VS overheating with new thermostat
VS Calais (V6) was overheating with coolant levels full and no leaks. I bought a new thermostat (correct one) with a gasket, reassembled spring facing engine, refilled coolant levels. Engine still overheats with coolant spewing out of expansion bottle??????????
Any ideas???????
Donating Member
Bad radiator cap - this allows the coolant to dump straight into the overflow tank as soon as it heats up - new ones are cheap.
bought a new cap this arvo, bleed the air out of the system which included topping up the coolant levels. I took it for a drive and again the temp went through the roof and when i pulled up the coolant was boiling over the expansion tank????
Are your radiator fan(s) working?
Donating Member
It's starting to look like a blown head or inlet manifold gasket - did you by any chance run her dry before all this started? Either that or your radiator is blocked internally. Is the car missing or running rough?
You can usually tell if it's a head gasket gone by the oily residue left on the radiator cap or run the engine with the cap off and see if any bubbles come up (do this with a cold engine otherwise you'll get burnt!)
yeah rdiator fan comes on about half way on the temp gauge. Nah the car wasnt run dry, just boils over when i do any driving. there isn't any residue under the cap but a couple of bubbles come up out of the radiator when the car is running. Im starting to think that maybe the thermostat isnt opening and letting coolant into the intake manifold. I might pull the housing off and see if there is any coolant under the thermostat
Donating Member
If the top radiator hose gets hot, that will prove that the thermostat is opening....if it's cold then it's not opening.
The bubbles in the coolant are not a good sign.....should be absolutely no bubbles unless the system has not been properly bled.
There should already be coolant under the thermostat,the coolant flows out the top hose to the radiator once the thermostat has opened.Unless theres an air lock under it(which would go through anyway once the thermostat was open).Feel the top hose ,if its hot ,the thermostat is working.Also check the bottom hose for collapsing(sucking in) when the engine is revved.
could be electrolysis. get it tested. i used to have a vs v6, apparently its common.
I whent through 3 radiators in 4 months.
Sounds like a either blocked radiator (and it doesn't have to be fully blocked for the car to overheat) or either a head gasket problem
When you replaced the thermostat and bled the system did you turn the heater onto full hot to make sure ther eis no air in the heater core? There may still be some air in the system you have to make sure you get it all out. If that doesn't fix it take the thermostat out and test it in a container of water you can bring up past it's opening temp and see if it's working.
My workin on the car face
sounds like a blocked radiator. I went though the same thing with my old VC 308. Flushed the rad, still overheated. new rad cap, still overheated. replaced the coolant, still overheated, switched to thermo fans, still overheated. REPLACED THE WATER PUMP STILL OVERHEATED. Then i noticed the rad was rusted and in poor nic, so i replaced it. BAM ran nice n cool. Nicey nice
Originally Posted by <TVR-161>
What does the coolant look like?Is it muddy looking or clean.
Last edited by Brett_jjj; 10-01-2010 at 11:13 AM.
You sure you put the thermo in facing the right way, mine wasn't facing the right "direction" when i replaced it and was overheating.
yeah i checked the rad, no rust and def not blocked. The thermostat is the spring side inserted into the block, engine side. the coolant is a bright green, no muck or oily residue. I will test the thermostat but im sure it'll be fine cause its the second one ive bought in a week.
Did you check the bottom radiator hose for collapsing (sucking in)when the engine is revved?
this morning i emptied the engine, radiator of all coolant. put all the hoses back together, filled the engine will coolant straight into the block through the thermostat recess, put the thermostat back in place (spring side down), hose connected, filled the radiator, bled the air out, started car checked for leaks (none) then went for a drive with the heater on and after about 20 mins the temp eventually got to 3/4 so i headed for home and by the time i got into the garage and popped the hood there was coolant spewing out of the new rad cap and expansion tank
It sounds like it might be a blown head gasket or inlet manifold gasket.And you dont always get coolant mixed with oil when this happens,so sometimes theres no white milky crap under the oil cap.I'd be getting the cooling system pressure tested.And also get the engine compression tested.These tests will show if anything major is up and they dont cost much to get done.
Last edited by Brett_jjj; 10-01-2010 at 01:09 PM.
hi i had a very similar problen try cutting a 1.25 coke bottle bottom off and ues it like a funnel you might need to wrap some tape around the opening of the coke so it fits perfect fill the radiator through the coke bottle and fill the bottle till its about 2 inches from the top start the car and you should see the bubbles once they stop it should be right give it a go atleast it dosent cost anything to try
No i mean rotate it in the hole. For example i turned mine about 30 degrees CCW and it fixed my overheating problems.
Gave up on VL's
How about removing the thermostat? This time of year I am sure it is not needed all that much, or this cannot be done on VR / VS?
If nothing is blocked, then the water pump maybe the problem, maybe the blades/fins are corroded?
These engines need to reach a certain operating temperature,removing the thermostat will make the engine run dead cold,which is not good.The ECU will think the engine is cold and make it run rich.Years ago you could get away with it,but not with engine management controlled engines.Although you can remove it just to get yourself out of trouble if its stuffed and not opening.How about removing the thermostat? This time of year I am sure it is not needed all that much, or this cannot be done on VR / VS?
Reyon,Id be getting the tests done I mentioned previously if you dont do any good with bleeding the system.Ive never had any trouble bleeding them,Just fill em up and thats it.Maybe loosen the bleed screw a bit.But most of the time you dont have to worry about it.Just recheck the coolant level after it has been going and has cooled down.Also you never said if you checked the bottom hose for collapsing when the engine is revving.The water pump can suck the bottom hose shut if the hose is a bit old or perished which blocks the flow.Sometimes they have a spring inside the hose to stop this happening,but some have no spring.
Last edited by Brett_jjj; 10-01-2010 at 03:25 PM.
the bottom hose is ok under reving. a couple of "mates" said the water pump might be gone
Usually the pump will be making a noise if its stuffed.Or leaking coolant..Can you see the coolant moving around (flowing)when the radiator cap is removed with the engine idling?
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