[Supras] oil pan noise: cracked off piston skirt?

[Hacker J]

----- Original Message ----

I would suspect that either there is a piece of some foreign object rattling around in the pan, or your oil pickup is vibrating and occasionally hiting the pan. Some sort of inspection would seem warranted.

Jon
90T




-----Inline Message Follows-----

Last night I wrote about a noise like pebbles dropping on the extreme
 rear
of the oil pan.  I could feel random pulses in the stethoscope
 diaphragm
holder also when the pebble noise occured.

The pistons were stock and I'm running 15-17 PSI boost, and am on the
 rich
side.  Just changed the first oil after 400 miles.  Analysis said not
 too
much aluminum in the oil (some lead though, presumably from the
 camshaft
soft coating after refininshing the bearing caps).  but I did find some
flakes of aluminum in the oil filter.  Did not seem abnormal, however.

The noise was found later, by about 50 miles.  There was also one
 instance
when revving the engine under the hood I did hear a muffled "crack"
 which
could have been anything, I suppose.  I'm half tempted to buy a
 borescope
and look in the pan through the drain opening or through the dipstick
 tube
(one is sold with a 90 degree mirror).

Has anyone had a skirt crack off a stock piston?  In looking for
 excessive
pistion rock or slap when warm, I squeezed closed the ISC hose to the
extent possible to reduce engine speed to just above he stall point.
  No
noise other than normal valve noise was produced.

As always, any thoughts would be appreciated.  I do not know yet if the
noise is getting worse.

Thanks.

Bernie




Last night I wrote about a noise like pebbles dropping on the extreme
 rear
of the oil pan.  I could feel random pulses in the stethoscope
 diaphragm
holder also when the pebble noise occured.

The pistons were stock and I'm running 15-17 PSI boost, and am on the
 rich
side.  Just changed the first oil after 400 miles.  Analysis said not
 too
much aluminum in the oil (some lead though, presumably from the
 camshaft
soft coating after refininshing the bearing caps).  but I did find some
flakes of aluminum in the oil filter.  Did not seem abnormal, however.

The noise was found later, by about 50 miles.  There was also one
 instance
when revving the engine under the hood I did hear a muffled "crack"
 which
could have been anything, I suppose.  I'm half tempted to buy a
 borescope
and look in the pan through the drain opening or through the dipstick
 tube
(one is sold with a 90 degree mirror).

Has anyone had a skirt crack off a stock piston?  In looking for
 excessive
pistion rock or slap when warm, I squeezed closed the ISC hose to the
extent possible to reduce engine speed to just above he stall point.
  No
noise other than normal valve noise was produced.

As always, any thoughts would be appreciated.  I do not know yet if the
noise is getting worse.

Thanks.

Bernie



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