piston damage

[dan2288]

I took apart an old block and noticed the pistons were scratched on the sides. Its like they were scraping on the walls. The walls also showed lines were the pistons were scraping. What causes this? I want to build the block and make sure it doesnt happen again.

 

[needsy]

To a certain extent that is normal. As the piston moves up and down the cylinder the skirt will rub against the wall and cause wear. Deep scores are not normal. I imagine particles in the oil are the most common culprit for scoring. Pictures would help figure out what went wrong in your engine.

 

[bpe121212]

I had the same problem with my newly built 2G short block. My scored cylinder wall and piston was primarily due to a blown Oil pump and parts from that doing it's damage before I could catch it! I had a local Mitsu shop do the rebuild and they did not replace the old Oil Pump (135,00 miles on the pump) when they rebuilt the motor even though I requested that they replace everything during the rebuild. The metal particles that were allowed to flow before It finally completely failed caused the damage. Your scoring problem could be from a myriad of causes. Pic's with a little more background can help in the diagnoses quite a bit.

In regards to a future rebuild, I would recommend that you do a complete blueprint rebuild paying particular attention to the Piston Cylinder wall clearances to ensure an optimal fit and follow the new motor break-in procedure religiously.

Good luck to ya!


Pres