1997 4.6 with 247,000. For the past few week on starting after sitting for a few days, things were rough - that is the starter seemed to run up to a point and then stop, almost like it was jamming. Once had to turn the motor by hand to free things up. After it was running it would run well, and startup fine the next trip ( which made me kind of ignore things). My guess was that there were some broken teeth on the flywheel (probably a bad guess).

Today after a few tries it started up and now makes a hideous clatter from the passenger side top end. I am assuming a broken something in there? Any ideas that it might be something manageable.

The truck body is not in great shape, everything is rather beat up and old - but I would like to get a few more months out of it. But a new motor or even a rebuilt of the top end probably does not make sense.

Any thoughts appreciated.

 

Remove the cam cover. See whats going on in there..

 

I had a similar sound, it turned out to be the PCV (pressure control valve) on the top of the passenger valve cover. You will feel a lot of vibration in the hose if this is the problem.

 

PCV = positive crankcase ventilation, not pressure control valve. A bad PCV can cause issues, but nothing like that.

 

Now I have had time to poke around some more - and let it run for a little while since it doesn't seem to get worse - I now think that the noise might actually becoming from the back of the engine, maybe from the flywheel area, and could be related to the starter issue noted earlier. Thanks for everyone's input and I will update when I take the starter out and see if I can see anything.

 

The easiest way to remove the starter is to jack up the truck
Remove right front tire
Remove inner fender well about 6 screws and push pins
Remove starter
Use a long extension with flex joint to remove top bolt next to the block

 

The starter looked good and I did not see broken teeth on the flexplate - but this point everything is pointing to a broken (I think). The noise seems to be coming from that area, the noise appeared suddenly, the engine runs just fine, and the starter issues got worse/different right when the noise started. The noise is the same when under load as it is idling. Anyway that is where I will look next.