overheating problem (and some questions)

[aj81spider]

I don't know much, and I trust Kieth who has helped me a lot in the past. That said, I don't have a heat shield on my 74 and my hood gets a little warm, but not hot. My fenders do not get hot at all. That would worry me a little.

Again I'm no expert, so can't comment on the temperature differential across your radiator. I don't have an IR thermometer or I'd measure mine, but that would be a big enough difference that I'd be trying to get some data from a car that worked well just to make myself feel warm and fuzzy.

[majicwrench]

"No one said it was normal"??
I said it was normal. Me. Been doing this my whole life professionally. I guess I am No One. Has any (expert) told you the "spec" for how hot a hood should get?? Have they gone out and measured their hood temperature??

Good Grief, Here is a news flash, if you have a 200 deg hunk of metal under a piece of sheet metal, the sheet metal gets hot.

How about you fix your problem (broken fan blade)

Keith

[azruss]

I'm not seeing anything in your numbers that would make me panic. If this is something you are real paranoid about, volvo makes a low pro fan that pulls a lot more air than the dinky fiat fan. Do a search. Many have made this mod. The exhaust manifold shield keeps the heat away from the coil and dizzy. As you drive, that heat is pulled under the car. If your radiator is OEM, you may have trouble finding someone to wrought it out. the tubes are smaller than most shops can handle. The fact that the fan is cycling with the gauge reading in the 190+ range means the system is working ok.
You also dont say if you are driving while running the heat test, or is the car just running in one spot. I'm surprised that fan is doing any good at all.

[btoran]

keith - i didn't mean to imply or state that you're no one. it's just that neither you nor anyone else said their hood gets too hot to touch and their fenders get warm. i'm trying to understand how these cars work and what's normal for them. if that's normal, i'll quit worrying. a new fan is on order. one question that no one has answered is whether the difference in temps between the top and bottom of the radiator is normal. if it is, i'll quit worrying about that too.

[majicwrench]

My words in above post "YES hood gets hot" I did not say if hood gets too hot to touch, just how hot is that?? I said

"YES hood gets hot".

And like has been said, if fan can control temp (even with missing blade) , system is OK. If you want to stress about temp of this or that, that is fine.

Keith

[btoran]

as stated, i'm trying to understand how this works and what is normal. since you;re sure this is normal, i'll stop worrying about the hood getting too hot. one down, one to go.

can you (or someone else) answer the question about whether the temperature difference i'm seeing between the top and bottom of the radiator is normal?

[chrisfiat]

the rad fan sensor is self contained and does not rely on the guage sensor, short the two wires in the sensor to test fan
don'k know the socket size, but probably 22 to 24 mm

yes there should be a big difference between upper and lower radiator, otherwise it would not be working and just be a hot water tank, it is designed to shed heat, but remember it must have flowing water and air moving across it to work properly, so if it sits and idles (ie no moving air till the fan comes on) the lower portion will show less of a differential in temp from the upper portion, hence the reason the fan sensor is in the lower tank

see my above post in your thread
your temps measured at the top and bottom of the rad indicate................a properly functioning radiator. the temp of the hood and fenders indicate.............excess worry

[aj81spider]

It was a beautiful sunny evening, so I decided to be helpful and took the car out for a half hour 15 mile drive (OK maybe I would have gone on the ride anyway!). At the end of it my hood was barely warm to the touch, the fenders had no heat and when I opened the hood I could put my hand on the air cleaner and leave it there without discomfort. I could not touch the valve covers for more than a second or so.

Based on that I'd say you're engine is putting out a lot more heat than mine (1974 1800).

[btoran]

thanks all. i will replace the fan and add an exhaust manifold heat shield and then retest it.

