77 running hot in traffic, fine on highway

[timspider]

I'm just finishing up my first month with a 77 spider and like a lot of you folks, I'm kind of mesmerized by this car. It spent 25 years covered in a barn after having spent it's first 8 years of life running up 85,000 miles as a regular commuter/runabout in Michigan.
Brakes replaced, new timing belt and a detail list of small stuff by the second owner, who I got it from, has this vehicle in excellent shape and running very well.
The one strange thing is that she tends to run hot in stop and go traffic. At highway speed the temp needle stays firmly planted at about 190 and life is grand.
But when I get in a city, after about the third light at a stop the temp runs up to and just touches the red. I don't think the electric fan is kicking on at this point, although it may be and I can't hear it over the engine (I don't think i have a fan ON light) I've only heard it run once after I got out of the car.
I'm thinking maybe I need to get a new switch set to something like 180?
I've seen threads mentioning putting in a manual switch. Any thoughts on that?
Maybe something else I haven;t thought of?
thanks much

[BEEK]

most likely the fan is not working, or you have a bad connection , most likely ground on the fan wiring. i would suggest replacing the fan sensor in the bottom of the radiator. then making sure the rest of the circuit is functioning properly, 77's had relays, so check the relay too. and all will be good, you can install a override switch if you want, but do not disable the automatic circuit, as if you forget it overheats.

[focodave]

I installed a manual switch on mine, in parallel to the automatic switch circuit.
My manual switch is located beside the radio in the upper console, where the power window switch would go.
When I know I am approaching a lot of stop and go situations (like at a line of stoplights) I flick on the fan, manually, and she stays right at 190.
Then when I get back on the open road, I simply flick off my manual switch.
Works like a charm.
I only need the manual switch when air temps are in the 90's or above, but it sure makes me feel 100% better seeing my temperature gauge at 190, as opposed to anything higher than that.
Definitely keep the automatic circuit in place as BEEK suggested, though, in case you forget to manually turn on your fan.
Also make sure you use a toggle switch rated for high amps and an in-line fuse if you install a manual override switch -- or -- make sure to use a relay if you don't use a high-amperage toggle switch.

[timspider]

thank you Dave!
I had gotten side tracked by my top install so had not seen this until this morning. Since I drive to Chicago on a regular basis, about a 3 hour drive, it will be a great relief knowing that she can deal with stop and go traffic.
And now I even have a top that keeps water out!
now all I need is...well, cam box gasket, eventually another new top with the newer style, rounded edge front bow, door locks that work, a new trunk lock and key, new air cleaner, 4-2-1 exhaust manifold, new pre muffler, muffler and tail pipe, new throttle cable, new shocks, and general weather proofing of wiring.
looks like a busy winter

[timspider]

update: after replacing fan switch, which was bad, and the thermostat, which seemed to be sticking, the car ran well but had similar issues until I bled the system of air.
For me, there was a lot of air that I bled out over an afternoon, and backfilled a 50/50 mix through a T in the top heater hose.
Drove in Chicago traffic yesterday and had acceptable temp the whole time, better while moving, but still ok stopped at lights.
So for me, bleeding the system was a huge deal.

[ga.spyder]

Scratch that one off the winter 'To Do' list

[timspider]

darnit. maybe not so fast. same kind of issue again.
Temp holds good on the highway, but having trouble getting the thermo to pop and the fan to go on when idling or sitting still at a light. Temp just runs up. If I can roll the car forward in first at just 15 mph, the cooling system will start working- usually not the fan- just the thermo will open, collant will circulate and the temp falls into normal range- UNTIL the next light.
So my question is what is the best method to make sure that I got ALL the air out of the cooling system?
I put a T on the long heater hose because it appears to be the highest point in the system and where air bubbles are likely to congregate. Initially, this seemed to work.
Are there areas on the system that are vulnerable to air bubble build up?
If so, how to best bleed the air out?
Thanks folks

[majicwrench]

It should not be that big of deal to get air out. Somehow I have managed for years without a "T" in hose or anything else. I do tend to fill fiats with nose a bit in the air, not sure if that helps or if it just makes me happy. If yoiu have a T, great, just fill there, and at radiator. Run a while, check fluid. If you are constantly getting air in system., you have a problem ie head gasket.

