Diagnosing Overheating Issues

[greg]

... check the cat converter if its old and the engines new it might be a bit blocked or to small for the hair dryer.

The Cat is a second hand one from an exhaust shop - it's 2.25" straight through and claims to be a "high flow" model from a VL to VN commodore... i don't expect this to be the problem

[mkpatrol]

Sounds like rour thermo fan is ok. If it comes on about half way and the switches off when the temp comes back down. You may not be able to hear the fan at highway speeds even if it is working.
Do you know what temp it is actually running when it is hot?
Anything up to 105 degrees is acceptable if the system is pressurised properly. This leads to my next question, what is the radiator cap like?
A lot of small Japanese cars rely on the system to be pressurised otherwise they overheat. This may be the case with yours.
Also, your boost could be causing it as the computer may not be able to supply the correct fuel ratioo on the low setting.
set it back to 9psi if thats what it was.
Do you have the right coolant mix? The coolant will act to keep the teperature down if the mis is correct.
Is the thermostat new or near new?
I replace mine every year. When i was on the spanners this was the single biggest cause of overheating. Also some time the engine needs the thermostat to restrict flow to keep the coolant in the radiator longer to stop overheating.
Defitately clean your radiator, if there is any mud on the outside this will give you the symptoms you are getting. Also if the radiator is internally blocked it will give you the same problems.
Check the top & bottom hoses for kinks and soft spots. If there are any then the hoses might be sucking in while the system is pressurised and the waterpum is moving at high speed restricting flow. When the engine is running at lower rpm than on the highway then it will be ok, but as soon as you hit the faster speeds then there is a problem.
Check the system for air bubbles. There might be an air pocket in the heater which wont move but is restricting coolant flow around the engine (anythings possible)
Chack the fan belt, is it tight? They can slip without making a screeching noise.
Lats but not least, check the water pump impellers have not corroded away. This will reduce the effectiveness of the pump dramatically and may be only noiceable at high speeds.
At 100kph ther should be enough airflow to keep the thermofan off until the ambient air temp reaches more than 30-35 degrees. Even then it should not stay on permanently, it should cycle normally.

I hpe this helps. Always check the basics!!!!

Give me some more information and i may be able to give you some more help.

[RaginRover]

Pull the radiator out and get the core cleaned out. This will fix the getting hot while highway driving. Trust me this will fix the problem.

MMMMMkay ........

"Go and throw money at it before we spend a few hours diagnosing the problem"

Reading all this tech dribble isn't going to fix it but a $50 core flush might and it wouldn't do any harm anyway Otherwise check the cat converter if its old and the engines new it might be a bit blocked or to small for the hair dryer.

Love to be your mechanic .. you'd be putting my kids through uni with your trouble shooting skillz j/k another good thing to look at but I reckon racing out and spending $$ even $50 is a waste of time until you understand the problem and work through it step at a time then you will end up chasing your tail trying to fix things

Tom

[grimbo]

are you sure the temp gauge is working properly?

[greg]

are you sure the temp gauge is working properly?

Bingo - this could be another issue... The gauge is a sierra one, and the reading for it is coming from a Cap motor...

So no - not really - though i would expect that the fan would come on consistantly with the reading from the gauge (regardless of how inaccurate it is)...

[grimbo]

is the thermostat for the Cap or for the Sierra, you're just using the standard Sierra radiator aren't you? Maybe the difference in radiator could be affecting the thermostat?

[greg]

is the thermostat for the Cap or for the Sierra, you're just using the standard Sierra radiator aren't you? Maybe the difference in radiator could be affecting the thermostat?

Sierra Radiator
Cap Thermostat



Where does the temp gauge take its reading from?

[paultherocksta96]

Pull the radiator out and get the core cleaned out. This will fix the getting hot while highway driving. Trust me this will fix the problem.

MMMMMkay ........

"Go and throw money at it before we spend a few hours diagnosing the problem"

Reading all this tech dribble isn't going to fix it but a $50 core flush might and it wouldn't do any harm anyway Otherwise check the cat converter if its old and the engines new it might be a bit blocked or to small for the hair dryer.

