Cooling system modification?

[SRCM]

My newly aquired carbureted '79 is running hot, so I'm starting to get familiar with the cooling system design and overheating fixes. This system is definitely not like American cars because of the location of the thermostat and its' split flow design. The engineer inside me wants to re-design this thing.
Proposed: simplify the cooling system by making a thermostat housing with a simple (180 degree?) American thermostat mounted in place of the water outlet from cylinder head, connect with radiator hose to top radiator inlet, eliminate existing thermostat housing and run radiator hose from bottom radiator outlet directly to engine. This setup would certainly look better and de-clutter the engine bay, and probably simplify or eliminate all the 'burping'. QUESTIONS: Would this work? Can the radiator handle the 'full' flow of the water pump? If not, does this create backpressure problems at the water pump or does it over-pressurize the radiator and force excessive coolant through the overflow into the overflow bottle? Anyone tried anything like this? All comments welcome.

[danaspider]

Before a redesign, what are you saying is hot? And are you basing this on the gauge or a actual measurement at the radiator?

Lt us know. A lot of engineering went into the current config ( and yes it was Italian) but a lot of work anyway.

[mgbgtn]

My 72 with a 1592 motor comes from the factory with the thermostat in the head just like an American car.

[So Cal Mark]

a "redesign" without knowing how the system works and was designed to work is an interesting concept. This concept is based on the belief the original engineers were idiots. This concept also requires the belief that all Spiders overheat or run hot since the original design was lacking.
Before you spend a lot of time "re-engineering" the system, I'd suggest reading "Engine Cooling Systems" by Ray Bohacz. It's available on Amazon for not much money

[narfire]

Air temp here during the day is around 85-90 deg F. My 2L when on the hwy is around 130-140 F and when stuck in the drive through at Tim Horton's it will climb to 190 when the fan kicks on as it should and the temp does not climb at all.
System works fine in my opinion. The older cars had the thermostat in the front of the head, but someone correct me if I mis-interpreted, but I read somewheres that they moved the thermostat outside the head to even the heat range in the head.
There are cars here that live in the desert and the stock system has evidently been working.

When you say hot, .... how hot under what situation?

[djape1977]

it's perfectly normal for a fiat twincam to run at 190-208'F. you need to run it with a G12 or equivalent coolant, 50% solution, all year round. lower running temperature causes bad lubrification and reduces engine life.

if you feel the need to have a "temperature safety margin" than something's probably not working as it should.

factory thermostat in the head is the same as for Yugo. one on the hoses is the same as for Lada. both are available with diferent opening temperatures, ranging from 150'F to 200'F
also, there are diferent cooling fan switches out there, some kicking in as low as 180'F, again straight bolt on from any fiat/lanchia/yugo/lada/vw/audi etc.

driving old fiats in hot southern european climate, where temperatures in the city regularly reach 108'F, has tought me it's useful to have bigger and better engine cooling fan and a new radiator since ones that are 30-40years old tend to lose efficency due to a number of reasons.

not a spider but just to give you an idea...

[SRCM]

Wow, thanks for lots of good replies. I say this car is running hot based upon a 20 minute drive around the subdivision in 90 heat with full radiator and overflow tank (although not necessarily burped according to recommended procedures), the temp guage and 50 years experience with engines. It was blazing hot in the engine bay and the smell of hot hoses was unmistakeable. No, I don't have a thermometer . . . yet. Moving forward, I'll check to make sure nothing is blocked, replace thermostat and radiator cap, flush and replace fluid and burp according to various procedures to try to get on the road as quickly as possible. However, I still like the idea of a simplified system.

Does the (earlier?) head with integral thermostat work on this 1995cc engine? What options do I have, if any?

[baltobernie]

Does the (earlier?) head with integral thermostat work on this 1995cc engine? What options do I have, if any?

Yes. You can also retrofit the older thermostat and housing on the 2L head, but you'll need to cut the thermostat mating surface on the head a couple hundredths. Next time I'm at our local expert's shop, I'll take some photos. Several of our club "experts" maintain that the in-head stat is a better design, and that Fiat changed it solely to accommodate other engine mods.

I too share other poster's opinion that a properly operating Spider cooling system is capable of withstanding higher ambient temperatures for longer periods than any driver would tolerate. I personally have been trapped in accident-related Beltway delays of more than one hour with ambients of 100°. I was toast, but the car was fine.

[rlux4]

A while back Ventura Ace and Hal Gaylord did some very subjective tests on the two systems; in head vs. external stats. I can't find their report, but I seem to recall them finding very little difference in the heat exchange capabilities. Hal has since passed on but these two guys are the ones to trust when testing is done.
Ron

[eman2112]

Pardon me for chiming in here but does anyone have a good current part number for the radiator fan switch mounted in the bottom of the radiator? The PO of my 81 spider did a butcher job of the electrical system. Also, is there a replacement thermostat part number that can be adapted to the spider or is this a one piece unit? (whole thermostat assembly) I can't seem to find a thermostat ANYWHERE for the 81 spider FI.

[So Cal Mark]

ALL of the real Fiat vendors carry those parts in stock

[eman2112]

Yes, I checked IAP and they didn't carry the thermostat. Although Vick's did. Got it on order along with door lugs and a thermostat hose and a clamp kit. WOW this is turning into a boat. (Break Out Another Thousand) LOL. And so it begins... Money for something. I look forward to the day I get to drive her. Haven't found a name for her yet but getting there.

[sierraspider]

My 82 was running hot and the proper burp procedure made all the difference. Start with the basics and like some of the posters have said the engineers ( Da Vinci and Micheangelo were italian) probably worked this out pretty well.

Dan

[bradartigue]

The engineer inside me wants to re-design this thing.

The engineer in you should study the design and why it is external to the engine vs. internal.

[profcucchi]

The PO installed two fan switches in the lower console. One is the fan in the engine compartment and the other seems to be coming from the back.

Can anyone tell me why?