I have a '91 Exploder and it taps pretty loud when it's cold. The tapping is cyclical adn quiets down (but doesn't go away) when it's warm. It's high pitched and sounds like the lifters. The oil pressure is good and I change the oil regularly, but I've only had the truck for a year. It's got 160K on it and runs really well otherwise. My question is what makes the noise cycle? It gets louder and softer! A friend who is a ford tech suggests a bent pushrod.

 

try replacing rocker arm and pushrods
I have a 91 also with the same problem and that's what I did to correct mine

 

I have a 91 Explorer and this is probably the most common problem with the engine. It's the pushrods, not bend, but the tips of the rods are probably very worn. I just had my fixed ($3/rod X 12) and had the rocker arm assemblies ($23 X 2).

 

I have a 4.0 in my 91 Aerostar, I'm assuming it's the same engine. It always tapped , but the oil pump went and I thought that replacing the pump would help, but nope, the tapping is even louder. Seems like it is just one cylinder tapping. After reading this post I'm thinking that if it's the same engin then the same fix should work. Yes? Any help would be appreciated. My mechanic old me that the cam would have to be replaced, and that I would need new lifters and he's saying $1500 on the low end. Any and all advice is appreciated.

 

Airstream_peddler: If it's your lifters, $1500 is a fair estimate. The gaskets for the 4.0 are expensive. I think mine were $400 when I did my lifters about 6 months ago. Your problem could be lifters - I'd try an engine additive to free stuck lifters. If that doesn't work and your mechanically inclined, pull the valve covers and inspect the rocker assembly, or better yet, pull it. Check the push rod tips. If they're worn, you may have found your problem. Mine were so bad when the rocker assembly was pulled, two of the rods were stuck into the assembly. The tips were sharp and three sided (should be round).

 

Thanks for the post ssayers. I just today put in a bottle of Lucas (was recomended by two mechanics). Drove it, but no joy, still loud tapping. Looks like next step will be pulling the valve covers and checking the rocker arm assemblies. I have been dreading this bcause in the Aerostar getting to the rocker arms is no easy task, but, it is the next logical step. Thanks for your post and advice. Much appreciated.

 

Anyone know who has the best (cheapest) price on a set of lifters for a 1991 4.0L explorer.
Thanks

 

Good news, guys! I replaced the pushrods and rocker arms and the noise went away completely!!

 

Congradulations. I just have a few questions for you. How much did it cost? How long did it take? Also, how big of a headache is it?

Chris

 

the cost was about $250; $3 apeice for pushrods, $13 each for the rocker arms, $28 for the gaskets. The job is kind of a pain, but not so bad. The rocker covers are under a bunch of wires and hoses. On the passenger side, the coil pack must come off. On the driver's side, the a/c compressor must be unbolted to be moved, but no lines were opened. Also on the driver's side, the vacuum lines and port were removed to gain access to the rear bolts on the cover. The job took about 5 hours. When you have the rocker shafts off the engine, it's kind of tricky to get the rocker arms off the shaft. I put the middle bolt through the shaft and tightened a nut on it and clamped that in a vise between two small plywood pieces. This held the rocker shaft so that I could use a hand clamp to twist and remove the mounting towers on either end. Then I used a wire wheel on a bench grinder to remove the gunk on the shaft where the spring is; then the remaining rocker arms will slide right off. If you work with a friend, don't use screwdrivers in either hole in the shaft to twist, the shafts are soft and will be deformed by the twisting screwdrivers. I know, that's how we did the first one and we had to file and stone the shaft to get anything back on! On the lighter side, my engine is so quiet now, that if you're sitting on the rear bumper, you might not know if it's running or not. Very much worth the money. Also, I changed the oil and am running full synthetic 5W-30. Hopefully this will keep the valvetrain in good shape in the future.

 

Sbk510,
How about coming up to Pennsylvania and fixing my 4.0, I like a man with experience. Besides I'm still recovering from swapping the 4.0 in my B2. I broke all of my nails.
http://home.comcast.net/~kmfrederico/ <---Bronco II Swap