Purging Air in Cooling System on Acura

My 1990 Acura Legend is giving me a problem with the heater/cooling sytem. It seems as though I might have air in the system but I cannot purge it.When the car is cold, it takes almost 15 minutes to get heat into the cabin.The coolant overflow res. is always full, never pulling back into the system. Could this be the problem? This one has me stumped! Jay

Reply to
The Doctor
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Is the problem you are trying to address a heater that doesn't work very well?

You may have a thermostat that is stuck open. If everything was working the way it is supposed to when the engine is not warm the thermostat would block the flow of coolant to the radiator and most if not all coolant flow would be directed to the heater. So does the heater hose start to warm up and the radiator hose remain cold a little while after a cold start? If both hoses warm up slowly at about the same rate then the thermostat is stuck open. If the heater hose warms up much faster than the radiator hose that would suggest the thermostat is working as it should. If the thermostat is not causing the engine to warm up as it should that could also explain what you are seeing with the level in the overflow tank.

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Reply to
jim

A standard first answer on a problem like this is that you may have an air bubble in the cooling system. Did this problem begin after some service work on the cooling system, like hose replacement, water pump replacement, coolant change, etc? Be sure you have all the air out, and then go to step two. (You may have to use some diplomatic resources to find the correct way to purge the air out of this system. I dont know Acuras very well. At one time decent repair manuals were not easy to obtain for them, IIRC. Seems Acura did not want this info into the hands of everybody)

Step two...is your thermostat installed and working? Should be, or your heater wont work right. Assume the fans are not constantly on?

Somewhat likely, flow interference in the heater core, either by mineral deposits or by a valve that is not operating properly. That could slow or stop heating, or reduce heating capacity.

Less likely, water pump not working properly.

Maybe other situations as well

Reply to
HLS

Yes, it happened right after the radiator hose (upper) was replaced. Any ideas on how to purge? Jay

Reply to
The Doctor

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There is a bleed nipple I believe.

Reply to
Bret

This manual shows a bleed valve in the radiator outlet neck. Surprised to find this freebie manual online, but good to know about.

Reply to
HLS

Hopefully everything you need to keep your Honda on the road :)

Reply to
Bret

Yes, it happened right after the radiator hose (upper) was replaced. Any ideas on how to purge? Jay

Go to the site provided by another poster. Go into that manual and it will give you hints about how to do the purge.

Come back here if you have problems...and best wishes

Reply to
HLS

The Doctor wrote in news: snipped-for-privacy@n10g2000yqm.googlegroups.com:

This engine has a bleed screw at the engine end of the upper rad hose, common practice for Honda in 1990.

The system is self-purging provided there is not a ridiculous amount of air in it. Large amounts of air prevent the system from uptaking coolant from the reservoir on cooldown, meaning you would permanently have air in the rad.

If your dashboard has a temperature control dial, turn it to full-hot (all the way clockwise) before starting work.

To purge:

1) Fill the reservoir to the full mark. 2) Engine COLD, rad cap removed, slightly loosen the bleed screw, then add coolant mixture through the rad filler neck until the mixture starts dribbling out of the bleed screw. (The screw may be clogged with crud. If so, remove it entirely and clean up it and its hole.) 3) Close the screw when coolant begins dribbling from it (7 ft-lbs ONLY! DO NOT overtighten!!), put the rad cap back and start the engine. 4) Run it to full-hot (rad fan comes on twice), then let it cool down again, all the way. 5) Check reservoir level. It should have dropped a bit from its original level, but the rad should be full right up to the bottom of the rad cap, with no air at all. 6) If there is still some air, add coolant until the level in the rad is once again up to the rad cap (put cap back), then run the engine to full-hot again. Let it cool down once more.

Is there still air in the rad? Is the reservoir also much fuller than it was before?

If so..

1) Check the integrity of the hose and connections between the reservoir cap and the rad filler neck. Any leaks there will prevent the cooling system from sucking coolant back in as the engine cools, ingesting air instead. 2) Try replacing the rad cap (with NEW OEM ONLY!). 3) Is the water pump aftermarket? Aftermarket pumps can admit air through the suction side of the pump, meaning you'll never be able to get rid of it. 4) The head gasket may be blown. Have a test done to detect combustion gases in the coolant. Hondas blow bubbles into the coolant when the head gasket fails. This leads to low coolant level, and poor heater output.
Reply to
Tegger

Well, I found the bleeder valve thanks to the manual you guys posted - thanks for that! However, 3 days later I had more air in the system and very low coolant. There are absolutely NO leaks in the system. I fear it might be as you stated-the head gasket. The engine has just over 100k on it and has been a great performer. I don;t know what could've caused this. Either way, I still think its worth getting fixed as the car has really been great. Thanks to all for the help! Jay

Reply to
The Doctor

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