Look at my Cylinder Wall

[Turbo 2g awd]

Here is a pick of my cylinder wall. Its a Slowboy Racing Ross/Eagle Stage II 6 bolt. The motor has 5 thousand miles on it. Is this marking ok???? I just took the head off to replace some leaking Valve stem seals.

 

[peregrine]

does that dark spot have any depth to it? if not i wouldnt worry too much about it. just looks like discoloration from heat maybe.

 

[builtTSi]

That looks like more than just heat discoloration to me. It looks like it's wiping out the cross hatches on the cylinder wall in that roughly one inch wide spot to me. Possibly a little bit of flashing left on the skirt of the piston.

 

[jott5555]

there goes the theory that the cross hatch is gone within the first 30 min or so of running.

it dosent look too bad email a pic of it to slowboy and see what they say.

 

[1fast97gsx]

that's quite a ridge on the top of the bore as well. I'd pull the piston and check out the skirt ... my skirt showed some signs of wall contact but my walls didn't look like that at all.

 

[half-cocked]

I would try to hone that out, put some good cross hatches on it.

 

[DSMJim]

What makes you think your oil consumption was valve seals?

Right were that scrape is on the cylinder wall, your piston also seems out of round as if it's farther away from the wall there too. If that is how it is, you have detonated on that piston pretty hard and your burning oil because you smoked the ring or the ring land dropped on that piston which is why your scraping the wall hard like that. To be honest, I wouldn't put the head back on with it like that.

On the flipside I can see the cross hatching still in that scrape mark so It can't be that deep and it looks more like a funny camera angle on the piston maybe you can clear that up. If thats the case and the piston is still round and the same distance from the wall as the rest of the way around then you should be fine, don't touch the wall if your not going to pull the piston.

 

[bigjangin]

take some pics from different angles. Is there scuff marks on the other side of the cylinder as well, or is it just the angle of the camera. There is quite a ridge at the top of the cylinder walls also.

 

[LaserDad91]

What makes you think your oil consumption was valve seals?

Right were that scrape is on the cylinder wall, your piston also seems out of round as if it's farther away from the wall there too. If that is how it is, you have detonated on that piston pretty hard and your burning oil because you smoked the ring or the ring land dropped on that piston which is why your scraping the wall hard like that. To be honest, I wouldn't put the head back on with it like that.

On the flipside I can see the cross hatching still in that scrape mark so It can't be that deep and it looks more like a funny camera angle on the piston maybe you can clear that up. If thats the case and the piston is still round and the same distance from the wall as the rest of the way around then you should be fine, don't touch the wall if your not going to pull the piston.

Top side of piston looks kind of pitted, which would further support some detenation. Looks like you got her hot and scrapped the cylinder wall some, but not bad enough to really hurt it. I would ck. the pistion as he recommends.

 

[terefic181]

Turbo 2g awd,

I would tend to lean toward builtTSi's theory that the worn area may be do to skirt drag at that area, see pix below and check out the location of the skirt compared to the worn area. Although it's possibly do to drag in a small area from ring damage as DSMJim exlained, but the area where it is located, looks more like it is pretty much lined up with the skirt. I would also be interested in wether there is anything on the opposite side of the cylinder wall.

1fast97gsx, bigjangin, the dark ridge at the top, I think, is most likely nothing more than the normal carbon build up since the cross hatching is still present in most all the other areas below that line, and it would need to wear away this crosshatching in order to form the ridge at the top.

 

[terefic181]

The more I look at this.... from what you can actually see in the picture, the wear area doesn't match up with the level of the lower skirt and more closely matches up with the oil ring or upper portion of the skirt level according to the pistons travel.

 

[LaserDad91]

The more I look at this.... from what you can actually see in the picture, the wear area doesn't match up with the level of the lower skirt and more closely matches up with the oil ring or upper portion of the skirt level according to the pistons travel.

I think you are right.

If it was just the skirt, it would not travel almost all the way to the top of the cylinder.

 

[half-cocked]

The more I look at this.... from what you can actually see in the picture, the wear area doesn't match up with the level of the lower skirt and more closely matches up with the oil ring or upper portion of the skirt level according to the pistons travel.

Well if its not the skirt, and obviously its not the ring land because the wear stops too low, all thats left is the rings right? Could a ring have broke up in there some how and cause this?

 

[PieTSI]

Could it be because he has forged pistons and forged pistons do not expand at the same rate as the cylinder block causing premature wear on the cylinder block? My buddy had forged pistons in his mustang and he didn't allow proper warmup (with forged pistons warmup becomes more crucial) and he eventually fried his rings. I dunno if this is also the same case here but if that were my engine I would at least rehone the cylinder before putting it all back together.

