Fixing Ford's 2.9: The Solid Lifter Conversion

1988 Ford Ranger Stx 4x4 2.9l V6 5 speed

I picked up this 1988 Ranger Stx 4x4 to use as a winter truck back in January of 2011 after finding it tucked away behind a small dealership. It had 260,000 miles and a misfire but I picked it up cheap, drove it home, and proceeded to tear it apart.


I started with a tune-up with new sparkplugs, ignition wires, distributor cap and rotor, but the misfire lingered. A compression check quickly revealed a cylinder with almost no compression. I bought a new head casting and went to work.

I found the left head had cracked and a valve had burned. After replacing it with a new recast it ran reasonably well but still had an odd problem: at stoplights it would load up and smoke black and while going down the freeway the valves would start to clatter. Hours of internet research revealed this was not a new problem and many, many other people had similar issues. Some believed it was overall oil pressure, some that it's caused by cam bearings letting too much oil past, others that the lifter bores are worn, and on and on. It appeared oil pressure was a factor no matter what, so I bought an oil pump and began the awful job of replacing it with the engine in. A video of my truck loading up at idle:

When I got the old pump out I was shocked to find the pickup screen completely clogged with sludge. I removed it from the pump and tried to clean it but couldn't get the screen cleared through the tiny hole in the pickup shield so I pried out the shield and screen, cleaned the screen by hand, then reinstalled it without the shield. With the pickup modified and ready I disassembled the old oil pump just to see how bad it was. sure enough the inside was badly scarred and the vanes were nicked. No small wonder it had oil pressure problems.

The clogged oil pickup

The gouged oil pump cover

Many dirty hours later I had a new oil pump and an autometer pressure gauge under the dash. Firing the engine revealed great oil pressure, over 50psi, but still there was clatter on the freeway and loading up at stoplights.

The loading up is really what confused me and it took me a bit before I finally realized what was happening: The lifters were collapsing at idle and the ECU was injecting fuel assuming it had a consistent amount of air going into the cylinder. Once the intake lifters had started to collapse the airflow was cut off and there was too much fuel. The ECU would try to correct for the drop in idle speed by opening the Idle Air Control and adding fuel, which only made things worse. This loop would continue until the engine was so loaded up it finally stalled.

Now you have to understand something about Ford's 2.9 v6. It's design goes back a ways and in a previous generation it was 2.8L and had a gear-driven solid lifter cam. This required lash adjusters on the rocker arms to set the gap between the rocker and the valve stem. When the 2.9 was created these parts were carried over even though they were not needed given the 2.9L's hydraulic lifters. but these adjustable rocker arms make this modification possible.

My 2.9's valvetrain. Note the hex-headed lash adjusters on the rocker arms.

I originally thought I would convert my 2.9 back to solid lifters using parts made for the 2.8 but after some research this proved to be problematic. I then thought about cranking the adjusters all the way in to compress the lifters and make them act solid. After making a trial run I quickly realized this would not work either. Finally I bought a single speed pro lifter from Napa and disassembled it to figure out how to make this possible. I took the unit apart and using precision measuring tools I gauged the inside diameters, heights, and lengths of the various parts. I then went online and began searching for hardened washers that might fit inside the lifter replacing the spring and check ball and acting as spacers.

After much searching I finally found a Metric tool and die washer that was through hardened and ground flat, that would fit perfectly inside the lifter turn them into solid lifters. These shims ended up not quite thick enough to perfectly match the original piston height but the lash adjusters easily made up the rest.

The piece that makes this all possible. Grainger #5RU10 hardened and ground tool and die washer

I purchased three five-packs of washers and went to work. The entire top end of the motor must be stripped down and both heads MUST come off. There is absolutely no way to do this without first removing the lower intake manifold and both heads. Once that was done I removed the lifters from their bores one at a time and disassembled them. I removed the check ball, its cage, and its tension spring. I also removed the secondary tension spring. I then inserted a single washer into the lifter body and replaced the piston and cup. I reinstalled each lifter back into the bore it came from.

The lifter in factory assembly. The large and small springs as well as the check ball and cup will not be reused.

The lifter assembly sequence with washer.

Everything went back together smoothly from this point and when I reached the point of adjusting valves I set them to the 2.8 valve lash specs.

Finally came the moment of truth and I started the truck. It fired right up and sounded strong with no surging or loading up during idle. The only noise that was different was a slight mechanical clatter that sounds kind of like a sewing machine. After purging air from the cooling system and making sure everything was tight I took the truck around the block. It ran great compared to before and now felt like it had some pep. I jumped on the freeway and was very pleased to find it had much more power now that the lifters could not collapse.

I personally believe that the collapsing lifter problems are created by failed check balls in the lifter, most likely due to weak check springs letting the ball bounce off the seat as the lifter moves up and down.

Over the next six months I would log several thousand miles on this setup with absolutely no problems. For having nearly 300,000 miles it ran pretty darn good. Finally I bought a newer F-150 and no longer needed the ranger so I put it up for sale. As far as I know it continues to run with this lifter conversion in place.