STILL overheating, never been so frustrated in my life :(

Heyya

Long story here but i'll try to condence it somewhat.
My car has had overheating issues since I purchased it in May. It maintains a decent temp while idleing and just putting around town and other low speed stuff but on the freeway or up hills when the engine is under load the temp steadily rises. The most i've seen is around 108c. And this was when driving as gingerly as possible and never coming on boost to try to keep the temp from rising further. Strange thing is when I pull over to stop or I am coasting down hill the temp will slowly drop again. Also when I turn on the heater to max this seems to help quite alot and drops the temp as much as 5 or 10 degrees. I'll just list my mods and what i've done to try to fix the problem to make this as breif as possible.

My car has the following:
Custom 50ish mm copper/brass radiator
18in thermo fan + alum shroud
Pod filter
GB FMIC
Lower rad hard pipe

What i've tried:
Re-fit stock clutch fan
New water pump
New thermostat and no thermostat
Radiator rodded and cleaned
Tried stock radiator
Top radiator air guide
Custom bottom air guide
vented nose panel
Vented bonnet

I've just had the cooling system pressure tested and the guy said there appears to be no head gasked leaks etc, and the flow appears fine. He was as stumped as I am. He said it sounds like a flow problem but he can't find anything wrong.

About the only thing I have not done is have the block flushed, however when I had the radiator serviced it was already pretty much perfect inside so you would think the rest of the system would most likely be in a similarly clean condition.

I am considering getting a koyo since they seem to be very efficent and i'm sure this would certainly help but i'm not convinced it will fix the problem.

I apologise for the length of this post but i'm really out of options here and getting EXTREMELY frustrated with the car and can't seem to find any answers.

Kind regards
Ben

 

Is the thermo-fan operating on both speeds as per spec?

 

Honestly i'm not sure, however since my main problem is while at speed wouldn't the aux thermo not really have any affect anyway?

Ben

 

Was the

engine over heating before the fmic install?

 

Where are you getting your temperture reading from?

From what you have listed there I would give the dam thing away if it was still overheating. If the reading is not from datascan I would not trust it. Also, stock temp gauge moves from midway to hot when temp goes over 103C, if that is not happening it is a sure sign the device you are using to get your temp measurement is out.

 

Not sure, FMIC install co-incided with aftermarket temp gauge install. That's about all I have left to try is remove fmic and test again. But even if this fixes the problem then that's not right either, as many people are running them even with stock radiators with no dramas.

Also, while doing all this testing I was monitering temps with both datascan and aftermarket gauge so i'm confident the readings are accurate.

Ben

 

Is it using coolant ?? I had a simalar problem and had it checked out by the radiator guy , the presure test was fine and so was the C0 test . It still turned out to be a head gasket.
See if there is milky crap under your oil cap.

 

Test thermo-fan operation is ok

A FMIC may create an air-dam at speed, thermofan aids cooling by drawing more air through.

 

its a long shot but does the water circulate well through the system if you flush it out using the garden hose? i imagine if its blocked up you would hardly get any flowing back out

 

What's the around town temp? Is a UDP fitted?

 

No milky crap the I can see and dosen't seem to use any coolant.
I have noticed that some coolant that has sprayed when I opened the cap yesterday has dried to a white powder sorta stuff, is this normal?

Ben

 

Yeah flows good when i've flushed it out with a hose.

Ben

 

whats a udp

 

Thats Minerals form the water/coolant , it's normal.

 

No UDP fitted, and i'll go check thermo operation.

Ben

 

Under drive pully .
It will cause your fan and water pump to work less efficiently unless a over drive water pump pully is fitted to compensate.

 

I went for a short drive to the radiator place today, say about 10 mins, and temp got up to around 85. It's about 22c here today.
On saturday when it got to 108 it was actually a pretty cold overcast and at times rainy day.

 

Interesting read.

A hypothesis is an educated guess that must be proved or disproved. It is not a fact, nor even an opinion, professional or otherwise. My hypothesis is that many cases of cyclical overheating (temp gauge going up and down repeatedly while driving at fairly steady speed and incline) are caused by combustion gasses escaping the cylinders into the coolant through a flaw in the head gasket.
I believe it possible that these gasses heat and pressurize the coolant and possibly fill it with small gas bubbles, all of which reduces the ability of the coolant to carry heat to the radiator. The engine heats up. Once the pressure becomes too great, the combustion gasses are "burped" out the radiator cap and into the reservoir, at which time the coolant is once again able to carry heat so the engine cools. But the exhaust gasses are still transferring and building pressure in the coolant, so soon enough the process repeats itself.

Nor is cyclical overheat the only outcome of exhaust in the coolant. On some cars the pressure pushes out coolant rather than getting burped out, resulting in a coolant loss. Note that this can happen even in the absense of overheating. Exhaust gasses in the coolant are a documented cause of unexplained coolant loss at steady medium to high speed driving.

If the coolant loss is massive, the loss of coolant results in overheating. Many readers have written me saying they've had the thermostat, coolant and radiator replaced, and a pressure test indicates no leak, yet it's overheating. I advise those readers to check for combustion gasses in the coolant, as explained later.

 

After a quick read of the aux fan tech guide and a test looks like the fan operation might be suspect, but unlikly to be the source of my problem.
According to the guide it should only kick in at 105c with the a/c off, well mine didn't kick in at all.
However stays on with the A/c switched on.

I had to remove the fuse for my main thermo to get the temp this high.
With the main thermo active again though it cycles on and off and the temp remains steady at around 86c with the car stationary.

So Beaver, your suggesting a water test of some sort to check for combustion gasses?

Ben

 

Yes

thats what id be doing, since you have tried just about every thing else, it wont hurt! Fates car runs in an overheated condition just about all the time, maby he'd like to comment?