How to Fix a Blown Head Gasket on an F-150by Francis Walsh
The Ford F-150 is a dependable truck, and the price for a used one can be very low. One reason someone might sell their F-150 is because of a blown head gasket. A mechanic might charge as much as $2,000 to fix it. If you learn how you fix a blown head gasket on a F-150 yourself, you can get a truck like this for almost nothing.
Park the truck so that it is on a level ground with plenty of available light and ventilation. Raise the front of the truck off the ground and support it on two jack stands. Remove both front wheels with a lug wrench or socket.
Disconnect the exhaust from the exhaust manifold that is secured to the engine head you will be replacing the head gasket on. Loosen the retaining bolts on the exhaust manifold and free the manifold from the head. Tie up the hanging portion of the exhaust that was connected to the exhaust manifold before continuing.
Replace both front wheels on the truck. Lower the truck to the ground. Position a stepladder next to the truck so you can reach all the way down, almost to the bottom of the engine while standing outside the engine bay. Lay a blanket or wheelwell cover over the paint on the outside of the truck as you work.
Disconnect the air intake tube and air box. Loosen the air intake tube at the throttle body and tie it back away from the work area. Disconnect the wiring that connects to the oxygen sensor. Loosen the valve cover and lift the valve cover off the head with a blown head gasket. Remove the intake manifold. Cover the exposed parts with a clean towel and store all parts safely off to the side of the work area.
Loosen the rocker arm retaining nuts and remove all the rocker arms and push rods. Store each one so that they can be returned to the same place they were removed from when reassembling the parts. Mark a line down the side of the head onto the engine block so that you can match up the head exactly as it was before.
Loosen the head bolts in a sequence so that the head separates from the block evenly. The center top hole is #1, the center bottom #2. Move to the bolts to the right of center: the top bolt is #3, and the bottom bolt is #4. Now move to the pair of bolts to the left of #1: the top bolt is #5, and the bottom one is #6. Now move all the way to the right for the last two bolts: the top bolt is #7, and the bottom bolt is #8. The last two head bolts will be all the way to the left of the head: #9 and #10.
Clean both the engine block and the head where the two meet with a plastic scraper and carburetor cleaner to remove all dirt and residue. Align a new head gasket in place on the head and use Perma-tech sealant to hold the gasket in place and help create a high quality seal between the block and the head. Hold the head off the engine block evenly and align the head bolt holes before lowering it back onto the engine block.
Tighten the F-150 head bolts in sequence so that the head seats onto the block evenly. Start at the middle of the F-150 head. The center top hole is #1, the center bottom #2. Snug the head bolt with your fingers as you move to set each head bolt back into place. Move to the bolts to the right of center: the top bolt is #3, and the bottom bolt is #4. Now move to the pair of bolts to the left of #1. Here, the top bolt is #5, and the bottom one is #6. Now move to the right edge of the head. The top bolt is #7, and the bottom bolt is #8. The last two head bolts will be all the way to the left of the head: #9 and #10. Tighten the hex bolts in two stages in sequences: from #1 to #10 first to 60 foot-pounds, then one more pass, tightening them all to foot-pounds. Flanged head bolts require a different tightening sequence. On the first pass, tighten them to 35 foot-pounds. On the second pass, tighten them in sequence to 55 foot-pounds. On the last pass, add an extra 90 degrees to each or 1/4 turn to set the flanged head bolts correctly.
Adjust the rocker arms once you replace the push rods and rocker arms back onto their retaining studs ("lash" the valves). Tighten the rocker arm retaining nut to apply enough pressure on the push rod to be tightened by the pressure and then turn the ratchet 1/2 to 3/4 of a turn more to set the valves correctly. Oil the rocker arms, push rods and lifters at the base of the push rods before closing up the engine.
Replace the valve cover and tighten the retaining nuts. Replace the intake manifold Tighten the bolts in stages. For stage one tighten each bolt to 96 inch-pounds, 16 foot-pounds then 25 foot-pounds. Reconnect the air intake tube and oxygen sensor wiring. Raise and lower the front of the truck with the floor jack and install the exhaust manifold using a wrench to tighten the manifold nuts. Use jack stands to support the truck when lifted. Secure the front of the exhaust pipe to the exhaust manifold at the flange. A ratchet and socket work best to reach and tighten this flange.
- Tighten eight, 3-inch screws into a foot-long piece of 2x6 wood and number them one to eight. Place each rocker in order on a numbered screw head as it is removed from the valve spring assembly.
- Do not score the head or the engine where the metal meets metal. Clean this area with a plastic scraping tool to prevent damaging the surface of the engine or the head.
- Overheating is the primary cause for a blown head gasket. To prevent future damage, maintain a well running cooling system.
Items you will need
- pickup truck image by Tonda from Fotolia.com