I've got a 96 F150supercab, 5.0 all stock, 228,000. Regular maintenance, I think, I've only owned it since last april. I am afraid it has a blown head gasket. It's leaking coolant from somewhere and I can't seem to find it.

It's had a problem with slowly dissapearing rad fluid. It would eat 1/2 gallon every two months or so. I had some problems with the dizzy and changed out the thermostat about 3 months ago. I checked the fluid about a month after that, and it seemed to be steady...

So on there I am, enjoying my Saturday headed up a hill and and the vents started oozing steam, just as I got on the gas. Not major leakage, but enough that I rolled down the windows in 20deg weather. I babied it the rest of the way home, and it didn't do it again. Monday morning I try to make it work for a few more days.. and nearly steam clean myself instead. I made it home ok, by leaving it in OD and cruisin nice and easy with the heat off and on cold (fortunately I was dressed nice and warm.)

Monday night I replaced the heater core (tested it leaky)and topped off the radiator, filling it with it running, I kept filling till it quit sucking, which was only about half a gallon. I cycled the throttle a couple times and noticed it sucked down about two or three inches while I was revving it. It seems like that shouldn't happen if it's full of water, since water can't compress right.

Tuesday I drove it back and forth to work, gently. I put in another 1/4 gallon. It was a frigid 16deg. The heat works fine now, but I'm worried about what caused the fluid to go low, and why it blew the heater core when I stepped on the gas.

I can't decide if it's steaming from the exhaust more than usual because it's so cold or because it's leaking water and spittin out the exhaust. Even after it was good and warm, when I revved it past 2000rpm it would spit a good amount of humidity(steam) out.

I don't think it's a complete gasket failure yet, I've seen that before, it looks like you have a vapor trail behind you. I'm worried it's the early stage, and If I ignore it, It's gonna get worse, and I deffinately can't affard to have the whole engine rebuilt.

Fearing the worst I went ahead and bought both the intake manifold gasket kit, and the Head kit. When I ran into the parts for 5 minutes and came back out, with the engine nice and warm, It started and stalled 3 times before it ran. My stomach sank as I becoming more convinced it was the head gasket. (Not a good feeling)

I did the compression check today, heres my numbers, I think they look pretty good for 228K miles...? starting at 1:
170, 160, 160, 160, 165, 148, 150, 152.

I don't think any of these are low enough to call a blown head gasket. What do you guys think?

I checked the dipstick, and there is no trace of water in the oil. It's a nice normal brownish/clear.

It's leaking fluid from somewhere though, after heating it up today for the compression check it was dripping coolant down the right side off the oil pan and near head, I couldn't pinpoint it though.

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Is there anything else I can do before starting exploratory surgery and pulling it apart?

I'm hoping it's only the intake gasket and I don't have to pull the heads. What would be the most likely cause of leaking more coolant when at or close to WOT?

This is my only vehicle, so If I don't need to pull it apart, I don't want too.
My wife has a car, but.. well, it's a car.

If I do take off the heads I have already talked to a machine shop that will run through them and do a 3> valve job, for ~120 for both.

Any advice appreciated.

 

why dont you take it somewhere and have it looked at.you could have a leaking frost plug.at any rate theres no sense in taking it apart till you know for sure whats wrong.

 

I think you are paranoid, with a leaking heater core you could use/lose a lot of coolant and when you change the thermostat it is common to trap air which when revved would compress and draw the coolant down. Is there any wetness, because frequently these engines leak at the intake manifold gasket edges in the front after time and the small hoses to the throttle body get pin holes also if the rad is original they leak/seep where the tanks join the core when it's cold, I'd exhaust all possible sources before i'd tear it down , also if it's a head gasket they normally run hot.

 

Ok, I didn't rip into it yet. I checked the Oil and it looks fine too, not milky or nasty at all. Sounds like the head gasket is fine <crosses fingers>

It was dripping fluid yesterday once it was warm, I didn't have an inspection mirror, so as close as I could tell it was dripping down the front right side of the block, onto the oil pan, then running back and dripping off. It looks like it is coming from the intake/water pump back side area, but I couldn't tell for sure. It was also dripping out of the tank on the bottom left, very slowly though, and there was some fluid on top of the bottom hose and fan blades where wet, like it had sucked some fluid through and blown it onto the lower hose.

I went ahead and put in some alumiseal this morning, since it's mostly a couple small leaks. After driving 20 minutes to work it didn't seem to be dripping. I'll see when I get home. I used once before in another engine and it didn't seem to hurt it.

I was getting ready to go on a road trip with a trailer in the next couple of weeks too, so I'd like to be sure. I would love the chance to rip this engine apart and cram it back together with a little more power, but I don't have the time or money right now.

If it's still leaking Saturday, I may pull it apart enough to check the water pump and intake gaskets? I'll get a mirror and see if it's still leaking first though. How much of a pain is replacing the intake gaskets? It looks at lot easier than the head gaskets.

 

Sounds closer to an intake gasket leak (just a pinhole, if anything) then a head gasket leak.

 

intakes are relatively easy just don't use the cork gaskets that go across the valley between the heads just run a bead of silicone about 3/16 in. thick across and put a small amount around each water passage at each end and torque evenly the cork gaskets tend to squeeze out while the silicone seals properly , make sure it's clean and use the silicone before it skins over.