Jump to content

IGNORED

Leak Down Tests Compared


txvepr

Recommended Posts

Does anyone have Leak Down specs for a newly rebuilt L28 engine versus a well used one?

I am starting a rebuild on an old engine and wanted to know how what I currently have would compare to an engine that will have new rings, valves, cylinder honed, etc....

The rebuild engine is not really showing signs of being worn out, and the previous owner indicated that it ran fairly well. It was pulled before I got it so I haven't seen it run.

Here are the Leak Down Test results for my project engine for comparison:

These are all in the green band on the gauge.

1: 15%

2: 27%

3: 30%

4: 15%

5: 17%

6: 15%

 

Link to comment
Share on other sites


On 1/9/2016 at 2:23 PM, txvepr said:

The rebuild engine is not really showing signs of being worn out, and the previous owner indicated that it ran fairly well. It was pulled before I got it so I haven't seen it run.

How long has it been since it last ran?  Results from cold dry cylinders may not be very representative.

Link to comment
Share on other sites

So, I am guessing that a new clean engine with clean valves would have almost sealed cylinders? And as time goes on, carbon, etc.. buildup will cause those valves to not seal completely plus any wear on piston rings would also have effect also.

 

  • Like 1
Link to comment
Share on other sites

9 hours ago, txvepr said:

So, I am guessing that a new clean engine with clean valves would have almost sealed cylinders? And as time goes on, carbon, etc.. buildup will cause those valves to not seal completely plus any wear on piston rings would also have effect also.

 

I learned what the term "lapping valves" means the hard way by not having the foresight you have. :rolleyes:

Carbon builds up on the valve seats and the valves causing them not to seal off, just like you said.

DSC01767.JPG

Link to comment
Share on other sites

9 hours ago, txvepr said:

So, I am guessing that a new clean engine with clean valves would have almost sealed cylinders? And as time goes on, carbon, etc.. buildup will cause those valves to not seal completely plus any wear on piston rings would also have effect also.

I was thinking more along the lines that an engine that sits will get a small amount of surface rust on the cylinder walls, maybe a valve seat or two (two or three of the valves will be open while sitting), and the oil will drain from the rings and cylinder walls.  Even in brand new engines.  If you just went straight to a leak-down test on an en engine that's been sitting, without spinning the engine or running it, results would be expectedly iffy.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.