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Premature cylinder wear.

MJcanada

Proven Member
3,130
68
Jun 25, 2011
Inman, South_Carolina
So my engine is at 90-100psi now. Deff am issue with the Rings. Around 10-15k into its life the tbelt stripped at the crank. I did hit the valves but it did not bend any at all. Car did sit with the head off for air 2 months.

Thing I noticed when I took the head off was that both thrust sides of the cylinder walls were worn. There was no cross hatch pattern left. The thrust walls were clean and shiny. This deff should not be like that as I've rebuilt a virgin block with mid 100k miles that still had the cross hatch left and I simply honed it as per the owner not affording to have it bored. Engine went together with good compression afterwards.

I do not know why this happened to my engine. I know power can do this but at that time it had never seen more than stock boost on the stock t25. Only mod being a set of aftermarket evo 8 cams.

This motor was done alil over 2 years ago. I was working Alot and left the assembly to (what I thought) more knowledgeable persons. And I had all machine work needed for head and block done. Gave it to the shop and said whatever needs done do it and ill pay. And I did. It was bored .040 and honed to match the pistons. They specifically said they would not bore it till they had the pistons.
And the guy my dad manages shop for assembled it for me as I didn't feel I had any time to do it myself.

So what I don't know us ptw and ring gap. I highly doubt the machine shop got ptw wrong being they waited for the pistons. So could incorrect ring gap cause this? I kinda fear that it was never checked and they were just installed as is.

Any ideas on what could have caused my car to lose compression so early in life or why my cylinders would wear so fast on the thrust side would be great. I am going to either re ring or rebuild sometime and I don't ever want this to happen a second time. I will be song everything personally this time and would like to figure out where the mistake could have been made so I can avoid it.

Thanks in advance and sorry for the long post.
 

viperlp01

Proven Member
2,521
74
Oct 9, 2006
Kalamazoo, Michigan
Too tight of PTW, too loose of PTW, and debris entering the cylinders.
 

killercolt

Proven Member
311
21
May 23, 2008
Acworth, Georgia
Did you hone the block with the spring loaded three stones hone? This is a a big "Hell No!" The finish is too rough and will eat up the rings shortly afterward. I made this mistake years ago. I had a 6 bolts that started out at 160psi and it went to 100psi in about 50 miles. I took the pistons out And noticed the ridges in the rings. A ball hone aka dingo hone is a better choice for deglazing the bores. Some people use the ball hone to clean up the three stones hone finish.

You should just use a red Scotch Brite to deglaze the cylinder if the cross hatches are still presenter. It will allow the rings to seat with eating it up. Get some new rings and have the machine shop brush hone aka plasma hone the bore. The brush hone will knock the shape points off the cross hatches and keep your rings from getting eaten up.
 

MJcanada

Proven Member
3,130
68
Jun 25, 2011
Inman, South_Carolina
I honestly don't know how it was honed but I know the machine shop guy and highly doubt that he used the spring style hone. Engine is still in my car as I have to drive it everyday. But when I took it apart from the tbelt instance there was no cross left on the thrust sides at all iirc.

I really Hope it didn't make my cylinders out of round as that would suck. Just trying to figure all the possible happenings for this so it can be avoided. Hopefully a new ring set can be the fix.
 

BogusSVO

Proven Member
5,891
308
Jul 1, 2009
Pensacola, Florida
Another thing is what grit stone was used? If they used a coarse stone for steel rings, that will be way to rough and chew the rings up.
 

MJcanada

Proven Member
3,130
68
Jun 25, 2011
Inman, South_Carolina
Another thing is what grit stone was used? If they used a coarse stone for steel rings, that will be way to rough and chew the rings up.

This is the issue. I don't know about any of this. I just dropped it off and paid for whatever it needed. The machine shop I emailed you pix of awhile back was the shop that did all the work.
This was a total rebuild. Did everything that was needed. As I wanted to just have it Done right the first time. But going have to do it again now.
 

BogusSVO

Proven Member
5,891
308
Jul 1, 2009
Pensacola, Florida
If it was a virgin block... why did they go .040? That would be normal on a .020 over with wear, or did the virgin block have some sort of bad cylinder scoring?

Pics will not let me know if they have the right grit hone stones for a moly ring or not.
 

MJcanada

Proven Member
3,130
68
Jun 25, 2011
Inman, South_Carolina
If it was a virgin block... why did they go .040? That would be normal on a .020 over with wear, or did the virgin block have some sort of bad cylinder scoring?

Pics will not let me know if they have the right grit hone stones for a moly ring or not.

That's true I was just insinuating I would think/hope they would know what to use but deff they may not have.
 

MJcanada

Proven Member
3,130
68
Jun 25, 2011
Inman, South_Carolina
And I can't write remember why they went that far. I think he said 30 may have straightened it but since 20 & 40 over pistons were readily available, we did 40 over.
I wanna say that one had a slight score in it but not 100% on that.
 
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