overheating vt everything has been replaced and still overheats ??

[JakeysVT]

OK major issue guys and it is also as you imagine quite annoying,
i have replaced..
- water pump
- radiator
- thermostat

Things i have done..
- Coolant flush
- bleed system
- check all water levels
- checked fans, both working

and it will be fine for months on end then will start overheating again, then sometimes it doesnt even last 20mins

Please Help

[acarmody]

Got the system pressure tested yet?

[Krisp]

could be intake or head gaskets

[JakeysVT]

yes i have had the engine pressure tested and it all checked out,
Krisp what do you mean by it could be the intake ?

[pablo]

How do you know it's over heating? Can you hear it boiling? If you are going by the dash gauge, perhaps its showing incorrect readings intermittently through an electrical fault.

[PRAVX II S]

OK major issue guys and it is also as you imagine quite annoying,
i have replaced..
- water pump
- radiator
- thermostat

Things i have done..
- Coolant flush
- bleed system
- check all water levels
- checked fans, both working

and it will be fine for months on end then will start overheating again, then sometimes it doesnt even last 20mins

Please Help

Does the thermo fan cut in? Check the coolant temp sensor.\
Check with a thermometer how hot it gets.

[Full Spectrum]

Inlet manifold gasket ?. Faulty sensors. Maybe check your cars temp as you drive, if it's plenty past 100deg like 110 upwards somethings wrong. if not and it's about normal 90-104deg something else is faulty in reading it.

[bogan_vk]

have you felt along the cores of the radiator for hot and cold spots indicating blocked cores in the radiator.

[Killr6]

if you have replaced most things that could be the issue and you have had it pressure tested im going to go with the sensor

[lout]

is the car overheating or is something telling you it has overheated
if it is overheating how about thermo fans or fan relays

[JakeysVT]

see thats the thing, when i open the bonnet it doesnt appear to be any hotter than normal operation, should i be able to feel a difference in temp ( i know its a stupid question but thought id ask ) yes the fans do turn on, and normally it sits at about 94 degrees, and what do you mean by inlet manifold gasket ? like right where it connects to the block ? or up higher near the plenum ? i can hear it boil, but the car is telling me it is overheating,, how can i check it manually ?

[JakeysVT]

also the oil isnt a milky colour if that helps diagnose the issue :S

[Huntington]

check your coolant when cold, does it have that rainbowy oily look, if so head gasket is my bet.

[JakeysVT]

hi huntington, i checked it this afternoon while it was cold, and the coolant isnt a rainbowy oil look, and its not slippery like oil when rubbed on fingers

[pablo]

If the coolant is actually boiling, you will see water vapour violently spraying from the over flow pipe (just beneath the radiator cap) if you remove it.

[machone]

its the same with most cars

first thing to look for.... are you losing water? if so with no apparent external leaks...then id say head gasket/ inlet manifold gasket or heater

if the radiator is cold and the reservoir is boiling hot maybe a collapsed thermostat (new ones can still collapse you should always check a thermo before putting a new one in your car boil up some water)/ blocked core in the radiator /blocked or bent radiator hoses heater hoses faulty heater tap...when your car is hot is there heat coming from your heater?

when you flushed your radiator did you refill it back up slowly it could have an airlock

if you had it pressure tested who tested it? if its a radiator guy he should be able to tell you what the problem is.

i dont think it will be sensor if the gauge is reading hot and you can hear the water boil

feel around the radiator and hoses if anywhere its cold id say there would be your blockage but dont burn yourself.

but id take it someone because the alloys dont like the heat to much.


and dont take out your thermostat out it needs back pressure to circulate properly and your car will be running colder than it should your comp will be thinking its running colder

[machone]

and whoops or faulty water pump

[JakeysVT]

so if i remove the coolant overflow hose it will be violently spraying out, and if its not boiling should it be slowliy cmming out or not comming out at all ?
Machone,,
i Have refilled it slowly so there SHOULDNT be an airlock, will have to test the new thermostat to see if its collapsed,
the radiator is brand new so it cant be the radiator, although when i feel across it once it heats up there are no significant changes across it (blockages)
the heater has been disconnected when i got the car, so it may have a heater leak but it has been bypassed,
the guy who pressure tested it said that it was fine,
and the water pump is brand new also,
Sounds like a stupid question but how can the inlet manifold gasket cause the car to lose water ? just out of curiosityy

[])R@G()N]

the radiator is brand new so it cant be the radiator,

did it come with a new radiator cap or did you use the old one ??

only reason I ask is when I got my new radiator it didn't come with a new cap, So if your still using your old cap it can cores over heating problems


Another thing to have a look at is your spark plugs take them all out and see if any are a different colour\condition, If you have one a different colour you could have a stuffed headgasket leaking water into the cylinder

[Dayvo]

Try hooking up an aftermarket temp gauge and see what the reading is . as said in other posts ,could be the temp sensor or gauge thats faulty .

[JakeysVT]

hey dragon i forgot to mention i got a new radiator cap about 3 months ago, i havent checked the spark plugs and to be honest it hasn't even crossed my mind, will definately do that tomorrow morning is there a particular colour i should be expecting if it is the head gasked ? will it be a rusty sorta colour ?,
hi dayvo do you know anywhere where i can buy a aftermaket temp gauge to check itt ?

[machone]

most of the time the inlet manifold gasket lets the V6 engines down water gets into the end cylinders on the early V6, and the VT and on water can leak into any intake port...but if it was the inlet you would or should notice water in the oil...also your engine car might be tapping... while the car is cold just undo your oil cap check to see if there is a milky sludge under the cap....as for the overflow no mate it should not be coming out...its building up pressure if it is ...i still think there is a blockage somewhere ...the heater by pass is a worry look around where its been bypassed as well make sure all the hoses are straight or have slight bends not sharp angles.....to check your thermostat....Remove the radiator cap when the car is cold ...check your coolant level as your engine starts to warm up.... There should be a drop in the level of coolant....If the coolant levels remain constant and doesnt drop, then there’s a high chance that your thermostat is stuck in the closed position which is causing your blockage.... or another way to check is put the radiator cap back on let the car warm up dont let it overheat now carefully without burning yourself touch the topmost radiator hose to check for its temperature. Is it warm? Is it starting to get too hot?... Now go to your lower radiator hose.... Feel the lower radiator hose. Is it warmer than the up most hose? or Is it still cold?...normally your bottom radiator hose should be hotter than the top if the bottom is cold and the top is hot 10 bucks says its a thermostat....you said you have replaced the pump so i doubt it could be the vanes worn out inside the pump.....hope that might help a bit.

[lout]

just replace your temp sensor as a cheap diagnostic (compared to what you have already spent)

[Brett_jjj]

normally your bottom radiator hose should be hotter than the top if the bottom is cold and the top is hot 10 bucks says its a thermostat....you said you have replaced the pump so i doubt it could be the vanes worn out inside the pump.....hope that might help a bit.

Thats not right.The top radiator hose should be hotter then the bottom hose,the bottom hose will be cooler as the coolant going into the bottom hose has already been through the radiator.The hot coolant comes out of the top of the engine, through the top radiator hose, and then into the radiator,so the top hose should be hotter then the bottom one..If the thermostat is jammed shut,then neither of the hoses will feel hot because if the thermostat is jammed shut,it stops the hot coolant from coming out of then engine ..

[JakeysVT]

hey guys, thanks heaps for all your help will check all of those things this weekend (spark plugs, overflow, thermostat, temp sensor, and manifold gasket), and i will let you know how it all goes
thanks again for your help its much appreciated