Uh Oh, Bore Picture and Question

[nuvolari]

Oh, JFP, one question I have is if it is possible to tell anything by how much the pistons rock in the cylinders? How much is normal and can you even tell how much is not? They don't rock excessively but they do move when pushing on them. Is there a method to test them? Should they be at TDC or BDC or can nothing even be determined by any of this?

Thanks as always for your help....

[elgyqc]

Originally Posted by nuvolari

Yes, that is the question....
I have posted this same question on Facebook M96 Engine Gurus and Lee Jenkins of Hartech seemed to think it's not so bad and just put it back together and drive it...

I really want to see what shape that piston is in but don't want to pay for ARP con rod bolts, more gaskets and seals and probably the internal tensioner pads and arm and whatever else I'm forgetting like rings, etc. Is it dumb to open a case and not replace all the rings? I suppose it is but what do you guys think? ...

So what do you guys think? If you had a couple thousand more dollars budget, what would you do?

If you disassemble far enough to see the pistons you might as well do the crankshaft and rod bearings, so add that and new bolts for the bearing carrier, crankcase and the heads, $$$$.

Hartech supposedly knows these engines so I would listen to that advice. I should post pictures of the cylinders of my blown 3.2 engine, which are worse than what you have, on that forum and see what they say.
Pictures of my engine are here:
http://986forum.com/forums/performance-technical-chat/82796-what-can-i-do-3-2l-engine.html

[JFP in PA]

Originally Posted by nuvolari

Oh, JFP, one question I have is if it is possible to tell anything by how much the pistons rock in the cylinders? How much is normal and can you even tell how much is not? They don't rock excessively but they do move when pushing on them. Is there a method to test them? Should they be at TDC or BDC or can nothing even be determined by any of this?

Thanks as always for your help....

No, because there is no spec for how much they should move, plus these cylinder liners tend to go oval with wear. The proper way to measure piston to bore clearance is to use a bore gauge to measure the bore at the thrust sides and use a micrometer to measure the piston skirt diameter, subtract one from the other.

[The Radium King]

ask yourself what caused the foreign object damage. i'd be suspicious that it was a little piece of piston ring. which means pistons have to come out regardless of what you do about the cyls.

[nuvolari]

Originally Posted by JFP in PA

No, because there is no spec for how much they should move, plus these cylinder liners tend to go oval with wear. The proper way to measure piston to bore clearance is to use a bore gauge to measure the bore at the thrust sides and use a micrometer to measure the piston skirt diameter, subtract one from the other.

Ah, ok, thanks, never heard it to be but worth a check.

Originally Posted by The Radium King

ask yourself what caused the foreign object damage. i'd be suspicious that it was a little piece of piston ring. which means pistons have to come out regardless of what you do about the cyls.

After some close up pics, it looks like the damage was caused with the engine apart since the indentation starts from outside the edge of the cylinder as would happen without the head and gasket installed. So that would point to mechanic error on a previous repair. I don't think the gouge itself poses too much of a problem but there is also a indentation/scratch parallel to the rings which must cause the rings to move slightly on every engine rotation.

Also, the last pic shows a detail of the silicon in the Lokasil coating. Pretty cool!

Oh, and I've been reading up on bore scoring and I never realized there is life with beginning bore scoring. Many videos with Charles Navarro and Lake Speed talk about using moly in the oil to slow the scoring plus oil analysis to show the progression of scoring so you know when to finally abandon all hope! That's a huge plus at this point and gives me hope about seeing this car run again.

For now, I'm going to borrow a borescope from Autozone and check the bottom of the cylinders to see if there is any scoring still not seen. My situation is unique as my damage appears to have been caused by a hack mechanic and not from traditional M96 methods so hopefully the bottom end(s) are all undamaged.

(Crossing fingers...!)

[elgyqc]

Nice pictures or should I say good pictures. To me your analysis is sound. Good luck.

