Temp Advice

Joe F

Joe F

Hi Miles, Lo Maintenance
(Also posted on Mirafiori)

My 1980 Spider w/weber has had a complete motor rebuild (great job Beek!). The motor runs great and strong and as long as I keep moving, the temp stays at 190.
However, waiting for a light or idling, the temp gauge rapidly runs up past the 190 to almost (but not touching) the red zone. When I get underway, the gauge falls back to 190 in a minute. The fan kicks in when the gauge is halfway to the 260 mark but seems to have no effect on the temp. Only moving, and the faster the better, brings the temp back to 190. I have installed the "high efficiency" fan from Auto Ricambi but I haven't noticed any difference.
I have tried bleeding by squeezing hoses, but I have not noticed any air escaping. I have struggled with over temps with my X-1/9 for years before finally changing the thermostat housing which solved that issue. I live with my 124 in SW Florida and I am very concerned about keeping it cool.
Any help or advise will be appreciated.
 
Joe F said:
(Also posted on Mirafiori)

My 1980 Spider w/weber has had a complete motor rebuild (great job Beek!). The motor runs great and strong and as long as I keep moving, the temp stays at 190.
However, waiting for a light or idling, the temp gauge rapidly runs up past the 190 to almost (but not touching) the red zone. When I get underway, the gauge falls back to 190 in a minute. The fan kicks in when the gauge is halfway to the 260 mark but seems to have no effect on the temp. Only moving, and the faster the better, brings the temp back to 190. I have installed the "high efficiency" fan from Auto Ricambi but I haven't noticed any difference.
I have tried bleeding by squeezing hoses, but I have not noticed any air escaping. I have struggled with over temps with my X-1/9 for years before finally changing the thermostat housing which solved that issue. I live with my 124 in SW Florida and I am very concerned about keeping it cool.
Any help or advise will be appreciated.
Click to expand...
Did the water pump get replaced? Is there a spec for impeller clearance on for the spider like there is for the X1/9? If here is excessive impeller clearance, the pump will not pump much at low RPM / idle.
 
Most likely an air bubble trapped in the cooling system. This happens because the radiator cap is below the high point of the cooling system. Some install a bleeding tee in the heater hose. My sons 124 did exactly as yours but I was finally able to clear it by pressurizing the system and removing the small hose going to the throttle body (his is injected).
 
We use to jack the front end up to help get all the air out of the system.
 
I've decided to go all out:
Since I have to drain the cooling system to replace most parts, I will replace the radiator, water pump, thermostat, all sensors and switches, and all hoses. I will refill and make sure its properly bled (it can't be worse than bleeding an X-1/9).
The car is 42 years old and 1000K miles, so it's due.
Thanks for all the input.
 
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Not knowing any better, I went through all of that with my first 124 spider. The problem turned out to be the temperature gauge.

I eventually used a laser thermometer to convince myself the car was not really overheating and realized it was the gauge.
 
Fiat gauges:
Speedo...indicates movement of the car but little else
Tach....indicates the engine is turning but not clear how fast
Temp gauge.....your engine temp is somewhere above absolute zero and the temp of the surface of the sun
Fuel gauge....if the needle swings about you probably have some gas in the tank
Oil gauge/light....you either have no pressure or you have and undefined amount of pressure.

When going for a drive, fill the tank and ignore the gauges. The drive will either be fun or the engine will smoke and then die.
 
carl said:
Fiat gauges:
Speedo...indicates movement of the car but little else
Tach....indicates the engine is turning but not clear how fast
Temp gauge.....your engine temp is somewhere above absolute zero and the temp of the surface of the sun
Fuel gauge....if the needle swings about you probably have some gas in the tank
Oil gauge/light....you either have no pressure or you have and undefined amount of pressure.

When going for a drive, fill the tank and ignore the gauges. The drive will either be fun or the engine will smoke and then die.
Click to expand...
Carl, maybe your statement is tongue in cheek but this has not been my experience at all. Veglia guages came in most Italian cars including Ferrari. Ive checked tachs against my Snap on tach/dwell meter and at most they differed by 200 rpm. Temperature gauges on mine show 190 when warm as it should be. Sometimes it creeps up a little at idle and then the fan kicks in And it drops back down. That tells me it’s working fine.
 
Temp gauges actually not bad. An X tach can be hilarious as I once had an X that I worked hard to rev to redline only to find out the tach was off by 1,000 rpm and I was trying to hit 8,000 rpm. Let's not even talk about Fiat speedos, they are very much hit or miss on accuracy.
 
I've owned 6 Fiats since '72 and ran 3 over 100,000 miles and never had an issue with inaccurate gages, however, I am not naive enough to believe that it can't happen.
Using a "laser" thermometer, I am pretty sure the gauge in my 124 is fairly accurate.
 
fastx19 said:
Also, go and buy a cheap IR temp gun and verify the gauge is close/accurate. Sometimes those can be an issue, however, I agree with the previous assessment on an air bubble.
Click to expand...
Ditto. Cost me $14 at Harbor Freight for an IR temp gun. After a good drive, I compare the dash gauge to a couple of points around where coolant enters and leaves the system. The gauge is pretty accurate. Warm fuzzy.
 
Last edited:
Ok. Maybe I should go back and edit my post to add some more detail. Initially, I was just suggesting the gauge could be the problem.

Using the laser thermometer actually had me convinced my gauge was ok also. But, sitting in the driveway was never a problem. My driving around town problem was quite similar to Mr. Joe F's. I could drive for days with no issue, then sometimes at every stop light the gauge would creep almost into the red. I didn't succeed in troubleshooting down to the final solution after changing most everything that could be changed.

I finally changed the gauge, only because it was the one piece of the cooling system I hadn't touched. I put a gauge from a '75 in and have just lived with the needle pointing down instead of up for decades. Never another problem.
 
In all my years of messing with Fiats I have actually had only one temp gauge fail....I think on on of my spiders. The needle would randomly go up and down making no sense with the actual driving I was doing. I checked everything else and used my IR thermometer and finally swapped out the gauge and all was good. I was quite surprised the gauge was bad because I had never had one fail before.
 
On a recent 3-hour trip, with the last 30 minutes in traffic, I heard a strange noise coming from under the hood. It turned out to be the coolant boiling in the catch tank. The needle on the temp gage was reading high, not in the red, but close.
 
Joe F said:
On a recent 3-hour trip, with the last 30 minutes in traffic, I heard a strange noise coming from under the hood. It turned out to be the coolant boiling in the catch tank. The needle on the temp gage was reading high, not in the red, but close.
Click to expand...
Definitely an air bubble In the system.
 
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