Hey i am a new member from australia...
I own 2 Fiat 850s (1 as a donar car)
One i am trying to get on the road and i carnt seem too keep the engine cool enough.. i installed a thermo fan on the otherside of the radiator and tryed to make an undertray to suit it... took the thermostat out (well actually someone beat me to it.) the thermo fan does seem to help a little and is sucking.

Does someone have pictures of these so called undertrays???

As far as i understand the air is ment to come in to top of the engine lid and though radiator and out the bottom.. so thermo fan setup for this.

The water pump seems fine i pulled it off and looked inside the tube to the impeller and its not rusted away..

The radiator cap is not correct i dont think?? as i leaks around that area once hot.. Is the radiator a special size cap? as i've got a new one that "feels" like it fits...

I am an apprentice mechanic so dont be scared to get techy!

Thanks Luke

for the record the problem was that the overflow pipe was bent on the radiator and cocking the radiator cap as i put it in.... felt normal but wasent.. also combined with the wrong radaitor cap to (short of a stem).. so i modified the radiator to suit the cap by using a couple of rubber washers/shims.. anyone else done this?

Hi there, did you fix your problem? I just bought one and made an undertray,, drilled holes in the thermostat etc. but still overheats

The 850's tended to blow head gaskets as they got older.
Often, overheating for no obvious reason was an early warning sign that the head gasket was about to fail.....

Al.

Justin850 said:

Hi there, did you fix your problem? I just bought one and made an undertray,, drilled holes in the thermostat etc. but still overheats

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If you haven't already done so , I'd suggest removing your radiator and giving it a good clean. The cooling fins tends to get clogged with oily dirt (hidden by the fan and cowling), the coolant tubes inside get furred up.

Remove rad, remove cowling, use de-greaser and hose off or pressure wash.
Fill rad. with a caustic soda solution, leave overnight, then flush thoroughly.
Or bring to a rad. specialist and have them work their magic.

No harm to back-flush the engine block/head also. Check the little by-pass pipe and passageways from the water pump to the cylinder head.

Carry out a 'cooling system pressure check' with everything back together.
Any garage should be able to do this for you if you don't have/know someone with the necessary equipment. If the cooling system can't hold pressure, the coolant and engine will overheat. So the fit/seal of the rad cap is very important. Make sure the one you use is the correct pressure rating.

Al.