 

[Tallen]

Could it be because he has forged pistons and forged pistons do not expand at the same rate as the cylinder block causing premature wear on the cylinder block? My buddy had forged pistons in his mustang and he didn't allow proper warmup (with forged pistons warmup becomes more crucial) and he eventually fried his rings. I dunno if this is also the same case here but if that were my engine I would at least rehone the cylinder before putting it all back together.

I second that, better safe than sorry...

 

[half-cocked]

Could it be because he has forged pistons and forged pistons do not expand at the same rate as the cylinder block causing premature wear on the cylinder block? My buddy had forged pistons in his mustang and he didn't allow proper warmup (with forged pistons warmup becomes more crucial) and he eventually fried his rings. I dunno if this is also the same case here but if that were my engine I would at least rehone the cylinder before putting it all back together.

I guess only the original poster can answer if he treated the engine right, but if he did wouldnt it be wide spread and not so isolated?

 

[burldude]

That is just some piston scuffing . If you look close you can see that in the cylinder (left side) there is another dark spot . Then You look at the piston pic and you can see the same polished look on the pistons in the same area as the scuffs . The piston hass propably been hammered on and isnt round anymore . One other noticable problem is the fact that the scuff has pretty strong terminating edges meaning possible contamination of combustion chamber . It could be many things such as improper cleaning during assembly or lack of air cleaner and ingesting particles. To many variables to really determine anything . Check for roundness of the cylinder and roundness of piston. I would have to say this car is running to Rich and to lean . OIl dillution by fuel contamination :thumbdown

My car is having the same issues , having to run extremely rich to avoid detonation (91 Octane) and then blowing out spark ( with msd dis ) . So water injection a must and bigger fmic.

Edit I look at the pics again and the cross hatch is so present I have to question oil dillution . Check for roundness a must.

 

[Turbo 2g awd]

Compression tests show 175psi across the motor. And leakdown test at 90psi is less than 1%. I always let the motor warm up before getting on it. And I pulled the head cause #2 exhaust port was soaking wet in oil. It is very obvious that those two exhaust valve seals are the problem. And the marking is on the other cylinders as well and only really on the back side of the block closest to the firewall. Could it be the way the motor rotates as the piston comes down under boost and its pushed more towards the back wall of the cylinder?

 

[92redman]

Looks like the skirt is rubbing. Did you try getting ahold of slowboy and see what they have to say? That is definately not normal whatever the cause.

 

[Turbo 2g awd]

Looks like the skirt is rubbing. Did you try getting ahold of slowboy and see what they have to say? That is definately not normal whatever the cause.

the piton skirt doesnt come up that high... the makings seem to begin where the oil ring would be if the piston is at tdc, not sayiing that is what its from just to make refference to where the markings are... how do you know that is is definately not normal... have you ever broked down a motor before?

 

[92redman]

Yes, I have broken down a motor before. I am building one now that has 90k on it and still has the cross hatch all the way around. The rings are supposed to ride on a thin film of oil and should only wear on the walls in the top of the cylinder since that is when compression is pushing the rings hard against the wall.

My dad took the heads off his 3.0L mitsu that had 120k on and still had a perfect cross hatch.
Most of the domestic blocks in my machining class that haven't been bored already, have a cross hatch. Never, ever saw a cylinder that was wearing normally look like that.

It may be just the way the pic looks, but it looks like the markings start about 3/4" below the top compression ring at TDC, which should put those marks below the oiling rings.

 

[Turbo 2g awd]

I know what a stock motor should look like. But I have a motor with forged internals and am running over 25psi on a rather large turbo. My motor will see more wear in 5K miles than most stock motors ever will. There is much more sress and cylinder pressure in my motor. I need to know if this is common at all in high HP motors with forged internals. Thanks

 

[92redman]

http://www.hastingsmfg.com/Service Tips/piston_cylinder_scuffing.htm
http://www.engineproblem.com.au/piston_pickedup.htm
http://www.tomorrowstechnician.com/tt/t230338.htm

So if you want to know if it should look like that, why haven't you called the people that built the engine yet?

 

[burldude]

Put it back together with new valve seals and thrash . This is common wear with 25 psi of boost and forged internals . This is why you have forged pistons, to deal with the stress of 25 psi.

 

[terefic181]

I sized the piston picture below as close as possible to his cylinder wall picture above. The level of wear on the cyl wall at TDC looks to be on or about the oil ring level on the piston.
If the picture doesn't change size on me , you can check this for yourselves.