Within the past month, my 560 SEL began to behave oddly. When the car starts cold and is run between 25 and 55 mph, it seems to be fine--plenty of power & smooth acceleration. Running at a constant 55 mph on a level stretch of road for about two minutes (so there is no change in the pressure I am applying to the accelerator), it suddenly accelerates, as though a load has been removed from the engine. It seems to do this consistently as the engine warms to about 60 deg. C. After this initial surge, the car behaves as if nothing has happened. I'm wondering if this is a sign that my water pump is about to fail or something worse.
The car has one other problem I know of, but I don't see how this could contribute to the strange behavior. The rear suspension has become very stiff over the past six months. The hydraulic fluid is also very low in the reservoir, but there is no sign of fluid leakage that I can see, so I am thinking that the gas has leaked out of the accumulators. If that leads to the fluid pump operating a lot more than it should, could that be the extra load?
I guess I should also mention that the car has a bit over 197K miles and the timing chain was changed this past August.
Cheers!
-Tom
Williamsburg, VA
1988 560 SEL
1989 260 E And once the proud owner of a secondhand
1979 300 D
1980 240 D
1982 300 D turbo
1985 380 SE