Thread: sick 4.6 not fully sick, just sick

Sounds like a few problems there, all may not be due to the same thing.

Water in a cylinder of a 4.6 would make me think slipped liner. The change of heads without block work can mean two things, one it was checked and found to be ok or two it was too much work to fix and they just put the heads on and hoped that it would not show enough signs before it was moved onto someone else.

Low oil pressure makes me think worn big end bearings which we would have a better idea about if you tolds us how many km the motor has done.

Resident gas expert is beeutey on this forum so he might come along and help out with your gas problems.

I think if you want to rebuild you will have to pull it down to see the extent of the problem with regard to slipped liner or head gasket issues. Lowe oil pressure is ussually a wear problem, there could be something on the pump side of things but I'd get that checked just to rule it out but otherwise it is just main and big end bearings as a minimum.

I am no LR V8 expert but I think that the blocks of the V8 around the time of the 4.6 are the same it is just a case of bore and stroke, the bigger the bore the less material left on the water jackets.

Cheers

Hi deano
Backfires on gas are either
1. too much plug gap, they should not exceed 0.7mm gap, 0.6mm is fine.
2. Plug leads should be in A1 condition and not bundled together, keep separators between them.
3. Coil pack has failed and you need another one. Chinese cheapie coils (ACA) are garbage and fail quickly. Use genuine only.
4. Head gasket failing between two pots, probably need another engine.
Also lean mixtures due to broken hoses around air intake always makes backfiring more likely if the plugs/leads aren't adjusted properly.

All P38/D2 blocks can slip liners and crack blocks. Best method is to have new flanged/top hat liners installed, then it will last longest. This is expensive but.
Also consider getting vapour injected gas installed, generally no way massive backfires can happen with this type of system.

thanks slug burner and beeuty, the engine has done 270,000 k's, cooked twice that i know of.Head gasket went the second time.went to get heads checked and were too soft to reuse, thats why i put new ones on.Been going through a hard time money wise so even new heads nearly killed me.I replaced the coils but appear to be working fine.the cyl with brown plug was brown with old coils too so would have to be a bad coincidence.A mechanic friend thinks the plug faied in that cyl when was found to be wet, i replaced it with another and has not been wet again, just brown.I will have to pull all plugs out and check them all again.Money is a real issue so want to try and get it to last till after xmas.....maybe santa will bring me a gass injection system upgrade as that would solve a few problems until i can rebuild the motor...properly this time.I am having to run that oil treatment stuff to keep oil pressure up a bit and is very noisy on start up, very slight big end knock.I have an offer to buy and pay off a 4.0 to run while i fix the 4.6 .can you see any issues i might have with this.Thanks again guys, i know im a bit of a nut but i like this car and would like to keep it.

deano