heat issues...maybe thermostat??
 

What temperature should the temp gauge show on an 89 560 SL??
Mine registers about 80 and I do not have enough heat...do I need a new thermostat??

Thanks

jtu

try flushing the cooling system and putting new coolant. if there is still little or no heat after that, check for any coolant leaks or you might have a restriction somewhere in the heater core. you might just have air in the system. use the search thread here relating to this issue, you will find alot of tips

You could also have a bad monovalve, not allowing hot coolant into the heater core. Other possible components are the control (pushbutton) unit and the temperature control relay.

Lots of posts on these components and their problems.

To respond to your original question - 80deg is about the right temperature so It doesn't sound like a stat problem - more like a heater issue as stated above.

Cheers

Jim

I agree it's probably not the thermostat...what happens when you turn the temp wheel so it 'clicks' into the MAX setting?

Bob

heat issue.........
 

When the temp wheel is clicked to the Max position, the temperature will slowly rise after driving for 20+ minutes, but never gets warm enough to need to turn the heat down.

Thanks for all the responses...I will flush the system and add new coolant.

jtu

monovalve
 

80 deg C is right as others have stated. Recommend you open your monovalve and check the state of the diaphragm. Easy and fast to do. If diaphragm is ruptured (I'll stake Strife's reputation that it is), get an inexpensive repair kit ($45 ?) from Fastlane Phil and fix your problem.

Let us know how you do.

BTW, I start getting heat almost as soon as the car starts moving and with the control set in the center of the white section get all the heat I want. Check that monovalve before draining, flushing and refilling. You will lose no coolant when you open the monovalve.