Hi all! I thought maybe it would be a good idea to register here since old Ford trucks seem to mysteriously wind up in my driveway all the time. Currently a 1991 F-150 has been sitting there for about six weeks, and a 1998 F-150 has been sitting there since 1998! They run.
Anyway, the 1991 F-150 has a 5.0 liter engine. It is a Lariat model with air conditioning and dual gas tanks. It loses about half a gallon of coolant in between fuel ups, so we're talking half a gallon or so every 400 miles.
Here's what I've checked:
Nothing drips out underneath the truck. I can't see any fluids on the ground at all. This rules out some gasket leaks, but not all.
The oil looks fresh and clear (the clear brown color, that is). This may rule out a leaking head gasket.
The truck smokes white in cold weather (roughly 50 degrees) for the first mile or so it is driven, then the exhaust is clear. This may also rule out a head gasket.
There's no overflow bottle to check, so I've been looking in the radiator a few days after my wife gasses up. I am going to get a bottle at the junk yard this afternoon. From this, I know for a fact that the overflow bottle is not leaking. :|
There's no smell of coolant in the cab, nor does the defroster cause the windshield to fog up. The only time I've ever seen the window fog up was when I sat in the truck for about an hour after shutting the engine off, but both trucks do this and I've only had to add coolant to the newer one once between changes. This could rule out the heater core.
The carpet is wet near the driver's
door, but it's bone dry under the glove box. I can think of no way at al that coolant would leak from the heater core, go all the way across the cab, and soak the carpet on the other side. Stranger things have happened... a leaky master cylinder showed up near the left front wheel, and another time what started off as a mess on the windshield in another car turned out to be coolant and led to a pair of blown head gaskets.
Here's what I have not checked but need to:
I haven't checked the t stat housing.
I don't know if any bubbles are coming up in the radiator during normal operation. I don't think so, but I wasn't really paying attention.
When we purchased the truck, there was still coolant all over in the engine compartment. A hose had broken during a recent test drive, and the person we got the truck from showed me where he'd replaced the broken coolant hose going into something near the throttle body with a fuel hose. I have not seen the "fuel hose" leak at all, nor have I seen any coolant leaks inside or outside the engine compartment (not that I've looked very close). I've owned three other vehicles with 5.0 liter engines, and I've never noticed that hose before. I don't know what it's for (besides coolant, that is).
I have not looked real close at all the hoses yet. I had thought that if they were leaking it would drip on the ground.
Yesterday I Fixed the battery on my newer truck, so I'm off to Repair something on this one today.
(ok, kidding, I'm a Ford man...)