Thought I'd look for some help on this one It's making me crazy. Have 91 150 XLT 2wd aod trans. Has had a coolant leak for about 4 mos. I replaced water pump couple of months ago because the bearing was hosed. Replaced all hoses including heater and put on new cap. Still leaking, Took off water pump and redid it with more silicone figuring that was it. Truck is still leaking. It is dripping down from the backside of the under oil pan crossmember so I dont think its coming off water pump. Does the aod run antifreeze back and forth as coolant? and might one of those be leaking? It's tough to see where leak is coming from because of grunge. I'd clean it but 25 to 30 degree weather just don't get it. Any ideas??

Thanx Svt4Cammer

 

Sounds like it could be an external head gasket leak or a freeze plug. Did you check those?

 

I just noticed it was leaking further back then the pump today and was busy doing something else. Didn't get achance to grab a flashlight and really take a good look If it was head gasket wouldn't it smoke on exhaust manifold?

 

Possibly, but it depends where its leaking from.

 

Does any coolant run back to aod transmission? I notice some steel lines running from fittings on upper radiator down and back in the general area of the leak but didn't have time to trace them. I will look at freeze plugs and head tommorow.

thanks

 

those lines are more than likely a transmission cooler not coolant, they would circulate tranny fluid.

 

It could also be the lower intake manifold. There are water jackets at all 4 corners, Gaskets could be shot.

 

my truck had the leak as described. it was the lower intake manifold. it had been eaten away by the antifreeze. i don't think it had ever been flushed before i bought it. i tried to buy an origional intake, but Ford is too proud of it. the cost of the replacement lower manifold was more than the edelbrock efi manifold you may be able to get the manifold repaired... if thats the leak is comming from. check at the back of the engine with a light and a small mirrior if you can. you should be able to see it around the valve covers or on the back of the heads by the firewall. good luck.

 

Thanks, everybody that gives me some ideas where to look until it warms up a bit im just gonna back off the radiator cap and keep driving. But atleast I know where to look now when it gets above 40. Worst case I have a built 302 on a stand I can pop in and fix this one at my leisure.

 

Check the timing cover to the block.