RCND82

I own a 1991 560 SEC with approximately 65,000 miles that is overheating and I need help with the diagnosis. Radiator, thermostat and water pump have been replaced. For instance, I drove the car at normal speeds this evening and within 25 minutes the temperature was close to the redline. The car has been to three different mechanics including the local Mercedes dealer in Fort Pierce, Florida. The conclusion seems to be that there is a "restriction" of some unknown form in the block that is preventing the coolant from circulating throughout the block and lower the temperature. Mercedes says the gaskets are not blown. One other mechanic says gasket is blown. The recommended course to me has been to scrap the car or replace the engine and I am told it is not worth it to replace engine. Anyone have suggestions for a definitive test to diagnose what is going on? If I want to keep who do I talk to about an engine? What kind of engine? Thanks for any help.

Richard

AdrianL

An engine from a scrap car is your best bet, if replacing. There were a lot of 560 Mercedes benz on the road, and there still are. The fact that you have something blocking the water channels seems a bit odd, see if there is an experienced independent shop that has experience with old mercs. Likely the dealer never sees these cars so that's not gonna help you. How are the fans?

Vander

Any update on this?

jhbrad

It has been a while, but I had a 380 SEC that overheated and blew a head gasket because the catalytic converter was clogged! New exhaust system fixed the cat issue, head gasket needed for the engine...back to good again! Strangest thing was how the overflow tank blew up like a balloon.

Yuri007

Look for a leak in the cooling system. If your radiator or cylinder head seem to be compromised, or if you open the coolant reservoir and the levels are topped up, you may have a leak in the cooling system. If you're experienced with cars, check the radiator, core plugs in the engine block, or cylinder head near the head gasket for any signs of leakage.

560secisforme

My '91 560SEC recently was running on the hot side, i.e., 102 to 105 on the temp gauge. My independent MBZ mechanic found it wasn't lack of coolant or a failing radiator... but rather a bad Mono Valve that was not allowing circulation (...top of M117 engine, at back, near base of windshield).