stevie_b Posted October 16, 2007 Share Posted October 16, 2007 I changed the coolant in the supe over the weekend. Having filled it with new coolant, the heater in the cabin no longer puts out any warm air, just cold air. I guess it's either an airlock in the matrix or an actual blocked matrix (shudder). Before changing the coolant, the heater used to get warm but not really hot. The coolant temp gauge reads normal under any type of driving (idling, cruising, spirited driving). I've tried squeezing the radiator hoses, but that doesn't seem to have helped. The coolant level in the expansion bottle is going down each day after driving, which I hope is air coming out the system and not a leak! The top rad hose gets hot when the engine is up to temperature, but the bottom hose barely gets warm at all: after driving for about half an hour, I turned off the engine and could hold the bottom hose indefinitely: I know this is the cool return hose, but I would have thought it would be a bit warmer than this. So, what's the best way of removing an airlock from the heater? I've tried the upturned powerade bottle in the rad cap hole, but 1) after idling for 20 mins, the coolant level was hardly increasing up the bottle, and 2) despite my best efforts, coolant leaked out around the bottle/rad interface. I've tried squeezing the hoses. Do I need to drain the coolant back out and re-fill, and hope for the best? Link to comment Share on other sites More sharing options...
captainchaos Posted October 16, 2007 Share Posted October 16, 2007 Jack the front end of the car up as far as you can get it and run it for a short while Link to comment Share on other sites More sharing options...
Whitesupraboy2 Posted October 16, 2007 Share Posted October 16, 2007 try the above first, I would also undo the hose for the pipe coming out of the matrix and slowly tip water into it. until it comes out the top of the hose, when you join the hose you will lose a bit of water but the matrix will be full of water which should hopefully should help push the air around the system and out the open rad cap. If its your matrix im near by and now thanks to Jezz's guide know all the shortcuts.....Did I just scare you. Link to comment Share on other sites More sharing options...
Stevie Boy Posted October 16, 2007 Share Posted October 16, 2007 Perhaps the mixer valve/motor for the interior heating isn't actuating as should. No idea exactly where it's located on a Supra though. Would have thought somewhere near the bulkhead but don't remember seeing it on mine, may be up under the dash in the heater/ A/C evaporator box. You could check the flow and return coolant lines running to the bulkhead area and see if the heat is getting through at all. If mixer valve/motor wasn't working i'm thinking it would possibly log a fault code in the A/C Heater control unit? Link to comment Share on other sites More sharing options...
Stevie Boy Posted October 16, 2007 Share Posted October 16, 2007 try the above first, I would also undo the hose for the pipe coming out of the matrix and slowly tip water into it. until it comes out the top of the hose, when you join the hose you will lose a bit of water but the matrix will be full of water which should hopefully should help push the air around the system and out the open rad cap. If its your matrix im near by and now thanks to Jezz's guide know all the shortcuts.....Did I just scare you. Sounds like a plan to me! Link to comment Share on other sites More sharing options...
stevie_b Posted October 16, 2007 Author Share Posted October 16, 2007 Thanks chaps. I'll try jacking the car up and running it on idle. When doing this should I remove the rad cap? I've tried looking for the hoses/pipes going into and out of the matrix, but around the bulkhead the engine bay is a maze of stuff! If I take a photo of my engine bay later, maybe someone would be kind enough to edit the photo to show me where the matrix in/out pipes are. Link to comment Share on other sites More sharing options...
TrickTT Posted October 16, 2007 Share Posted October 16, 2007 Turn the heater temp control up to maximum when you run the engine to fully open the water control valve to the matrix. Link to comment Share on other sites More sharing options...
Whitesupraboy2 Posted October 16, 2007 Share Posted October 16, 2007 Yes you'll need to remove the rad cap. To find the heater pipes; start at the top right hand side of the engine bay and work your way round to I think just under the passanger side wiper. and on the back (flat bit) of the bulk head there will be 2 pipes sticking out with rubber hoses on it that do a 90 dgree bend upwards and then join 2 more metal pipes and off to couple more hoses. There is no other pipes sticking out of the bulk head in this area. P.s Stevie boy said it may be actual control bit which I suppose it could be though I doubt, simple way to tell is by once the engine has been running touching the pipes if they are both hot then it could be this and if so I have http://www.mkivsupra.net/vbb/showthread.php?t=127564 Although will be going to the dump this weekend. I will hunt for a pic for you to show the pipes. Link to comment Share on other sites More sharing options...
