Technical Timing belt tension and overheating

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Technical Timing belt tension and overheating


New member
Mar 10, 2006
mk punto 1.2 8v

first a little tail of woe to set the scene.

The misses hit a small wall at low speed with the corner of the drivers side bumper. This somehow moved the radiator so that the bottom ns mounting peg snapped taking some of the radiator with, this promptly dumped all the coolent on the floor but the misses didn't realise, not even when the heater didn't work, so she drove it some 15 miles home. She said it cut out once just before she got home but started ok. :eek:

Now I have changed the radiator and the engine did not appear to have suffered any major damage, as it started and ran ok, however after a little trip the heater still refused to work and although the radiator cooling fan was on the radiator was cold.

I bleed the system but still no heat and a cold radiator.

Having disconnected the top hose and turning over the engine there seems to be no water flow at all. Is it possible the water pump has had it, looking at the one in the haynes manual the vanes appear to be plastic so assume could have been damaged or melted !! How likely is this??

Also if I have to change the pump I will change the timing belt however the haynes manual says that it's procedure is only a guide and the tension must be checked by a fiat dealer. Is this true as I have changed many timing belts on various cars and have never had any problems.

many thanks in advamce - John
i use the twist test for tension on belts same as you probably.

TBH i wouldnt be surprised if your wife has done some damage to the make it home with no coolant is impressive. you may be better doing the head gasket at the same time if your doing the pump and belt anyway
I removed the thermostate before doing this and there is absolulty no flow
To be honest its not much of a job just to whistle the pump off anyway, when you fit a new pump/belt/whatever use the twist test to set the tension WHEN HOT!!! Using moderate finger and thumb pressure you should be able to twist the belt along the front stretch through 90 degrees, never set the belt tension cold as the belt will tighten when hot and go very tight and cause damage and noise.
Well have got the water pump out and it looks ok, no broken fins or anything. Will fit a new pump anyway as I have it. But could an air lock have caused the non circulation ? The engine block was hot (had done about 4 miles) if you opened the rear bleeder steam came out, the top hose and radiator were cold but the cooling fan was one - presume the sensor is on the engine somewhere. I presume it could be a faulty themostat, but didn't get any water circulation with it removed. Anybody any ideas as it's driving me mad
If you have the Mk2, look close to the firewall and you will see the coolant hoses that go to the heater. On one of those heaters you will see an inline bleeder (screw type). With the engine running (Using extreme care & caution)
start backing that screw (counterclockwise about a 1/4 of a turn) you will begin to hear a slight hissing followed by droplets of coolant. When the coolant starts coming out close the bleed screw back up. Almost like bleeding the radiators in your home.

Just an update, I have finished the work and all ok now, replaced the water pump, thermostat and cam belt. I have a fiat manual on cd and the way it suggested to bleed the system works fine. it says to open both bleed screws and fill the radiator to the top so that water comes out of the bleed points. Then whilst water coming out tighten the bleed on the rad then the heater hose one. Run the engine through a heat cycle. When cool check the water level and remove / add water to bring to the max level -= worked for me :)