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anyway to differentiate between air leaks during pressure test?

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i dont think there is but is there anyway to differentiate between a center case gasket leak, pv linkage leak or crank seal leak (worst comes to worst well just pulloff the right case cover to check the crank seal)?

just did a bottom end on a 01 cr250. performed a pressure test and found air exiting tranny vent tube.

we used regular valvoline "moly fortified" grease (pretty much just ngli #2 wheel bearing grease) for the pv cavaties. brand new crank seals of course that were greased up before install. everything seems fine and no leaks anywhere outside the cases where the halves meet. so if its a center case gasket it must be leaking internally.

so like i said, is there any tricks to help differentiate between the 3 on where the leak is coming from?

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Leak at PV will cause pressure test to fail, but certainly will not affect the way bike runs. So, I'd try to rule out leak at PV 1st by packing with grease.

If not PV, then look for bubbles around crank seal, maybe have to take drive gear off?

if it's neither of those, then must be center cases into tranny

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yea but that would defeat the purpose. my question was, is there a way to differentiate between the three (actually we're worried about the center cases as that would mean splitting again) without removing anything.

i read somewhere that you could remove the trans drain plug and that would let you know if you had a crank case leak, but that doenst make sense since the tranny vent tube acts the same way.

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Get yourself a o-ring kit. (bought mine from harbor freight) remove the PV cover from right side. remove the pinion arm and linkage from the top of shaft. slide a snug o-ring w/grease on the shaft and replace parts and cover. do the pressure test again, this time you won't loose pressure unless you actually has a problem. it works:thumbsup:

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i tried the oring. still lot pressure but MUCH slower. also found that once the oring was in place the leak slowed down significantly.

should note that the oring was not big enough to seal perfectly (it was an a/c oring, but the linkage did not compress it enough to make a perfect seal). we didnt find any leak anywhere else and none out of the trans anymore. somehow we still lots pressure, where to, i dont know.

also found a small leak in the pressure testing equipment. we used some white pipe tape instead of the yellow gas pipe tape (that i have at home) when we had to swap sizes from the kehin to the mikuni on a whim. oh well. good enough for him he says. that white tape sure doesnt seal as good as the yellow.

i plan to make my 00 100% leak tight soon as i get my parts in from TT. i tried to get my buddy to make is leak tight, but he just doesn't share the same passion i guess.

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i tried the oring. still lot pressure but MUCH slower. also found that once the oring was in place the leak slowed down significantly.

should note that the oring was not big enough to seal perfectly (it was an a/c oring, but the linkage did not compress it enough to make a perfect seal). we didnt find any leak anywhere else and none out of the trans anymore. somehow we still lots pressure, where to, i dont know.

also found a small leak in the pressure testing equipment. we used some white pipe tape instead of the yellow gas pipe tape (that i have at home) when we had to swap sizes from the kehin to the mikuni on a whim. oh well. good enough for him he says. that white tape sure doesnt seal as good as the yellow.

i plan to make my 00 100% leak tight soon as i get my parts in from TT. i tried to get my buddy to make is leak tight, but he just doesn't share the same passion i guess.

To put pressure on the o-ring, grab the shaft with needle nose pliers while holding them level. squeeze and pull down with handle end then tighten. that will pull up on shaft and push down on the pinion arm. you can also stick a scribe or ice pick in the clip hole and lift before grabbing the shaft to pick it up and take out more slack.

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To put pressure on the o-ring, grab the shaft with needle nose pliers while holding them level. squeeze and pull down with handle end then tighten. that will pull up on shaft and push down on the pinion arm. you can also stick a scribe or ice pick in the clip hole and lift before grabbing the shaft to pick it up and take out more slack.

good idea

Wouldn't the spark plug be wet with tranny oil if the crank seal was leaking?
it would, but this is on a brand new rebuild. hasnt even been ran yet.

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