Crank Seal leak
Thread Starter
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Cruiser
Joined: Jul 2009
Posts: 154
Likes: 0
From: Central, TX
Crank Seal leak
I have been battling a mystery leak for the past year. I have been in the primary about six times and have even replaced the main drive gear. A buddy of mine remembered some problems with the early 90's Dyna's where the hole in the block was a smidge too big for the crank seal and it continuously leaked. I am wanting to know if anyone has had this problem in the past and what you did to correct it. Thanks in advance.
Tourer
Joined: Apr 2010
Posts: 293
Likes: 7
When you say mystery leak, I assume you mean to the outside of the vehicle.
If the crank seal leaks, it leaks to the inside of the primary.
Where is the leak coming from?
Is the primary filling up?
When you say main drive gear, I assume you do mean the transmission?
I do not quite follow your thinking yet.
If the crank seal leaks, it leaks to the inside of the primary.
Where is the leak coming from?
Is the primary filling up?
When you say main drive gear, I assume you do mean the transmission?
I do not quite follow your thinking yet.
Thread Starter
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Cruiser
Joined: Jul 2009
Posts: 154
Likes: 0
From: Central, TX
I have transmission fluid that is coming out the shaft and hitting the back of the front sprocket and then runs down the back of the inner primary. We have replaced seals, and I have even installed a Baker high torque bearing in place of the standard bearing race combo.
My buddy said that he thought there were some problems where the hole where the crank seal goes is a little too big not allowing the seal to properly seal up and allowed it to leak. We have tried different seals and some seem to leak quicker than others. He said back in the day they were replacing the 'block'? because of the leak. Just looking to see if anyone had this experience in the past.
My buddy said that he thought there were some problems where the hole where the crank seal goes is a little too big not allowing the seal to properly seal up and allowed it to leak. We have tried different seals and some seem to leak quicker than others. He said back in the day they were replacing the 'block'? because of the leak. Just looking to see if anyone had this experience in the past.
Grand HDF Member
Joined: May 2008
Posts: 4,329
Likes: 3,623
From: Picayune, Ms.
I tossed about $1500 at that leak at two different HD dealers, if you find a fix please post. As for now it doesn't leak so much that I have to top off the transmission, it makes it to the 5,000mi oil change in good enough shape. Does make one hell of a mess though.
Stellar HDF Member
Joined: Oct 2005
Posts: 2,379
Likes: 226
ok, forgive me cause I'm a little confused with this quote.
If you are saying "I have transmission fluid that is coming out the shaft and hitting the back of the front sprocket and then runs down the back of the inner primary. "
If your referring to the front sprocket as the pully on the transmission that the drive belt to the rear wheel goes to - then I'd reccomend you get the updated pully kit from H-D along with the quad Seal and replace the quad seal , the main seal and the pully and then test for leaks.
Or if :
"My buddy said that he thought there were some problems where the hole where the crank seal goes is a little too big not allowing the seal to properly seal up and allowed it to leak. We have tried different seals and some seem to leak quicker than others. He said back in the day they were replacing the 'block'? because of the leak"
That is totally different - then I take it to mean that your for your primary, there is the front sprocket and compensator with a chain that runs to your clutch hub in the primary and that it is actually motor oil that is leaking into your primary.
If that is the case - then yes - from late 88 to early 92 there were casting issues where the race for the crank was pressed into the 1 half of the lower engine block and either a loose fit or a crack would appear and that would cause a leak. The repair is to dissasemble, replace case half with the pdated part and reassemble. not fun, but that is the deal.
If you are saying "I have transmission fluid that is coming out the shaft and hitting the back of the front sprocket and then runs down the back of the inner primary. "
If your referring to the front sprocket as the pully on the transmission that the drive belt to the rear wheel goes to - then I'd reccomend you get the updated pully kit from H-D along with the quad Seal and replace the quad seal , the main seal and the pully and then test for leaks.
