I have a 94 F -150 2x4 with a 4.9L inline six with 78,000 miles on it.

When accelerating hard or lightly and going up hills it has a ticking sound like a diesel that's not real loud but drives you nuts after awhile. I was told by just friends it may be a sticky valve or a small exhaust leak.

Can't see it being those because the motor sound quite and smooth at idle and and even while revving in park. Cant find a exhaust leak because it dose not make the noise when idling.

The ticking seem to come more from the lower passenger's side when driving. I even tried High octane gas to see if its a fuel grade pinging issue but it did not seem to quite it down.

Any suggestions will be looked into believe me.

 

probably is an exhaust leak that only occurs when the engine is under load. The exhaust route goes right under the passenger side of the vehicle so that make it even ore possible that, that is the problem

 

It is a leak from the air tubes that screw into the head, probably #6.

 

I had the same problem, and it was the air tube. It aint cheap to fix.

 

If I just say "The F%*# with it" will it hurt anything?

 

I had the same problem on my 95. It was the air injection tube #6. If you have access to a wire feed welder it is a cheap fix assuming the tube is not rusted out. Pain to take everything apart just to get to it. I took the whole rail off to fix it.

 

Sometimes hard to tell where a sound really is coming from. I had a ticking like that and it turned out to be a spark plug that was just a tad loose. Easy to check--if it wiggles, it's the culprit.

 

I agree paul, i had problems with loose spark plugs the first day after i bought my truck. 4 out of 6 of them were loose, and they were causing a ticking sound.

 

If everything else fails (spark plugs, air tubes, exhaust leak) check if your lifters are knocking.