Coolant in Expansion Tank drops slowly

[Silece2k6]

Hi Guys.

 

I had a little problem with my Supra

 

The expansion Tank is right the Batterie (FMIC)

 

As I get the car, the coolant was about "MIN", so I filled up close to "MAX"

Radiator was full with green Coolant. And its a Aftermarket Aluminium one

 

after about 800km the expansion Tank was close to "MIN"

 

I checked the engine compression and all was fine about 12bar. If the engine is hot and I open the bonnet, sometimes it smells shorty due coolant "sweet smell"

But I can't find any leaks, all Is Dry.

 

Are there any possible Hoses, that can be sly because of age?

 

Or can it be the Headgasket?

I just get a CO2 Test for German "TÜV" and all was fine.

 

Sorry for my bad english

 

Regards Patrick

[Chris Wilson]

It sounds fine so long as the expansion tank is not emptying completely. I think you are worrying needlessly. Your English is excellent, no need for any apologies, you could teach some English members here how to write

[Kristian_Wraae]

You can get a special device that can connect to where the radiator cap goes and will allow you to put the system under pressure. Then you can look for places where it drips or gets wet.

 

It can be very difficult if the engine is warm because the coolant will just evaporate. So I would test on a cold engine. It will also allow you to detect if pressure is lost and how quickly.

 

Also look for hoses that have been removed and put back. Sometimes if the clips are not put exactly where they were before and the hose will then not seal properly.

[Havard]

Have you checked the passenger footwell? If so, your heater matrix is dead.

 

You are obviously losing a small amount of coolant over time/miles from somewhere.

 

I would suspect either the radiator cap or a hose with a small crack that only opens up under load. I had this with my NA but found a pipe rubbing at the back of the engine.

 

Good luck.

 

H.

[DodgyRog]

A few of us have had the hoses go between the rear of the engine and the bulkhead

 

I also had the one from the back of the Water Pump to the underside of the Turbo's go

[Dnk]

This pdf is on the cooling system, page CO-18 shows how to pressure test it.

 

I'm guessing you only have a small tank if it's next to the battery so your

losing say around 0.5 litre every 800 km or 500 miles ?

CO.pdf

Edited July 4, 2014 by Dnk (see edit history)

[mattdavies]

A few of us have had the hoses go between the rear of the engine and the bulkhead

 

If its this then its a pain to replace. I had to climb on my engine to get to it

[Silece2k6]

Thank you guys. At the weekend I changen the radiator to a new one. I filled all up to max and let the engiene run to "entlüften" the cooling sYstem (heater on)

 

After that I drove a little bit and checked the coolant and filled it up to max.

 

I think I had to to this three times.

 

Today I checked all again and the expansion tank was a little unter "max" (when it's hot it is over max)

 

Maybe it's the Zylinderhead gasket?

[Chris Wilson]

The expansion tank level will and should fluctuate with temperature. If it still slowly empties you have a leak or other issues though. I would do a coolant system pressure test next, if it's still playing up. Then a combustion gasses in the coolant test.

[Dazzi]

My girlfriends supra was doing this. It was coming out the back of the water pump as steam. Couldn't find any leaks, pressure tested it and held pressure. We put some rad seal in and it gummed up the leak on the water pump so was easy to spot.

[Tommyd16]

This happened on mine when I first bought the car. Changed the rad cap. Job done

[Silece2k6]

Thank you, i will Check this.