Any mechanics out there? Help.....please!

[redtamada]

I have a VT wagon on LPG. The problem all started on a hot day about 2 months ago when I parked the car and turned it off. I could hear a bubbling noise coming from under the bonnet. My next stop and it did the same thing, only this time when I returned it had dumped about a litre of fluid on the ground. Flushed the radiator myself and replaced the thermostat and topped up with some new coolant, but did not bleed the system properly.

The car ran perfectly for about 3 days and I thought it was fixed. Took it to work one cold morning and got about 10 minutes down the road and the car overheated. I pulled over and let it cool down, continued to drive it and the temp gauge stayed down but the car was making a discrete creaking and rattling under acceleration and it died on me at the next set of lights. The RAA came and it had overheated once more (stupid to keep driving I know).

The car got towed to a radiator joint which ended up replacing the radiator, cap and all hoses. I drove the car home (about 45 minutes up-hill) and it was fine. Since then I have replaced thermostat again and bled the system numerous times. There are no visible leaks under pressure and the waterpump is only 4 months old. The oil appears to be ticketyboo. Once I bleed the system it is usually ok for a day or so, then I need to bleed the system and top up the coolant again. The car has recently been struggling to start the last 5 days on petrol and has backfired twice dislodging the vaccum hose under the throttle body (not sure if related or just a horrible coincedence). It is possible this hose was dislodged prior to the first initial backfire though.

The car is reaching about 119c and cooling to about 105c soon after, however the night after a bleed she sits just under the 95c mark but gradually overheats more often in the coming days. Is it possible there is still an airlock in the system or does it appear to be a dreaded head gasket? I have searched here and read hundreds of threads but none that help specifically. What other things can I do to rule out and identify the culprit? Any help would be greatly appreciated, cheers.

 

[Boonz]

run it with the radiator cap off and check for bubbles appearing quickly.... the amount of times you have overheated it i think its safe to say that its a headgasket or intake manifold gasket thats blown out....

 

[redtamada]

Only slight bubbles for a second or two then nothing, car has only been truly overheated once. All other times is only around the 119c mark which others have told me is not a huge problem as long as there is cooland in the block.

 

[adamc11]

i had a problem with my old nissan pulsar...
... i noticed the coolant water was all rusty so had it all flushed out, took me ages there was so much bloody rust, anyways, afterwards started overheating (i bled it myself and i had it professionally bled too) and then started having problems starting and running. Turns out it was the head gasket. And this all happened after i flushed it out. Would probably have happened eventually though, but i did speed up the process =(.

Check your engine oil cap, is there any white froth on it? What about your radiator water, was it rusty? All signs of a blown head gasket.

 

[pablo]

Get the cooling system pressure tested to determine if there are any internal hidden leaks. Most competent mechanics should have the simple equipment to check this.

Pablo

 

[KRUPTD]

You must have a blocked heater core,very similar symptoms as you described,try flushing out just the heater core through the heater core pipes.Have experienced this on some customers cars,also if the heater is blocked you will never be able to bleed the cooling system properly.As for the gas backfiring,i would clean the throttle body and gas throttle body and check your spark plugs,remember on gas the spark plug gap has to be 10% smaller than petrol so close the gap up alittle.

 

[Not_An_Abba_Fan]

The ecotec doesn't like being overheated, they warp pistons. Does it rattle when you rev it?

The coolant issue would most likely be an inlet manifold gasket, they are very common to leak.

 

[lout]

Try fitting a new radiator cap
Mine pressure tested ok but radiator was always down an inch or two even though coolant recovery was full

 

[redtamada]

Just a quick update, radiator cap is new also, still no signs of any dodgy oil....Just bled the system again but noticed the thermostat did not open until just over 100c once thermo opened I bled small amount of air out. I assume air will stop the thermostat opening at correct temp. Why is it that other than taking a little while to warm up the car seems to run sweet without the thermostat? Keeping in mind this is my third one and it is a genuine holden part.

 

[adamc11]

Just a quick update, radiator cap is new also, still no signs of any dodgy oil....Just bled the system again but noticed the thermostat did not open until just over 100c once thermo opened I bled small amount of air out. I assume air will stop the thermostat opening at correct temp. Why is it that other than taking a little while to warm up the car seems to run sweet without the thermostat? Keeping in mind this is my third one and it is a genuine holden part.

My nissan pulsar, as mentioned above, overheated as the head gasket was gone. WITHOUT the thermostat it worked a treat, no overheating. As mentioned maybe you have done your head gasket? Edit: It could be though that you havn't bled the system right, as it is harder to bleed with a thermostat. Also on my nissan pulsar there was a certain way the thermostat was supposed to be inserted... have a look for an arrow showing which way is up.

Also, you could try bleeding the system like i did with my pulsar... I'd assume the process is the same for any car though.
You should get a large coke bottle and cut the bottom of it off. Then place the top of it into the radiator and half fill it with water; basically you have made a funnel. Then run the car and when you do this you may see air pockets come up through the bottle. The level of the water will drop, so make sure it is topped up half way all the time (have a hose handy). But don't fill it too much as the water level will rise when the water temp increases. Be careful, the bottle may warp as well; i would suddgest holding it with a wet rag as it will get hot too. Anyways, squeeze both of the radiator pipes as well to help remove excess air pockets. Once this is done and you hear the fans turn on (which means hopefully the thermostat has opened) then you should be all done. Another way to test that the thermostat is openeded is to make sure both radiator pipes (inlet and outlet) are hot. If only 1 is hot, then the thermostat hasn't opened and the water isn't circulating. Once it is all done, turn the car off with the bottle still ontop of the radiator, as the radiator may suck a bit off water back. Also use the hose to make sure the bottle has water when ur doing this..
On my pulsar there was also a bleed screw for the cooling system... it was just above the thermostat (essentially the highest part of the coolling system), and to bleed the system i removed this screw and pushed water with a hose through the top of the radiator until a constant stream of water came out of the bleed screw. I then re-fittred the screw while a constant stream was coming out. Maybe have a look to see if there is a bleed screw on your car? Check your manual.

Edit: when the car is running make sure the heater is on and set to the re-circulating setting. If you feel hot air as usual it means water is circulating through the heater core. If it isn't hot air, then it means there is a blockage in the heater core or the system hasn't been bled properly.