Overheating Again!!! I'm over it!

[redandy3575]

Well where can i start............

Swapped over the radiator, put a new thermoclutch and fan in, new thermostat, flushed the entire cooling system, checked electrosysis & brand new coolant, all in all the problem still excist in overheating. Took it for a test drive, and within around 10 kms from leaving home on the freeway the temperature creeped up into the red.

First thoughts were maybe some air left in the system, so slowly released the pressure from the expansion tank with bubbles shooting out from the bottom hose even when the engine was off. Poured another 2 - 3 litres of coolant in after the remaining coolant got sucked back out of the expansion tank when the bubbling stopped, all was good then and temperature returned to normal. Continued driving with the right eye constantly on the temp gauge as we drove into a small town where the roads were a bit hilly and good test the cooling again.

Driving uphill the temp remain good with no signs of overheating. Then driving back out of the town downhill we speed up to around 100 km/h then shortly after the temp began to climp again. Before it had a chance to spike into the red, i pulled over and switched the engine off, hopped out and checked the coolant level, all was still good, but pressure did build up again with bubbles bubbling out of the bottom hose of the expansion tank. By this stage i was getting suspicious of the condition of the engine, had i blown the gasket?

Waited 10 to 15 mins then continued on, as the temp again climbed. I then put the transmission into neutral while on the move, and gave the engine a good rev, the temperature then slowly moderated again. I managed to limb the vehicle back home with the temperature being a little erratic until i pulled up in my driveway with the temperature back in the red.

Now trying to diagnose the symptoms, would you all say that 1.) the head gasket is leaking? 2.) possibly water pump failure 3.) Trapped air in the block? 4.) the ultimate, cylinder liner slipping with either a cracked head or block??

So far it's not looking good!

Got me a bit stumped.

[mtb_gary]

redandy

Is it possible that your temp gauge is reading incorrect, ie the sensor is stuffed? Especially since it started increasing on the downhill run.

Gary

[redandy3575]

redandy

Is it possible that your temp gauge is reading incorrect, ie the sensor is stuffed? Especially since it started increasing on the downhill run.

Gary

Thought about that. But also found when speeding up to 100kms it started overheating, and when i stopped, coolant was spewing out of the radiator cap under pressure. I just did a spark plug check, and noticed one of the plugs was hard to get out, though the plug itself did not indicate wetness, but the thread was corroded.

Can the heads crack in the spark plug threads? ( like in the VW Beetles?)

[TheTree]

Hi

I have the same madness going on and I am blaming the thermostat, I used a laser temp gauge and there was a big diff between top and bottom hoses when they should have been the same temp. New thermostat going in on Sat I would not trust one until it proves itself!

Also how long since your water pump was changed?

Steve

[daf11e]

Same issues and checked as Steve with the thermostat gun .....as said before third thermostat fixed the overheat issue...and redandy, is your pressure cap in good condition,I believe that original OEM is the best way to go.....just a thought?

[Keithy P38]

If the water pump is cactus, the coolant will boil, build up pressure in the system and spew out in a horrible way!

If it's the only thing you haven't done and are clutching at straws, that's where I'd be looking! As much of a P.I.A as it is!

Could also be the cap or thermostat (as mentioned above). Take your pick!

I remember the water pump going in my old red 6 in the Torana. I didn't run a thermostat in that motor so I popped open the radiator cap when the engine had cooled to check if there was flow with the engine running. Low and behold, my first water pump change!

Anyway, I'm just rambling now! I do hope you find the issue without much more headache!

Cheers
Keithy

[redandy3575]

Well i had the waterpump changed when the heads got done last year. I did put a new thermo in the other day, so you'd expect it to work.

Are these thermos really that unreliable Steve?

And the water pump, how quickly would they fail under normal circumstances? Bear in mind, mine was off the road for about 4 months, could it have corroded.

I'm so not hoping it's a cracked block.

[daf11e]

What about the pressure cap?

[LandyAndy]

Im not doubting your skills but its possible to fit a thermostat back to front,assuming its one you can simply replace,unless its like a D2 where its encased in the plastic hose union.
If its a free thermostat that you can simply replace(old school),drill a 6mm hole in its face plate,it eliminates air pockets that prevent it opening,especially if a leaky head gasket is introducing "air" into the coolant.
If it has the said D2 style thermostat,this advice is useless.
GOODLUCK
Andrew

[redandy3575]

What about the pressure cap?

Got that last week from British car components. The cap seems in good shape, a lot better than the old one and does what it should, that is release the pressure when high.

