overheating problem

[Exarkit]

we bought an 1986 944lux with an know overheating problem, apon looking at it serviceing history its had 2 raidator's and about 6 thermostats.

ok so far we have flushed the raidator, check pipes and rails, - the water seems to be free to go full circle around the engine, heater, and raidator with out no problem, - altho we cant get the heater to give out any heat any more, - the engine overheats with in about 30-40 mins of running on idle, the fan kicks in only once the engine has cut out once, but the raidator is not hot.
we have filled and blead the system from vaiouse point on the engine to see if its blocked etc, and apon checking the thermostat, we found there was not on installed - an possible fix from an old attemt to fix the problem before the pervious owner got the car. the only thing we can see that is rong is the water is too presherized a) from the bleed screw, b) from the filler cap on the expand tank. so we are thinking that it might be an blown headgaskit. the water is not oily when it comes out nor is oil messy it looks clean, (the oil filler cap has some white spots on it but we put this down to normal condersation etc) and we have hurd that the HG can go an not send oil into the water/water into the oil etc. so i ask is there anythink else we can do to fix this problem before going to replace the HG and is it possible not have the head skimmed, as all our enginerring contacts have gone ??? so is there anythink else we can try to fix the problem??

Oliver Rawlings

 

[Stu Alderson]

Oliver, not a definitive answer but you could try the following, even better if you have a friend with access to a motor dealership.
1. Cylinder leak test, time consuming/complex but test for a number of things "diagnose problems with pistons, rings, and valves. Cylinder leakage gauge makes it easy to conduct leak-down tests--more accurate than standard compression tests." also please note if you need to buy, instead of borrow the kits is quite expensive.
2.There is also a cheap tester available (c25-30) which consists of a dye which changes colour when exposed to exhaust gases. This is a very simple test performed at the expansion tank.
3. Clarks Garage have a reasonable test schedule which may assist. (http://www.clarks-garage.com/ look at COOL-3)

Regards
Stu

 

[u63af]

Having read the post, you have said that the water is free to flow around but have you checked that the water pump actually pumps the water around? If the water pump is broken then water will circulate around a bit due to convection but not a great deal.

 

[JamesO]

I agree, take the top belt cover off and make sure the pump pulley is spinning, athough if it were siezed it would eat the cam belt fairly quickly. check for any odd sounds from the pump.

Is it losing coolant?
Are you sure its overheating and not just the guage showing hot. A poor earth can cause incorrect temperature readings, the needle raising when you turn the lights on is a dead give away.
Headgasket job is not a bad one on an 8v car, when i last did one the head was fine but somebody had changed the old one without cleaning off the remains of the last one.
I just checked it with a straight edge and feeler guage.
The expansion tank cap is a cheap replacement to eliminate it.

 

[elvis]

Do the checks as suggested by Stu above but I have to say that if it's pressurising the cooling system excessively then it does sound like the head gasket. No thermostat is not a good sign in my experience.

If the head gasket is blown between a cylinder and a coolant passage then depending on the relative pressures at any given time you will loose coolant into the cylinder or pressurise the cooling system. Lack of oil/water mixing does not mean that the head gasket is OK, it just means that it hasn't blown between oil and water passages.

Having said that it could still be that the water pump isn't pumping (for example if the impellor has fallen off - not impossible although I don't know how the 944 one is constructed) and double check that water really is free to flow round the system before pulling the engine to bits...

 

[Exarkit]

the water pump is damaged where the thremostat sits in so, from the experments to see if the engine is blocked we can tell the pump works as we can see water cycling thought the expasion tank, with talks with an local mechanic, - he thinks 95% that its the HG, so we going to overhall the head at the same time and give it an good service, belts etc, and i will look at getting the rocker cover + head soda blasted to restore the look of the engine, plus i can get the engine bay t-cuted with half the engine out i hope or most of it.

oliver rawlings -

 

[924nutter]

It sound like the HG as water should not noticably circulate through the expansion tank.

 

[Exarkit]

ok so we got the head off the car at last, and by looking in some of the air intake systems and there was an lot of white/brown goo. - and when we got to the HG, it was in desprate need to be replaced, and we found one of the rings of it was comming off from the gasgit. so the head and cam was sent away to be cleaned and skimmed.
just found out from the place that was going to do the skimming, that the head is cracked and its not worth welding up.

so does any one have an head for sale? or an engine in gwo.

 

[James_G]

A that's a shame. Mind you there have been a few cars being broken for parts recently, so hopefully a good head will be available.

Nice to hear that you are trying to keep it on the road though - good luck.

 

[Exarkit]

yes i want to keep in on the road, there is only an small amout of rust to tackle to get the bodywork back to mint con, and with that rust removal most of the body will be resprayed. but it does not look in an sorry state at the min, and with the need for an new head/engine it will give me the change to clean and t-cut the engine bay with the engine out of it

 

[Exarkit]

just thought i would update you all to how things are going for me, i found an replament head at the porsche auto jumble an month or two back, and before then i have gotten an replament engine from JMG, and after waiting on equipment, i have managed to clean it up not 100% but close, will do the original one to 120% , getting some turbo 220 brakes for it as well. so she will be on the road again in aug time

 

[zcacogp]

Good to hear the news.

Beware of fitting those Brembo calipers; I'm not sure that it is an easy job fitting them to something that isn't a Turbo or S2. Others will be here soon to correct me ...

Hope the project finishes off OK. On the road in August - that's soon!


Oli.

 

[Exarkit]

i getting the cals, hubs, disks, etc for an full conversion on the front from an 220turbo, and the disk and cal's for the back end just waiting for it to be off the doner car.

 

[944 man]

Early cars dont have a proportioning valve, so youll need to do a little research.

 

[Exarkit]

good news is she runs, and i have been introduced to the cost of good oil.... bad news is i having to get some helicoils to hold the front whishbones onto the car.... and she needs 4 wheel tracking, but well i have it done after i gotten the turbo brakes on her.

- the old engine has been fully taken apart and it would apear that it would of lasted an nother 1000miles before it cesed, the middle thurst bearing and crank had been eaten into and also it looked like the crank had slight started to wear on the block....... good think i went for an replacment engine over an rebiuld.

 

[Exarkit]

ok months later, and an cracked oil cooler hosing, luckly not the oil cooler matrix. we have the engine running again and no water leeks with antifreeze in it, but - when we where working on it to find the water leak, he had issues getting the cooling system fully blead, the heater was allways cold, what tips and tricks can i use to make it easy to get the cooling system fully blead of air and the heater kicking out hot air when asked to???

 

[alwigley]

I am guessing you have tried waiting for it to reach operating temperature, then pumping/squeezing the radiator top and bottom hoses by hand, with the expansion tank cap off ? Otherwise, are you sure that the thermostat is functioning properly as the heater on some cars will not come on until the stat has opened - not sure if this is the case for the 944 as I've not owned one long enough to have to replace it, but it's sure to pack up some time soon [].

 

[pauljmcnulty]

when we where working on it to find the water leak, he had issues getting the cooling system fully blead, the heater was allways cold, what tips and tricks can i use to make it easy to get the cooling system fully blead of air and the heater kicking out hot air when asked to???

They are tricky to bleed, having the nose parked uphill helps.

 

[Mike_Pollock]

Run it Bleed it Run it Bleed it........ etc 4 times at least[]
Mike