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Can you believe this?

Turbofiat on Sun February 12, 2012 8:40 AM User is offline

Year: 1980
Make: Fiat
Model: Spider
Engine Size: 2000
Refrigerant Type: R134a
Country of Origin: United States

Last summer after air conditioning my Fiat Spider, I drove the car to Nashville (about 300 miles from East TN) for our Fiat club gathering. Because Nashville is larger, it's hotter in the summer. It was near 100F if not hotter in the heart of the city. I experienced some overheating even on the outskirts on I-40. The car is supposed to run at 190F but it would sometimes hit 230F.

Turning the A/C off helped drop the temperature down somewhat. Got to the Cumberland Plateau at a higher altitude/cooler and it cooled back down so I turned the A/C back on. Got into Knoxvillle and it started running hot again! Just when you need A/C the most I would have to turn it off.

Got out of Knoxville and headed home on the old 11W state highway driving at 55mph. Finally got to turn the A/C back on and continued on my journey back to Kingsport for 80 miles on the rest of the trip home.

The weird thing was the engine ran hot even while driving at speeds of 70 mph. That should provide plenty of airflow through the condensor and radiator.

I swapped out radiators which did nothing. Even tried a 70/30 mix because I read a 70/30 mix will cool better than a 50/50 mix. Still nothing.

Then I wondered if my Euro number plate had any effect. I removed it and what do you know? The car runs 190F all the time now. I even tried simulating by driving in 4th gear at 60 mph near 5K rpms and still could not get the car to run hot. My conclusion was the number plate must have been acting as an air dam forcing air away from the radiator. Apparantly the only thing keeping the car from running any hotter than it was, was the radiator fan was running all the time which is only good for removing 30F degrees of heat.

Edited: Sun February 12, 2012 at 8:47 AM by Turbofiat

mk378 on Sun February 12, 2012 12:45 PM User is offline

Nice car. You are talking about 70% water, 30% glycol, right? Mixtures with more than 50% glycol should not be used.

Turbofiat on Sun February 12, 2012 1:10 PM User is offline

Correct. 70% water, 30% EG.

I was more concerned about the lack corrosion inhibitors using a 70/30 mixture rather than increasing the freezing point to 5F as opposed to -30F because it seldom get's below 10F where I live.

Since the problem seems to be the licence plate rather than the condensor restricting the airflow to the radiator, I may go switch back to 50/50 this summer.

bohica2xo on Sun February 12, 2012 6:45 PM User is offline

Nice spoiler - except it was spoiling the airflow into the heat exchangers!

Actually in the third frame it would appear that it was capable of helping to evacuate the flow from the lower air dam as well. The Coanda effect from the top edge of the plate to the hood would be strong. Perhaps enough to completely negate the effect of the lower air dam.

Mount the euro-plate on the face of the lower air dam. Or on the garage wall...

Glad you got it sorted out.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Turbofiat on Mon February 13, 2012 1:13 PM User is offline

Some say that spoiler's main purpose is to increase air flow to the radiator. Most get broken off because they are made of hard plastic.

I never imagined that licence plate would have that much effect on cooling until I removed it.

Cussboy on Mon February 13, 2012 1:15 PM User is offline

Good detective work.

Was that radiator you swapped in brand new or used?

speedy car on Tue February 14, 2012 2:35 AM User is offline

I didnt knew that licence plate can be an issue of my car getting heated up soo early.


Turbofiat on Tue February 14, 2012 11:36 PM User is offline

Originally posted by: Cussboy
Good detective work.

Was that radiator you swapped in brand new or used?

It was a "repaired" radiator I had fixed for another Spider back in 1997 I lated junked out. It had been sitting in my barn loft since then 1998. Before installing I flushed it out with water and laid it on the floor and I poured CLR in it and allowed it to sit overnight. Then flushed it out with water. The top of the core looked like a new penny!

I wanted to try this before buying a new radiator.

The radiator that was on the car when it was overheating I had recored back in 1996 so it had been on the car for quite some time. Trouble these days most of the radiator shops have went out of business and the only way to fix a radiator is to either fill it full of some acetic cleaning agent to give it an enema or if it's leaking, pour in a tube of stop leak.

Back in the 1990s there were out five radiator shops in town and usually charged $20 to rod one out and repair any leaks. Now there are none and I live in a town of 50,000 people.

Cussboy on Wed February 15, 2012 8:53 AM User is offline

Agree about the radiator shops. I bought a new radiator for my 1988 truck 1.5 years agao, brand-new all-metal 2-row, to replace a plastic-topped 1-row radiator that was 2 years old. That made all the difference, as 1-row was marginal, especially for Arizona.

Why do I say marginal? Factory truck with everything the same except with automatic transmission came factory with 2-row. Wonder why such hassle was worth it, why not fit all with 2-row....

Turbofiat on Wed February 15, 2012 11:07 PM User is offline

My Spider has a 3 row radiator, about 20"X15". Back in the summer of 2000 while going to a club event I stopped at a rest area (to take a leak) and noticed my car decided it needed to take a leak as well! While re-routing some wires, I forgot to put the spacers in the fan bracket and the bracket rubbed a hole in the core about 100 miles into the trip.

The leak was about halfway down yet the temperature guage never got about 190F and this was in the summer. I think the cooling system holds about 2 gallons. So the cooling capacity is quite good. But the radiator neck is lower than the engine block which makes bleeding the air out of the system a trick. I've owned this car for 20 years and it has been a good car but I've always had some issue with the cooling system. Usually the fan not kicking on when it's supposed to. The radiator cap can "go bad" which will cause the fan not to kick on until 225 (despite having a 185F fan switch). I keep a spare cap in my trunk. I could never figure out why the radiator cap effects what temperature the switch at the bottom of the radiator trips at. These are those Stant caps with the red pressure release lever. My guess is either the seal on the cap is stops sealing after 2 or 3 years. Or it builds up with funk and won't release pressure.

One day I took a bunch of caps to a radiator shop (when it was still in business) and had the guy to test all of them. The one that checked out bad was the one that came off my 68 Ford yet I was not having any cooling issues with that car. He said it was bleeding off pressure around the release lever.

Since then I have using the proper cap for my Fiats (11 pound). I don't know if running a 15lb cap was an issue or what. I've also quite using those caps with the release levers.

Before I got my Mustang I had a 96 Explorer V8 with 100,000 miles on it and believe it had the original radiator cap yet never had any cooling issues with the vehicle. But like my Fairlane, it has a mechanical fan. I've always thought mechanical fans cooled better yet I realize they pull some HP.

The radiator on my Subaru is wafer thin. I have no idea how these thin radiators can possible cool an engine.

Edited: Wed February 15, 2012 at 11:23 PM by Turbofiat

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