"Usually not the fan" why isn't fan running??? If system overheating and circulating, fan should be running. Let it get hot well above the 190, is radiator hot?? If not, coolant not circulating, gotta fix that. If radiator hot, why isn't fan running?? Gotta fix that.
Keith

[TX82FIAT]

Take a look at your overflow tank. Is it high or right were it should be. Along with bleeding air in the system the radiator cap is a critical piece of the cooling function that can actually suck in or restrick rubber hoses. Any white smoke from tail pipe. If you have filled the system and you are getting air in the system you have a leak. Hopefully an external leak that you can find and not an internal leak related to a head gasket or some other coolant passage.

Magicwrench is right about diagnosing if the coolant is flowing, is the radiator hot, are hoses at bottom and top of radiator close to the same temp. Some increase in the engine temp is normal at stop lights. A lasor temp sender measuring the radiator temp while the car is stationary in your driveway is a good way to compare temp reading to gauge and test the cooling fan.

[azruss]

I think this issue is with your water pump. At idle you just arent pumping enough water to get the thermostadt to open. as soon as you get some rpms, coolant flows and you are back in business.

[4uall]

darnit. maybe not so fast. same kind of issue again.
Temp holds good on the highway, but having trouble getting the thermo to pop and the fan to go on when idling or sitting still at a light. Temp just runs up. If I can roll the car forward in first at just 15 mph, the cooling system will start working- usually not the fan- just the thermo will open, collant will circulate and the temp falls into normal range- UNTIL the next light.
So my question is what is the best method to make sure that I got ALL the air out of the cooling system?
I put a T on the long heater hose because it appears to be the highest point in the system and where air bubbles are likely to congregate. Initially, this seemed to work.
Are there areas on the system that are vulnerable to air bubble build up?
If so, how to best bleed the air out?
Thanks folks

works every single time

http://wwwe.fiatspider.com/f08/viewtopi ... verheating

[timspider]

ok, amazingly, I just discoverd that the radiator cap is only 7lbs. I'm pretty sure that's too low, correct?
But i also have read here that throwing on a standard 16 pound plus can cause problems.
So, just wanted to try to confirm, exactly what pressure should I have on my radiator cap?
thanks

[majicwrench]

Don't know what rad cap is required on old fiat, but 7lbs should work and is not causing your problem.

[timspider]

but why not make it right, which is 13 pounds?
it's been leaking coolant at the cap so while that probably did not cause the issue, it's not helping to have a leaking rad cap that is set to just over half of the designed pressure spec.
For just under $5 at napa, it's just one more new thing replacing something that wasn't quite right.
UNLESS, someone on here know why a 7 pound cap might be a good idea rather than 13?

[Fi8spider]

Leaking at the cap could be a worn top seal in it or a damaged radiator neck or the bayonet catch worn out or not the right cap? Irrespective of the spring strength (although 13lb is the correct type) the top seal of the cap should totally seal closed, the over flow bottle should be steaming before radiator cap.

I've seen this happen, where the radiator over flow outlet had broken off the neck. I took it to a radiator service place to get sorted and when they were filing out the outlet hole in the side of the neck to prepare for a new outlet they damaged the bottom seal landing in the neck with their file. Not happy and difficult to repair as this surface needs to be perfect so the rad cap and system can do it's job properly.

Having read this thread I see that the car had been stowed away for some time and brought back to life.
During the course of breathing fire back into this baby have you had the Radiator checked out? It could well have some blockages in the core and it only takes a small amount of engine scaling to enter the radiator and block up the galleries.
Ensure you open the heater tap if you're planning on giving the system a flush.

A well set up cooling system in general does not need a fan override switch, consider a lower opening radiator fan switch as it may be better suited to your driving conditions. I think I have about an 80deg cel in mine and I've run it hot and fast on many race days and in thick traffic with lovely results.

Being a car that was stored away for some time you are going to get some curve balls thrown at you, this may be one of them.