Hi All,
Someone on this list sent me a note asking about main and big end
bearing replacement without engine removal. I believe they wanted to
try it on a Herald. Unfortunately I lost the message, but here goes
anyway.
On the Spitfire 1500 it is dead easy to change big end bearings by
dropping the sump. Some recommend that you change them at 35000 mile
intervals to prevent wear on the crank. I was advised by John
Kipping (we are not worthy!) that it was also possible to change main
bearing shells, but that he hadn't actually tried it on a Spitfire.
Well I gave it a go and it was very straight forward. Remove the
sump, remove the con rods from the crank, and then take of the main
bearing caps. There is only just enough clearance to get a socket on
the front bearing cap bolt, but it's still easy enough. When the
caps are released the crank will drop down and the upper shells can
be removed by sliding in your new shells. Similarly, the shrust
washers can be replaced. The whole lot is then put back together as
normal making sure everything locates correctly. I've missed out
steps here such as removal of the bridging piece and subsequent
replacement with gasket sealer, but this is the gist of it.
According to John Kipping, the crank will go on and on without a
re-grind, if you change the bearings early enough (when oil pressure
drops off, rather than when the bearings are acctually knocking, at
which point it's probably too late for the crank).
Of course all this is not as good as a full engine out rebuild, but
it'll keep you on the road if, as I do, you need the car to get to
work every day.
Hope this helps,
Jonathan
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