Vehicle & Technical > Range Rover
Missing a beat
Garth:
N0 8 is on the LH side (looking from front)
I presume whoever did RH head put a composite head gasket on hence the difference in compression
Range Rover Blues:
So the head with better compresion is running the worst :?
I think you shold take both heads off then if you go that far, get them skimmed and refit with composite gaskets. I'd expect a minimum of 165 PSi though and up to 185/190 on a good 'un. Mine does over 200 but I now it's been tweeked.
Garth:
Well took heads off this weekend and passengers side was NG leaking between 1 and 2 and 1 and waterway.
Has been off before not to long ago buy the looks of it. Had composite 10 bolt gasket fitted to a 14 bolt block and head. Minor pitting on head between no 1 and waterway.
Drivers side head and block was OK with a 14 Bolt tin gasket (could be original but no signs of witness mark on head if it has been changed its been done properly, new lock tabs on exhuast etc)
So heads are off ready to be skimmed and here is where advice is needed.
As it many years since I have done this sort of thing. Do I decoke the heads/ports with wire brush and drill (they are not that bad) or do engine company's now have a magic solution they can dip heads in to clean them up.
Also do I lap valves in before or after getting the heads skimmed.
Composite or tin gaskets. Why?
10 or 14 bolt? again why.
Acording to manuals should have 14 bolt tin gaskets.
The piston tops look OK no major carbon deposites, so will leave well alone, but what lateral movement is accepable.
Yours in anticipation Garth
Range Rover Blues:
Strip the heads and have them skimmed, as one has been done already you may need to have the other skimmed more to 'catch up'.
There is a witness mark on the front of the RH head (back of LH head) to judge how much has already been skimmed.
Composite gaskets are 1.2mm once fitted, alloy ones are 0.5mm. Get the heads skimmed by around 0.7mm and fit the composites, they are far more reliable.
The outer 4 bolts can actually distort the head and cause gasket failure, dealers were advised to refit heads with the later 10 bolt gasket. You can also buy a 14 bolt composite so I'd say go for that but tighten the 4 outer bolts to the absolute minimum torque, so they are hardly doing anything. One of them holds the alternator bracket after all.
You should be using a thread lubricant/sealer rather than copper slip on the head bolts.
Once skimmed you need to clean all the swarf from the heads, that's the time to clean everything up.
WD40 will desolve all the carbon deposits nicely with no scratching, use a kitched scourer (not wire wool, the green plastic thingy) and seal the edges of the pistons with grease before starting, do both the pistons and the heads the same way.
Lap the valves in, rude not to. You should all but get rid of the small round black marks on the valve/seat mating faces when you lap them in. Any sign of deeper pitting then replace the valve, look particulary at the exhaust as these are the ones that go.
Put new valve springs in and renew all the stem seals.
I spent a little time fetling the cast surface of the inlet too, don't go mad unless you are measuring the gas flow but getting rid of any big ridges is a good idea.
As for the tolerable slap on the pistons I can only refer you to the relavent manual, but if the following advice helps....
Was it making a piston slapping noise before you stripped it? if not I'd say if it's not bust don't fix it.
If it was slapping a little, look for signs of scoring in one cylinder or a ridge indicating a possible broken top ring.
Does it use a lot of oil too.
A new bottom end (short engine) will set you back £1700, is it really this bad?
Did you ever do a compression test?
Chances are the bottom end will be ok, expect it to be unless you see evidence to the contrary.
Take you time and keep things clean.
Garth:
Thats a prity comprehensive reply THANKS
Yes to matching heads had planned to do that
Still can not find whitness marks but have found original dimensions for thickness of heads so will bring verners home tommorrow to check
Yes to outer head bolts (read somewhere 30 for outer 2 and 20 for inner 2)
Leaving piston tops alone as they are not bad
Lapping valves in as a matter of course (as you say rude not to) leaving original springs in as never had problem with valve bounce etc. and dont rev over 4K if I can help it.
Bores are as smooth as, oil use acceptable, compression tested posted earlier.
Just wondering as I have memories of Mini days doing heads up and knocking bottom ends out a month later
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