Low compression after rebuild

[BogusSVO]

Do a leak down test. It will tell you more than a basic compression test

 

[pmanaresi]

Yea it will tell me I have ring leakage which I already know. I was hoping for ideas as to why this occurred and if it would be due to the larger ptw and ring end gap.

 

[BogusSVO]

PTW will have minimal affect on blow by. Same with ring gap. I gap rings more than you do and have good compression and leak down numbers.

You may have chewed the rings up if the hone was the wrong grit for the rings.
That or you could have over heated and lost tension in the rings.

 

[pmanaresi]

PTW will have minimal affect on blow by. Same with ring gap. I gap rings more than you do and have good compression and leak down numbers.

You may have chewed the rings up if the hone was the wrong grit for the rings.
That or you could have over heated and lost tension in the rings.

Yea I was kind of worried that might be the case. In the first drive during break in, some how a core plug blew out and I lost all the coolant immediately. I shut down and pulled over right away but may have fried the rings real quick. I was hoping to avoid tearing the engine back down to bare block and simply rehone the cylinders with the engine installed. Any recommendations on where to find a high quality ball hone to suit my needs?

 

[arrowhead]

Why did you not say that at the start of your thread, you had the reason all alone.
How hot did it get, did you shut the engine when you saw the smoke, you may have bigger problems.

 

[pmanaresi]

I didn't start the thread, but yes I did kill it as soon as the plug blew.

 

[curt-s]

If that's the case, it would take longer than that to overheat after the coolant left the building.. even if both your sensors are shot and somehow (1) reporting to the cluster a nominal temperature and, (2) reporting a believable temperature to the ECU.
It's sounding like the rings didn't seat because either the gauge is faulty (measurement and/or seal), the hone was not proper for the rings used, or the cylinders were out of round to begin with and the rings could not seat evenly. ...or you have a significant enough head issue due to seal or timing.

 

[motomattx]

PTW will have minimal affect on blow by. Same with ring gap. I gap rings more than you do and have good compression and leak down numbers.

You may have chewed the rings up if the hone was the wrong grit for the rings.
That or you could have over heated and lost tension in the rings.

This ^^^ and meaning not that the coolant overheated, but rather that you got the rings too hot and killed the spring tension in them.

 

[curt-s]

Following that, OP, how have the AFRs been since rebuild? In check or constant lean?