Cooling System

[n/a]

Group,
I would like some feedback regarding the cooling system temperature indicated on my dash guage.
My question is: can the guage be off-calibration and can it be recalibrated? Is there an easy means to confirm the guages calibration?
With the car at ambient temperature (overnight), the temperature on the guage is mid-way between 100 and the next higher dot (?? degrees). The temperature rises to an indicated 180 within a couple of minutes. After warming up and sitting in traffic on a 90+ degree day the temperature will reach the mark indicated in red (??degrees).
I have flushed the cooling system, replaced the radiator with a 4 pass core and have replaced the thermostat with 75 degree type. Aside from the radiator, I have not seen a perceptible difference in the indictaed temperature.


Regards,
Stan

[Ricardo]

I'm pretty sure these gauges aren't very accurate in terms of the actual number reading, but I'm also fairly certain that the needle should drop to the bottom when the car is shut off. If your needle sits half way at rest, then I'd be suspicious of the indicated temp. What you could try doing is to find a shop that has one of the new hand held temp guns that are simply pointed at the engine, or anything else you want to know the temp of, and check what average temp. you get with a warmed up engine. This would at least tell you how far off your gauge is. I can't imagine running into the red zone with a new 4 row rad, unless you had plugged passage ways in the head or improperly connected hoses.
Richard V

[athadani]

Its been real hot in Geneva this week and even with a new 75 degree thermostat, the temp needle went into red and past. Just managed to get into a parking lot and left the car to cool for half an hour.  Had a hard time starting it and had to leave it to cool for another 30 minutes and then it started and worked just fine. All systems seem to be in order and I would really appreciate any help on how to diagnose. While driving, needle is at 180 and goes quickly to 190 and more when stopped at traffic lights or in a jam but then comes down fast to 180 when the going is good.

Some people here have made the following comments
Change radiator
flush radiator
test radiator water color with additive to see if it might be an
engine issue
Clueless.

Thanks in advance for your help.

Ashok

PS. I'm afraid won't be able to make it to Heidelberg in Aug due to  imperatives. Was so looking forward.

[athadani]

Just to complete my post:

US 280SL 1970

Ashok

[ja17]

Hello Stan,
You can double check your guage by buying an inexpensive universal replacement guage. These are available at any autoparts store or Walmart etc. About $20.00 should do it if you shop around. It must have a capilary tube with a bulb at the end. Remove the radiator cap on the overflow tank and drop the bulb in the coolant. Warm up the engine. When the thermostat is open the original guage and your test guage should nearly correspond. Some sources of overheating can be; clogged cooling system or radiator, bad radiator (rotted), bad fluid coupling on the engine fan, problem with the water pump or its housing, bad thermostat, no thermostat or improperly installed thermostat (thermostat MUST always be in place for the cooling system to function properly!). when running hot,try turning the heater on, if this makes a noticable difference then the radiator is probably bad. If the car runs cool on the highway the fluid coupling on the engine fan may be bad causing overheating in traffic or at idle. Good luck!


Joe Alexander
Blacklick, Ohio