I recently purchased a used 1989 Ford F150 XTL Lariat with a 5.0L V8 as my first project car. The truck has 175000 miles. I have decent mechanical experience but this is my first true dive into car mechanical diagnosis and repair. The truck has two main issues I am hoping some to get some valuable feedback about through this forum. The first being a misfire in cylinder 8. I did a leak down test and found it has no compression, when pressurized the only air leaking I noticed was into cylinder 7. My assumption is a head gasket leak? Which I plan to soon replace. I haven't noticed any coolant and oil mixing. First wondering what are some other decently easy things to replace while I am in the engine. Yesterday I tried to drain and flush the cooling system. Started by pulling the drain plug on the radiator with the radiator cap open. I drained until it stopped then started the truck with the heat blasting to push anything left, but in total only about a half a gallon came out the truck. I tried to refill to begin flushing, filling from the radiator cap and then starting the truck to release air bubbles and continue filling. I only got about a gallon in the system total. Even after idling for about half and hour the truck appeared to remain full with me only putting just under a gallon in. I am wondering why there appears to be such little coolant? Could it be related to the head gasket leak? I have never had overheating problems even driving for about an hour non stop. Temperatures remained normal while idling. Not sure if I drained incorrectly or what the problem may be.

The second issue deals with the transmission. This I have done nothing yet to diagnosis. When driving the truck shakes pretty hard between gears like 2nd to 3rd and above. Transmission fluid levels are good and the fluid appears to be a decent color. It has been getting slightly worse recently. If you give it a little gas it seems to get into the next gear faster. They guy I bought the truck from says this is common for old ford AOD transmissions? Not sure where to start to fix this problem or if it would be worth to just explore replacing/rebuilding it. Everything mechanical on the truck is stock, just looking to get it riding comfortable and stay that way for as long as I can. Any help is appreciated. I know this is a lot but any answers I am grateful for. Thanks!

 

To get all the coolant out you would have to remove the engine block drain plugs as well as the radiator drain plug. There is a drain plug on each side of the block on a V8 engine.

Just draining the radiator as you did I would guess it should have taken maybe around 2 and a half gallon to refill it. Are you sure the drain hole on your radiator drain didn't plug up part way drained? Also some engines can be a beast to get coolant into them after being drained or even partially drained, but it sounds like you ran it long enough to see.

 

At 175k I would replace the oil pump and the timing chain (2 separate procedures so I would wait but plan)
When you get the heads off look closely at the rear cylinders exhaust valves (the metal mites like to eat those rear cylinder exhaust valves)
Cylinder #7 should be missing too if the head gaskst is blown between the two cylinders
Double check where that air is going with cylinder 8 at TDC on the firing stroke
You are right that if coming out 7 it is a blown head gasket, just check the valves sealing with some Brakleen for GPs

 

Shaking with speed could be tire coming apart, bent rim, bad ujount, etc. Start with easy stuff. Also verify TV cable operation and correctly adjusted (easy).

Keep it out of OD around town. Saves it from needless wear on 4-3 and 4-2 downshifts.