2003 VY 3.8 constant spike in temperature

[jays2]

Help please.

Cooling system pressure test = slowly losing pressure.

Can't find any leaks or hissing noises.

Engine compression test is constant 150 at operating temperature.

New MACE inlet manifold gasket, new thermostat.

When trying to bleed, it has occasional bubble coming up through the Coolant Refill Funnel, then leave it idling for 15 mins and it suddenly boils.

270,000 km

 

[Immortality]

Sounds like you still have an air lock, make sure you have the heater on full hot when bleeding the cooling system. Use the bleed screw on top of the thermostat housing to let air of system.

Loss of pressure might the radiator cap.

 

[jays2]

Sounds like you still have an air lock, make sure you have the heater on full hot when bleeding the cooling system. Use the bleed screw on top of the thermostat housing to let air of system.

Loss of pressure might the radiator cap.

Thanks for your reply. Heater is on full. Still working on bleeding the system. There seems to be an occasional air bubble coming up thru the funnel.

Will take it for a test run & see how it goes. Then maybe bleed again

 

[krusing]

When filling the system, or bleeding it,
Use a head of water to fill it, that should help discharge the air in the system.
(ie: 2L Orange Juice container with the bottom cut off, tip it upside down on the radiator inlet, and fill with water, and open the bleed screw/s]
(Works on my L67 and that is normally a PITA to bleed)

Also as mentioned above ^^^^, Radiator cap is common cause of loss of coolant.

Could also be the radiator is weeping on the bottom of the cores, or on the tanks.

 

[Immortality]

For the ecotec my normal is to drill a small hole (2mm) in the thermostat body to help get the air out when the thermostat is closed. There is a bleed hole in the thermostat housing but these can become blocked with time/age.

 

[jays2]

For the ecotec my normal is to drill a small hole (2mm) in the thermostat body to help get the air out when the thermostat is closed. There is a bleed hole in the thermostat housing but these can become blocked with time/age.

Yep. Already did this. Ran a 2mm drill bit thru the hole. Made sure it was clean. Didn't use any silicon or gasket goo. New thermostat & refitted housing after resurfacing the base

 

[jays2]

When filling the system, or bleeding it,
Use a head of water to fill it, that should help discharge the air in the system.
(ie: 2L Orange Juice container with the bottom cut off, tip it upside down on the radiator inlet, and fill with water, and open the bleed screw/s]
(Works on my L67 and that is normally a PITA to bleed)

Also as mentioned above ^^^^, Radiator cap is common cause of loss of coolant.

Could also be the radiator is weeping on the bottom of the cores, or on the tanks.

Yes. Bought one of those u beaut Coolant Refill Funnel Kits - does a good job. Bleed screws were opened.

Had a good look at the radiator , didn't seem to be weeping.
Will try a different radiator cap.
Thanks for your help

 

[Fu Manchu]

It suddenly “boils” when the thermostat opens and trapped air is released. It can be quite violent. You don’t want it to drop to empty so have a premix ready to top it up.

100% normal.

 

[jays2]

It suddenly “boils” when the thermostat opens and trapped air is released. It can be quite violent. You don’t want it to drop to empty so have a premix ready to top it up.

100% normal.

It suddenly “boils” when the thermostat opens and trapped air is released. It can be quite violent. You don’t want it to drop to empty so have a premix ready to top it up.

100% normal.

Okay. Thanks for this info. Good to know it's completely normal when bleeding.
Any idea why the gauge on the radiator pressure tester slowly goes down ?

Sorry, I should have explained the original problem why I've done all the work on it so far. It was getting hot & spiking in temperature whilst driving. Doesn't do it every time I drive it, just intermittently.

Seemed to be a little bit of brown oily substance in the radiator water, so went straight for the LIM gasket.

Then new thermostat, new radiator cap & now at the stage of bleeding it to test drive.

All tips greatly appreciated.

 

[Immortality]

Yes. Bought one of those u beaut Coolant Refill Funnel Kits - does a good job. Bleed screws were opened.

Had a good look at the radiator , didn't seem to be weeping.
Will try a different radiator cap.
Thanks for your help

If you have one of those you should be able to bleed most of the air out before starting the engine (except any in the heater circuit).

With the bucket fitted, I open the bleed screw and keep adding water/coolant until only coolant is coming from the bleed screw, then start the engine and keep adding coolant to the bucket so it's about a 1/3rd to 1/2 full. Occasionally crack the bleed screw to get any air out from the heater circuit. You'll know when the thermostat opens as the coolant level in the bucket will suddenly drop (and the top radiator hose should get hot), keep the level to about a 1/3rd full. As everything comes up to temp the coolant level will rise again in the bucket. When it stops bubbling turn off the engine and allow things to cool down. Then remove the bucket, fit the radiator cap and ensure the expansion tank is full. Run the engine and it should pressurise as normal as it warms up. Any remaining air in the system should accumulate at the top of the radiator and get pushed out to the expansion tank as the system heats up and pressurises and as long as there is plenty of coolant in the expansion tank it will purge out any remaining air over the next few heating/cooling cycles.