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Losing coolant through expansion bottle (only on hard pulls)


add heywood

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Been reading some old posts but I cant understand why this is not happening all the time...

Coming home from Oulton Park at the weekend had a little play with a S14, recorded the pulls for about 3 mins with the Defi's and everything was fine, all temps were normal etc. About 2 mins after the warning light/sound starts as the water temp is hitting about 110c. Checked the Power FC commander and that was reading 100 ish. Pulled over to find the overflow pipe on the expansion bottle had pissed coolant down the front of the car. Got home (without the temps going any higher) and it took about a litre of cooland to fill the rad back up.

 

Now the car had run 200 miles or so normal driving and the water level was fine (checked before I set off to Oulton Park that morning).

 

It happened a while ago when the car was being dyno'd at SRR aswell. Drove the 200+ miles and checked all fluid levels before mapping. All was fine until about the 5th pull when I saw water pissing down the front bumper.

 

Ive changed the radiator cap for a brand new TRD 1.3 bar cap...

 

Any suggestions? :search:

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Head gasket has blown between cylinder & water jacket? Cylinder pressures are blowing coolant out the system.

 

Surely if this were the case the water would be blown out all the time.

 

Put a stock rad cap on it for starters is where i'd start

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Surely if this were the case the water would be blown out all the time.

 

Put a stock rad cap on it for starters is where i'd start

Nope, mine wasn't on the Supra (and on my old MR2 IIRC). Was blown out under high boost heavy load situations only. If the car was left stood coolant would "seep" back into the cylinder slowly so next time I started I would get A LOT of steam out the exhaust. Was fine under normal light driving conditions

 

Also I only suggested this as he said in OP he had just swapped cap for new TRD unit

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Easy way to tell if the hg has gone is fill the expansion bottle to the max line or abit higher and look in the expansion cap, open the throttle up by hand till it near the limiter, and let it go and watch to see if bubbles come through the water, if so it hg gone or going,

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Nope, mine wasn't on the Supra (and on my old MR2 IIRC). Was blown out under high boost heavy load situations only. If the car was left stood coolant would "seep" back into the cylinder slowly so next time I started I would get A LOT of steam out the exhaust. Was fine under normal light driving conditions

 

Also I only suggested this as he said in OP he had just swapped cap for new TRD unit

 

If you had seepage into the bore causing steam on startup, you must have had mayonaise in the oil too?

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i was just about to say ill get a sniff test done lol :)

 

Car was stood for around 3 months over winter and when started there wasnt an adverse amount of steam from the exhaust, just the usual amount i was expecting...

 

If the test comes back negative ill flush the coolant system and put new in, try to see if there is any airlock i suppose. Rad cap shouldnt be the problem as said there is a brand new trd cap on there.

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Easy way to tell if the hg has gone is fill the expansion bottle to the max line or abit higher and look in the expansion cap, open the throttle up by hand till it near the limiter, and let it go and watch to see if bubbles come through the water, if so it hg gone or going,

 

:( did this today and saw a few small bubbles everytime I let off the throttle.... car booked for sniff test tomorrow...

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  • 4 weeks later...

Sounds like Air lock to me. Bossco had the same issues when his car came back from motorscope as second turbie came in. Water temp would go upto 120 degrees.

Took me ages to find to narrow it down to an air lock.

I did a sniff test, Changed thermostat and water pump with no difference. Eventually put a massive alloy rad in and spend 3hrs bleeding it off and hey presto.

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Sounds like Air lock to me. Bossco had the same issues when his car came back from motorscope as second turbie came in. Water temp would go upto 120 degrees.

Took me ages to find to narrow it down to an air lock.

I did a sniff test, Changed thermostat and water pump with no difference. Eventually put a massive alloy rad in and spend 3hrs bleeding it off and hey presto.

 

Sounds like a plausible cause

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