The problem I'd asked about, last month, of coolant leaking somewhere but not being able to trace the leak seems to have remedied itself. Last week, however, a leak had developed where the passenger side tank is crimped to the core. The person that pointed it out to me thought it was the water pump, but I looked and said "no, it's too far forward to be the water pump," which of course prompted me to open the hood, and try to see where it was leaking. The seam didn't leak, while under pressure, but as the system was depressurizing after engine shut down, just like a bad water pump would.

Earlier this week I'd called several radiator shops, and junkyards, inquiring about either repairing the radiator, or possibly getting a good used one, and repair the bad one at a later date. On Wednesday, having driven to several places out of town, then to a junkyard that had a radiator from a '92 F-150, I got to noticing that the radiator was no longer leaking. The level inside the radiator isn't going down anymore, and the coolant/overflow tank level is holding steady.

I'm beginning to think my truck has become possesed. Any thoughts? There's a check valve (part of the emissions system) between the manifold and firewall that I still need to replace (have the part, just not yet the motivation to tackle the task)...could that be effecting my cooling system? The truck is a '91 F-150 w/5.0L & AODE w/AC. I did replace the radiator cap with a pressure release cap, on Wednesday.

Matt

 

The side tank seals have had enuf, you are probably correct, it is coming out between the core and plastic tank. When my side tank was leaking it was also intermittant. The seals are just a thin rubbery black gasket. I would just get a new radiator, unless you know a good radiator repair shop. I paid 150.00 bucks for a nice Canadian made radiator November 2004, it looked exactly like the factory radiator and works great.

I hope you looked up the specs for your radiator and installed the exact cap that the radiator calls for. Most caps are pressure rated, that is, they will automatically open and allow excess coolant into the overflow tank when the coolant expands too much, don't forget, this a completely sealed system, there is no way for the coolant to escape other than that cap. If it can't get out the cap, it tries to get out of a hose, sidetank, or worse yet..a headgasket.

The air lines you mentioned are not affecting the cooling system.

Why are you changing the valve in your emissions? If its the smog pump air by-pass valve....that thing rarely fails. If the valve isn't working, maybe the vacuum line to it may be busted, or the air bypass relay valve may be inop.
You should own a vacuum pump and gauge to properly check all vacuum-controlled components, ...it is a very handy and inexpensive tool to own.

 

A new radiator, or getting the current one repaired are going to be my two options, then. I forgot to mention that my truck has a heavy duty, 4-core radiator, as opposed to a regular 2-core radiator, like what was in the '92 F-150 at the junkyard. The valve I'm talking about looks kind of like a flat topped bell, with a tube sticking out of the top, and is attached to a 1 1/4" nut. The nut screws onto a steel tube, and a rubber hose is clamped over the tube at the top.

Do you have any information, about the place where you bought your radiator? Since I'm planning to eventually tow my other vehicles on a trailer, I'll want to stick with a heavy duty radiator. Thanks for clarifying/confirming my suspisions, about the leak. At least now I know where my coolant had been "mysteriously" disappearing to, especially after the problem made itself more apparent, last week.

Matt

 

My 96 done the same thing but then leaked all the time. I took it to my local radiator guy and he fixed it for 35.00 6 months ago.....

 

I bought mine at a radiator repair shop. The guy that I go to does good work, it is just a local shop, and he fixed my sidetank once for 50 bucks, I ran that truck 325 miles the next day full of firewood to a camping trip in the Pocono mountains. The reason I changed the radiator soon afterwards was because the top hose plastic inlet just cracked at the base. I would have needed a new sidetank, so I went for the whole works.