Im currently the lucky mechanic working on a 2000 land rover discovery v8. Engine was rebuilt recently (over 12 months by owner)

now posses a really bad knock. Isolated it to no 7 cylinder by unplugging the ign lead and knock goes away, which tells me its the big end bearing. I unplugged the opposite cyl. lead to see if it could be a main bearing but knock was still present. had a look underneath and ended up pulling off the sump and No 7 rod cap. Bearing looked ok but to me had too little contact area. To try describe- had a wear point on the bottom, and areas near the top where the two shells meet. I think it may have too much clearance but am waiting on some plastigage.

What do yous guys think?

anyone......

Did some of my apprenticeship on Land Rover.

Not a fault that we came accross in the workshop.

Do you know what the owner has done to the engine? Machined parts does the guy know his stuff etc ...

yeah, the engine dropped a sleeve so it was re sleeved, to match piston sizes. But recently i found out the crank was not machined but just supplied with STD bearings. We checked the clearance. Had bout 0.0025 thou. Bit on the excessive side but im not sure if its enough to cause knock. But someone has told the owner it may be a piston?

ZCompression test showed ok buy still maybe..?

Yeah guy knows a bit bout engines.

0.0025 thou. Thats about equal to 0.6mm.

Sounds a bit on the big side to me. But compare it to another cylinder or better yet, or a generic manual.

Keep in mind for yourself, some of the earlier blocks had an issue with the sleeves of the middle cylinders have been known to move.

yeah, had all sleeves redone.

Yeah apparently the max clearance is 0.5mm?

I dont want to give you the wrong information, so Ill say grab a generic workshop manual or download one if you can find one.

0.5mm sounds like a big gap.

Sorry just have to chime in here,
2 and a half thou(.0025") is equal to 0.06mm which to my way of thinking is probably not too bad. But 0.5mm or 0.6mm (approx 20 thou to 25 thou) I think would knock!!

Hope this helps

yes sorry, gap is 0.05mm. bfxr6 put me off by saying it was0.6mm.

Mic clearance .. Don't rely on plasti gauge !!

whats wrong with pastigauge???

if the crank was ground and fitting the correct bearings------dry fit plasti gauge to check the crush,running the crank may be worn with new bearings-so may not get all the clearance,gudeon pins ok,piston clearance.i think you may have to check and record all of them,to see where the crank is and to get a average of the clearances.can you get a snake camera into the spark hole?if you get any top end issues.

owner has been told it may be piston slap. Not sure bout gettin snake camera down there, will that tell you much?

can see top of pistons and any marks from valves,or any or thing that looks strange-different,with out lifting the heads off.what type of oil was used in the motor?

15 w 40

im thinking the clearance is to big and if the journals are tapered and worn its worse,mains may be ??? then the rod pins to pistons,you may have to get a spec book and measure it up,a real p-----,he tried a quick fix.

Sorry about the gap!

Ballsed up that.

Have you checked the end float on the crank since this fellow had it re-sleeved? I'd have a look at the thrust bearings to see if they have bad wear. Also measure the crank journal where the knock was worst. Possible out of round since the re-sleeve caused by a twisting motion and forces on that journal. My guess is that the motors bores are not in centre with the crank and the journals. Motor will have to come out and measure everything to make sure it's right unless you get lucky and find something simpler giving him grief.

lucky owner of disco V8.firstly dont buy one as it would cost you more than its worth.secondly,i have been tinkering with motors for many years and this ones got me stumped.cylinder 7 has the knock...piston to liner clearance 1.5 thou......suspect main bearing.....1.8 thou clearance......big end..1.5 thou clearance ....bearings look ..ok...no excessive crankshaft movement....could it be low oil pressure causing the knock??????? wrist pin was also found to be ok. any help would be greatly appreciated.
I have had to bring my xr8 out of retirement because of the unreliability of the rover.

time for an F-series EFI 351W I reckon