Air in Cooling System - Toyota Nation Forum : Toyota Car and Truck Forums

dlf60 · 06-23-2006, 11:29 AM

I know air in the cooling system is a common topic and I have researched previous posts several times but I seem to be unable to successfully bleed my system. I have an 89 turbo automatic and I had air in the cooling system (flowing sound under the dash) when I drove it home after purchase. Since buying it I have replaced the cylinder head and turbo with rebuilt units. The head is resting on an Toyota OEM head gasket, secured with ARP studs torqued at 80 ft lbs. Every hose, gasket, etc. that I have replaced have been factory and I have sealed up numerous leaks but still can smell hot coolant when I return from a spirited run. I have been unable to detect any visual indication of a leak, only the odor and the level does not seem to be dropping. Could this be where I am getting air in the system? Can I use Bars Leaks to attempt to stop this miniscule mystery leak without damaging anything? When I have been bleeding the system , I have been elevating the front of the car and turning the heat on to max temp and max fan while I am running. Is this correct? I have done this several times and have thought myself to be successful only to have to perform some other task which requires opening the cooling system and getting the air again. (As well as driving the car a couple of times and hearing the water flow again) I don't think this is a heater core problem as I have never seen any wet spots on the passenger side carpet. I didn't want to trouble any of you with this common problem but would appreciate any guidance as I must be missing something or doing something wrong. Thanks in advance for any assistance/guidance you can provide.

Dirtjump9 · 06-23-2006, 12:34 PM

Hmmm... I have smelled coolant a couple times after driving my Corolla. I have never noticed any leaks or a drop in the amount of coolant but I have smelled the aroma a few times. It kinda has me worried now... Maybe there is a leak somewhere but you are not noticing a drop in the coolant level because of the small plastic tank that holds excess coolant. When it leaks, the system could be sucking up some of the coolant from that tank back into the radiator and that could be why you are not noticing a drop.
Good luck though... I really don't know how to help you but I'm sure someone here does.

Doctor J · 06-23-2006, 01:33 PM

If the rebuild head was overheated before, it is getting warped. The machining could restore the flateness of the sealing surface, but heating/cooling cycles will eventually restore the once aquired warpage. This conditon is common on earlier Supras/Cressidas.
Ideally, the shop must straighten the head prior to machining. Bar's leak will clog the radiator on Supra. Use block tester kit to check for exhaust gases in the coolant.

Jeeves · 06-26-2006, 09:17 AM

Checked your passenger side carpet to see if it's damp? Could be a blown heater core.

dlf60 · 06-26-2006, 08:44 PM

Thank you all for your responses! I have not found any moisture on the passenger side carpet at any time since I owned the vehicle. I just had a block test done today which came up negative. I have replaced the water pump, radiator cap, thermostat, upper radiator hose, cooling hoses on the following: turbo pump, throttle body, ISC, short 90 deg. on the head front passenger side, all with Toyota factory parts. After the last coolant air bleed I get much flow noise even at idle until the thermostat opens and then I still get some flow noise (under the dash) during acceleration. Thank you all for your assistance!

Doctor J · 07-18-2006, 10:53 AM

You may also pressure test the cooling system by pumping the radiator up to 14 psi with the cold engine using pressure tester you can rent from Autozone. Leave system under pressure for 15 to 20 minutes, and then check for leaks.
Most popular leak spots are the plastic radiator tank seals, coolant bypass pipe connections,etc
Hope this helps.