How to Replace the Motor Mounts on a 1997 F-150

For a ninth- or tenth-generation truck, the mount replacement procedure is basically the same.

Engine mounts aren't the most glorious parts on a truck, but they do perform an important job and will manifest some noticeable results when they fail. Big V-8 and diesel engines like those used in the ninth- and tenth-generation F-150 (both produced during 1997) transmit quite a bit of torque to the frame, and the truck's rubber motor mounts must compress to absorb this torque on a consistent basis. This compression -- combined with constant vibrations from the engine -- produces heat, which eventually causes the rubber to break down and fail. The result: an engine that dances the fandango every time you hit the gas.

Things You'll Need

• Basic hand tools
• Floor jack
• Block of wood
• Carburetor cleaner or degreaser
• Lint-free rag
• Medium-strength (blue) threadlocker
• Torque wrench

Instructions

1. Set the truck's parking brake and kick a set of wheel chocks ahead of and behind the rear tires. Loosen the leg nuts on the front wheels. Slide a jack under the driver-side frame rail, lift the truck until the tire just dangles off the ground then lower the frame onto a jack stand. Remove the wheel and repeat on the passenger-side front wheel.

2. Crawl under the transmission to identify the bolts that secure the transmission mount to the crossmember. Loosen the bolts by three to four threads. Don't remove them completely; just loosen them a bit so the transmission can tilt upward.

3. Place a large wooden block on top of the jack pad, and slide the jack under the passenger side of the engine's oil pan, just off center. Slowly raise the jack until the wood comes into contact with the oil pan, then lift it another quarter-inch to ensure the jack is taking the weight of the engine.

4. Reach through the wheel opening to identify the lateral (front-to-back) facing through-bolt that connects the motor mount to the frame mount. To ease removal, consider liberally spraying the nut and threads with penetrating oil and allowing it to sit for 20 minutes to an hour.

5. Remove the nut from the through-bolt, then tap the bolt out from the threaded end with a hammer. Once you get it halfway out, you may find it easiest to lock a set of large vice-grip pliers onto the bolt shaft just below the head and tap the pliers with a hammer to remove the bolt. If it's really stuck, play with the jack height and tension to release it.

6. Slowly jack the engine up by 2 to 3 inches or by as much clearance as available. Have an assistant keep an eye on the engine from above to ensure that it's not hitting anything important. On the driver side, keep an eye on the power brake booster and steering column, both of which are fairly close to the engine. On the passenger side, watch the heater core housing and the electrical box on the firewall. On top, watch the airbox and remove it if necessary. The engine will pivot upward on the driver-side bolt, providing enough clearance to get the passenger-side motor mount out.

7. Identify the four bolts that secure the motor mount to the engine block; you may need to scrape away a layer of grease and gunk to find them, but trust they are there. Once you have the motor mount off, clean the block's mating surface with a gasket scraper and some degreaser/carb cleaner. Keep the gunk out of the mount's bolt holes, then spray carb cleaner into the holes and sop up what runs out. Clean the bolts thoroughly.

8. Place a drop of blue (medium-strength) threadlocker on the threads of the four motor mount bolts. Do not use high-strength threadlocker unless you expect the new motor mounts to last forever. Install the motor mount and the four bolts hand-tight, then torque them to 45 foot-pounds. Apply a dab of grease to the ends of the rubber mounts to prevent squeaking.

9. Slowly lower the jack to realign the through-bolt holes in the chassis mount and the motor mount. Once you get them roughly aligned, tap the bolt through with a hammer. But don't force the bolt if it doesn't want to go; play with the jack height and tension until the bolt slips through. Forcing the bolt can damage the engine mount, the chassis mount and the bolt threads.

10. Use a lint-free rag to wipe any grease off of the bolt threads, then clean them with carb cleaner. A completely clean and dry surface is necessary for the threadlocker to work. Once you've cleaned the bolt threads, place two drops of medium-strength threadlocker on the threads and tighten the nut to 150 foot-pounds.

11. Repeat on the other side. You may need to remove the starter or the power steering pump, depending upon which transmission you have and which direction the bolt is facing. You'll have to use some discretion here; the two generations of F-150 produced during the 1997 model year used nine different transmissions and eight different engines, and the specifics differ for all of them. You can reinstall the through-bolts from either direction -- whichever leaves enough room to get the bolt in and tap it with a hammer. When you're finished, reinstall the wheels, tighten the transmission-mount bolts to 80 foot-pounds and lower the truck.

Tips & Warnings

• Technically, you're supposed to use an engine lift and attach the chains to the lift hooks on top of the engine. But the jack method is time-tested, works fine for this application and is far easier than hauling out that heavy cherry-picker -- assuming that you even have one.

• If you don't have the clearance to tap the through-bolt in with a hammer, you can accomplish the same thing by placing the flat of a large chisel on the bolt head and tapping the chisel with a hammer.

• You don't actually need motor mounts -- at least, not flexible, rubber ones. Solid polyurethane mounts cost about the same as rubber mounts, install the same way and will instantly transmit all of your engine's torque to the transmission. The result is instant throttle response that you're just not going to get any other way. Of course, those solid mounts will also transmit every bit of engine vibration straight into the chassis, but if you don't mind the vibration, then you'll likely find your truck a pleasantly changed beast. If you don't want to pay for poly mounts, the alternative here is to weld (with the engine in place) quarter-inch plate steel in between the tops and bottoms of the engine mount and chassis mount.

References

• "Haynes Repair Manual: Ford Full-size Pickups and Bronco, 1980 through 1996"; Haynes Publishers; 1998
• "Haynes Repair Manual: Ford Pick-Ups and Expedition, 1997 through 1999"; Haynes Repair Manual; 2001