How long after a rering to get good leakdown #s?

[Bobalouie]

How long after a rering does it take for your leakdown numbers to get back in shape? I know that if you dont need a renic job, that it takes a little while to get the rings seated in. Any estimation of hours that takes?

I have about 6 hours on my engine post rering, about 2 hours on it since switching from Dino oil to full synth, and when I checked my leakdown today it was still pretty bad. The motor had one sleeve put in it, but the other 5 were good, no renic. All the pistons were replaced with top pin wizards.

I think something is wrong with my gauge set, so I have a new one coming so I can recheck it with a higher quality leakdown test setup. Just wondering if anyone has any idea about how long it takes to get the new rings worn in to the existing cylinder shape.

Thanks

 

[catfish123]

Bob, what do you mean by "pretty bad"?

 

[K.Kiser]

I'd expect you to be under 6-7% or so on a warm engine..

 

[FLYING BUTCHER]

Bob, sorry to hear of your engine problems AGAIN??? You couldn't have had very many hours on the last rebuild?? I have gone 20 hours or more on some rebuilds before the new rings get a good seat and develop good compression. Hope you and the misses are doing well.

have fun be safe

 

[Bobalouie]

Catfish,

These readings were taken on a warm engine.
#1 140, 19%
#2 140 10%
#3 140 25%
#4 140 14%
#5 140 20%
#6 145 16% This bore has a new sleeve.

The readings were bad enough that I pulled the odd side head to see whats what, and everything looked pretty good. Crosshatch still there, pistons in good shape (why wouldnt they be, they only have 6 hrs), nothing to make me think there is somehthing amiss.

Like I said, I think my gauge is bad, when I dead head the gauges, the leakdown gauge does not read the same as the reference gauge, it is 10-14 psi less. Conversely, when I remove the air pressure, my reference gauge never returns to zero. So, I think my crappy gauges dont tell the truth. So, I have one of Balzy's gauges hopefully on its way.

Flying Butcher,

No, not again, this is the same rebuild that was done last year. I just didnt get a chance to run it much last year, and this weekend was the first chance I have had to de-winterize it. The new baby keeps us pretty busy, LOL.

I thought I had heard 15-20 hrs before, to get completely broke in, but wasnt sure. The engine runs good, it is turning 7900rpms with the hoss 26P at 100mph, so if its down at all, its not down much, which got me thinking about the leakdown gauge set up.

 

[catfish123]

I'm a very bad person to be attempting to answer mechanical questions, but I would believe it to be impossible to have the compression you have at 140 with leakdown numbers as high as you have recorded. I would think there was something wrong with your gauge as you have stated or your technique in doing the test.

 

[Bobalouie]

I hadnt thought about technique, does anyone have any pointers on that? Here is what I have been doing:
1. Use a dial indicator in the plug hole to rotate the engine to TDC
2. thread the hose for the leak down tester into the plug hole
3. hook up the hose to the leak down tester
4. hook up the air compressor hose to the tester, air compressor regulator set to 110psi
5. fine tune the reference air pressure regulator on the leak down tester to 100 psi
6. read the leakdown gauge reference pressure, if its at 90 psi then 10% leakdown, etc.

I have read that you should rotate the engine counter clockwise to do leakdown on the stbd side, and clockwise rotation to leak down the port. It has to do with the thrust angle of the rod helping to close the ring gaps a little bit, since you dont really want to read leakdown past the gap. I did not do this, I rotated clockwise for all cylinders.

Any validity to this? Should I rotate different directions for different sides?

 

[catfish123]

I have been told by my most reliable source that yes, you do need to rotate the flywheel a different direction for different sides.

 

[SLOmofo]

Re: How long after a rering to get good leak down #s?

When you get the BALT read it's instruction page. I have one of these and use it at work, it's an excellent tool!
A compression test will give you an over all look at compression.
Should be done with a fully charged battery with a big charger hooked to it.
Put the muffs on it and turn on the water, don't want to run a water pump dry!
Watch the gauge for the first hit of a complete cycle and then at the forth complete cycle.
The first hit will give a look at ring/cylinder wear.
Example: first hit is 90 psi and then builds to 140 on the forth hit.
First hit is 120 psi and then builds to 140 on the forth hit.
If the compression is lower on one cylinder then the BALT will show how much loss as a percentage and then you listen where the air is escaping.
On a four stroke listen at the air cleaner=intake valve. Exhaust pipe= exhaust valve. At the oil filler cap= rings.
Two stroke not valid because it uses crank case compression and reed valves.
The cylinder leakage test can be used to see how much the rings and cylinders are worn by making a flywheel stop and doing the same test with the piston held just above where the exhaust port would be exposed/open.
I had an engine once that had 140/145 psi across all the cylinders but had as much as 39% leakage and as low as 7%.

 

[John Richied]

I wouldn

 

[FLYING BUTCHER]

Hey John, ya old dog, how did you get back on here??? Hope you and the boys are doing well. We are leaving in the morning RVing for the summer. Good to hear from ya.
Have fun be safe

 

[SLOmofo]

All I know is his knees were all ruffed up during the first few days of the WAR13.

 

[Bobalouie]

Thanks to all who commented on this thread, just to let everyone know, I got the Balz gauge in and retested. The results were:

#1 - 4%
#2 - 4%
#3 - 6%
#4 - 4%
#5 - 4%
#6 - 5%

So, it seems the cheap gauge I bought 2 years ago worked about as long as I paid for it would suggest.

Thanks everyone!

 

[ssv1761982]

Sounds like a winner