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journeyman sled/motorhead
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the recent topic on rebuilds lead me to thinking. how many here have done or do regular checks on their engines. any of you do leakdown checks? I am hoping you know what I am talking about. the test checks the seal on your rings .by putting 100 psi in and seeing what they (rings) will hold you can determine leakage past the rings. what is good or bad? I see a 10 percent leak and I do the rings. that is my rule of thumb. the engine will still be running but not like it should. leakdown gauges, they are also availabe from harbour freight or by making your own ,snap on as well as others. however a recent test of the hf unit, showed it as having not so acurate gauges. it showed an extra 10 percent leak that was not present when we used a snap-on gauge. my homemade set uses Parker gauges and a good regulator. between the regulator/gauge and second gauge , you use a damper valve( in my case a piece of 1/8 inch pipe filled with epoxy and drilled using a .040 drill bit). from the second gauge to the plug hole adapter. after setting the regulator to 100 psi, you read the second gauge seeing what it will hold. easy to figure the leakage% that way. without the damper valve the second gauge will recover to fast and you will not see the leakage. I will post a pic of the rig soon.
 

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journeyman sled/motorhead
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Discussion Starter #2
sorry about the size I have yet to figure that out. the briggs in background well that needs a bore job :rolleyes: .maybe I figured out the pics
 

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So do you do this on a hot or cold motor ,Or don't it matter.I would like to do my 700 has 12,500 miles with good compression & seems to run the same as when I got it.
 

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journeyman sled/motorhead
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warm engine. piston up to eliminate leak through the ports.
 

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Every 3000 miles I cap all the holes (exhaust ports and reed valves) apply 15 inches of vacuum to the injection nipples one at a time to see what the lower end sealing is doing. Found lots of interesting vacuum leaks and failed crank seals that way.
 

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journeyman sled/motorhead
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I'll get you the parts from Parker and you make me one? :p[/b]
not a problem . I knew you would like that part. I have one already made for you.
 

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OK, somebody educate me, why would you do a leak down test on a 4 stroke engine ( assuming that the Briggs is a 4 stroke). Compression test, yes. A leak down test on a 2 stoke to check the crank seals and crankcase gaskets, yes, but on a 4 stroke? Somebody clue me in.
 

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OK, somebody educate me, why would you do a leak down test on a 4 stroke engine ( assuming that the Briggs is a 4 stroke). Compression test, yes. A leak down test on a 2 stoke to check the crank seals and crankcase gaskets, yes, but on a 4 stroke? Somebody clue me in.[/b]
I've never heard of applying 100+ pounds of pressure to a two stroke, I'd be afraid of blowing the crank seals if the ports were not covered. In the past I've done a pressure test on the crankcase by sealing exhaust and intake and applying 15 pounds pressure to check the seals. A compression test should reveal if the rings are in good condition.
 

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I'll get you the parts from Parker and you make me one? :p[/b]


Sweeeet!! That regulator is one of my products. I work for Parker Pneumatic division. Actually that is one of our only "made in mexico" products, but it originated here in Richland michigan. I could probably get some parts pretty easy.

What I don't understand, is don't you have to shut off the pressure supply from the reg to measure leak at the cylinder?? A simple 2 way ball valve in-between the reg and the 2nd gauge would do the trick. That may be what you have, I just don't see it.
 

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I've never heard of applying 100+ pounds of pressure to a two stroke, I'd be afraid of blowing the crank seals if the ports were not covered. In the past I've done a pressure test on the crankcase by sealing exhaust and intake and applying 15 pounds pressure to check the seals. A compression test should reveal if the rings are in good condition.[/b]
You are not plugging any intake or exuast ports when performing this test. Leave them wide open. This is the only test I use. The great part of this test is you can apply the air to the cylinder and rotate the crank so the piston travels don the bore. As it does you may even find a bad spot on the cylinder wall as the leakage may jump suddenly.
As for why on a 4 stroke. Why not ? As you apply the air to the cylinder you can check to see fi you have any leakage past the intake and exhaust valves as well as the rings.
 

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You boys are talking about to different tests.
A crank case presure test is done by blocking the intake and exhaust ports and then applying a low presure to the engine to check the seals.
A clyinder leak down test checks the condition of the piston rings and clyinder by apply a much higher presure to the cumbustion chamber.
 

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journeyman sled/motorhead
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Discussion Starter #13
Sweeeet!! That regulator is one of my products. I work for Parker Pneumatic division. Actually that is one of our only "made in mexico" products, but it originated here in Richland michigan. I could probably get some parts pretty easy.

What I don't understand, is don't you have to shut off the pressure supply from the reg to measure leak at the cylinder?? A simple 2 way ball valve in-between the reg and the 2nd gauge would do the trick. That may be what you have, I just don't see it.[/b]
SnoFast :there is more to a compression test than just rings, they include valve timing and other variables. thus a leakdown test it will tell you how well they(rings) hold the psi. yes in a 4 stroke it could be leaking valves that would cause a leak but easily found with the test. like mr670 stated they are differant tests, the test your thinking of is the one Simon(TD) is talking about.catdoo no chance of blowing the seals if you do it needed more than rings. now to crnsuperdutys question: no need to stop the air, the damper valve I speak of (1/8 inch pipe filled with epoxy and drilled with a .040 hole) slows the primary feed air (psi) enough to let you get the leakdown reading off the second gauge. without this small hole it lets the second gauge recover much too fast and you will not get the reading.you need the constant feed 100 psi to find the leakage%. I think I covered all the questions. and yeah it says mexico on it. :rolleyes:
 

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not a problem . I knew you would like that part. I have one already made for you.[/b]
Barry, I don't suppose you could make me one of those, please? :D
 

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journeyman sled/motorhead
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Discussion Starter #15
Barry, I don't suppose you could make me one of those, please? :D[/b]
I will see if I can scrounge the parts up to do that for you Dave. I had to get the gauges out of the scrap yard at work for these. we stopped using 1/8" gauges and they are hard to find. I know I have atleast 1 left :wink: .
 

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journeyman sled/motorhead
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Discussion Starter #18
You can buy a two gauge leak down tester from Jeg's or Summit racing for around $60.00-70.00[/b]
got less than $20 in mine. I was thinking the jegs ones were closer to 100 bucks. harbour freight has one for around 30 bucks. the one we tested was around 12 psi off that is a lot of leakage that is not present, but the gauge said it was. yep planning on attending the bbq @ idooskis.
 

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journeyman sled/motorhead
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Discussion Starter #19
Barry, I don't suppose you could make me one of those, please? :D[/b]
Dave, I have everything but the gauges. and yes its a parker regulator also.
 

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Barry, I would be interested in one also,,, looks to me like your in business here I guess I will hang out at the end of the line,,, thanks,,,
 
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