How long should these usually last before leaking?

I had mine changed (with all PCV plumbing) approx 10k miles ago and they've started to leak quite badly from the back. Quite cheesed off that ive got to replace them again so soon. (Im pretty certain my mechanic used gaskets directly from Land Rover).

My question is ...assuming that the PCV+hoses are working ok, what could possibly cause the gaskets to blow so soon?

I'm no expert on these engines but I'm about to tackle mine next week it seem the main cause is under bonnet heat which is high compared to most engines and Cooks everything plastic and rubber under the bonnet, i will be doing the 80 degree thermostat mod at the same time and inspecting everything else while I'm there.
Just done these on a mates m62 after a rebuild less then 200 miles and there weeping getting new ones in under warranty form euros and yes followed rave and used rtv sealant where required.

Yep had mine done 10 k again pass side bank is weeping going to try tightening the bolts first Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

The manual only says to put a small amount of sealer either side of the half round cut outs but I smear the correct loctite sealer in the cut outs and along the back edge

The irony is the garage did the bank which I think is leaking the one I did is fine lol - I am going to try to source the leak and tighten bolts around it first Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

holidaychicken wrote:

The manual only says to put a small amount of sealer either side of the half round cut outs but I smear the correct loctite sealer in the cut outs and along the back edge

When this happened to my 2004 4.4 I was advised that gasket replacement might not solve the problem, and that the alternatives were a new engine or a new car. It was running fine at the time, but apparently the leakage signalled something bad. I hope yours are not in that position. Only Range Rovers since 1988

Any further details? What did you do? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

A new engine would have cost much more than the car was worth, and by the time this happened (9 1/5 yrs, 97,000 miles) the car had for some time been in a "there's aye something" money pit phase, so I traded it in for a 4.4TDV8. Unfortunately I got no details on what would happen to the engine (other than keeping blowing oil out the back) had I just kept going with it, sorry. Only Range Rovers since 1988

Oh ok - if it was blowing oil out the back that's probably a different issue I too had that which was a duff pcv but nothing to do with the rocker covers Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF