Help needed - running hot!!!

[jefft]

Hi all,

Have just fitted a new rad fan sensor and guage stat today.

Ran the car and watched the guage climb reasonably fast all the way to the shaded bit - switched off and checked for probs.

The radiator and the bottom hose were cold - so conclusion thermostat not opening.

As the thermostat was changed when belts and pump were done in May and it was working before can this be down to air?

Have run the car with the bleed screw undone and expansion cap off and no air comes out - any suggestions???

Desperate to get it sorted as got tickets for Castle Combe race day on Monday [][]

Cheers,
Jeff

 

[Mike_Pollock]

Could be air - they are notoriously difficult to bleed - minimum 4 times I reckon, make sure heater controls are on hot, take it for a short drive. Mike

 

[Riverside]

You should bleed the car with the engine switched off. When topping up the header tank with coolant, open the bleed screw to allow some air out. Then close the bleed screw (and replace the coolant cap) and warm the car with the heater on full heat until you hear the rad fan come on (so you know it's above the temp at which the thermostat should open), switch off the car & crack the bleed screw open slightly. Let any air escape including any spitting & spluttering & once you have a solid trickle of coolant seeping out close the bleed screw. Switch on the car & repeat until you have eliminated all the air (should be no more air by the second or third time). If you continue to get air out check for leaks.

 

[jefft]

Thermostat issue now resolved - new stat fitted 82deg instead of 88deg. Running from cold thermostat opens between half and three quarters on the guage and the rad fan cuts in at just over three quarters - brilliant I thought [][] Did some extra bleeding as per "Riversides" instructions and got an extra bit of air out. Took her for a run and within a mile temp guage was up into the shaded part. Pulled over rad fan not running and radiator was cold to touch. So I left it on tickover and radiator warmed up, rad fan came on and temp went back to just over halfway on the guage ???????? Switched off, cracked open the bleed screw and a load of air came out. [][] And so it went on !!!! Is this down to air getting into the system, if so, how ? Any suggestions ??? Cheers, Jeff

 

[JamesO]

That sounds perfectly normal, I certainly found the early Lux I had was total pig to bleed, it was a case of run for a bit, let air out, top up coolant and repeat. I believe there is an air trap in the cylinder head which causes the issue. Go careful letting it get hot. Also the early guages are great for scaring you if the grounds are a bit iffy. On my '82 lux if you turned the lights on the temperature guage would go up and oil pressure guage would drop. Just re-read your first post, by guage stat do you mean sensor? Is it the correct sensor? Why did you change it and are you sure its getting hot and not just indicating hot? If you continue to have issues it might be worth taking it to a garage and getting the coolant sniffed for exhaust gasses.

 

[robwright]

It helps immensely if you jack the front of the car up (quite a bit in fact) so that the bleed screw is the highest point in the system. I.e it has to be higher than the heater matrix which does sit quite high up. Your other option could be to pressure bleed it. This could be done with the correct equipment or by mouth to mouth on the header tank if you have enough puff.

 

[Mike_Pollock]

Sounds normal to me so far - I'm sure they have a compressed air cylinder hidden, they take so much bleeding. After 5 or 6 bleeds your still getting air then I'd agree with James and get the coolant checked for exhaust gases. My guess is there was lots of air pockets. Also try to have the car pointing up any slope. Mike

 

[alwigley]

I think our American friends on 944online recommend the use of a turkey baster to force coolant into the bleed screw hole [] had some similar issues with mine after changing the DME temp sensor, but it cleared the airlocks itself after a week or two of driving.

 

[DivineE]

I second the idea of jacking the front of the car up as high as possible. It was no fast fix but after 10-20mins of squeezing hoses and starting/stopping the engine I got mine bled perfectly well.

 

[jefft]

Thanks for the replies guys. Popped in to Exeter OPC earlier today and the workshop foreman suggested there could be a problem with the expansion bottle cap. [8|] For the sake of £7.00 have ordered one for Friday - also rules out something else. Will let you know. [][]

 

[Mike_Pollock]

My experience with the cap is that it will pee water out very obviously if it is faulty. Mike

 

[jefft]

ORIGINAL: JamesO Just re-read your first post, by guage stat do you mean sensor? Is it the correct sensor? Why did you change it and are you sure its getting hot and not just indicating hot? If you continue to have issues it might be worth taking it to a garage and getting the coolant sniffed for exhaust gasses.

Yes, it was the temp guage sensor. I changed it because the indie that changed the belts, pump and thermostat said that the guage was showing a higher temperature than the engine was running at. I wasn't convinced, as in my opinion, it was running hotter than it should, but changed it anyway. After changing it there was no difference. Rad fan sensor was changed because it was faulty (the fan was always on unless the battery was disconnected).

 

[robwright]

It is possible that the cap could be letting in air I suppose. Generally though the cooling system is pressurised greater than atmosphere and because it is sealed this allows water to be at more than 100 degrees. When the pressure becomes too much it will overcome the spring in the lid and vent to atmosphere. Usually the spring will get slack and it will blow off prematurely. If the cap is not sealed properly I suppose it would let your coolant boil off. I have spent more money for peace of mind before now though []

 

[JamesO]

[/quote] Yes, it was the temp guage sensor. I changed it because the indie that changed the belts, pump and thermostat said that the guage was showing a higher temperature than the engine was running at. I wasn't convinced, as in my opinion, it was running hotter than it should, but changed it anyway. After changing it there was no difference. Rad fan sensor was changed because it was faulty (the fan was always on unless the battery was disconnected). [/quote] This may be of help:- http://www.clarks-garage.com/shop-manual/elect-19.htm#coolant

 

[jefft]

ORIGINAL: JamesO This may be of help:- http://www.clarks-garage.com/shop-manual/elect-19.htm#coolant

Yes, Thanks. That confirms the thermostat is opening and the rad fan is coming on at about the correct temperatures. Allowing for 28 year old electrics i'm happy with that. So that leaves me with changing the expansion cap and more bleeding on axle stands. And then all will be well. I hope.

 

[Gavin944s2]

I always wondered why Ford RS style vents were never fitted for a good under bonnet air flow,& to disperse some heat.[8|]

 

[Riverside]

ORIGINAL: jefft So that leaves me with changing the expansion cap and more bleeding on axle stands.

Just park the car on a slope [] Bleeding the cooling system isn't something you have to do on your driveway, just keep a 12mm (iirc) spanner with you in the car & crack open the bleed valve whenever the opportunity arises. Also bear in mind that with an old car there may be more than one fault. If you keep getting air the most likely cause is probably just an old top or bottom hose that may only be allowing coolant out when hot. I had a slight crack in the top hose joint on my rad a while back, it only leaked (steam) when the car was warm & the thermostat was open & was barely noticeable.

 

[peanut]

you did have the heater on when you bled it I take it []

 

[jefft]

ORIGINAL: peanut you did have the heater on when you bled it I take it []

Certainly did. Riversides instructions were straight forward enough and up until the point where I took it for a drive it was all good. Collecting expansion bottle cap in the morning, so hopefully get sorted tomorrow. [][] And nice drive to Bovington on Sunday [][][]

 

[peanut]

bleeding the coolant system on these is a nightmare job. My local indie put a new waterpump and belts in my car then didn't bleed it properly.The result was it had a blown head gasket and white smoke when I collected the car. They denied all knowledge and I had to pay them a further £500 to fix the head gasket[] Never been back there again.