EVO crankcase pressure test?
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Novice
Joined: Oct 2009
Posts: 17
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From: Wisconsin
I think you made an excellent points about seal diameter variance & use of retaining compound. Sounds like maybe you've gone down this road before too? I had a couple new James seals on hand and used one in this repair. The initial new seal appears was cleaned to bare metal for Loctite 620 the crank shop said was applied. Evidently something went wrong as that seal popped out of the case. Maybe not enough Loctite to hold up during break in blow by? I just measured the old seal to the other new James seal I have. Old is 2.504" new is 2.506 but new still has red sealant on it so that's probably worth a couple thousandth's.
I chemically removed the new seal red sealant then scotch brite buffed to bare metal for use of Permatex (green) sleeve retaining compound. I used brake clean & acetone to clean then applied Permatex surface prep activator in conjunction with the compound to both surfaces, installed seal and let it cure the specified 24 hrs also. Permatex not as robust as Loctite 620 and 680 per the specs but does have 3000 psi shear strength and good to 400 degrees so I think it will hold up.
Time will tell but so far so good. Thanks for your feedback.
I chemically removed the new seal red sealant then scotch brite buffed to bare metal for use of Permatex (green) sleeve retaining compound. I used brake clean & acetone to clean then applied Permatex surface prep activator in conjunction with the compound to both surfaces, installed seal and let it cure the specified 24 hrs also. Permatex not as robust as Loctite 620 and 680 per the specs but does have 3000 psi shear strength and good to 400 degrees so I think it will hold up.
Time will tell but so far so good. Thanks for your feedback.
HDF Community Team
Joined: Dec 2005
Posts: 5,374
Likes: 2,570
From: NC USA
I think you made an excellent points about seal diameter variance & use of retaining compound. Sounds like maybe you've gone down this road before too? I had a couple new James seals on hand and used one in this repair. The initial new seal appears was cleaned to bare metal for Loctite 620 the crank shop said was applied. Evidently something went wrong as that seal popped out of the case. Maybe not enough Loctite to hold up during break in blow by? I just measured the old seal to the other new James seal I have. Old is 2.504" new is 2.506 but new still has red sealant on it so that's probably worth a couple thousandth's.
I chemically removed the new seal red sealant then scotch brite buffed to bare metal for use of Permatex (green) sleeve retaining compound. I used brake clean & acetone to clean then applied Permatex surface prep activator in conjunction with the compound to both surfaces, installed seal and let it cure the specified 24 hrs also. Permatex not as robust as Loctite 620 and 680 per the specs but does have 3000 psi shear strength and good to 400 degrees so I think it will hold up.
Time will tell but so far so good. Thanks for your feedback.
I chemically removed the new seal red sealant then scotch brite buffed to bare metal for use of Permatex (green) sleeve retaining compound. I used brake clean & acetone to clean then applied Permatex surface prep activator in conjunction with the compound to both surfaces, installed seal and let it cure the specified 24 hrs also. Permatex not as robust as Loctite 620 and 680 per the specs but does have 3000 psi shear strength and good to 400 degrees so I think it will hold up.
Time will tell but so far so good. Thanks for your feedback.
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,004
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From: Poolville
Or there is too much run out and or vibration...
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Novice
Joined: Oct 2009
Posts: 17
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From: Wisconsin
Thank you and I appreciate yours and all others feedback on this issue. All I know for sure is the first seal came out of the case as shown in pic I attached previously in the thread. That pic shows exactly what I saw when I removed the rotor. It was completely out of the bore and then some. As explained previously resulting from my tests there is no evidence of crankcase pressure beyond cranking speed nominally 2-3 psi or running low idle rpm a couple few hundred below 1000 on my carbed 94. The fresh build injected 98 doesn't idle much if any below 1000 rpm. Otherwise both the 94 and 98 are just vacuum in the range of a pcv test on my vacuum gauge (2-5 inches). My thoughts are either improper previous seal installation or maybe on initial start up there was a lot of blow by until the rings seated in freshly honed cylinders. Or perhaps a combination of these two possibilities. I'll probably never know but I'm confident in my seal installation workmanship and hope it doesn't happen again! Nice thing about being retired is having enough time to get obsessive about such matters... Thank you again.
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Novice
Joined: Oct 2009
Posts: 17
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From: Wisconsin
FWIW when I got the crank & cases back from the crank shop I checked crank run out on the pinion side. If I remember correct it had .001" next to the bearing and .003" at the end of the pinion shaft. I didn't check the sprocket side. Being crank was assembled in the cases and seal was installed I didn't feel it would be accurate to take a reading off the threads. And being one side will affect the other I was satisfied with what the pinion side run out showed me. Regards vibration, I don't sense anything unusual. The engine has a relatively speaking smooth idle and mechanically runs very quiet.
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