Many years ago I rebuilt a Volvo B16. About a year later when I pulled the head
for some reason I found a piston in about the same condition. The top
compression ring was in pieced and there was a small channel or chunk missing
where I assumed a piece of ring had broken it out. No other rings where broken.
My theory about it was I hadn't set the end gap on the ring correctly.
Dennis
67 MGB
David Councill wrote:
> I finished disassembling my engine from my 71BGT (ironically a 72 B engine)
> which I will put in my 72B when I finish rebuilding it. I have only done
> two engine rebuilds, both 18V engines. This particular engine was my second
> rebuild which I did on my own after having help on the first one (a
> different engine) about four years earlier.
>
> It was a successful rebuild as I did this last one in 1983. Outside of
> premature cam failure a year later, the engine ran quite well over the
> years, initially under extensive daily driving (104 miles a day round trip
> work commute the first four years). It had started to leak a moderate
> amount of oil but no sign of any oil burning when the car met its end in an
> accident almost two years ago - my son was driving and a girl ran her van
> into the side of the car, her fault.
>
> I can only guess the mileage on the engine at maybe 130 to 150 thousand
> miles as the speedometer was not working during a few stretches over the 17
> years the engine was in service. So I was quite curious how the engine
> would look when I took it apart. There was no noticeable bearing wear (all
> grey). But the cam had one lobe with significant wear, the intake lobe for
> the #4 cylinder. All the cylinders look fine subject to the machine shop's
> inspection next week.
>
> But two pistons showed some unusual wear, reminiscent of the engine
> failure that preceded my very first engine rebuild (1979 - an interesting
> story in itself) where one piston was missing a chunk off the side and a
> few rings.
>
> I have two pistons (#3 and #4) which seem to be missing a small portion of
> the top ring and there is a tear or cut in the side of the piston. #3 was
> the worst one - I have attempted to get clear pictures which are here:
> http://www.imt.net/~dcouncil/mg/piston.html
>
> #3 shows the cut or tear, a loss of 10-15% of the ring, and another curved
> indentation below that. #4 has a much smaller tear but a similar ring loss.
> It was hard to get good pictures because the top of the pistons are black.
> Pistons #1 & #2 are shiny (not black) in those areas. There are no visual
> markings or scorings in any of the cylinders (just a slight ridge is all).
>
> As I mentioned, the engine gave me many miles of service and showed no
> problems when I took it out of service, outside of the oil it left on the
> driveway from the rear engine seal leak. So I'm just curious as to what
> caused this wear as the engine would eventually have failed due to this
> unusual piston wear. Any ideas?
>
> David
> 67 BGT
> 72 B restoration project
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|