4age cooling system
Posted: Fri Nov 03, 2017 4:41 am
Short history: I did a rebuild on my 4age in an '87 ae82. Installed a new water pump in the process. No overheating problems in break in period. At about 1000 miles, engines overheated drastically, and although I wasn't watching the gauge constantly, I think very quickly. Warped the head. Pulled the head, had it planed, reassembled it, installed a spare radiator, ran it through warm up and cool down cycles in the yard. Got heat from the heater, all hoses hot, cooling fan cycling. Ran the car up and down the road, all Ok, and then a sudden overheat, head gasket blown, white smoke etc. Pulled the cylinder head from the original engine with who knows how many miles on it, because now I've thrown way too much money into this thing. Reassembled it with a three layer steel head gasket, went through all the coolant bleeding procedures, as above, and have been running it some, maybe a 150 miles since the new gasket. I ran it a few days ago, about 10 miles, some of it to redline, no sign of overheating, got home and checked under the hood, because now I'm paranoid about it. Bottom radiator hose was cool, top hose hot, t-stat housing hot. Let it idle for 5-10 minutes, lower hose got hot, cooling fan cycled. Air temp about 50 F. This does not seem normal. It's been suggested that perhaps the impeller on the new water pump is loose on its shaft, and not impelling at higher rpm, but aside from that, a lot of head scratching.
What's the path of the coolant in the system? How does the bypass under the intake work? I read the thread about the bad temp sender connection, but my problem seems outside of that discussion. Any suggestions, short of pulling the water pump, which I'm not eager to do.
What's the path of the coolant in the system? How does the bypass under the intake work? I read the thread about the bad temp sender connection, but my problem seems outside of that discussion. Any suggestions, short of pulling the water pump, which I'm not eager to do.