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My mechanic told
me it was that time of the year to change the oil in my cars. My answer
to this was that the engines burn so much oil that the oil changing
process was continual without my intervention.
With this at the
back of my mind, I approached a couple of well known engine re-builders
who gave me horrendous reasons for the oil consumption, worn valve
guides, worn piston rings, the engine probably needed new cylinder
liners and of course if all this was undertaken, a tremendous stress
would be placed on the crankshaft bearings and some other parts. Whilst
they were recounting all this with practised glee, it was at this
stage my eyes clouded only to hear them say that there would not be
much change out of £10,000. They said that just taking the engine
out was a 45 hour job on the MKVI !!
Mentioning this
to Ashley James, he referred me to an article on his website http://www.kda132.plus.com/Technical/SectionB/oilleak/oilleak.html
that explained that the situation was most probably not as serious
as everyone was telling me. Having studied this article, here is my
experience of his suggestion.
Firstly as Ashley has explained, all those faults that could
possibly be the cause might not necessarily be the case. The
most probable cause was large quantities of oil seeping through
worn inlet valve seals. (This engine has 6 overhead inlet
valves - the exhaust valves are side valves.)
The original seals are made with wound asbestos string that
had been impregnated with Russian Tallow. Over the course
of the past 50 years and many thousands of miles, these could
well have disintegrated making them useless as a seal.
Ashley's
suggestion is to buy some Payen seals, part number HR336,
for a General Motors engine. These seals are placed over the
valve stem under the valve springs and deflect the majority
of oil away from the disintegrated seal. The seals are available
through most motor factors at a cost of £9.00 for a
pack of 4 though of course you will need 6 seals. The earlier
versions were made of rubber with the latest version being
made of metal. These need to be filed down to a maximum height
of 0.425"
"WHAT!! Off with her head" do I hear you groaning!!
No, this is not necessary. After removing the overhead camshaft,
a simple job of undoing 6 bolts, the valve springs need removing
with a valve compressor to get at the seals.
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There are
two methods to do this to ensure that the valves do not drop
down into the cylinder.
Method
1. If you have an airline with at least 90psi available,
this can be connected to each cylinder in turn and with the
respective valves fully closed, the valve spring and collets
can be removed.
Method
2. Rolls-Royce made a special tool, that when inserted into
the spark plug hole, holds the valve up securely in place. (See
photos and diagram from the Service Manual alongside Ashley's
home made version.)
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Fig.
B25. Rolls-Royce tool with valve compressor above
Printed with permission of Bentley Motors Ltd
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Rolls-Royce
tool
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Ashley
James' hand made tool using a spark plug
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Old
broken down Oil Seals
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New
Oil Seals
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Whilst doing this, it made eminent sense to also replace the original
seals at the same time. These cost about £2.00 each and are available
from Ristes amongst others. These seals should be soaked in a light
oil for about an hour before inserting them.
All went very
smoothly except for one hiccup. The last valve to be done was on cylinder
6 against the bulkhead. The special tool could not be operated correctly
as the chassis oil reservoir attached to the bulkhead was in the way.
It was either a question of removing the reservoir or finding a way
around. This we did by inserting the tool into the sparkplug hole
at an angle and then tying it in place.
The
cost of parts was £26.00 in total. Bonnet up time was 4
hours but I cheated. Ian Bowdery, the local (South London) Rolls-Royce
and Bentley trained mobile mechanic did the dirty work.
I supervised, took photos and generally got in the way whilst
also doing my day job, computer programming. Within 5 minutes
of starting the engine, the exhaust pipe was heaving a sigh of
relief with a very noticeable reduction of smoke. This will further
decrease when old oil in the system is burnt away.
So next
week it is the turn of the R Type and maybe the Cloud II before
Xmas.
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Ian
Bowdery
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now a few weeks later, it was the R Type's turn............
Horrors.......
Eveything
was going according to plan, when all of a sudden one of the
colletts had a mind of its own and jumped out as if chased by
a ferret - straight down one of the push rod holes. The push
rod was in place but that did not stop the little blighter.
"Forward and onwards" it cried disappearing
into the depths of the engine below.
To retrieve
this, the side panel that provides access to the exhaust valve
tappets had to be removed. ( It is a part side valve, part overhead
valve engine). Before doing that though, the forward manifold
had to be removed also to get at the side panel. Having done
that, the collett was found cowering in a pond of oil.
SOLUTION
- Before tackling the other oil seals and valves, we stuffed
plenty of garage towelling paper and rag into every orifice
we could find.
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