[btoran]

an update......success

i replaced the fan with a 14" unit from Autoricambi and put the front of the car up on blocks and burped the cooling system. i tested the car in the garage as well as on the road and temps are down. As an added bonus, the new fan is silent from inside the car and virtually with the hood open, yet it moves considerably more air than the previous, stock fan. after the car runs a while, the hood is now warm, rather than hot and the fenders are no longer getting warm. i am still looking into an exhaust manifold heat shield, but i don't think they were made for pre-1979 cars and the stock manifold on my 1975 doesn't have any attachment points for a heat shield.

thanks to all for the help.

[kacperix]

Gentlemen,
First of all greetings from Poland (sorry for my english), I am new owner of fiat 124 spider from 1981
I have a problem with the overheating so I will join to this topic and asked for Your support.
Description of fault:
When I start the engine and leave it for 10-15 minutes, temperature indicator goes just before the red area on the gauge and stops there, it will not go over the red area.
So the temperature on the gauge is around 230-240degree.
Then after a while thermostats opened and a big water cycle run, and heater get temperature after a next 2 minutes fan is switch on and drop temperature down to around 210-220 degree

After a next 3 minutes temperature rise to 230 degree fan switch on and drops temp. down to 210 and it's run in the same cycles...
When I go for a ride (outside temp aroun 15deg. C - 59 deg F) temp goes around 200-210 and stay on this level all the time when I'm riding, when I stop temperature rise slowly to the read area but never goes there.

In my opinion it looks like I have a air in the cooling system, so I mount addition vent
(heating in the car runs all time cause I blind the valve in a open position.). I opened the vet couple time to vent the system from the air, and water came out from the vet, air bubbles show in the overflow tank. but it didn't help.

Strange for me is that the cooling liquid doesn't seems to be so hot us it shows in the gauge, normally when You open the water tank or the cap from the front heater with this kind of temperature it should boiled, or spray out and You can be burned but this is not. So it's look's like only the temp is on the cylinder head (unfortunately don't have a heater gun the measure temp on cylinder head).

So I think about the head gasket problem, but there is no leaks, coolant level ok, I 've done also test for content of the exhaust gas in the cooling system, but the result was negative.
I think maybe the thermostat doesn't opening completely or jam from time to time..

Next idea is o change the water pomp, but in case I will do so it can be easly done the head gasket but not sure what else I can checked before do in it,

can be the problem with the head sensor?
Other ideas what should be checked?

[RoyBatty]

Are you having to add coolant after driving the car? In other words, does the engine seem to be consuming the coolant?
If not, then you probably don't have a bad head gasket or cracked head.
Start with flushing your radiator and engine coiling passages and then install a new external thermostat.
Test and move forward from there.

[redcars]

I would get an infor red gun and check the temp with it. It sounds to me like you have a bad temp sending unit or a bad temp gauge and in fact you engine is not over heating. It would be nice to know for sure which it is.

[azruss]

the gage can read high if the ground and electrical connections from the sender are dirty. clean the wires to the gage, the connection to the ground pod under the dash and the connection from the sensor on the head. It definitely sounds like your thermostat is sticky. The long hot cycle before the thermostat opens could also be air trapped below the stat in the lower radiator hose. This is a difficult area to clear the air, but once the stat opens, it should clear and be okay. If you are still getting the hot/cold cycle after that, then it could be a sticky stat. Since its seams to run cool while driving and heats up while sitting, i would suspect the cooling system is ready for a flush, radiator needs cleaning, or you are ready for a new water pump.

[kacperix]

Guys, update after today's fight with overheating...
today i connect wiring from the sensor1 which is close the timming belt to the sensor2 which is closed to cabin interior, and termostat open in 190degree F, and fan start around 210degree F at a standstill car.
When i go for a ride temp was all the time 190degree F.

The sensor which is closed to the timming belt was disconncted because wiring from the sensor 2 was too short to conntect it, so imo it's impossible to make a mistake with connection.

As i know sensor 1 is responsible for the ovearheat light, question where is the light so i dont have any indicator for it on a dashboard.