Engine temperature for 5 litre V8?

[kahuna500]

I have a 1993 500SEC and cannot get anything but lukewarm air out of the heater even with both controls set on max. The engine temperature gauge never reads higher than 80 degrees. All the manual says is that it may go as high as 120 in hot climates or when working hard but there is no word as to what 'normal' is. Anybody know? I'm hoping this is just a thermostat stuck open.

 

[davidsl500]

80 degrees is pretty much spot on. My 500 sits at just a little over 80 most of the time and creeps up to the 100 in the summer when i am pushing on a bit.

I think you need to look elsewhere - airlocks, stuck control valves, blocked heater matrix.

 

[kahuna500]

Needs fixing for winter

Thanks David. The forecast is for a tough winter so I will need to fix this or I will be dependent on the seat heaters for warmth.

I am guessing the heater core will be a big job so will start looking for airlocks.

 

[guydewdney]

more likely to be the monovalve or duovalve that control / regulate the flow of water into the heater matrix.

 

[kahuna500]

Good one. Turned out to be the duo valve with an obstruction in it. Local Indie fixed it and a jammed driver's seat lock at a very reasonable price. He warned me that the valve is a common failing part and runs £296.89 from MB.

 

[davidsl500]

Thanks for the feedback kahuna, at least you wont freeze this winter - and its definitely getting a bit chilly at the moment!