Technical haed gasket and overheating problem

[joester]

hi, i have a bravo 1.4 12v '96. it keeps overheating. i've had the head gasket replaced as that was what was originally diagnosed as the problem. the head was skimmed and tested and replaced but the same problems continued. the car is overheating with no heat coming through the vents and the cooling fan not coming on. i also replaced the thermostat. the coolant doesn't seem to be circulating even though there's no blockages in the system..the radiator or heater matrix etc. the water pump was changed only 12 mnths ago aand looks good. there is only steam coming from the bleed points. Any ideas???

 

[the mk1 kid]

hi, i have a bravo 1.4 12v '96. it keeps overheating. i've had the head gasket replaced as that was what was originally diagnosed as the problem. the head was skimmed and tested and replaced but the same problems continued. the car is overheating with no heat coming through the vents and the cooling fan not coming on. i also replaced the thermostat. the coolant doesn't seem to be circulating even though there's no blockages in the system..the radiator or heater matrix etc. the water pump was changed only 12 mnths ago aand looks good. there is only steam coming from the bleed points. Any ideas???

One or more:

Air lock - check all the water pipe are getting hot, and the radiator is hot all over (not just through heat soak, so dont wait too long) - need bleeding? thermostat not opening? blockage? - everything should 'open' and get hot.

Low water level - dont over fill 'just in case'

HG - Poor job, or bad/no skim despite charging for one

I expect its something simple such as an air lock, or dodgy temp sensor. Put it this way your fan should work, and you only need hot flowing water and a working sensor to turn that on - we'll find the problem quite quickly!

Tom

EDIT: Put differently:

If your rad it hot, as are the pipes either side and when revved (ask someone to help) you can see water flowing into the expansion bottle your water pump, temp sensor, rad and vast majority of the cooling system are fine. If this all happens you fan should kick in if left to heat up/idle for long enough.

If your rad does not get hot (but your dash says otherwise) you have either got a blockage, duff water pump, faulty thermostat or an air-lock. Q, do you know the water is boiling/getting very hot, or could perhaps the dash be wrong - does it boil over?

With you heater controls set to warm (could the controls be broken? Are they electronic or manual, can you really feel things moving when you go from hot to cold?) you should be able to feel the pipes coming from the back of the engine through the bulk head getting warmer - if they dont you have a .... see above.

More info please

 

[btmaldon]

Before going to too much expence. Try changing the expansion tank cap. Loss of pressure would cause the engine to overheat at lower temperature and can stop the coolant circulating properly.

 

[the mk1 kid]

I was coincidentally in a mechanics Bravo last night, and i brought up your car - he advised me you have two bleeds on them, and one is situated (IIRC) on the pipes that feed the heater matrix!

Bleed it from both and let us know if lots of air comes out...

Tom

 

[Adrian Bravo]

The 1.4 has three bleed screws,
One on the left of the radiator (looking towards the windscreen)
One on the left of the engine bay sort of infront of the auxiliary belts.
One on the right side of the engine bay towards the back going into the heater matrix

 

[xander_trippin]

I had similar problems a while back, i changed the temp sensor on the thermostat and got a new fan switch which sorted the problem. Blow down the expansion tank to force the coolant round and out the bleed screws.

 

[the mk1 kid]

Any progress on this - i'm sure others are keen to hear how you've got on?

Tom