Love to be your mechanic .. you'd be putting my kids through uni with your trouble shooting skillz j/k another good thing to look at but I reckon racing out and spending $$ even $50 is a waste of time until you understand the problem and work through it step at a time then you will end up chasing your tail trying to fix things

Tom

Your joking your not really a mechanic are, you your workshop must be full of pulled apart jobs spend all day talking about stuff.
This is only my 2cents worth. If you don't like it don't say nothing

[RaginRover]

Pull the radiator out and get the core cleaned out. This will fix the getting hot while highway driving. Trust me this will fix the problem.

MMMMMkay ........

"Go and throw money at it before we spend a few hours diagnosing the problem"

Reading all this tech dribble isn't going to fix it but a $50 core flush might and it wouldn't do any harm anyway Otherwise check the cat converter if its old and the engines new it might be a bit blocked or to small for the hair dryer.

Love to be your mechanic .. you'd be putting my kids through uni with your trouble shooting skillz j/k another good thing to look at but I reckon racing out and spending $$ even $50 is a waste of time until you understand the problem and work through it step at a time then you will end up chasing your tail trying to fix things

Tom

Your joking your not really a mechanic are, you your workshop must be full of pulled apart jobs spend all day talking about stuff.
This is only my 2cents worth. If you don't like it don't say nothing

No mate i am a server engineer for an major Aust company.
I was just saying look around and think things through. That works for me in IT and while fixing cars, besides I was only giving you a gentle ribbing ... hence the icon It will probably end up being the radiator then I will look like a di*k

Tom

Edit Damn spelling

[Area54]

is the thermostat for the Cap or for the Sierra, you're just using the standard Sierra radiator aren't you? Maybe the difference in radiator could be affecting the thermostat?

Sierra Radiator
Cap Thermostat



Where does the temp gauge take its reading from?

From the sender screwed into the thermostat housing, honestly if you don't know this motor inside and out after doing a conversion like this, seek advice for the heating problem.

[Guy]

Hey Gerg, I have an infra red thermometer you can borrow ... find out where the heat is and tell you the temp of any surface up to about 450c..

The point of the infra red thermometer is that you can see hot and cold areas in the motor and or radiator etc etc if the Rad is clogged internally it will shop up cooler than the surounding area's ...

[greg]

honestly if you don't know this motor inside and out after doing a conversion like this, seek advice for the heating problem.

Sorry - i though that was exactly what i was doing here

[grimbo]

Hey Gerg, I have an infra red thermometer you can borrow ... find out where the heat is and tell you the temp of any surface up to about 450c..

The point of the infra red thermometer is that you can see hot and cold areas in the motor and or radiator etc etc if the Rad is clogged internally it will shop up cooler than the surounding area's ...

cool just like Predator greg do it just for the cool factor of holding a gun like thing to your engine whilst standing in your driveway shouting "Don't move or the engine gets it" everytime someone walks past

[greg]

cool just like Predator greg do it just for the cool factor of holding a gun like thing to your engine whilst standing in your driveway shouting "Don't move or the engine gets it" everytime someone walks past

Yes grimbo - that would be funny wouldn't it




Okay - you've got me - once you said Predator - i was always going to agree to your idea

[zooki]

I had this problem on my zook when I changed to just a thermo fan. Turned out that not enough air is pushed through the radiator at highway speeds due to the large gaps either side of it (zook radiators are set back in the engine bay) I solved the problem by making up some shrouds to force all the air coming through the grille into the radiator. after this even on a hot day it would run cool

[grimbo]

So Greg did you ever fix this problem?

[greg]

So Greg did you ever fix this problem?

Yes. Melbourne stopped having days that were more than 30 degrees on the weekends - and so the car no longer overheated

No. Still working on it. Haven't driven it since i posted the message actually I'll adjust the boost back to stock tonight and then keep moving through the other tips.