[Homeoboxter]

Can you remind me, was this engine actually running with these deep scores? I'd be surprised.. FYI, there's a Boxster S engine with an alleged IMS failure for $200 in L.A. I'd take a look at it if I were you, the bores can be easily checked with a borescope, they might still be great even though the timing got messed up.

[nuvolari]

Originally Posted by Homeoboxter

Can you remind me, was this engine actually running with these deep scores? I'd be surprised.. FYI, there's a Boxster S engine with an alleged IMS failure for $200 in L.A. I'd take a look at it if I were you, the bores can be easily checked with a borescope, they might still be great even though the timing got messed up.

Yup, it was running great. I bought the car in LA and drove it for a couple weeks around LA and then drove it cross country to Nashville where it now sits disemboweled.

Where is this $200 engine? I checked craigslist but didn't see it there. It's far from me now but worth a look maybe....

Thanks.

[Homeoboxter]

Originally Posted by nuvolari

Yup, it was running great. I bought the car in LA and drove it for a couple weeks around LA and then drove it cross country to Nashville where it now sits disemboweled.

Where is this $200 engine? I checked craigslist but didn't see it there. It's far from me now but worth a look maybe....

Thanks.

Strange. I would think those grooves get rounded after the engine running like this.
The ad is on facebook marketplace. 2004 Porsche Boxster S Motor for $200, was $500; in Marina del Rey, CA, near Venice.

[nuvolari]

Originally Posted by Homeoboxter

Strange. I would think those grooves get rounded after the engine running like this.
The ad is on facebook marketplace. 2004 Porsche Boxster S Motor for $200, was $500; in Marina del Rey, CA, near Venice.

Thanks, found it and asked how bad it is but no response. Pretty difficult to deal with on the other side of the country but for $200, it's worth considering.


I got a couple borescopes but, geez, these things are not easy to use! And that's with the engine out, on an engine stand and turned upside down! And I'm trying to see into cylinder #2 which is the easiest of all to get into! Then when I was able to get the camera into the cylinder, the fact that what you're trying to see is basically a half circle of shiny aluminum makes the view extremely difficult to make out due to reflections and focusing. Also, I am using a scope with the tiny 45 degree mirror on it which completely destroys the quality and adds all sorts of reflections and focusing difficulty. I think a 90 degree camera tip is needed but that adds much expense to the scope and makes it impossible to find one to borrow from an auto parts store.

So, does anyone have any tips? Of course, I'm talking about trying to use the borescope to see the bottom ends of the cylinders, going in from the sump. I don't think it's really possible to use the mirror attachment for this purpose; has anyone used this attachment successfully? The scope I bought was an Amazon $30 part and without the mirror, the quality is very good, much better than you would expect for such a low price. And you really must have a 90 degree view once inside the cylinder or all you will see is the underside of the piston.

It's a very frustrating process and I can't imagine being able to see into all the cylinders. As I've said, the middle #2 has the easiest access but the others....Well, I didn't even try as once inside #2, I really couldn't see anything. I thought saw scoring but it was too tough to tell if it was scoring, reflection or some other anomaly.

Ok, time top research more borescopes/endoscopes....

[Homeoboxter]

Originally Posted by nuvolari

Thanks, found it and asked how bad it is but no response. Pretty difficult to deal with on the other side of the country but for $200, it's worth considering.


I got a couple borescopes but, geez, these things are not easy to use! And that's with the engine out, on an engine stand and turned upside down! And I'm trying to see into cylinder #2 which is the easiest of all to get into! Then when I was able to get the camera into the cylinder, the fact that what you're trying to see is basically a half circle of shiny aluminum makes the view extremely difficult to make out due to reflections and focusing. Also, I am using a scope with the tiny 45 degree mirror on it which completely destroys the quality and adds all sorts of reflections and focusing difficulty. I think a 90 degree camera tip is needed but that adds much expense to the scope and makes it impossible to find one to borrow from an auto parts store.

