"Simon Kiing" <skiing1966@direct.ca> wrote in message
news:YCNFc.953481$Pk3.305393@pd7tw1no...
> My Range Rover did overheat once when I was in the freeway. Unfortunately
I did not stop until the vehicle lost all power. Afterwards all seemed Ok
after the water pump and fan belts and clutch fan was replaced. It was only
a year later I started to notice the over heating. Is there a possiblity the
heads are crack? That is some suggestion I've been getting
>
> Thanks Simon
Very rare for rover V8 ally heads to actually crack, more likely to warp but
that would have given you overheating and water usage issues right from the
day it happened. More likely that the ally block has locally overheated,
loosening it's grip on the steel liners and allowing absolutely miniscule
movement of the steel to ally dimension against the head gasket due to
expansion and contraction. Over time, this causes the head gaskets to leak
very slightly, normally from the no. 1 or no. 2 cylinder into the water
jacket, and only when really hot.
Best bet is to pull the heads and carefully inspect for what looks like a
crack between the steel liners and the ally block. The areas that will give
problems are the 4 corner cylinders, adjacent to the water jackets. If it's
immediately visible after cleaning the gasket face with scotchbrite pad then
you have a problem. If you have to look really closely to see it, then you
will probably get away with replacement head gaskets - NOT rover ones, but
aftermarket composite ones such as McCord / Permatorque (available in the UK
from Real Steel, dunno about suppliers in Canada but they are made in the
USA) and a cylinder head stud kit to improve the clamping force. The head
bolts on later 4.0 / 4.6 engines are stretch bolts anyway and must not be
reused or gasket failure will happen again fairly soon, so add in a bit
extra and make it bomb-proof by fitting the stud kit (made by ARP). Put a
very light smear of Hylomar Light jointing compound or preferably a fine
spray of Hylomar aerosol jointing compound on the block face prior to
reassembly. Oh, and have the heads checked for warping, 4 thou is an
acceptable limit end to end or diagonally, but I wouldn't use a head with
more than 2 thou across the narrow. Maximum allowable skim really ought to
be no more than 15 thou.
Hope above info of some use to you.
Badger.
B.H.Engineering, Rover V8 engine specialists.
