Coolant overheating (keteling)

[GGilbert_MR2]

Mine did exactly the same, but i'd only done a 10 minute spirited drive and was datalogging it on the Laptop and it was showing temps of 135, which is extremely high imo.
The car even stalled the engine when i hit those temps, but fired back up again.

[JJ]

Mine did exactly the same, but i'd only done a 10 minute spirited drive and was datalogging it on the Laptop and it was showing temps of 135, which is extremely high imo.
The car even stalled the engine when i hit those temps, but fired back up again.

Gilbert, you sound like you've got other problems.

Bleed the system thoroughly first.....

Then check... Radiator... have you got any fins left in it...??! Look through the bumper and check....What normally happens though is a gradual increase in engine temps as the rad isn't being cooled... you'll also hear the rad fans working hard away !!

After checking the above, next thing you need to do is run the car from cold with the rad cap off... check to see if you're not getting a steady flow of bubbles appearing in the next... on the intial bleeding, its normal, but not after its been ran up and down temps a couple of times.

What sort of boost have you been running ??! Have you been experiencing misfires when you hit high boost ??

Check the expansion tank is correctly filled and dry the dump pipe.

If you drive the car off boost, is it reasonably fine.... ??!! Run the car with the heaters on, if you start kicking it and the heater goes cold after 10 mins , pull it up quickly .. early signs of the engine going to boil over... check to see if coolant is being pushed out of the expansion tank / dump tube....

[GGilbert_MR2]

currently running 1.8bar.
i get MAP cut because the temps are so high. no missfires

Driving the car off boost no problems at all.

Will use my new piece of kit when it arrived to bleed the system then give it a whirl. I'll be honest and say i've never heard the rad fans going, but i've spoke to a few others and they say the same...

[JJ]

Double check the bubbles rising in the filler neck whilst running....

You have ARP's fitted ? Steel HG ??

[GGilbert_MR2]

I get the odd bubble, but doesn't seem like there's much movement.

ARP's and Cometic HG.

[JJ]

Its looking like something else.. but I'm not going to say it yet....

Bleed the system correctly, check the expansion tank dump tube is dry, point it to the engine or something, take the car for a quick blast... +1.2 bar come back to see if theres been coolant thrown out.
The issues you've identified do suggest its related to boosting, unlikely for the head to lift....

[GGilbert_MR2]

not a cracked block is it?

[JJ]

not a cracked block is it?

Go see if its blowing out first.. also check to see if the rad / filler cap is seating correctly too, there can be a little corrosion on the valve seat and allowing it to push coolant out when its upto pressure.

It is showing symtoms though .. mine ran faultless, very sweet and fast as hell... apart from running hot after 20 mins of kicking @ 1.7 bar... I'd carry out several hard pull's, then pull up at lights... you would see the temps rise to mid 90's, but it wouldn't cool off, the heaters would go cold and then temps would shoot up..

I stripped my block.. couldn't see it at first, but there was a fine hairline crack...

[Steve-O 2007]

I think its normal, I did a 1 hour motor way drive and when I parked up I got a few gurgles (only lasted a few seconds). Water Temp guage sat at 90 deg all the time when running but when you shut the engine off it rises to 100 - 105 deg area as the water has stopped circulating. Im guessing this is what the gurgling sound is. As soon as you turn the engine back on it starts circulating and temp drops to below 90.

Gilbert, I dont think its a Radiator fan problem, My Fans Never used to come on and temp sat at 90deg, I now have the Rad fans on all the time and water temp still sits at 90deg. I think due to all the radiator pipe work / coolant in the MR2 the fans dont realy do much..

Mines did exaclty this last weekend on a long drive to Newquay. I was told over on the MR2oc.com that it is perfectly normal. It proper put the frightners on me when i saw the needle go up, but with in seconds it dropped back to just below halfway.

My Temp guage on the Dash / clocks doesnt rise past half way, Its my Aftermarket Water temp guage thats plumbed into the radiator pipe work that rises when you turn off.

135 deg sounds very hot. Thats like 40 - 45 Deg too hot

[GGilbert_MR2]

I agree its far too hot, hoping to try a few things tomorrow and hopefully its not a cracked block

[GGilbert_MR2]

Invested in a vacuum kit to see if i can sort this problem out. It appears that it has made a massive difference and on a reasonably spirited drive it was running between temps of 91 to 96 degrees ECT.
When it idled it climbed to 99, but didn'tgo any higher... so a darn sight better than climbing well into the hundreds.

Are the temps i have stated above normal or is it still too hot?
My ECU limit is set to 5000rpm's if ECT is 100 degrees, and noticed i was hitting the rev limiter at 6500 at temps of 95 degrees.
It should rev limit at 8000. Would it be wise to up it on the ECU??

[GGilbert_MR2]

Right...

This is becoming very frustrating!

I have now done the following:

New Thermostat
New ECT Sensor (ECU)
Re-torqued Head Bolts (1/4 of turn)
Emptied the coolent and vacuumed through as above.
Checked the Rad Fans are working

Still seeing temps between 96-99 degrees on the Data log. No longer seeing 135 degrees that i did at one point as per previous post. That was solved by draining the coolent and starting again.

Anything else i can do?
Sniffer test?
Could the head gasket of gone? any tell tale signs i can look for?

I havent discounted it could be a cracked block.

There is a tiny bit of oil dripping from the car as i could see a small bit when i left it on the road last night.

I'm getting to the stage where its getting sooo frustrating that i will probably break the car and sell the bits.

Please could anyone help?

TIA

[Tiamat]

When you have done the coolant bleed and refill you have done it with the heater matrix open and the back of the car jacked up haven't you? Failing to do so does cause a lot of problems.

[GGilbert_MR2]

When you have done the coolant bleed and refill you have done it with the heater matrix open and the back of the car jacked up haven't you? Failing to do so does cause a lot of problems.

Yes, Car was slightly elevated at the rear, but we used a vacuum system, so should be no more air blockages.

[Steve-O 2007]

how about a thermostat that opens at a lower temp?

[GGilbert_MR2]

how about a thermostat that opens at a lower temp?

Could do.... but reluctant to spend anymore money if its something more serious...

Anyone??

[RENOFOXX]

could be pipes from hell ??

[-:[KM]:-]

could be pipes from hell ??

He's not losing coolant...

[Steve-O 2007]

how about a thermostat that opens at a lower temp?

Could do.... but reluctant to spend anymore money if its something more serious...

Anyone??

Try running without the thermostat for a while and see if you still overheat??

[JJ]

This is baffelling...

Can't remember if I've mentioned this, check the rad for visable fins... as these cars age, the fins dissapear.. since the fins are used to created resistance for heat dissapation...

I had a honda years back that had half the fins missing, found continuous kicking, the temps began to rise, cooling fan rattling away... but due to 50% of the fins missing, the cooling wasn't effective enough.

I change my rad last year after consistant high temps sitting around 87 > 90 degrees just tootling about..... now I see a constant 82 > 84 deg.

The MR2 has a reasonably large rad, but the exposed area is only the lower 50% of it..

Temps should be between 82 and 86 degrees.

"Try running without the thermostat for a while and see if you still overheat??"

Steve, normal cooling systems would run okay without the stat in place ( overcool the engine), but with the MR2's / Celicas, theres a circulation valve on it which when the stat opens, shuts this circulation channel which forces all the hot coolant to goto the front to the rad. If the stat isn't it, the circulation channel is open and the block with overheat ( excessive kettling ) when the engine is switched off.

Purpose of this is to yield a quicker warm up... thats why its important to fit the correct length stat in these engines...