Water / eng temp too high at warm idle

[Torxx]

I have been chasing an issue with the engine temp. The car runs at a range at or just a touch over the 190 deg mark on the temp gauge when driving. If sitting at idle (i.e. traffic jam, slow fast food line) the temp will raise to about half way from mid to max on the gauge before the fan kicks in (seems like fan should come on sooner). The fan will bring temp back down to normal, and / or as soon as I drive, the temp goes down.

Air pocket?? I have bled the system repeatedly by running the car with heater on and then the next day top off the coolant at the bleeder plug on top of the engine.

I noticed today when I was under the hood (car completely cool) that the top rad hose leading to the thermostat was collapsed in the middle. I unscrewed the bleeder plug to relive the suction, or vacuum, or whatever, and found the colling system was fill up the hole.

What gives? any ideas? Thanks

[rlux4]

Is the hose going to the overflow bottle clear? Sounds like instead of pulling the coolant back from there as it cools, it's pulling it from the hose.
Ron

[Torxx]

I thought I checked this before, but, I now noticed that the top of rad is hot and the bottom is not. Radiator was just serviced ( I don't know if they check flow?). Does that mean a bad radiator?

[TulsaSpider]

That sounds like they didn't do their job to me! I used to be involved in dirt track racing and we sent out a radiator to be serviced and all that season had problems with overheating. We tried everything to fix the problem we could think of. We dismissed the radiator cause it had just been serviced right?? WRONG! When we pulled it at the end of the season it was 1/2way clogged up ohhhhhh we were pissed! My car takes forever to get to 190 and while moving at a good pace stays below 190. Did you put new hoses on? I haven't had my Fiat too long so I can't really guess at your problem but there is plenty of help here!!
Good luck!

[So Cal Mark]

could be a plugged radiator, did they rod it out or merely flush it? A plugged rad will usually have cold/hot spots across is. Rarely do all of the tubes get plugged since 10-20% restriction will cause overheating.
The trouble could also be a thermostat that isn't opening properly either

[Torxx]

Here is the latest: Switched out the new thermostat (the one one teh car) with the old one (that seemed to work fine before), with no improvement or change. We eliminated the external therm. and ran bottom hose direct to water pump. Radiator temp is pretty consisitant from top to bottom now. Car runs much cooler, but the temp still goes up to to 225 +/- at idle before the fan will kick in. Also, (maybe unrelated) the heater was putting out heat and I could not stop it with the heater valve lever. It worked before the change??

No thermostat at all now.

[rlux4]

How long does the heater put out heat Torxx? It still has to dissipate the residual heat to the point of ambient temperature. This could take a while in warm weather. If it keeps on after a decent interval, the only explanation would be that the valve is not shutting. Have you observed the cabled is moving the control arm?
Ron

[So Cal Mark]

running without a t-stat can cause the motor to run hotter; reason being that the coolant flows through the radiator too quickly, not allowing enough time to transfer heat. Engines like a constant temperature, not fluctuations. Hence one reason for a t-stat

[Torxx]

Can someone explain how to install an external thermostat on a "79 spider? That is how do I know which port goes to which hose? I am pretty sure I installed the external improperly before. My new one doesn't look exactly like the old.

Any opinions on the merits, if any, to eliminating the external therm, and putting the thermostat on top of the engine like in the older spiders?

Thanks

[mbouse]

a picture is worth a thousand words

[So Cal Mark]

there is one leg of the stat that looks like it was machined. That leg goes toward the water pump.
As for the stat in head, the cons are; no bypass when the engine is cold, and the tiny bolts that hold the water outlet to the head. It's really easy to strip those bolts after removing/installing them multiple times. You still need to bleed air from the system with an in-head stat

[mbouse]

stay clear of the in head stat is what i was told. cooling circulation issues abound is what i was told.

and those threads for the upper hose neck EASILY strip..very EASILY. (from the office of BTDT)

[adrians]

I have just gone through all of this, my car was running ok, then I noticed a slight crack in the seam on the top radiator tank, ended up getting the entire radiator rebuilt ( recored ), $700 dollars later !

Then the car started overheating, temperature would climb all the way up to 230 and the bottom hose was cold and the fan didn’t kick in. Pulled out the thermostat and tested it repeatly on the stove ... it worked every time. Next drive the same thing.
The following day left the car idling in the driveway and the thermostat and electric fan worked fine.
Again that afternoon went for a drive and started overheating again.

The conclusion, blown head gasket ! ! – So it’s being towed on Monday to the Fiat Mechanic for a full head work, at least that was planned work.

[mdrburchette]

Can someone explain how to install an external thermostat on a "79 spider? That is how do I know which port goes to which hose? I am pretty sure I installed the external improperly before. My new one doesn't look exactly like the old.
Thanks

I don't want to hear anything from the Peanut Gallery here, but this is how I figure which port goes where on an external t-stat. The port attached to the lower radiator hose should be closed when cold. I blow through the ports to find which is closed, and viola!...my t-stat can be installed correctly.

[racydave]

But, can you hear me thinking?