Well my 4.6 block just failed pressure testing in my 04 Disco II. There is a crack behind one of the liners.

I need a block that has no coolant channel leaks, or any cracks in the cylinder liner walls.

Let me know if you have any laying around or from a part out Disco. My plan is to just pin and Loctite the new block.

Thanks.

 

If it were me, I would buy a 4.0L block, and swap over the rotating assembly. The 4.0L block is worlds more reliable, and identical to the 4.6L block, save for the poor machining and casting.

 

According to the book "how to power tune your rover", the 4.6 blocks are superior.

After sand casting the block's walls are measured for thickness. The blocks with the thickest walls are marked with a red paint daub in the valley. Blocks with walls that had the medium range of thickness were designated yellow. The thinnest walls were given a blue rating.

All 4.6 engines were made from red grade, unless red was not available, then yellow was used. All 4.0 engines were made with blue, unless not available, then yellow was used.

I have heard that the high rate of failure on the 4.6s is due to the extra pressure based on larger explosion in the chambers.

Good luck.

 

I have also read that the later produced blocks had more problems with slipped liners because the tooling used was getting old and the tolerances were not as tight.

Knigtmetro: how did you pressure test the block? I'm curious about the method.

RacerX: are you referring to the crank, rods, and pistons when you say rotating assembly?

Thanks

 

I put block plates on all the cooling channels and fitted an air line to one of the plates. Just a drilled piece of aluminum and a flat piece of rubber underneath to seal.

Cranked it up to 40PSI, and that's when you can see if you have any leaks. A little soap can help around edges of the liner top if it's not immediately apparent. It'll make pretty bubbles. You can also fill the block with water, pressurize, then look for water leaking out of anywhere.

Mine showed itself right off the bat when water started working its way out the top of the liner.

 

So this was done on a bare block correct?

Would you be interested in fabbing up a set of block off plates and a plate with rubber for the air? I would buy it and also saw somewhere in the wanted section someone looking.

Let me know.

 

Still looking for a 4.0/4.6 bare block.

 

I have them. Are you still in AK?

 

Yep, still in AK. Still frozen.

 

I have a 4.6 block in Seattle. Shoot me a PM if your interested.