Help... my car is overheating

[extendor]

Thankyou for the reply. At this stage I can only answer a couple of those.
The car has just had an oil change in the shop. The shop were to do a full service but could not get all the parts so asked me to take her away for the weekend and bring her back next week to finish off. Before that the oil was normal and no milkyness.
The heater worked fine and blew hot air.

I noted the overheating in traffic when stood still. Once it started getting hot it was very quick.
At the time I was at an intersection crossing the bottom of a big hill and the traffic was stopped with me right across the downhill. Suicide city.
Once I could stop safely I lifted the hood and could hear steam hissing through in the radiator cap. There was steam in the expansion bottle. The engine did not smell hot but then again it is not caked in old oil and grime.

I have now had another HG tast done and the shop reports all fine. I have had the water pump removed and checked and this is also fine.

I am hoping that the problem was an air lock that blew the coolant out. Why it never came up on the shop test drive I dont know.

Oh well, what a Supra life he he

[GOGS]

hi
the worst time for gulping air must be when fitting a stat.Jap motors in general need burped when the stat opens throwing out a bit of water but allowing full water throught system-perfect.A resevoir working on a thermo syphon system cant do much else +aint ideal.
Drilling a hole in the stat may work fine but without a jiggle or complete blocking of thermostat youve surely adversely affected the specific aperating range to one of guesswork.the stat being fitted to obtain maximum engine operating efficiency quickly,encludes a restriction in my mind vital to allow coolant to slow down enough to absorb heat to allow system to work right. Lots of garage probs exist cos the stat didnt open right first time before it was burped ,or
it had an underlying prob not so easy noticed without spending extra time that customers are loath to pay for possibly nothing cos time is money!
With enough information from you im sure folk here can eliminate likely faults ,id try motor again if garage says ok but dont trust the gauge if air may be an issue cos you wont know if it boils. :blink:

hi and thanks for that,

I have had the car back now 24hrs and seems fine but I do have the hole in the thermostat. I am keeping a close eye on things and going a few short distance runs in both open road and heavy traffic before I do anything adventurous.

I trust that on this occassion I was lucky and got away with it.

I am intrigued to hear two sides of the story about thermostats. That should be a bigger issue in the same way that HG bolts have been debated.

[suprra_girl]

well it spose it would be an interesting debate... i was told that trick by a radiator company

their reasoning:

occasionally the little toggle thats in the top of them gets stuck so they drill the hole to counter it in case it happens...
i myself haven't done this as i haven't needed to...
but if you don't feel you want that in yours.. thermostats being as cheap as they are you can always buy one hehe

good luck on the car and my best hopes your overheating problems are gone

Hello again.
After all that I had the waterfall again and this time I just had to trust my instinct. So, after one weekend, three evenings of cleaning and reassembly I have a new CHG.

For anyone who is interested DONT be put off by thinking this is a hard job. Get the manual and photocopy it all out into the right order as many manuals flip backwards and forwards to other chapters, get all your tools out, put the car on ramps, depressurise the fuel system, disconnect the battery, use lots of labels to attach to things and get on with it.

The only thing I had a problem with was not having six fingers on each hand that were about 10inches long and with universal articulating joints. That would have made the whole job a lot easier as EVERYTHING is just so hard to get to. In the end I bought a pair of locking artery forceps and thay gave me the extra reach and grip. I bought those from a sporting store as they sell them for fishermen to get hooks out of toothy fish.

The timing belt was a doddle and you dont even need to take the lower cover off. Just clamp the belt carefully against some packers before you release the tension and then lift if off the sprockets. Usual cautions apply.

The turbo was a pain to get off because of the oil feed pipe location. In the end you have to make up some really long extension sockets and get it from underneath but it can be done.

I decided not to have the head/block or manifolds skimmed because all were straight and flat when checked with a feeler and straight edge. The only time you need any help is to lift/drop the head. To make that easier I raised up a platform around the car with pallets so we were could be more comfortable when handling the head as it was quite high on ramps.

So far the car is behaving impeccably and I will give you an update if there is one.

[eandris]

Okay, I've ran out of options. I read your message on overheating and can't seem to pin point the problem. Things I've done so far:

1) Brand new radiator.
2) Removed the thermostat
3) New fan clutch
4) Added K&H Bloc Seal - Hoping it would help if I had a BHG.
5) New radiator cap

I did remove the fan shroud because it was damaged but I doubt if it would overheat because of that. I've ran it for an hour and a half in the drive way. Take it for a ten minute trip on the freeway doing speeds up to 90 with no problem. Head back up the hill which is about a mile and half with about a 40 degree incline and it OVERHEATS. The temp gauge goes immediately to red and the radiator begins to bubble. No bubbling in the reservoir.

I read that I could a have air lock and should burp the system. I've set it on an incline ran it for an hour with the heater on so I'm assuming that's enough though I'm still getting small bubbles when I take of the radiator cap. Also, what is the viscous fan. Just a weekend mechanic who loves his supra (87 non turbo) so please make your answers for a "mechanic dummy". Thanks for a great forum.

Hi, sounds like the dreaded cylinder head gasket. Sorry.

I did mine as reported almost 6 months ago and all is well. Dont be afraid to have a go yourself.
If you need convincing get a sniff or block test done at your local garage. That is a chemical added to the coolant. If it turns (green I think) then you have exhaust gas in the coolant.

I would not mind a bet that when you do get the head off the leak is between 5 and 6. thats always the one to look for.

Best regards

Chris

[Tateslikeink]

Originally Posted by Supra GuestEXTENDOR

Hi, sounds like the dreaded cylinder head gasket. Sorry.

I did mine as reported almost 6 months ago and all is well. Dont be afraid to have a go yourself.
If you need convincing get a sniff or block test done at your local garage. That is a chemical added to the coolant. If it turns (green I think) then you have exhaust gas in the coolant.

I would not mind a bet that when you do get the head off the leak is between 5 and 6. thats always the one to look for.

Best regards

Chris

Oh dear. Everything i've read here i've done. Block test, thermostat, burping, flush, blah blah blah.. On block test there is no exhaust gases in my cooling system, the car was purging through the overflow and yes, i too got extremely scared about a BHG.. Although i guess its not the problem. I had a coolant leak through my thermostat res,.. fixed that, no more overflow. BUT!!! it still overheats randomly, weirder part.. if i put it in neutral while driving and its overheating, the temp gauge imediately drops to normal operating temp, and stays there.. answer that riddle

[suprra_girl]

Had a similar problem, when throttling it would overheat but as soon as i backed off/decelerated it would cool down again, I was leaking between combustion chambers. Have you done a compression check?

[Tateslikeink]

Originally Posted by suprra_girl

Had a similar problem, when throttling it would overheat but as soon as i backed off/decelerated it would cool down again, I was leaking between combustion chambers. Have you done a compression check?

Yea, the numbers were all over the place. From the 6th cylinder to the 1st everything was weird. 1st was 120 2nd.. i can't remember.. 3rd.. i can't remember, 3rd 145, 4th 155 6th 160. How would one go about fixing this issue if it was a leak between combustion chambers?? Because thats kind of how it is... Except, if i turn the car off, then start it again, its at normal temp.