Leak Down Test- Need Help Please!

[19-911-65]

Just completed a compression & leak down test on a '80 ROW 3.0. All looked pretty good except there is a air leak ( @ 70 lbs) coming from the spark plug hole on cyl. 1 & 2. You can hear air from the oil fill on all cylinders @ 35 lbs during the leak down.

The engine has been sitting for about 4 years and not run other than in the garage per the previous owner.

So.....what do you think I am going to have to fix on cyl. 1 & 2 concerning the air leak??

Your comments would be appreciated!

Glenn

Results of test:

Cylinder___Compression______Leak down

__1__________150_____________12%
__2__________148_____________10%
__3__________151______________8%
__4__________150_____________11%
__5__________151______________8%
__6__________160_____________11%

[john walker's workshop]

a leakdown test on a cold engine that's been sitting for years is useless.

[19-911-65]

Good point John...I did run the engine about 30 min. prior to each test. The engine is in a roller at this point and can't take it out on the road. Just doing the best I can with what I have to work with ;-}.

Glenn

[Jim Sims]

Perhaps you should get the engine warmed to operating temperature, then run it at 4K for 20 minutes and then repeat the leakdown test.

[afterburn 549]

leak dwn is good only for- Freight trains ,, (when you can get the spark plugs out) UFOs (when they need their annual TBO on the lite speed warp drive ) and most of all on the irreversible valve on a UHIH. The rest should not be used as abstract info will always occur.

[rotorhead]

Goodness.. its been years since I have inspected an irresversible valve or a swashplate for that matter. The UH-1H is the Harley Davidson of the skies.

[DW SD]

If air leak on 1 &2 is coming from the spark plug hole, isn't that just the seal with your leak down tool? Mine has a rubber o-ring that seals. It doesn't seal with the threads. Before threading the tool's hose in, did you lubricate the o-ring, so you can tighten it snugly without tearing it?
John's advice is spot on. However, I would consider those numbers to be pretty acceptable for an engine that hasn't run in four years. They may not be conclusive, however.

Doug

[19-911-65]

Originally posted by DW SD
If air leak on 1 &2 is coming from the spark plug hole, isn't that just the seal with your leak down tool? Mine has a rubber o-ring that seals. It doesn't seal with the threads. Before threading the tool's hose in, did you lubricate the o-ring, so you can tighten it snugly without tearing it?
John's advice is spot on. However, I would consider those numbers to be pretty acceptable for an engine that hasn't run in four years. They may not be conclusive, however.

Doug

Yes... it could be I don't have the seal/o-ring seated properly, and I will try it again with some lube on the o-ring.

Thanks Doug for your positive remarks and helping me get closer to correcting problem!

Glenn

[afterburn 549]

I am still looking for a good (or bad) harley of the sky with leaky seepy systems, bumpy vertical, high freek problems. With or with out swashplate. Most all are so canabilized is unbelievable. There, this thread went off topic. but everyone should bury their leak dwn tester!! In static mode all sorts of ghostly ghastly eronous leaks can show, but are not real. flat tires on freight trains are hard to air up............

[DW SD]

Originally posted by afterburn 549
everyone should bury their leak dwn tester!! In static mode all sorts of ghostly ghastly eronous leaks can show, but are not real.

How did you come to the conclusion we should all bury our leak-down tools? Is this from personal experience or vendetta ? Or something you've read?

I, personally, believe in their value and it seems most reputable shops do as well. Great scores from a leak down can be hard to dispute, though anomalies are not necssarily conclusive and require more investigation.

Thank you,

Doug

[Rot 911]

I agree with Doug. Good numbers are hard to dispute and bad numbers, like my 80% leakdown on on cylinder on my 3.2 gave me cause to search for the source of the leak which proved to be a burnt valve.

On this particular engine those numbers are not in the serious range and I would install the engine and run it for awhile to see if the numbers improve.

[afterburn 549]

A leak dwn tester is a great sales finder, in the wrong hands or ignorant hands they will provide much false and useless info and lead to lots of unnecessary repairs. Just cold hard facts

[DW SD]

Originally posted by afterburn 549
A leak down tester is a great sales finder, in the wrong hands or ignorant hands they will provide much false and useless info and lead to lots of unnecessary repairs. Just cold hard facts

I'm not directly saying you are wrong, but sounds like a subjective opinion rather than "cold hard facts"?

Don't know how many folks decide to rebuild their engines because of one leak down test. If you work with a shop which preys on folks by use of a leak-down result, without other data that is very very poor.

My opinion is unchanged on the value of their results.

Doug

[afterburn 549]

Case in pt the thread starter 19-911-65 (above) thinks the eng is bad....useless info and can be construed......yes it is a good instrument in cape-able honest hands......but so is a scalpel. Just time and again here I see this thing used as the tie breaker for all arguments, and generally is being used wrong..........................

[Grady Clay]

Chill guys.

George clearly doesn’t understand this Forum, let’s welcome him and educate him as to the proper protocol. He may have something useful to offer. Pelican 19-911-65, you apparently have the skill to provide clear data that we can help you analyze. You are asking the right questions, let’s not get distracted.


I agree those are acceptable numbers for an engine that has been sitting. Can you put the engine in a running 911? Getting some “break in” miles on it is invaluable for diagnosis and its long term performance. Is there someone in your area with their engine out? You can get together and run your engine in their car to both of your benefit.

Having compression and leak measurements after an extended drive will give you far more information.

Best,
Grady

[afterburn 549]

Well some are more serious then others, and most of the time I know nothing and can prove it...if ( it DID ) roast -ya sorry,,, - my humor is shy of dry to wet, I just stated that facts best I know how. If you are here to get a education like most of us then once you filter threw the all the latest hype of what works and dont and try a few things......you might find my explanation a little humorous but true. So SORRY. I was stateing the fact that a leak dwn test is only as good as the operator- that was my pt in education .I will be more carefull around you