Come to think of it, i did notice the top of the radiator was not really hot, just warm.

[daf11e]

Redandy another check is to see if the hose from the radiator to the coolant tank is hot ( the thin one) if that's cold and the car heats either blockage or air.

[redandy3575]

Im not doubting your skills but its possible to fit a thermostat back to front,assuming its one you can simply replace,unless its like a D2 where its encased in the plastic hose union.
If its a free thermostat that you can simply replace(old school),drill a 6mm hole in its face plate,it eliminates air pockets that prevent it opening,especially if a leaky head gasket is introducing "air" into the coolant.
If it has the said D2 style thermostat,this advice is useless.
GOODLUCK
Andrew

Nah its a seperate thermo, outside the engine tucked behind the radiator. I did wonder that, but the hoses wont allow you to put it on the wrong way.

[redandy3575]

Redandy another check is to see if the hose from the radiator to the coolant tank is hot ( the thin one) if that's cold and the car heats either blockage or air.

I did check that and seems tempramental. It would be cool one moment, then quickly heat up.

It does sound to me the water pump.

Can air pockets potentially deztroy water pumps?

[daf11e]

If it's cool sometimes could have grime inside building up at times.....it'd pay to blow through it...I'd remove it at the coolant end as the radiator end is brittle and can break...you don't need another rad...doubt an airlock would wreck your pump that is I have not heard of it.

[Nomad9]

Hi redandy,
If you top the system up to a normal level and start the engine with the rad cap off if you get constant bubbling up through the coolant this would be an indicator for the head gasket, another check would be a compression test, all plugs out, foot to the boards spin the engine and record all the compression test results. Look for a duff cylinder or anything suspicious, pressure should be between 150 and 175 psi I think.
Thermostat in hot water with thermometer and check function of the thermostat.
Collapsed hose internal, delamination of the hose.

Maybe try some of that lot.

[Hoges]

A word of warning: Don't just remove the plugs etc. you need to remove specific fuses so that the ignition system is not energised. My understanding is that you can cause damage to the ECU letting the high tension leads fire off with no load..

[Gippslander]

One other thing which can cause overheating is a partially blocked exhaust system either a failed baffle in the muffler or some other obstruction. This is usually indicated by a gradual heating up of the engine during operation, you can check by having some one rev the engine up to about 2,000RPM whilst being at the end of the exhaust and listen for a hissing sound as the air is being forced out past the restriction or taking one of the thermo couples out and connect a manometer up to the exhaust to check pressure.

Gippy:) been caught before way back with an FC Holden.

[TheTree]

A word of warning: Don't just remove the plugs etc. you need to remove specific fuses so that the ignition system is not energised. My understanding is that you can cause damage to the ECU letting the high tension leads fire off with no load..

Hoges

You beat me to it!

Do not turn the engine over with the plugs disconnected, unless you want to replace your :censored:plug packs as well

Steve

[Nomad9]

Hi Hoges / Steve,
Thank you, forgot to mention that important little detail....

[wayneg]

Got that last week from British car components. The cap seems in good shape, a lot better than the old one and does what it should, that is release the pressure when high.

Come to think of it, i did notice the top of the radiator was not really hot, just warm.

I doubt its your problem but worth a mention as Myself and at least one other have had a new tank cap prove faulty. Mine does not seal 100% so the coolant system never pressurises properly. If the coolant does not pressurise the boiling point is much lower than it should be therefore although a boil over can occur its not in theory overheating if that makes sense. Mine also lost small amounts of coolant presumably through evaporation. If your top hose does not get hard after the thermostat has opened and stays hard for a good period when the engine is turned off you are losing pressure. I did an extended pressure test and the system is 100%. I then realised it was the cap. Now I know, I can hear it hissing with the pressure escaping. New genuine cap and tank to be picked up from the UK soon.

[benji]

I believe it's the coil packs that can be damaged. I just unplugged mine, and pulled out the fuel pump fuse. The motor won't wind over with the coil pack fuse pulled.
I believe 155psi is the figure for low compression motors.

Sent from my GT-I9305T using AULRO mobile app

[Rage Over]

I'm a little late to this thread but I just want to back up what a few other people have said with regards to the cap.

I just bought a brand new one when I pre-emptively overhauled my cooling system and it was dead on arrival. It just wouldn't hold much pressure and every so often spewed out my fresh coolant.

I put the old one back on and it's back to normal. Just something to check again, even if for the tenth time, to be sure. It can sometimes be the little things...