It's a Saturday job. From $50 to maybe $150 bucks for parts depending on whether you'll need head bolts or not plus your labor, which if your not the worlds best mechanic will take you 7-8 hours. If you have, or can borrow the tools and maybe have a friend who's tackled these jobs before, then go for it.
1. First, and this is important!. Check carefully to see if you'll need new head bolts, try questioning the guy at the local dealers parts counter. Many cars and trucks use head bolts that are heat treated to be harder at the ends than at the center of the bolt. These bolts, when torqued down are designed to actually twist like a liquorice stick a bit at the center so as to absorb differing expansion rates between the head and block, the twist is permanent. Those bolts are designed for a single use only and can't be re-used, you have to buy new ones. If you try to re-use them they'll snap at some point down the road, the gaskets will blow and you'll have to do the job all over again. Head bolt sets can get expensive. For my 1987 Ford Aerostar the dealer wanted $9 each, that's over $150 just for the bolts. Fortunately, I was able to find them from a local wholesaler for about $4 each so the whole job still cost me less that $180.00. The dealer wanted $1800.00 to do the job. I don't know if your truck needs them or not but all Ford V6 3.0 Vulcan blocked engines do (many Aerostar, most Taurus, some F150 PU).
2. Don't be intimidated by the job. It's really not all that difficult, just a bit labor intensive. I did the same job on my 1987 Ford Aerostar that had 193k when it blew both gaskets. I'm a pretty competent mechanic but that was a real job because minivans are no fun to work on. I'm glad now that I did the job rather than scrapping it because that was 5 years ago and the van now has 279k.
3. Go down to the local PEP Boys, R&S, Autozone, whatever and buy a service manual on your truck, check that it fully covers pulling the head and replacing the gasket. It should have good pictures and the torque specifications as well. Read the manual until your comfortable with the repair.
4. If you don't have one, then borrow a digital camera and take pictures from every angle in the engine compartment. Don't miss anything, you'll be real glad you did later on when your trying to figure out what goes back where, by the end of the day you will have forgotton where everything goes, guaranted. Shoot closeups of where wires and plugs go, etc.
Also, don't skimp on the gaskets. There are the run-of-the-mill sets for maybe $35.00 and then there are the blow-proof sets for about $60.00. Go for the blow-proof sets if you can find them. Cars (and trucks) can really last a long time if their carefully maintained and the popular mind set that cars get too expensive to repair after a time is usually just plain wrong. A new car or truck can easily cost 18-20k+. I can do one hell of a lot of repairing for 20 grand.
Do not use silicone sealer on the valve covers or head gaskets. A lot of so-called mechanics have done this and there have been no end of lunched engines as a result. What happens is that if too much sealer is used, when the bolts are tightened, excess sealer is squeezed out and protrudes into the inside of the valve cover where it is heated and softened by hot oil and eventually comes off in little round balls that lodge in oil passages or the oil pump pickup, blocking the flow. Usually the rod bearings wipe out from oil starvation. Use the proper gaskets and never use silicone where it could get into the engine oil.
I have personally seen a least a half dozen blown engines where this is exactly what happened. Typically, a mechanic(?) repairs leaking valve covers by smearing them with silicone sealer. A week or two later, a few hundred miles down the road the engine wipes out. Disassemble the engine and find little blue rubber balls doing a great job as corks.
Silicone sealer is great stuff, and used correctly in the thinnest of layers, it works wonders but nearly everyone uses way too much.
Al
