Proper leakdown test procedures

mark1905

mark1905

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Could anyone point me in the direction of the proper documentation and/or steps to perform a full leakdown test on a 3.0LX?
 
Bondo

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Re: Proper leakdown test procedures

Ayuh,.... Are ya chasin' an Issue, or just wantin' to know,..??

I just hook my shop air to my compression tester, 'n put the air to it, after ya block it from turnin' the motor over(at Tdc of course)...

If ya hear air leakin', is it to the intake, exhaust, or base...

That's where ya wanta look Deeper...
 
mark1905

mark1905

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Re: Proper leakdown test procedures

I'm getting a good amount of blow by/air pressure and foamy oil out of the valve cover vent.. and hoping it's not my rings going bad. Engine is also starting to be able to rev way too high. She used to max at 4800 and now I can get her up to almost 5100 with a 19P prop on her..
 
Bondo

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Re: Proper leakdown test procedures

almost 5100 with a 19P prop on her.
Click to expand...

Ayuh,... So put a 21" on her....;) She's gainin' Horsepower,.... :D

Maybe it's foamin' cause yer Revin' the crap out of it....
 
tpenfield

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Re: Proper leakdown test procedures

mark1905 said:
Could anyone point me in the direction of the proper documentation and/or steps to perform a full leakdown test on a 3.0LX?
Click to expand...

You'll need a leak tester and a compressor

leaktest1A.jpg

You can google procedures, and there is probably one that will accompany the tester. Essentially, you put the cylinders at TDC one at a time and then connect the tester to each cylinder. The difference in the gauges is used to calculate the leak. 10% leak is good, 20-30% is fair, and 30+% is not so good.
 
S

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Re: Proper leakdown test procedures

Leakdown tester has 2 guages. Set the shop air guage at 100 psi. Get your cylinder so both valves are completely closed,and stay closed, whatever it takes to accomplish this. Screw air hose into spark plug hole. Open the air valve on the tool, and read the second guage. Keeping the shop air guage at a 100 psi, you can now read the leakdown as a percentage.
 
mark1905

mark1905

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Re: Proper leakdown test procedures

Bond-o said:
Ayuh,... So put a 21" on her....;) She's gainin' Horsepower,.... :D

Maybe it's foamin' cause yer Revin' the crap out of it....
Click to expand...


Lol.. I don't make it a habit.. but it occurred to me like a ton of bricks yesterday that maybe she's able to rev higher now because there isn't as much resistance in the form of compression..

Getting a good amount of air just at idle. I can't keep my finger plugging it.. it blows it right off..

..and enough oil blowby that it's puddling against the valve cover and running down the engine, all over the starter motor and into the bilge..


Thanks all for the tips. I've read up on automotive websites about how to do it, but am wondering if there are any special tips for doing it with our engines/manifold/cooling setup..

scoflaw said:
Get your cylinder so both valves are completely closed,and stay closed, whatever it takes to accomplish this.
Click to expand...


This would be just TDC for each cylinder, correct?
 
tpenfield

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Re: Proper leakdown test procedures

mark1905 said:
Thanks all for the tips. I've read up on automotive websites about how to do it, but am wondering if there are any special tips for doing it with our engines/manifold/cooling setup..




This would be just TDC for each cylinder, correct?
Click to expand...

Nothing special for the marine engines versus the automotive on the leak testing. Valves are closed at TDC (hopefully), so that is where you want to be. I use the timing mark on the Harmonic balancer as a reference point and then make the additional marks (with chaulk or something) for the other cylinders. A 3.0 is a six banger (right) so you'll have 3 marks 120 degrees of rotation apart. I have a V-8, so I get 4 marks 90 degrees apart. Then it is a matter of turning the engine to the next mark (breaker bar on the balancer bolt) and testing the cylinders according to the firing sequence.

Let us know your numbers when you're done. :)
 
Don S

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Re: Proper leakdown test procedures

This would be just TDC for each cylinder, correct?
Click to expand...

It's a 4 stroke engine, crankshaft turns 2 times for the cams one time. You have to be on TDC of the cylinder you want to test, while on the compression stroke, NOT the exhaust/intake stroke.

This may help http://www.animatedengines.com/otto.html
 
mark1905

mark1905

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Re: Proper leakdown test procedures

Don S said:
It's a 4 stroke engine, crankshaft turns 2 times for the cams one time. You have to be on TDC of the cylinder you want to test, while on the compression stroke, NOT the exhaust/intake stroke.

This may help http://www.animatedengines.com/otto.html
Click to expand...


Lol.. I knew what I was trying to say in my head.. just it didn't come out right. I gotcha.

tpenfield said:
A 3.0 is a six banger (right) so you'll have 3 marks 120 degrees of rotation apart.
Click to expand...

No.. inline 4..
 
tpenfield

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Re: Proper leakdown test procedures

4 cylinder . . . then the marks are even easier; 2 marks at 180 degrees. so, like Don says you'll turn the crankshaft 2 revolutions to get all 4 cylinders.
 
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