So, does anyone have any tips? Of course, I'm talking about trying to use the borescope to see the bottom ends of the cylinders, going in from the sump. I don't think it's really possible to use the mirror attachment for this purpose; has anyone used this attachment successfully? The scope I bought was an Amazon $30 part and without the mirror, the quality is very good, much better than you would expect for such a low price. And you really must have a 90 degree view once inside the cylinder or all you will see is the underside of the piston.

It's a very frustrating process and I can't imagine being able to see into all the cylinders. As I've said, the middle #2 has the easiest access but the others....Well, I didn't even try as once inside #2, I really couldn't see anything. I thought saw scoring but it was too tough to tell if it was scoring, reflection or some other anomaly.

Ok, time top research more borescopes/endoscopes....

I use an "Uniojo" borescope, also from amazon, it's not a high end unit but works well for me. I think getting into the cylinders from the crankcase is very difficult with anything. I don't really understand your efforts in seeing the cylinders from the sump, maybe it's written somewhere in the thread. That engine is toast as it is now, you either resleeve it or replace the cases, but the cases have to be split either way, so why bother with borescoping the cylinders?

[Gilles]

Originally Posted by nuvolari

Ok, time top research more borescopes/endoscopes....

The boroscopes used to inspect the aircraft engines gives you an amazing resolution, unfortunately these professional boroscopes cost several thousand dollars

[nuvolari]

Originally Posted by Homeoboxter

I use an "Uniojo" borescope, also from amazon, it's not a high end unit but works well for me. I think getting into the cylinders from the crankcase is very difficult with anything. I don't really understand your efforts in seeing the cylinders from the sump, maybe it's written somewhere in the thread. That engine is toast as it is now, you either resleeve it or replace the cases, but the cases have to be split either way, so why bother with borescoping the cylinders?

Originally Posted by Gilles

The boroscopes used to inspect the aircraft engines gives you an amazing resolution, unfortunately these professional boroscopes cost several thousand dollars

I think the main problem was trying to use the tiny mirror attachment in order to see the cylinder walls. I have ordered a 90 degree borescope. This scope has two cameras: the normal straight ahead camera and then another one on the side where you can see 90 degrees to the side which is just what's needed to see if any scoring is present. And it's only $50 on Amazon so not too bad. I'll let you guys know how it works.

Oh, and, homeoboxster, the reason I want to see the bottoms of the cylinders is because this is where traditional scoring occurs first and where it will be the worst generally. My situation is unique because of the gouge in cylinder 2 but I'm not as worried about this gouge as I am in the slight damage on the opposite side of the cylinder which looks like it may have been caused as a result of the gouge, either when it first occurred or later as the piston reacts to the gouge. Therefore, I want to see the bottom of that cylinder just to see if anything bad is going on or not. Also, I want to check the other cylinders although as already stated, they are much more difficult to see into from the sump so not sure how successful that process will be. But this is a 3.2 engine which isn't usually too prone to scoring.

And the engine isn't toast yet. This is all part of the information needed to make the best decision. Lee Jenkins said to put it back together and not worry but I'm a pessimist so I need more reassurance in how long it will last if I do just that.

[Homeoboxter]

Originally Posted by nuvolari

And the engine isn't toast yet. This is all part of the information needed to make the best decision. Lee Jenkins said to put it back together and not worry but I'm a pessimist so I need more reassurance in how long it will last if I do just that.

That small horizontal gouge right where the rings ride nearly at highest speed would bother me just enough to not reassemble this engine as is, but that's me usually ending up losing when gambling
It's your call, I hope it'll turn out fine whichever decision you go with.

[The Radium King]

i'm no expert, but that latest round of pics of the scratch seems pretty damning. if that scratch is as deep and wide all the way down as it is at the top of the cylinder then i doubt you will get anything for compression, will get a tremendous amount of blowby into the crankcase, and lots of oil into the combustion chamber (which appears to be happening given how dank the top of your piston looks).

dunno why you took the engine apart in the first place so can't really correlate cause to effect, but did you send these latest images of the scratch to lee jenkins? i'd agree with him if all he was working with was the initial images which look more like bore polishing than bore scoring, but the scratch seems a bit more than all that.