cylinder wall scoring? what should I do? Help?

[motavated]

I am honestly clueless.

 

My engine was sounding like shit the past couple months. That is why I decided to "re-tighthen" the head bolts.

I opened her up today. And this is what I found. Is this ok?

 

What should I do? ring job and hone?

Short block rebuild?

Run it?

Ideas?

[MicroMachinery]

Does your finger nail catch on it?

[motavated]

Does your finger nail catch on it?

 

 

There is a small scratch on piston one. like an inch from top to bottom. A thin one...

[MicroMachinery]

Does your finger nail catch on it?

 

 

There is a small scratch on piston one. like an inch from top to bottom. A thin one...

 

... was that a yes?

[motavated]

Yes.

[Javin]

eek is that what my engine looks like on the inside too? Had the damn thing for 8 years but never personally opened it.

[MicroMachinery]

If it's just that one little spot, I wouldn't sweat it. If you took the pistons out(I see they're cleaner), you have to re-ring it. If you re-ring it, you'd better knock the glaze off w/ a hone. But like I said, if that's the only spot your nail catches on on that one piston, don't bother taking it apart. It shouldn't affect your engine enough to warrant a rebuild. Run it. That little scratch shouldn't be making your engine run badly.

[Pumpkn210]

If it's just that one little spot, I wouldn't sweat it. If you took the pistons out(I see they're cleaner), you have to re-ring it. If you re-ring it, you'd better knock the glaze off w/ a hone. But like I said, if that's the only spot your nail catches on on that one piston, don't bother taking it apart. It shouldn't affect your engine enough to warrant a rebuild. Run it. That little scratch shouldn't be making your engine run badly.

Word, then... Get it back together and do a Comprehenshion Test! :lol:

 

 

[datzenmike]

Looks like you have rotated the motor... are the #1 and #4 scored too?? If so this would indicate that the motor was overheated sometime back. Have you pulled the pistons yet??? Look for broken rings/ring lands.

 

When you re-built it did you just hone it and re-ring it??? OR did you bore and go oversize??

[motavated]

#1 has a small scratch. #2 & #3 has scoring/glazing #4 ok.

 

 

After the head gasket "tighten" incident. It over heated twice. It was supposedly rebuild like less than 20k ago.

 

What do yah think? hone it out with rings? Or run this bitch as is?

[motavated]

Cant I just sand paper that glaze out? Or do I take off the pistons for damages?

[metalmonkey47]

I'd bore it, hone it, and put in new rings and pistons. But that's just me of course.

[motavated]

Looks like you have rotated the motor... are the #1 and #4 scored too?? If so this would indicate that the motor was overheated sometime back. Have you pulled the pistons yet??? Look for broken rings/ring lands.

 

When you re-built it did you just hone it and re-ring it??? OR did you bore and go oversize??

 

 

Bore and oversize. It says .50 on the piston.

[datzenmike]

0.50 is 1/2 mm or about 0.020". When over-boring, the piston for that cylinder should be given to the machinist. He should measure it and bore to match it. For example you get a set of Z24 89mm pistons and want to bore your Z22 block out. Seems simple just bore the block to 89mm right? No, not quite. For one thing there has to be some clearance for the piston, they and the bore can't both be 89mm.

 

The Z24 piston must have a side clearance of 1 to 1.8 thousandths of an inch. Think about that... that's 1 thousandth to 1.8 thousandth or an inch. So no mater what the piston diameter is, the bore must be 2 to 3.6 thou larger. Because pistons are mass produced they are not all exactly the same size for proper clearance.

 

If your machinist bored to exactly 85.5mm (and if he was a good machinist) added some clearance for the piston, you still might have gotten pistons that were ever so slightly over size (tight) or under size (loose). I'd be concerned with a loose piston as it doesn't support the ring properly and can snap the ring lands.

 

Did you place the rings in the bore one at a time and measure the end gap?? This is even more critical for the top ring that gets the hottest. If there is not enough, or no gap, the ring will expand from the heat and break, possibly scoring the cylinder bores. The scoring in your pictures are very sharp edged.

[motavated]

I didnt do it. Some re-builder guy did. I just ran it till something was not felling right no more. I just paid. Didnt feel right. Checked the timing and the teeth were off by 3. So I did the timing. Ran it for a year and a half and overheated. Then I took of the head for a new gasket to find this.

 

The block still rebuild-able? In other words. Can I install bigger pistons and new rings?

[banzai510(hainz)]

wrong ring gap

 

I had a L18 that had marks on all 4 cylinders w/only 50k. all in the same spot

[motavated]

I will send it in for a short block re-build. I can take care of everything else. Thanks!

[datzenmike]

The cylinders need to be measured and compared to the pistons. As long as they are within 1 to 2 thousandths? of side clearance you can hone the marks out (as long as this does not oversize the bore beyond spec) and re ring the pistons. This time check the ring end gaps. top ring is about 0.010 to 0.015" second ring is about 0.012 to 0.020". Oil ring is about 0.02 to 0.035". This will allow enough room for the ring to expand when the motor heats up.

 

Did you pull the pistons out yet and look at the rings????

[motavated]

The cylinders need to be measured and compared to the pistons. As long as they are within 1 to 2 thousandths? of side clearance you can hone the marks out (as long as this does not oversize the bore beyond spec) and re ring the pistons. This time check the ring end gaps. top ring is about 0.010 to 0.015" second ring is about 0.012 to 0.020". Oil ring is about 0.02 to 0.035". This will allow enough room for the ring to expand when the motor heats up.

 

Did you pull the pistons out yet and look at the rings????

 

 

No. I will do that today since I have no choice. I am going to rebuild her anyway.

[Master-O-Turbonics]

Cant I just sand paper that glaze out?

 

:-O

[datzenmike]

You could, but if you can feel the score with your fingernail it's deep enough that scowering in one spot with sandpaper would only make a low spot and the bore wouldn't be round. Even honing may remove too much material. Only way to know is to measure it.