VT cooling issues

[sweetchilliphilly]

Hey guys,
I own a 2000 manual VT S-pack v6 that keeps driving me up the wall with a recent overheating issue, it has been a great car up until now.

The temp gauge will get to its normal temperature and then shoot up to the max for about a minute and then go back down again.
The car runs fine, my oil isn't discolored and it blows absolutely no smoke.
I've already replaced my thermostat, water pump, radiator and radiator cap. I even flushed the system. The problem went away for 3 days after replacing the radiator and then came back again.
There are no visible coolant leaks anywhere. And I've made sure to bleed the system of air every time i put coolant in it, however I may not being doing it correctly.
Is it possible my intake manifold gaskets require replacing and is there anyway to check?

I just cannot figure out what it is. Any help/ideas are appreciated.

Cheers!

 

[billythakid]

Sounds like a Dodgy coolant temp sensor , look for the electrical plug on the bottom of the thermostat housing
If the brown sludgey looking coolant appears it's the intake gaskets , usually the have pools of oil on top of the intake manifold under the throttle body etc

 

[Turtl3]

For the temp to be spiking like that on the gauge its either an air pocket in the cooling system, or a faulty sensor

 

[sweetchilliphilly]

Thanks guys! I just re-bled the system and its running at normal again, but for how long is anyone's guess!

 

[sweetchilliphilly]

Just did it again today, this is just what I need before christmas!

 

[billythakid]

Just did it again today, this is just what I need before christmas!

Did you have the heater on when bleeding ? Is it loosing any coolant ?
Coolant temp sensor still sounds like your issue

 

[sweetchilliphilly]

Yeah I have the heater on whilst bleeding, and it has lost a bit of coolant, my brother noted that my exhaust smelt rather strange, as if it was running on e85 which makes me believe its burning the coolant afterall.

 

[billythakid]

Could be a sticking thermostat even though it's new , usually the lim gaskets don't overheat the car in a day or 2 , usually build up of gunk under rad cap kills the seal and it can't hold pressure or draw it back from overflow bottle when cooling . I drove mine for 4 hrs from bris > nsw border and back in one trip doing a airport drop . Never got hot or moved on the gauge . The LIM gaskets were shot but was booked in the mechs following week to be done .

Check the cap is 135kpa/20psi and the overflow hose is not split / loose or blocked .
Hold the mode and up button then start car and let them go , flip through to temp and see what it's doing next drive ( they can go up to 104 deg and drop again but usually sit at 91-95 deg when at running temps with thermostat opened
Other option is a rad shop pressure test and they may pick up what's going on

 

[devilly]

if it has lost coolant at night time with a torch go over car looking for the leak source as this may be letting air into your system.

 

[sweetchilliphilly]

Ended up pulling the heads off. Both gaskets were blown. Time to save up for the heads to be reco'd.