Hey fellas . I got a 2002 F250 5.4l with 219k KM on it . I've lost compression in cylinder 8 and losing it in cylinder 3. Just looking for some input on what it could be and if any of you have any tips on removing the heads with out taking the cab off or pulling the engine . Thanks !

 

Do a wet a dry and a leak down test to pinpoint the problem.

A dry compression test is performed on the suspect cylinder. If the cylinder’s compression is found to be below specifications, oil is injected. Introducing oil to a cylinder with worn piston rings increases the cylinder's compression. The oil fills the gap between the ring and cylinder wall. If there's no increase after adding oil, an intake or exhaust valve is faulty.
Worn piston rings / cylinder walls: After running the first test, squirt 2 oz. of oil into the cylinder and rotate the crankshaft three more turns per cylinder. If the compression increases, the piston rings are at fault.

Burned valves: If results remain the same after injecting oil, one of the valves are bad or not seating correctly. Low compression in only one cylinder typically indicates a bad valve. Exhaust valves burn due to hot gases passing through. Intake valves have the advantage of being cooled by the incoming fuel.

Leak down test; this test pinpoints specific leakage.
Leak from crankcase indicates the piston rings are not sealing or a burnt piston.
Leak from the air intake indicates a bent or burnt intake valve.
Exhaust leaks from the exhaust manifold or muffler indicates a bent or burnt exhaust valve.
Leak from the radiator indicates a leaking gasket or cracked cylinder head or block.
If air is leaking from the companion cylinder it indicates a blown head gasket.

Even with methodical service as in regular oil changes since day one it may simply be a tired engine. You’re at or close to life expectancy of a gas engine.

 

^Great info right there. I have to ask though, how is 219,000 KM close to engine life expectancy?

My 99 f250 5.4L has 307,000 M on it and still runs like a champ.

 

Ahhh didnt catch kilometers was thinking miles. 130K miles or 219 kilometers on a gas engine is nothing. There must be a mechanical problem or it was really neglected.

200K miles out of a gaser is ok with routine maintenance. At 200K miles your nearly 2/3 or more done(IMO). 300K miles you are in the minority with gas. Diesel not so. It takes methodical service to get a gas to go 300K miles and still be healthy. Most do not do methodical maintenance.

 

Understood, and I agree for the most part. I really like the design of the modular engines and I believe they can last a long time if they arent neglected. I did just do valve seals, timing components, and an alternator on mine.

I agree about OP's truck, has to be a mechanical failure.