4.0 update

We got the motor out of the wife's pickup last night,finally! We were too beat to tear it down,but with the tappet cover off the right side,we can see that it's not the timing chain or guide,the gear is off the end of the jackshaft.
Don't know if a key sheared,or the nut came off if it has one,or what happened. The boy is bringing the engine stand back home after he gets out of work tonight and we'll tear in to it. Looks like just one of those freak things that happens,not excessive wear.

Can't really tell about the wear until you tear it down, right? Could be wear that caused the gear to come off in an indirect way......will be interesting to hear how it looks after you get it apart.

And with the valves not moving on that side, it might have suffered valve to piston contact.........

Freak things do happen.

A buddy of mine had a cam bearing work loose in a 3.8 engine in a Pontiac Bonneville and cause an oil pressure problem.

Nobody had ever heard of that happening on a 3.8 before, and that included all of the techs at several GM dealers. He's a full time farmer now, but he was a GM tech himself at one time.

That is part of the problem, there is, no, key. 1 bolt goes through that jackshaft, and holds all of the gears together, no key, that 1 bolt takes care of all 3 timing chains, and the chain to the anti vibration device.

I can attest to crazy things happening to engines. I had an 89 Chevy 3/4 ton with a 350. I was driving down the road one day in overdriven when I heard a heck of a noise. Engine was still running and knocking and had no oil pressure. The crankshaft broke clean into at the front main. The only thing holding it on was the timing cover.

Look at this TSB. Says only 6 hrs to replace all these parts! Better hurry!
Ha Ha Ha!

*Engine - 4.0L SOHC - Rattle noise from primary chain drive area between 2K-3K RPM - Cold engine operation only

*Noise - Rattle noise from primary timing chain drive area between 2K-3K RPM - Cold engine operation only - vehicles equipped with 4.0L SOHC Engine only

Ford: 99-02 Explorer, 01-02 Sport Trac, Explorer Sport, Ranger
Mercury: 99-02 Mountaineer

Issue:

Some vehicles equipped with the 4.0 SOHC (Single Over-Head Cam) engine may exhibit a Primary Timing Chain rattle noise. The noise is audible during hot and cold engine operation (but predominantly found on cold engines) under acceleration, typically at 2400-2500 rpm. To confirm presence of this noise, accelerate in 2nd gear between 2000-3000 rpm and listen for rattle noise that sounds similar to spark knock. This may be caused by the Primary Timing Chain Tensioner system.

Action:

Replace the Primary Timing Chain Tensioner, Chain Guide, Jackshaft, and Crankshaft Sprockets with a Primary Timing Chain Tensioner Kit. The kit includes an improved Primary Chain Tensioner, as well as updated Primary Chain Guide, Jackshaft, and Crankshaft Sprockets. Required fastners, primary timing chain, and front cover gaskets are also included. Refer to the following Service Procedure for details.

Service Procedure:

Verify the condition. Obtain the correct kit and follow the sheet supplied with the kit.

Use kit 2U3Z-6D256-AA (balance shaft engines) for:
-99-01 4x4 Explorer/Mountaineer
-01-02 4x4 Sport/Sport Trac
-All 02 Explorer/Mountaineer, except engine codes 2G-960-AA and 2G-964-AA

Use kit 2U3Z-6D256-BA (non blance shaft engines) for:
-99-01 4x2 Explorer/Mountaineer
-01-02 4x2 Sport/Sport Trac
-02 Explorer/Mountaineer with engine codes 2G-960-AA and 2G-964-AA
-All 2001-02 Ranger

Labor Time: Estimated around 6 hours

Ya,we're thinking it's likely.

theres no keyways on anything in that engine I don't think, including the front harmonic balancer and sprocket, if you loosen the balancer bolt , which is a torque to yield bolt, and crank that baby over, you just knocked it out of time. Not do it yourself friendly engine by any means.

It's been about a year but I recall a key on the crankshaft but no keys or dowels beyond that. It's all clamping friction.

There are slots in the ends of the cams. It's in time when they are parallel with the head but if you don't pay attention you could be 180 out.

This was a 2002. I was told I needed $200 worth of fixtures to time it. I told him no you don't. It runs too good to be off.

RT (my 2 cents)