Vehicle & Technical > Discovery

Knocking V8

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bogie:
The followers are turning mate.

Range Rover Blues:
If you change them now the engine may be better for a while.  V8 followers are an odd thing, the cam lobe is ground non=parallel so that the follower is made to spin by the action of the cam lobe running off-centre.

The followers wear around the edges and rthe cam lobes wear along the edge, you can sometimes see a dirty mark where it wears.  This makes the follower contact patch move towards the middle of the follower.

Camshafts and followers wear together, a badly worn follower or followers almost certainly mean a worn cam too and often swapping followers is a false economy.

Talking of which, excessive fule consumption is often the first sign of cam wear!

Anyway, if your followers are sticking some of the time then spinning again you might be able to eek a year or so out of the existing cam by just swapping the followers, be warned though that the cheaper ones have a high fault rate, RPI now only supply OEM.


It is important that the follower spins because the spinning action makes it scoop up oil (apparently) which fills the follower making it expand to take up the valve clearence, not being full of oil makes the clearence too great and effects both valve lift and timing, hence the poor economy often experienced.

denzil:
I think I will have to bite the bullet and strip the top end of my engine and see what has happend.I have a K&N cone filter to fit, when
I get a chance I intend to fit a sports exhaust with four branch manifolds. Suggestions as to the best cam to refit with this set up
would be appreciated.

Regards Doug

MuddyMike:
How many miles has the engine done on the current cam? Has the oil been changed regularly? Both these questions are important because Rover V8s eat camshafts and followers if the oil is not regularly changed. If the cam has less than 60,000 on it and the oil has been changed regularly your problem may simply be sticky followers. This is quite common on Rover V8s that have stood idle for a while and can often be cured with a thorough flush.

For flushing add a liter of ATF to the engine oil (if the oil level is already high you should drain some off first) then take it for a steady run, at least 30 miles. Then change the oil and filter.

Does the engine have good oil pressure? Low oil pressure is another cause of noisy cam followers and can only be cured by re building the oil pump. These pumps use a pair of steel impellers in an aluminium  housing. Grit gets embedded into the aluminium  and wears the steel impellers, so both often need changing.

If new followers are needed you should change the cam and oil pump whilst the engine is stripped down, and if you are doing all that you might as well replace the timing gears and chain as well.

Mike

denzil:
Hi Mike
Thanks for the reply, milage is about 118,000 I have got some service history not all , so its difficult to say how well its been looked after.I take your point I will change the oil pump and followers also take the heads off and regrind the valve seats.What cam do you
suggest I refit standard or other?.

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