r1on1wheel

I have a 96 tacoma 3.4 4wd just recently did an engine rebuild. Everything was running fine up untill the truck overheated one day. There aren't any coolant leaks. Water pump t-stat is new clutch fan is working properly. I blead the system and for sure there was air in it. After bleeding the system the truck would hold the temp untill I turn on the ac then after about ten minutes it would then overheat and I would have to bleed it again. How would the ac put air into the system? Also I am running green antifreeze Toyota says that shouldn't be the problem. Any advice would be good before I go out and buy a new radiator. Thanks!

nothingbetter

the a/c would not put air into the cooling system as they are not connected in any way. Your air is getting in elsewhere. Over heating when you turn on your a/c makes sense as the condenser, which is in front of your rad, puts out lots of heat when in use.

What was your reason for rebuilding? Did you use a cooling system "stop leak"? That stuff is known for clogging cooling systems and rads. Have you tried back flushing your rad?

r1on1wheel

The reason for the rebuild was due to a misfire caused by a burnt exhaust valves. I myself didn't add any stop leak. Can't really be sure of the PO. The fins on the bottom of the condenser did break off during the build. But the ac has been running for almost a month with no problems. I keep thinking heater core because I get a gurgling sound when the heat is on and I give it gas. And no matter what I do it never goes away. The radiator has been flushed but would a clog cause air in the system? Also when burping the rad with the heat on full blast there is no signs of air pockets. But turn on the ac and it's endless air pockets. My buddy says the rad is clogged because when it overheats the bottom isn't warm. I just have to be sure before I sink another couple hundred in this truck.

enapa

Just disconnect radiator and check flow with a hose. If its good replace the upper and lower radiator hoses as they can collapse under load. Was the hg replaced during rebuild?

r1on1wheel

Yea the head gasket was done during the rebuild. I never even thought of the hoses next weekend I'm just going to replace the rad and hoses flush and use Toyota red. This weekend is just to hot.

nothingbetter

if your hearing water "splashing" behind the dash, thats means your system still has air in it and hasn't been purged properly. Once you get your new rad and hoses, take it to a shop and have them use a vaccufill on it. Much better results. Since it will be under heavy vacuum they can watch the gauge and tell you if there are any leaks as well.