dzelanko

Ive got a 97 f150, 4.6 that had 50-60lb in 2 of the cylinders, so i decided to do an engine swap. we decided to go with a 2003 grand marquis motor, and swapped parts accordingly to make things work. Now, after the swap, and putting 700 miles on the motor (while noticing the valves were chattering) the marquis motor lost compression in 6&7, and appeared to need a head gasket replacement. After the replacement, the truck has only gained 20LB for a total of 65lb average in the 2. What next steps should i take to resolve this? the gentleman that is performing the work seems to be leaning toward rings, since the cyl wall had slight rust residue (wiped right out). any indications of what it could possibly be?

Manuellabour247

Have you had the heads checked or done a leak down test?

dzelanko

We had the heads tested, and they were perfect. Only required slight resurfacing. Have not done a leak test, but once I get a tester it will be tested.

Manuellabour247

The other thing is pull your plugs and check them. Might have loosened up and not be tight. Check for carbon build up around the hole.

dzelanko

we have checked most minor things, unfortunately.

dzelanko

Update:

We completed a leak down test, and the air was coming from the tail pipe.... Am i looking at valve troubles???

Manuellabour247

Have you scoped the cylinder to see if the valve might be bent? Might not be that bad.