Ideas please - Slow overheating issue - 2JZGTE

[sbyder]

You cant mount the thermostat in reverse as it fouls on the pipe mount, but you make a very good point that i will try and explain. The issue with the thermostat staying shut is that the cold coolant passes through the thermostat opening causing it to shut, then the coolant being bypassed around the engine tries to open it again, only to be put off by the cold coolant causing it to shut again. Its a cruel circle, but since ive drilled a few holes into the outside of the thermostat, it allows the coolant to pass through even when the thermostat is shut, which eventually leads to all the coolant getting hot enough for the thermostat to open. The only problem with this set-up is that it takes a while for the engine to warm up. Hope that makes sense.

The 16" thermo isnt shrouded, but that shoudnt matter as its just aiding the engine fan by directing air flow into the condenser/radiator.

Heres a pic, please dont mock the crappy looking shroud I made. I couldnt find any decent size alloy at the time.



Cheers
Ben

[thechuckster]

fins in radiator blockedbent?

flushing will not clear channels that are blocked with corrosion - unless you take the tanks off, no about of flushing the system will confirm that the rad flows well.

low speed and slow heat-soaking does suggest radiator is simply unable to get rid of heat with the fans only.

or the thermo fan out front is running backwards making the airflow thru the rad at low speed particularly shit.

[sbyder]

no mate, its a new radiator and the thermo is going the right way.

[Kyosho]

New aftermarket? Or OEM replacement?

Did you replace radiator and then get this problem?

[IN 05 NT]

might be stupid. but have you got a RETURN type rad cap?

[sbyder]

I replaced the OEM radiator with the aftermarket unit as i though the old one was clogged causing the overheating issues. Obviously it wasnt the cause.

I have a normal radiator cap which seals until the appropriate pressure then releases to the overflow.

[Kyosho]

Once the car sits and cools, does it suck the coolant back from the over flow bottle?

[sbyder]

actually, once it gets up to 100° it doesnt return below 98° until i switch her off no matter what rpm or vehicle speed.

I recon im screwed. Gotta get this bloody dye test done to save me a headache!

Ben

[Kyosho]

Yes, but once switched off, and cooling, does it suck the coolant back in?

Or are you continuously topping up coolant?

Checked your oil lately?

[sbyder]

yes it will suck the coolant back in after a few hours. I dont really have to top up at all.

Oil is perfect. and no smoke.... so very strange.

[brett_celicacoupe]

check the accuracy of the gauge with a infared heat gun



that said, my 2jz temp rises above normal after about 10secs of full boost/WOT

[sbyder]

the gauge works. It wouldnt piss out fluid unless it was overheating, lol.

[wa5]

what happens when your heater is running full blast, does the car still over heat?

[The Real Roadrunner]

thought about changing everything back to std?
if you put decent cond parts back in and put the entire cooling system back to factory i dare say your problem will go away,
then start fitting all the modded stuff again to figure out what part isn't doing its job or just leave it the way millions of $$$ worth of R&D had proved works.

the only cars ive had problems with overheating have either had dud factory components or somebody had modified the cooling circuits coz they believed it was a good mod (which makes me wonder why the factory engineers didn't think of it?)

cheers
linden

[sbyder]

i totally agree. I wouldnt have converted to aftermarket parts if the OEM parts didnt fail.

I have converted every aftermarket bit onto the car peice by peice trying to solve the issue. 1st radiator, then thermostat, then fan, then bypass... etc... etc...

I have a very bad feeling its a head gasket. Find out tonight when i do the dye test.