Hey guys,

I just picked up a 03 Disco 4.6l from a friend who could never seem to fix it.
After pulling the plugs I noticed cylinder one has oil in it and the compression is only 62 where all the others are between 171 and 175 on average.
Any help on where I need to start on fixing this problem?

Only one code p301... This code comes and goes while driving...
truck starts right up idels @ 675-750 runs fine just has a lack of power.

 

301 is misfire on cylinder 1. Under valve cover you could exam the rocker arms. And there is always head gaskets.

 

Is it common to only have one cylinder lose compression?

 

Probably not uniform wear, like all rings. If you pour in about 2 table spoons of oil in the cylinder, and repeat test. If PSI goes up, rings. If not, valves or gasket.

 

I'll do that and a leak down test tomorrow.

 

You may have pressure in your cooling system from Cylinder #1.
The water jacket is near by in the head itself

There is a small opening in the block...



You can see the water jacket on BOTH sides of the head which can pressurize if the head gasket is bad

 

Did the compression test again when adding the oil to the cylinder nothing changed.
Leak Down test allowed air back up into the intake.
I'm now thinking broke spring or cracked valve.
still not sure why I had oil in the cylinder to start with when the rest were fairly dry.

 

Time to pull the valve cover and inspect from there down to the head gaskets. With oil in the cylinder an oil ring problem be also be causing this.
Let us know what you find.

 

Can the oil pan on this truck be pulled easily with out alot of effort?
It has a small leak as well and I figured I might as well take care of it too.

 

Yes, pretty easily. If you are planning on pulling the pan, might want to also pull the front cover to inspect the timing chain and oil pump since at your miles one or both may be showing some wear.