loosing coolant from expansion bottle / boiling over

Hi all

having a issue with loosing coolant , when driving hard the coolant boils over into the over expansion bottle and then spills over , this results in coolant lose and I have to keep topping up. I had a over heat issue last year and was down to the rad cap snapped so replaced the rad cap , only a euro car parts one 1.1 bar so its not that old.

Its crossed my mind that this could be a head gasket failure pressurising the system , the oils normal , coolant pinky orange , no smoke out the exhaust .

when taking the rad cap off and running the car from cold the coolant raises and starts to over flow within a minute with the thermostat closed .when the thermostat opens I can feel the bottom rad pipe get hot so know its opening.

whats peoples thoughts

What radiator do you have? Have seen similar happening with mishimoto rad before

Im currently dealing with coolant loss to. Im not over heating. Have made 2 trips from Northampton to Gatwick all fine. Oil is clean, coolant is clean. Done a dye test and nothing is showing up. Done the heat gasket block test and passed..done it with a cold engine...then hot..both passed. As soon as i put the tester to the exhaust pipe i get a change. So it works. Heating is fine in the car and footwell is dry. Water pump and housing were replaced and is not leaking. Im stumped. And no bubbling in the reservoir to...

I have a stock TT rad Mike. But the shroud broke at the top but it's only just started doing it and the should broke last year. I think I had this before some time ago with a rad cap when I first got the car so I might get a new Toyota one . As the £5 euro car parts one might not be up to it.

Evinx

How much coolest you loosing if I drive like a mad man for 15 minutes i recon I could loose a litre leaving a line of water out the over flow. But if I drive like a granny hardly any will go

Mines going down slowly every few weeks, after a couple of months i need to top up the rad maybe 1.5 to 2 litres. Might be different now as ive been busy ish. Not as much as yours though.

If your overheating it could be the thermostat is stuck? orrr check your expansion bottle with the pipe from the rad still in it, check for bubbling. If its bubbling its a BHG sign

Not over heating but would once enough coolant has disappeared.i thought the thermostat but can feel the bottom rad pipe get hot . Saying that though that was when stationary testing might not open when happens will check when . To be fair I'm going the cam belt soon so thermostat was getting changed may just do that with the rad cap to see

Bleed the system again in case of air lock..

Make sure to open the heater valves, parked on an incline to allow the coolant to flow down to the heater.

Is the cap the stock spec? The 1.3 bar caps cause such issues.

The broken shroud will definetly affect the performance of the fan. Maybe you didn't see the issue last year cause it was winter, isn't it summer over there now?

I had this in my TT Auto with stock, losing it slowly over time and the mechanic couldnt crack it, then the rad got damaged and forced me to replace it with another stocker and it went away. Not sure what knowledge you can glean from that but it sounds similar. It was needing a top up every 10 days to two weeks depending on mileage and if the lead foot came out.

its a 1.1 cap , im pretty sure its the cap gone /not holding decent pressure, its the only logical thing that would let it boil over into the over flow , plus was going to be doing the water pump, thermostat and cam belt soon so it will also rule them out

Pound to a penny its your rad cap that's causing the issue

I changed my rad cap for one of those with a pressure gauge built in on my most recent Supra, it lasted about a week. I'd say you're getting some good advice! Easy way to tell is spray a bit of WD40 around it before a journey and you'll get beading water if its going.

I changed my rad cap for one of those with a pressure gauge built in on my most recent Supra, it lasted about a week. I'd say you're getting some good advice! Easy way to tell is spray a bit of WD40 around it before a journey and you'll get beading water if its going.

Not if its failing internally which it sounds like this one is possibly doing

Good point but when mine failed the internal valve allowed it to leak slightly but it always appeared around the neck as its raised all round it seems to be the obvious path of least resistance but just saying what happened to me. Mine was rated to 1.3bar as well and my car was totally stock at the time too.

Update new radiator cap sorted this . Had a good run out to the ace cafe meet and back booting it . No coolest loss

Update new radiator cap sorted this . Had a good run out to the ace cafe meet and back booting it . No coolest loss

Wysłane z mojego SM-G950F przy użyciu Tapatalka

Was struggling to make it to toyota . So got a blue print one which a few said are good quality

Thanks

Wysłane z mojego SM-G950F przy użyciu Tapatalka

This thread has come at the right time for me. I have owned my bus from new in 1996 and always had the "Forlife" coolant in the cooling system, i have never had to add more than a quarter of a litre to the expansion tank just every few months.

So after 19 years of ownership i have an NAT Conversion, fantastic performance and no overheating or loss of coolant.

MY car has 42,000 on the clock and two weeks back i look in my expansion tank and it is empty? I filled it up , 1 litre or so and i start observing the exhaust gasses and even when hot i am pluming, so i know this is the hall marks of a failed head gasket.? The oil is ok, so if there is a break in the seal it is from the water gallery into one of the cylinders. I was mega pissed off so i added "K-Seal" it is the only product that can seal a head gasket and approved by the "AA". I am now waiting to see if it works?

I have managed to find a complete OEM gasket kit £130, most others are in the £230 mark, i am prepared to change the gasket but it is a big job and could involve the flatness test and then a skimming job, i am not sure if this can increase the compression pressure and put another strain on the replacement gasket?

Chris Wilson who i know quite well asks circa £1,500 to £2,000 for the job, but at least you will know it is right and guaranteed.

The whole thing puzzles me as the functional charachteristics on the gasket are the same IMHO pre and post NAT, the RPM, the running temperature and the cooling system? the only thing i would put into question , post NAT, is the under bonnet heat increase when you park the car after a quick blast? i have had to deal with the brake master cylinder overheating and the battery overheating, 3 new ones in 2 years, and more recently the starter relay, which has a temperature cut out inside it, the replacement relay does not have this and all is now ok, unfortunately this was after i had rebuilt the starter motor.

So i just put all this to the post NAT learning curve,BUT, it was OK for 2 years so fatigue must play a part? What do you guys think? Herbie.