Coolant system issue and car stalling

[WadiaAbushanab]

I have a 1980 Spider carbureted and I’ve been having this issue for a few months. I got a new aluminum radiator and thermostat from Autoricambi and new hoses. I installed everything, bled it, and it was overheating. I jammed the thermostat open to always for the mean time so I could drive it. With this, it was perfectly fine and performed really well. I got a new thermostat and bled it, and now it’s still overheating, and the car will shut off while I’m driving. I’ve read hundreds of forum posts on tips to bleed it, watched countless videos. I also ran it with the cap off on the radiator and waited till the thermostat opened to see if there was flow, and there was. It seemed fine. I don’t know why it’s overheating and what else it could be. I need help I’ve been stuck on this issue for so long.

[Nut124]

Sorry about your troubles.

How did you assess which way the new thermostat ports should be oriented? I'd suspect incorrect porting.

[WadiaAbushanab]

Sorry about your troubles.

How did you assess which way the new thermostat ports should be oriented? I'd suspect incorrect porting.

I looked at pictures and followed the Autoricambi guide and vickauto guide. The port that does not pass fluid goes to the lower radiator hose I know that. I also drilled a little hole in it to let air pass but still issues and I don’t know why.

[Nut124]

Based on your reporting, I'd say there are three possible causes:
1. Incorrectly installed thermos.
2. Bad thermos
3. Air in the system.

However, sounds like you have already figured out how to get the air out previously. You state that with a gutted thermos it ran OK. Now, with a new thermos it gets hot.

These things work when properly installed and in working order. I have never had trouble with air in 30+ years w Fiat twin cams and never done anything special to mitigate it.

[Spider951]

A couple of comments:

1. I have never drilled a hole in the thermostat to see what happens, but I am guessing that might be at least part of the problem. Wouldn't a hole in it negate the purpose (at least in part) of the thermostat?

2. The difficulties I have had with overheating after coolant drainage, etc all came down to air trapped in the system. [Once, I thought the t'stat was sticking and I did some gentle tapping on it, plus applied some heat with a heat gun to "help" it open, but it still turned out to be trapped air causing the problem.] The air has to have a means of escaping the system.
I think some people raise the front of the car to make the highest point the radiator fill opening (and hence the escape route). After my heater core went kaputt a few years ago, I have simply bypassed the heater by routing the hose from the back of the head to the small pipe running from the back of the water pump; I put in a valve in the hose at its highest point to bleed air out of the system (kind of messy but it works). But I live in a warm climate and rarely used the heater anyway - may not be a good option for you.

[Spider951]

Correction to my last post: the "valve" I mentioned in the hose coming from the head to the water pump is actually a "T" fitting with a removable cap that allows you to add coolant there during the "burping" process.
Also, I recall that it is helpful to keep the reserve tank about 3/4 full during the process. I think the purpose of that is to have coolant available as the air is displaced by fluid.
The Haynes manual mentions to keep the valve to the heater open to prevent trapping air (I don't worry with that because my heater is out of the loop).

Steve