Mystery coolant leak

[Gandhi27]

Hello,
I am very new to this forum so please excuse me if this has been covered before?
I have a mysterious coolant leak, I have been unable to find it now for about a year!
I will run my car from where I live to work every morning which is about 10 miles, by the time I have got there and let the car cool down it will have lost approximately half a pint of coolant, this will happen every time I use it.
The car is running fine, no mayo on the dipstick or the filler cap.
It pressurises up nicely, there is no white smoke or misfire?
Recently I have noticed a slight glug coming from the dash (I think possibly the heater matrix) when I am driving, the heater is cool, but I can't find any sign of the leak, no wet carpet and no water under the car?
Can someone please tell me how to test the heater matrix or have any idea where the coolant is going? It is really driving me nuts.
Thanks in advance

Gareth

[jimGTS]

welcome

how you bleed the system properly??

there is a bleed port in the frunk (front boot) for the heater matrix.
you should also have some clear hose there for the bleeding procedure.

i suggest you pop that hose on and open up the bleed valve and see if any coolant is coming out of there? your heaters should get warm.

the matrix system is 1 big loop from engine, to matrix, back to the engine. nothing inbetween.

the radiator is 2 separate pipes totally from the engine.


try bleeding the entire system and have a good look around all the drain ports and coolant hoses for a leak.

there is a drain on the block, 2 drains under the fuel tank and 1 on the radiator.

hopefully that gives you some ideas.

[thomp1983]

as jim says and also the pipes that run across the tank fail (search heater hose from hell), they normally go at the brazed joints where there mounted to the body through poor design but mine have gone in several places along the whole length on both pipes, it's not a massive leak a few drops in places that sit on the fuel tank and then are probably dispersed when driving.

my heater has also been poor, the issue i suspect isn't so much that im losing coolant through the leak but air is getting back in the system allowing the coolant to boil and evaporate during use.

as it happens im on replacing the pipes today, just stopped for dinner

[Gandhi27]

Thanks for the advice guys, I will have the car up on the ramp tomorrow as I have the frontpipe alternator and thermostat to replace! Car has been sat off the road for 4 years and I'm now using it again as my daily runner!

[Driftlimits Performance]

Every single mk2 will suffer from pipes from hell. Even if rev4+ when toyota fixed it but only on one side. Check them.

[thomp1983]

Every single mk2 will suffer from pipes from hell. Even if rev4+ when toyota fixed it but only on one side. Check them.

Unfortunately mine went at the brackets hidden by the fuel tank, i only found it as i had to swap fuel pumps. id recommend removing your tank and replacing the whole pipes with rubber hose. It's taken me 4 hours to do on axle stands on my drive in the snow so it's not a huge job, the hose, mounting clips and clamps have cost around £25 and the job will now outlast the car.

[Gandhi27]

Just been doing a few more checks today and trying to bleed through.
the system now doesn't seem to have any pressure, can take the rad cap off when the engine is hot and no volcano!
So rad cap off and gave the throttle a blip, sprayed water a full foot out of the filler neck, also when I removed the oil filler cap the engine almost stalled!
Am I right in thinking this is a headgasket gone and its combustion gas in the water jackets?
Thanks for your advise soon far, very helpful!

[Peter Gidden]

So rad cap off and gave the throttle a blip, sprayed water a full foot out of the filler neck!

That proves the water pump is working.

when I removed the oil filler cap the engine almost stalled!

Rev1/2 turbo by any chance?

[Gandhi27]

Good morning,

Yes you have guessed correct, she is a REV2.
Does this make a lot of difference?
Cheers

[thomp1983]

Because rev1/2's use an air flow meter opening the oil filler creates a massive unmetered air leak the engine struggles to cope with hence it nearly dying. It's not related to your coolant loss

[foxy-stoat]

If you have checked the normal leak spots, remove the bleed screw at the frunk, the one on top of the radiator.

It has a plastic O ring, check that its not broken or perished.

Did you replace the thermostat for a genuine one, test the existing one as well.

[Peter Gidden]

Because rev1/2's use an air flow meter opening the oil filler creates a massive unmetered air leak the engine struggles to cope with hence it nearly dying. It's not related to your coolant loss

[Gandhi27]

Thank you all again for the feed back.
I will add these to the list of Sunday morning jobs and check them over.
In answer to the stat question, no I bought a non genuine stat.
Nothing wrong with the original one just been in the car for 23 years and as the coolant is a bit scabby I wanted to change that as well!
I think my best option is to do a complete flush of the coolant system and start again, taking note of the extra things to check.
Has anyone had any experience with the vacuum coolant exchangers?
A mate of mine has one and thought I might get all the airlocks out easier with it?
A little worried about putting a 23 year old cooling system through this??

Cheers

[Mike]

Cooling system issues are an absolute nightmare to sort, particularly with the SW20 it seems.
If filling and bleeding doesn't yield any results, I'd say its worth investing in a sniff testing kit to detect hydro-carbons in your coolant. They aren't particularly expensive (I paid about £40) are very easy to use and are a handy addition to your tool kit. It should confirm either way if your head-gasket has failed.

There are several coolant pipes hidden away within the 3SGTE that can leak without leaving any tell-tale puddles and you can find yourself going round and round in circles chasing a leak. IMO if it isn't obvious after some basic investigation take it to a specialist. Best of luck to you!

[foxy-stoat]

Either replace the stat for a genuine one or at least test it in a cup of boiling water, just to cross it off the list.

[Harrodbear86]

Second thats