It's now over heating

I got my freelander 1.8 k series back on the road today after doing the head and head gasket and new cam belt, took it for a drive after 20 miles back and forth to the next village the white smoke vanished all looked good, i stopped and checked under the bonnet every 5 miles to make sure the coolant was ok and temperature gauge stayed in the middle so drove home.

I got home parked up with the engine running looked under the bonnet, as i was looking the engine over the coolant in the expansion bottle started to blow out of top of the bottle, switched the engine off, waited for it to cool a little then did a sniff test and the test liquid remained blue so the new head gasket is still ok.

What can be causing the coolant to overheat, the thermostat is new, can a new thermostat be faulty, the temperature gauge remained in the middle, what should i be checking, i thought i was finally up and running again today.

Air lock?

yes a new thermostat can be faulty best take it out and put in in a pan of water and boil it and see if it opens also did you bleed the system.also did you take the thin tube of the expansion bottle and blow into it to open the jiggle valve in the head.

I undid the thin tube that goes onto valve put a piece of tube on then blew into it a few times, i bled it from the screw on the hose that goes to the heater.

I will remove and check the thermostat tomorrow, the thermostat is a vernet from eurocarparts as anyone used this brand are they ok.

digi said:

I undid the thin tube that goes onto valve put a piece of tube on then blew into it a few times, i bled it from the screw on the hose that goes to the heater.

Click to expand...

Theres two bleed screws to do digi...did you do both?

digi said:

I undid the thin tube that goes onto valve put a piece of tube on then blew into it a few times, i bled it from the screw on the hose that goes to the heater.

I will remove and check the thermostat tomorrow, the thermostat is a vernet from eurocarparts as anyone used this brand are they ok.

Click to expand...

Test the thermostat in hot water, use a thermometer to measure the temperature, should open at 82 degrees Celsius
......I use gates thermostat,working good

That's probably were i've cocked up, i only did the one bleed screw on the heater hose, i should have read the manual more closely, i didn't know there was a second bleed screw, i've found were it is now.

I'll test the thermostat then refill and bleed using both bleed screws this time, do you bleed the system with both screws out at the same time or bleed one then the other.

Bleed the system from the lower bleed screw first, moving on to the upper one when air stops from the lower screw.
Also check the cap and expansion tank for splits around the cap.

Make sure heater on hot when filling

Yep as nodge and fanatic above

I had both screws open while slowly filling the tank ...when the lower one stops bubbling tighten it, then the same for the heater one.

Re the jiggle valve....the ball bearing has been removed from mine so it cannot stick and cause problems - you can see coolant returning back to the header tank when the engine is running ....if for some reason it stops flowing back -you know there is a problem too.

I took the thermostat off and tested it in boiling water from the kettle it didn't open, then tested it in a pan of boiling water and still didn't open, eurocarparts exchanged it without problem.

I tested the new one in a tub of boiling water direct from the kettle and it didn't open so dangled it in a pan of boiling water that was still on the gas and it opened, does this suggest the new thermostat is also knackered as boiling point is 100degrees c and it should have started to open at 82.

I'm not sure about (vernet) this make of thermostat if they are faulty or not, they don't have anymore in stock and it's the only brand they do, but they've ordered me another one for Monday.

check out your old one, if it works , refit it.

You should bring the water to the boil with the stat already in it, measuring the water temperature as it heats up. This is because the stat takes a few minutes to warm through to the wax. If however you have been boiling the stat for 10 minutes and it still isn't opening, it's unless.

My old thermostat was stuck in the open position it looked like someone had jammed it open.

I re did the test on the 2nd thermostat and put it in the pan then warmed it up bringing it boil and it opened just as it started to boil so i've fitted it.

I fitted the 2nd thermostat, blew in the wiggle valve and bled the system using both bleed screws with the heater on full, i ran the engine for 20 minutes with the cap off the expansion bottle so any air could escape, i put the cap on the bottle and ran the engine on idle in total for 65 minutes while monitoring the coolant temperature as i'd plugged my scanner in the obd socket, after 65mins it reached 205 degrees F ( 96.1C).

I kept feeling the hoses through out all got hot except the bottom radiator hose this stayed cold until the 50 minute mark it then felt aired, by 65mins it was warm, does this indicate that the thermostat as opened when the bottom radiator hose starts to warm up.

The coolant in the expansion bottle had risen from the max line to just above plastic joint in the bottle then seemed to stay there while the engine was running on tick over, after i'd switched off and let it cool for a couple of hours the coolant had gone down to just above the min mark.

I will drive it to work tomorrow, that will be the test.