99 4.6L Head Gasket Leak
 

My '99 F150 has 120K miles on it and is great overall shape for a 20 year old truck. However, I've found that the passenger side cylinder head is leaking oil towards the rear of the head. Thankfully no signs of coolant loss or contamination in the oil.

So, my plan of attack is:

1. Coolant flush (since it will have to be drained anyway)
2. Replace Waterpump (since I will have the engine apart anyway)
3. Degrease (i.e. clean up) the heads, valve covers, and intake
4. Replace gaskets and seals

This is just a daily driver / putt around truck, but I would like to increase the power under the curve to make it a bit more pleasant to drive. The pig is sluggish. Does anyone have suggestions on worth while upgrades while I've got the engine torn down? Considered doing a PI swap, but was told the gains probably wouldn't be worth the money and effort.

According to this
https://fordcobraengines.com/ford-mo...r-differences/

some 99 4.6 engines got the PI heads.

A superchips tune did wonders for the power and throttle response on my 2002 5.4. I would recommend it especially since you can buy a used 1715 cheap. Just make sure it's not vin locked because Superchips does not support these any more. If you want power, a lower rear gear will make the most difference in getting power to the ground.

That's interesting, I have always been under the impression that the F150 didn't receive the PI package at all until 2001. Time to verify what I'm already working with. Thanks for sharing.

You are correct - for the 4.6. The 5.4 went PI in 99.

Other than doing a PI or 5.4 swap, a programmer and some good custom tunes would be the best improvement for the money. Regearing can get costly but would make a big difference, you would also need to reprogram for the gears.

our 03 5.4 has that same leak, loses about half a quart in 4k miles and it has for over 100k miles and not got any worse.
now at 355k it seems silly to repair it.