Normal temperature on dashboard gauge?

[rutger kohler]

Have just got my 1969 280 SL running again after detailing the enginebay.  I aslo replaced the radiator hoses and the thermostat (Autohaus 79C).  I have only run the car at idekl in the garage since then but noitced the temperature gauge is climbing above the normal (for me) 180F and the thermstat hasn't opened yet. Waht is the normal warm temperature  at idel plse?  I put the therostat back in the same way as the old one, as per attached picture.

[Richard Madison]

My car is a Euro version with a Celsius temp gauge but the pointer position should be the same for a Fahrenheit dial.

At almost all times, the needle stays in the center of the gauge at about 80 C (or 175 F.)

It can creep up to the next marker in stop-and-go traffic on a hot day but has never gotten near the red area.

Richard M, NYC

[DavidBrough]

It sounds like you may have an air lock in the system, try warming it up with the pressure cap removed and pump the top hose with your hand as the engine reaches temperature, if that doesn't do the trick you may need to get a bit more creative and start bleeding the system from some hose connections. If that's OK then you either have a faulty thermostat or a faulty guage, with a 79c thermostat the engine is not very hot when it should open so no real smell or feeling of heat so should be easy to tell if that point has really passed.

[thelews]

You have air in the system as David said.  Not uncommon when draining and refilling.  On my 190 SL I'd bleed the system where the water temp gauge mounted, letting off air until fluid showed up.  Open your heater also.

[bsimaz]

I know this may sound goofy but on  a related note....

Last spring/summer I found a water leak.   Water pump...

Bought a new one a replaced.

Before I replaced the water pump my temp was a steady 175 deg.  I could idol all day
and driving did not effect the temp.  Fast, slow, stopped the same 175.

Now with a new water pump I am seeing the same thing that many have commented on here.
sitting at an idol, temp rises.  When driving fast, or up big hills or in really hot weather.  I see the
temp rise.   

Just seems goofy to me.

[glenn]

(SAC) My temp rises when I set near an idol- like a bikini clad one on Beach Drive.  Seriously,  if your 280 has a filled thermal system(FTS) temp gage coming out of the standoff near 2/3(?) plug it should read head coolant temp (and WRD temp).  Later 280 heads had the FTS located in the head at plug 6.  FTS seem to keep their relative accuracy over the years.  Be careful not to bend, fold or mutilate the tubing between the head and the dash readout. 

Sounds like the old pump was better than the new.   Does the gage go to ambient temp after engine cool down?

[rutger kohler]

Thanks for all those replies, away for a few days so will try when i get home.  The air lock sounds good, I did open the heater however i have noticed that the top radiator hose is very cold as is the top of the radiator which seems to say (to me) that the thermostat is not opening.  I will also try with the reservoir tank cap off.

[thelews]

Thanks for all those replies, away for a few days so will try when i get home.  The air lock sounds good, I did open the heater however i have noticed that the top radiator hose is very cold as is the top of the radiator which seems to say (to me) that the thermostat is not opening.  I will also try with the reservoir tank cap off.

The thermostat is not opening because there is not water circulation because there is an air lock preventing the hot water from getting to the thermostat.

[J. Huber]

Then there is my issue. I sent my center cluster to PAS to repair the capillary tube in 2009. Once back in the car (hang-on. back spasm...) I proceeded to drive the car -- only to find that the temperature gauge was reading low. As the engine starts to warm-up, the needle rises but not to the low part of the 80 but to more like the 60. Never higher. Alarmed initially that something was wrong with the engine, I investigated. PAS said it may have been calibrated wrong but that car was fine. They offered to remedy it -- if I just sent it back (ooh). I decided to just live with a false reading for a bit. Now its been three years! Car runs as perfectly as one could want, just reads low. Does that make my car cooler than everyone else's?