Kranz Posted October 16, 2007 Share Posted October 16, 2007 Easier than jacking the car up is to find a very steep slope Use a Powerade bottle stuck in the rad filler neck and then fill it with coolant to add more 'head' to the radiator. Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 16, 2007 Share Posted October 16, 2007 In my opinion the MKIV heater matrix and cooling system needs no bleeding or faffing about with. Sounds like the `stat is stuck open to me, or one of the heater controls is stuck. try a new `stat first, especially with the rad being cool. I keep them in stock if you need one, together with new sealing rings. Link to comment Share on other sites More sharing options...
stevie_b Posted October 16, 2007 Author Share Posted October 16, 2007 Turn the heater temp control up to maximum when you run the engine to fully open the water control valve to the matrix. I've already done that, but thanks for the reminder. Use a Powerade bottle stuck in the rad filler neck and then fill it with coolant to add more 'head' to the radiator. I've tried that too, but the coolant barely rose into the bottle, and even when it did it tended to leak out (see first post). Good tip about the steep slope! I'm sure there must be one in Basingstoke somewhere.... Link to comment Share on other sites More sharing options...
stevie_b Posted October 21, 2007 Author Share Posted October 21, 2007 This weekend I drained the coolant, flushed the heater matrix through with hose water and changed the thermostat. When re-filling with coolant, I did it by the book. I put the heater control to the top temperature, pre-filled the heater matrix with water to ensure it would be filled with water, and filled the system SLOWLY via the rad cap. All to no avail though: the coolant seems to get hot as expected, the temperature indicated on the dashboard is normal, the rubber hoses get hot (including the ones to/from the heater matrix), but the heater puts out no heat into the cabin. Any ideas before I resign myself to getting the dash taken out? Link to comment Share on other sites More sharing options...
Supra Pilot Posted November 20, 2007 Share Posted November 20, 2007 Hey Stevie, any update/luck with this...? Link to comment Share on other sites More sharing options...
stevie_b Posted November 21, 2007 Author Share Posted November 21, 2007 Yes, it's all working again! Turns out it was an airlock in the heater matrix, *possibly* caused partly by a hairline split in one of the hoses. I flushed hose water through the matrix in both directions. In one of the directions (1st flush), the outlet tube taking water away from the engine bay and onto the ground jerked around a bit for a couple of seconds, which I assume was air pockets being forced out of the system. When using the hose, it pays to give it a good helping of water pressure (although probably not full whack). There also seemed to be a tiny leak on the matrix inlet rubber hose, so I cut off 1/4 inch from the hose and re-attached it. It now doesn't leak. Link to comment Share on other sites More sharing options...
Supra Pilot Posted November 21, 2007 Share Posted November 21, 2007 Nice one... Mine recently started misbehaving and would only offer cool/slightly warm air when it felt like. Other times it would be rather hot... Funny enough just today I had time to have a proper look at the whole system. Started with the controls, removed them and all connections and pcb contacts are fine. Then checked all hoses/pipes in the system(engine bay side really) and all is fine. Flushed some water from the Rad and started refilling, reving and blasting the heater as required. It's now blowing pretty hot once again on demand... I will monitor it and see how she goes for a couple of days before I am 100% convinced it's sorted. One thing I did notice was the Temp control unit, With the blower off(no noise), Temp controller knob when starting from full cold and moving over slowly to Hot(clockwise), you can hear the main units motor reacting to the changes, but only up to the 1 o'clock position then nothing. Seems that it's only working up to about 20 degrees instead of the full range of 30. Or maybe thats how it is? Link to comment Share on other sites More sharing options...
SkinnBa Posted November 22, 2007 Share Posted November 22, 2007 Nice one... One thing I did notice was the Temp control unit, With the blower off(no noise), Temp controller knob when starting from full cold and moving over slowly to Hot(clockwise), you can hear the main units motor reacting to the changes, but only up to the 1 o'clock position then nothing. Seems that it's only working up to about 20 degrees instead of the full range of 30. Or maybe thats how it is? I think that's how it's supposed to work as mine does the same. If you adjust it to a temperature above the ambient temperature it opens the mixer flap fully, therefore moving the temp control round to 30 wouldn't do anything as it's already full open. I think this is right anyway Link to comment Share on other sites More sharing options...
stevie_b Posted November 22, 2007 Author Share Posted November 22, 2007 One thing I did notice was the Temp control unit, With the blower off(no noise), Temp controller knob when starting from full cold and moving over slowly to Hot(clockwise), you can hear the main units motor reacting to the changes, but only up to the 1 o'clock position then nothing. Seems that it's only working up to about 20 degrees instead of the full range of 30. Or maybe thats how it is? I think mine did the same too. The motor that switches between hot matrix air and cool outside air seems to be "digital" (i.e. either on or off, no part-way middle ground). Link to comment Share on other sites More sharing options...
megawatts Posted December 18, 2007 Share Posted December 18, 2007 Fill the system, with a top up through the heater matrix return pipe,(the upper pipe that goes over the engine) until you get some minor overflow via the rad cap, as then quite a lot of potentially trapped air can be pushed out of the system. Re-attached this tube, and then rev the engine hard to clear air through the system, that may be holding on . Drive the car to a steep slope, and make sure you are able to clear any air locks still in the system to bleed out through the rad cap. Make sure that both and in and outflow pipes are equally hot. Of course make sure that the matrix is flushed clear of any limescale first. Never known a car with such heater problems!! .One very nasty trap is the Passenger foot well. It is possible to un hook the heater flap control rod, with the toe of a deeply stretched out foot! Found the lower actuator rod dislodged, so while all heater controls would work, this final lower rod was actually not attached. Link to comment Share on other sites More sharing options...
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