Temperature Gauge and Corresponding Actual Temps F/C

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dubiousgarage

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Hi I bought a 1970 2800cs project and am new to older BMWs. I just got it running after 10+ years but concerned it might be running too hot.

1. What are the actual temperature ranges in degrees F/C that correspond to the RED zone on the BMW gauge? In the shop it’s running just under the red. (I’ve installed a temporary manual F temp gauge to check it since no idea if the cluster one is working).

2. What numbers are the normal range running temps?

3. What numbers are “worried” hot but can still drive?

4. What number and above is “stop car immediately” hot?

Much thanks!
 
Just under red means turn off the engine NOW.
You will create so many expensive problems running your engine like that.
 
The extra temp gauge is unlikely to tell you much. If the gauge in the car gives you a reading, it likely works. The circuit is very simple - switched power is supplied the gauge and the sensor is the ground. As the sensor heats up it allows more electricity to flow, which moves the needle upward. I've never had one fail on me, and I've never seen anyone on this forum (in more than ten years) state that they have had one fail.

As to the temp ranges the gauge will show, that depends on the thermostat, and there are a handful of thermostats for the M30 engine, each of which will give you a different operating temperature. My spares are with my BMW project car right now, but I know I had an 84C in my hand a few weeks ago and that his is higher than the one I have in my car.

All that said, it is likely that the problem is that your engine is not bled properly. I don't follow the BMW recommended mechanism to do this, but instead use the following method, which works every time: Obtain a duplicate hose to the hose that runs from the radiator to the expansion tank. Disconnect the expansion tank end of the hose that is installed in the car from the radiator to the expansion tank. Leave the radiator end connected. Connect your duplicate hose to the expansion tank at the junction for the expansion tank hose. Get a rag and hold the hose connected to the radiator just above the top of the expansion tank. Now move to the duplicate hose, which should be connected to the expansion tank, and blow gently until you first expel all the air from the system and then move just a small amount of coolant onto the rag. Remove the duplicate hose and reattached the hose from the radiator to expansion tank.

Then run your engine again.
 
Other version.


28A4B7E3-97D4-4A08-93B7-BA2CF05309EF.jpeg
252F47F8-480F-4FC0-9588-1040AFC493F0.jpeg
3070FFA9-876A-4261-8101-54E5CCF787AD.png
 
HB Chris said:
I vote clogged radiator, gauge should never, well almost never, go above 3:00.
Click to expand...
Chris, I replaced the new (but wrong) 88 thermostat with a 71 and then bled using a technique posted. Still no go. I think youre correct about a bad radiator. See my post about cheap Champion radiators and if they fit. Thanks for your suggestions.
 
Concur with opinions here.

Mine always ran at about the 90 degree position marked on the photo above and never went higher. Yours should be about the same.
 
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