Just curious about symptoms of scored cylinders...

recycled sixtie · recycled sixtie's Garage

If an engine had scored cylinders how would the engine behave? Also what would cause scored cylinders? Noticed it in a Cayman ad and the engine had been replaced due scored cylinders.

1990C4S · 09-22-2015, 04:53 AM

It would burn oil and eventually lose compression...

Why are you speculating?

recycled sixtie · recycled sixtie's Garage

I was just wondering if this was a common problem on Caymans?

John Rogers · 09-22-2015, 05:49 AM

A scored cylinder in anything will result in what the seal is trying to keep sealed to leak by. It can be compression, oil, hydraulic fluid, water, steam, etc, etc. It can be caused by several things: metal on metal wear, contaminates in the oil/fluid, poor clearances, over heating that damaged the metal, etc, etc. It can be caused by casting sand that is not cleaned out well and it contaminates the internals.

At a vintage race at Palm Springs years ago a Can-Am car with a big block Chevy and those big 'ol Hilborn injector stacks was sucking down lots of sand every time it ran! By the last race on Sunday it looked like a mosquito fogger with the plume of smoke out the back........rings were toast!

KNS · 09-22-2015, 05:49 AM

I believe it's a problem on most if not all of the water cooled Caymans, Boxsters and 911s.

Search bore scoring on the various Rennlist forums and you'll get hits everywhere but the M97 seems more common.

Brando · Brando's Garage

Best way to be sure... Pull the heads & inspect, or put a camera down in there...

RANDY P · RANDY P's Garage

pull the dipstick while running and see if it smokes like a BBQ. ...Blowby is good times

I've seen some that blow out the dipstick..

john70t · 02:22 PM

Quote:

Originally Posted by Brando

Pull the heads & inspect, or put a camera down in there...

$180 inspection kit.
Through the spark plug holes.
Harbor Freight Search results for: 'endoscope'

LEAKYSEALS951 · 09-22-2015, 12:57 PM

Quote:

Originally Posted by RANDY P

pull the dipstick while running and see if it smokes like a BBQ. ...Blowby is good times

I've seen some that blow out the dipstick..

My 2006 997S had no dipstick to pull!!!

Hugh R · 09-22-2015, 01:50 PM

Sand/grit through the air cleaner. In my old Aston Martin DB4 I had SU carbs with a wire mesh for an air filter.The wire mesh wouldn't stop anything from entering the engine. I sandwiched some oil-soaked motorcycle foam air filter material between the wire mesh so it looked original, but actually worked, and wouldn't suck the foam into the SUs. Had to adjust the carbs for the change in air flow, IIRC.

wdfifteen · wdfifteen's Garage

Quote:

Originally Posted by afterburn 549

Why are they scoring if so common?
I thought FOD was a major player...Is the air filter not working on these?

It can be the result of designed-in insufficient lubrication or pistons and cylinders that get too tight during part of the warm-up cycle. I would only suspect poor air filtration (FOD) on a certain make/model if occurrences were a function of location, ie more frequent in the dusty Southwest than in the soggy northeast.

afterburn 549 · 09-22-2015, 02:52 PM

I think you are getting piston scuff mixed up with scored .
FOD will leave its tracks .

Jeff Alton · 09-22-2015, 03:27 PM

There is lots of speculation as to the cause. Some have even suggesting not starting your car in cold weather, but they won't define what cold weather is....

The symptoms are a "ticking" noise from one bank that will get progressively worse. Oil consumption will go up. Dark tail pipes will be seen. We have compression tested a few motors with very badly scored cylinders and they all make great compression (some how).

The failure on a M96/97 motor seems to begin in the #6 cylinder in our small sample size. A couple of motors have show both #5 and #6 scoring.

We see this problem far more often than a bad IMSB. But, IMSB represents an easily marketed solution to a problem you may or may not ever see... The problem with creating hype about scored cylinders is that the marketable solution to the problem is not 2,000 parts and labour, it is more like 20,000 plus which makes it unmarketable and a waste of energy to promote....

Cheers

afterburn 549 · 09-22-2015, 03:41 PM

YIPES !
If you ever get a pic Jeff please post it ( Of a scored cylinder bore)

KNS · 09-22-2015, 04:25 PM

When it's really bad the piston skirts are scuffed up as well.

wdfifteen · wdfifteen's Garage

Quote:

Originally Posted by afterburn 549

I think you are getting piston scuff mixed up with scored .
FOD will leave its tracks .

What do you think the piston will scuff against? The cylinder wall.

afterburn 549 · 06:00 PM

On further staring It does look like skirt seizure with the two horizontal ring marks@ top and bottom.
It would appear to be a piston skirt problem being that marks start at or below the wrist pin.
I would also be checking glycol in the oil.

matt demaria · 09-23-2015, 06:21 AM

Pictures

All from a borescope. 2002 to 2009. 60K to 118K.

afterburn 549 · 09:44 AM

If i stare at post 15 long enough..it becomes obvious the damage is happening below the piston rings , not above .The top 1/4 of cylinder looks good from here.
SO the damage is not from inlet FOD
This has to be piston skirt to cyl wall conflict..
Perhaps too fast a warm ups?
Great pics with the borescope!

RANDY P · RANDY P's Garage

looks like the bore itself went oval.

Garbage.