I've perused several of the threads regarding head gaskets and the cooling system issues, so I believe I already know the answer, but wanted to check with the guru's before digging any deeper.

Here's what's going on. I have a 1996 4.9L F-150. I know I've had a problem with it running hot, particularly in the summers when in stop-go traffic. I'm pretty sure that was due to the fan clutch, however last spring I was driving it on the highway and it shelled the serpentine belt. I know the belt wasn't in poor condition before that happened. As it began to overheat the coolant began to run out of the overflow tank. I let it cool, put on a new belt, refilled the radiator and got about another 8 miles and it overheated again with coolant running out of the overflow tank and belt in tact. Sadly, it's been sitting in my driveway ever since the ride home on the rollback. I've started it a couple times since then and it ran good 'til the cooling system was under pressure. There was no smoke from the tailpipe. The upper hose was bulging after only running 3-5 minutes at idle and coolant ran out of the overflow tank. I suspected it might be the thermostat, but my neighbor across the street who seems to know a bit more than I do about engines thought it was the head gasket. I haven't had the $$$ or time to mess with it until last night...... I pulled the thermostat and put it in the boiling pot of water...... it didn't open up even a little bit. I thought maybe the neighbor was wrong, so hooked the lines back up without the thermostat and ran it for about 6 minutes. No coolant overflow, however it was blowing white smoke out of the tailpipe. My neighbors were loving me. It never smoked a bit the times I've started it after getting it home until the first time last night.

Now after all that, here's my question. White smoke would seem to indicate coolant being burned..... right?? I was thinking perhaps it may be the old gas. Before I drain the tank and put in some fresh petrol I wanted some input on whether the old gas would cause the white smoke or if it is more likely a blown head gasket and burning coolant.

I've got to get my truck running or sold and am trying to figure out which direction to go. The motor still sounds good, no missing, no leaks, the oil is still the color of honey with no sign of any foreign fluids etc. It's only got 178K on it and I know it should last at least another 150K, so it'd be worth fixin up in my opinion.

What are your thoughts?

Thanks,
John

 

You could try this. Fill the rad right up to the neck, leave the cap off and start the engine. With engine at idle look for a steady stream of bubbles in the water at the rad filler neck. See if there is an exhaust smell from the rad neck.

 

Thanks for the reply Lazy K. I'll give that a try this afternoon after work. I assume if there are bubbles and exhaust odor that would verify that it is the head gasket??

John

 

John

I would put a new thermostat in the truck. It will not run right without it. If it's a head gasket remove each spark plug and look for water or antifreeze on them if it's bad you will know. Sounds like it's a head gasket to me.

 

yes it`s a good indicator.