Thermostat

My Supe runs at a constant temp on the temp gauge, but not much heat comes out of the heater. Could this be an air lock or the thermostat...... Thanks for any advice

Airlock

Thanks Ian is there anywhere that the air can be bled out ... thanks for your help

Or it could be an old, inefficient heater matrix. My supra has the same symptoms. A year ago I changed the coolant (partly to flush out the matrix to make it work a bit better), and took great care to try and eliminate airlocks. I get a bit of heat out of the vents, but not much. I didn't improve (or degrade) the performance of the heater though.

Would an airlock prevent any heat from being provided at all, since it prevents coolant flow?

Thanks Ian is there anywhere that the air can be bled out ... thanks for your help

Get the front of the car up via axle stands, jack, wheel ramps, some planks, or just a steep driveway. This makes the radiator cap neck the highest point of the cooling circuit.

With a cold, switched-off engine, take the cap off and reach down the left hand side of the radiator to the lower coolant hose. Squeeze it enthusiastically a few times - you'll notice the coolant level in the radiator rise and hopefuly some air bubble out. Keep doing that to get as much air out as you can. Once that's gone as far as it can, put the cap back on.

Fill the expansion tank to the top with coolant. Turn the heater on full heat and run the engine. Let it warm up a bit and then rev it some to keep changing the speed of the coolant flow. Switch off and let it cool.

The expansion system works as it warms up by pushing air into the expansion tank so it bubbles up and out. Then, as the system cools, it sucks coolant back in through the same hose, thus replacing the air with liquid. Genius

That should sort it. You may hear a rushing bubbling noise behind the dash while the engine warms up, that's normal.

Hopefully it is just an airlock and nothing nefarious with the matrix of doom.

-Ian

Thanks Ian will deffo give that a try and I hope it cures the problem because I've also heard of the matrix of doom. Sounds like a nightmare to deal with.

Get the front of the car up via axle stands, jack, wheel ramps, some planks, or just a steep driveway. This makes the radiator cap neck the highest point of the cooling circuit.

 

With a cold, switched-off engine, take the cap off and reach down the left hand side of the radiator to the lower coolant hose. Squeeze it enthusiastically a few times - you'll notice the coolant level in the radiator rise and hopefuly some air bubble out. Keep doing that to get as much air out as you can. Once that's gone as far as it can, put the cap back on.

 

Fill the expansion tank to the top with coolant. Turn the heater on full heat and run the engine. Let it warm up a bit and then rev it some to keep changing the speed of the coolant flow. Switch off and let it cool.

 

The expansion system works as it warms up by pushing air into the expansion tank so it bubbles up and out. Then, as the system cools, it sucks coolant back in through the same hose, thus replacing the air with liquid. Genius

 

That should sort it. You may hear a rushing bubbling noise behind the dash while the engine warms up, that's normal.

 

Hopefully it is just an airlock and nothing nefarious with the matrix of doom.

 

-Ian

bens747, any update on this chap?

Yeap haev the car well up at a good angle, and squeeze the hoses. Check the inflow and outflow pipes going into the matrix, if they are both warm, you have water going in and out of the matrix.

It is possible for a foot to dislodge the lower Heater Flap control rod, which CAN be dismounted from the actuator, by a foot that can get into under the matrix... It happened to my witha tall girl, who did n't have the leg room.

Get the front of the car up via axle stands, jack, wheel ramps, some planks, or just a steep driveway. This makes the radiator cap neck the highest point of the cooling circuit.

 

With a cold, switched-off engine, take the cap off and reach down the left hand side of the radiator to the lower coolant hose. Squeeze it enthusiastically a few times - you'll notice the coolant level in the radiator rise and hopefuly some air bubble out. Keep doing that to get as much air out as you can. Once that's gone as far as it can, put the cap back on.

 

Fill the expansion tank to the top with coolant. Turn the heater on full heat and run the engine. Let it warm up a bit and then rev it some to keep changing the speed of the coolant flow. Switch off and let it cool.

 

The expansion system works as it warms up by pushing air into the expansion tank so it bubbles up and out. Then, as the system cools, it sucks coolant back in through the same hose, thus replacing the air with liquid. Genius

 

That should sort it. You may hear a rushing bubbling noise behind the dash while the engine warms up, that's normal.

 

Hopefully it is just an airlock and nothing nefarious with the matrix of doom.

 

-Ian

Just round to doing this and it seamed to do the trick like you said. Had a problem with overheating the other day and since the last time I flushed the system the heating wasn't working. Did a long run to the coast and it started to over heat with the temp guage going up and down. I believe that the air lock cleared and reduced the amount of water in the system which then started to overheat and overflow the expansion tank causing the temp gauge to rise and fall. Heater is now working and I hope it has sorted the problem. Thanks Ian for your advice on clearing the air locks.