Detroit 671 rebuild, wrist pin cover won't hold vacuum

[tobyyost]

HI, I am helping a friend rebuild his Detroit 671's. We are assembling the new pistons, rings, liner etc... As we pound in the wrist pin covers with the tool we are checking them for holding vacuum. All the covers are holding just fine except for one. I have googled my brains out and I cannot find anything that tells you what to do if you have one that is leaking. I have to assume we have to pull that cover and try a new one. the cover is in perfectly straight and it looks just fine, but it won't hold a vacuum for more than a second. Can anyone who has experienced this give us some advice of the next steps.

Thanks for all your help

 

[heysteve]

If all else fails, try contacting the Bus Grease Monkey. He seems to have a LOT of experience with those older Detroits.

 

[DennisB1]

Ask the question on boatdiesel.com. There are lots of info and members that maybe able to help.

 

[SIBERNUT]

Chain saw motor

Now my Navy days are dim. But I believe the buttons are to keep the wrist pins from hitting the cyl walls. As to why you would want them to hold a vacuum I can't figure. They are below the rings, right?

 

[Lepke]

The purpose of the cap is to keep oil returning from the sprayed piston head and grooves in the piston bushings from flooding the cylinder walls. Depending on the model some steel caps are held in by a clip. There is no requirement for vacuum.
There are rings above and below the pins.

 

[C lectric]

On BOATDIESEL DIRECT YOUR QUESTION TO RONALD SPARKS.

He is the expert about DD engines and I mean expert.