Help... my car is overheating

[ddmcse]

you need to have the head checked to see if it's warped .also check the block for smoothness
you shouldn't just replace the gasket .
going with a metal hg is not cheap and is really for someone who wants to go mental with boost
a stock gasket doesn't need the surface as smooth as a metal gasket . the stock gasket material is more forgiving of the block and head surface
condition
http://www.ddmcse.com/turbo/bhg_2003.htm

here is a shot of a metal headgasket
http://www.ddmcse.com/turbo/images/mhg.JPG

tearing apart the head is really not as hard as you may think
just takes time, not really any special tools need a torque wrench

i used this guide when i did my 1st one ,, but i didn't go through the effort of preparing the block which is why I got to do it again.
http://www.geocities.com/MotorCity/Speedwa...y/1636/bhg.html

[mrnickleye]

Why, you ask, won't radiator sealer work on the 7M BHG problem.??

Because the "usual" BHG starts out as a tiny hole from a combustion chamber (usually #6 cyl) to a water passage.

The enormous pressure during combustion pushes the gasses 'into' the cooling system. This then builds up too much pressure and causes coolant to eventually over flow into the recovery bottle.

The sealant only works when the coolant is trying to leak 'out of' the cooling system to atmosphere. It plugs the hole.

[mrnickleye]

Gasses get into the heater core due to a BHG.

Air gets into the heater core when the coolant level is allowed to drop in it. I suppose you could pinch the 2 heater hoses before you open the system, to prevent the coolant from coming out.

But I don't recommend this with old hoses, as it may cause them to leak later.

Also, the dangly thing on the thermostat can be snipped off before you put it into place. This will allow air to 'more easily' escape from the engine, and into the radiator, where it eventually will be pushed out into the coolant recovery bottle.

And....even opening up that hole by drilling it to 1/4" will NOT effect the operation of the thermostat, as it will still open and close normally, to allow the flow of coolant.

When your system is up to temp, the thermostat is wide open anyway.

Remember, the 7m motor (with a standard pump) does not flow much coolant at idle. AND...the fan does not draw much air at idle. I read many threads where the fellow says it gets hot at the stop light. Thats why I use an electric fan here in the desert.

I am mostly driving in town, with the A/C on, so I want lots of air thru the radiator at all those stops.

[Inlinesix]

Originally Posted by extendor

A little bit more information for you all to ponder. I collected the car this afternoon from the shop and had a really good report on the engine etc. The shop said they had test driven the car and she was still warm so I guess that was true. Within a mile of leaving the car started to overheat and I pulled in and stopped just as the needle touched the red. I just could not get in any sooner because of the road and it would have been suicide to stop.

I had the shop come out and their mechanic let it cool off, topped it up with about 1.75l water from a 2 litre bottle started her fine and drove back.

He took her out for a test drive of 8 miles and she was fine. Got her back to the shop and let her sit with the heater fan off and engine on tickover. The secondary fans came on OK and she behaved as normal.

I have let the shop keep her for a few more days as I want them to do a few cold starts and run ups to see if this happens again.

My own feeling is that they forgot to connect the fan sensor but i was wondering if there was any chance of any damage especially after such a good report on the engine beforehand.

Many thanks to anyone who thinks about this and makes a comment.

If you have problems like this or any other heating problems check ur car, if you have 100k+ miles and you replaced the thermastat... and it still over heats go to a parts store and just buy a new fan-clutch! many people think the fan is just the fan, IT'S NOT! the round metal part that the fan it self bolts to is the fan clutch. to test if it is your fan clutch, simply turn the fan by hand, if you can turn it with eas, replace the fan clutch, i garanty that it will fix your heating. a good fan clutch will have a strong resistance to being turned. it should not be easy to turn. P.S... it will fix your overheating, even with a blown head! i buy supras for cheap from people who think the head is blown. then just replace the fan clutch. trust me it works!

[mrnickleye]

Originally Posted by Inlinesix

replace the fan clutch, i garanty that it will fix your heating. P.S... it will fix your overheating, even with a blown head! i buy supras for cheap from people who think the head is blown. then just replace the fan clutch. trust me it works!

What kind of guarantee?? $$$ ?

All the 'cooling' in the world did not 'repair' my BHG.

[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.

[suprra_girl]

If it's that ALL OVER the place then yes head gasket has fubar'd.

It's not overly common to blow between cylinders, usually you get the water mixing with oil variety.

What work has been done on it? Is it stock or got mhg or what?

[Tateslikeink]

Its completely stock. Nothing at all done to it. Its weird because the car runs like a top. Just randomly overheats. Definitely not a all the time deal. Once in a while. And it stopped spewing when i changed the thermostat housing bolts from the leak i acquired from the bolt i broke