Technical Fiat 900t overheating

[phate316]

Well lil blue has had her first year on the road in 20 years, and now shes decided to throw a spanner up, overheating, if you turn the heater off at the front she pushes the temp gauge up significantly, nice in the winter bad now, especially as we have a 2 week trip down to italy amd back planned in her, under trays are intact vent duct intact, ive just performed a full chemical rad flush and still no joy, thermostat is fine, water was a bit rusty on the flush but 5 rinse throughs later she was clean as a whistle, im thinking its time for a recor on the rad ive a spare one so i can send that one off and have nice new insides, made a few more modifications on her this year, a high ratio 850 spider coup gearbox ( she now sit on the road comfortably at 60-65 without screaming the engine) and a nice 4 branch exhaust for better mid range torque, i didnt go with the twin choke webber as i dont think it would give a great gain and pour away alo more petrol total cost of mods £350
Cheers me dears

 

[the stig/130]

Sounds like the rad, if, after flushing with hot water, the rad should be hot all over, if not...

 

[spannerdude]

Very sensible choice of modifications. Pretty much what I have planned once the tinworm is vanquished.
Is the thermostat opening? Is it even fitted? Without the restriction presented by the thermostat water is not forced around the entire engine block. This can cause localised overheating around the furthest cylinders.

Is the water pump pumping?

If the rad was gunged up, is the block full of sediment too?

 

[phate316]

Did full chemical flush and she ran clear afterwards had to put some pressure behind it when flushkng backwards from the thremostat housing but im guessing its because of the water pump, im guessing the water pump is ok because she doesnt overheat in traffic, if fact thats when shes at her best, its when te engine is under strain up hills or alot of harsh acceleration, ive tried it with and without the thermostat still to no avail, a ive got a spare rad im goong to try that, and then its off to the local rad rebuilders, £135 for a new core or £165 for a more efficent one, how much more efficent i dont know but weheee its only money
Did anyone see the auction on ebay italy of the panorama fiat 850 she was a nice lil thing made €11000
Later

Tim

 

[phate316]

Just discovered as well that the water is being thrown out of the expansion vessel im a bit puzzled as the lid has a rubber gasket inside it with a slot big enough to fit ur little finger in ?????

Any clues

Cheers me deearss
Tim

 

[Jayarr]

Just discovered as well that the water is being thrown out of the expansion vessel im a bit puzzled as the lid has a rubber gasket inside it with a slot big enough to fit ur little finger in ?????

Any clues

Cheers me deearss
Tim

Mine has a slit, rather than a slot in the rubber gasket. As this side of the radiator cap is not under pressure, it just stops the water slopping out.

Make sure you have the right radiator cap if you have the Fiat radiator top tank. The 850 ones are a long reach type. I had issues until I got the right cap as the cooling system was not holding pressure.

Cheers, John

 

[Maigretnz]

Make sure the underbody tray is in place that seals the area to the right of the sump behind the radiator. The fan blows the air forward and it then comes out the duct and flows under the tray and out the rear of the van.. If the tray is not there the hot air gets sucked back up by the fan instead of the desired fresh air from the vents in the side of the van.
I used to drive mine hard and fast up the mountain roads of New Zealand with all the 850 sport bits on it. I never had an overheating problem.