Ditto on mine----6/7 years ago. Had a complete engine rebuild as a result.
> [Original Message]
> From: BJ8Healeys <sbyers@ec.rr.com>
> To: healey <healeys@autox.team.net>
> Date: 1/9/2007 8:20:58 PM
> Subject: RE: Pistons damaged again
>
> Hi, Ken -
> I had the exact same thing happen to my BJ8 engine about 7 years ago. I
> heard the pieces breaking off the pistons and rattling around, but had no
> idea what it was. Between the first time I heard the noise and the second
> time was about 6 months. It was a loud, rattling sound like a wire coat
> hanger caught in the fan, but it only lasted a split second -- just enough
> to startle the crap out of me. Following the second occurrence (the
engine
> still seemed to be running fine), I did a compression check and found
> compression way down in #4. After pulling the head, I found small pieces
> missing from #2 and #3 piston edges, with one larger piece missing from
#4,
> just as you describe.
>
> After removing the pistons, I found that the rings had broken up and wore
a
> triangle pattern (wider at the bottom) up through the remaining rings and
> piston lands until the pieces broke off at the top of the piston. #4 had
a
> smooth score in the wall that required a sleeve to repair.
>
> I asked on the list what could have caused it, and got the general opinion
> that it was either detonation or running hot. I never heard any
detonation,
> and the engine continued to run about the same (well), as far as I could
> tell. Before the problem, I used regular gas with a lead substitute after
> leaded gas disappeared. Now, I use only premium and maybe I should be
> checking my distributor advance as Dave Russell suggests. I have a
Mallory
> dual point with mechanical advance only. So far, so good.
>
> Good luck!
> Steve Byers
> HBJ8L/36666
> BJ8 Registry
> Havelock, NC USA
>
> -----Original Message-----
> From: owner-healeys@Autox.Team.Net
> [mailto:owner-healeys@Autox.Team.Net]On Behalf Of Freese, Ken
> Sent: Tuesday, January 09, 2007 7:17 AM
> To: healey
> Subject: Pistons damaged again
>
>
> I cleaned up the compression reading columns.
> Ken
>
> Saturday, I removed the head from my BJ8 to have steel valve seats
> installed because of #4 exhaust valve recession and low compression. I
> figured #4 was now burned enough, I should get it fixed. After putting
> on the hardtop on New Years, I could hear rougher running.
> Now I see that #2, 3, and 4 pistons have 1/16 to 1/8 inch notches
> missing and I can see the top ring on #4. Preliminary inspection of the
> notches don't show smooth melting. So, new set of problems. I figure the
> causes are:
> 1. Swallowed debris
> 2. Detonation
> 3. Defective pistons
> Incidental facts:
> A - oil never filtered only changed for about the past 40000 miles due
> to faulty spin on filter adapter.
> B - last rebuild in 1982 and 70000 miles ago due to melted pistons
>
> Compression 1997 Compression 2004 Compression 2007
> 165 130 110
> 155 135 90
> 150 145 70
> 150 90 70
> 155 130 115
> 175 150 145
>
> Any thoughts on the cause until the pistons are actually out?
> Ken Freese
> 65 BJ8
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