Or if :
"My buddy said that he thought there were some problems where the hole where the crank seal goes is a little too big not allowing the seal to properly seal up and allowed it to leak. We have tried different seals and some seem to leak quicker than others. He said back in the day they were replacing the 'block'? because of the leak"
That is totally different - then I take it to mean that your for your primary, there is the front sprocket and compensator with a chain that runs to your clutch hub in the primary and that it is actually motor oil that is leaking into your primary.
If that is the case - then yes - from late 88 to early 92 there were casting issues where the race for the crank was pressed into the 1 half of the lower engine block and either a loose fit or a crack would appear and that would cause a leak. The repair is to dissasemble, replace case half with the pdated part and reassemble. not fun, but that is the deal.
Tourer
Joined: Apr 2010
Posts: 293
Likes: 7
I have transmission fluid that is coming out the shaft and hitting the back of the front sprocket and then runs down the back of the inner primary. We have replaced seals, and I have even installed a Baker high torque bearing in place of the standard bearing race combo.
You really are not making sense here. The inner primary bearing type has nothing to do with the transmission.
Help me here..........
Are you trying to say your gearbox is leaking, or your primary?
My buddy said that he thought there were some problems where the hole where the crank seal goes is a little too big not allowing the seal to properly seal up and allowed it to leak. We have tried different seals and some seem to leak quicker than others. He said back in the day they were replacing the 'block'? because of the leak. Just looking to see if anyone had this experience in the past.
You really are not making sense here. The inner primary bearing type has nothing to do with the transmission.
Help me here..........
Are you trying to say your gearbox is leaking, or your primary?
My buddy said that he thought there were some problems where the hole where the crank seal goes is a little too big not allowing the seal to properly seal up and allowed it to leak. We have tried different seals and some seem to leak quicker than others. He said back in the day they were replacing the 'block'? because of the leak. Just looking to see if anyone had this experience in the past.
Seasoned HDF Member
Joined: May 2008
Posts: 21,173
Likes: 12,740
From: South Carolina
You have a transmission leak, it has nothing to do with the engine.
If the transmission lube is leaking on to the inside of the front pulley, the leak is most likely the big seal, the pulley spacer and the quad seal. Always replace these as a set. Unless you really like removing inner primary covers.
I recommend replacing all the seals when an inner primary is removed.
Big seal
Pulley spacer
Quad seal
Mainshaft/main drive gear seal
Shifter shaft seal
Starter jackshaft seal
Inner primary seal
What 89FLHT said about the upgraded pulley/lock/spacer/nut is very important. If you have the original pulley on the bike, you should toss it into the scrap pile and get the upgraded setup.
If the transmission lube is leaking on to the inside of the front pulley, the leak is most likely the big seal, the pulley spacer and the quad seal. Always replace these as a set. Unless you really like removing inner primary covers.
I recommend replacing all the seals when an inner primary is removed.
Big seal
Pulley spacer
Quad seal
Mainshaft/main drive gear seal
Shifter shaft seal
Starter jackshaft seal
Inner primary seal
What 89FLHT said about the upgraded pulley/lock/spacer/nut is very important. If you have the original pulley on the bike, you should toss it into the scrap pile and get the upgraded setup.
Last edited by Dan89FLSTC; Sep 2, 2010 at 04:55 PM.
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Thread Starter
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Cruiser
Joined: Jul 2009
Posts: 154
Likes: 0
From: Central, TX
You have a transmission leak, it has nothing to do with the engine.
If the transmission lube is leaking on to the inside of the front pulley, the leak is most likely the big seal, the pulley spacer and the quad seal. Always replace these as a set. Unless you really like removing inner primary covers.
I recommend replacing all the seals when an inner primary is removed.
Big seal
Pulley spacer
Quad seal
Mainshaft/main drive gear seal
Shifter shaft seal
Starter jackshaft seal
Inner primary seal
What 89FLHT said about the upgraded pulley/lock/spacer/nut is very important. If you have the original pulley on the bike, you should toss it into the scrap pile and get the upgraded setup.
If the transmission lube is leaking on to the inside of the front pulley, the leak is most likely the big seal, the pulley spacer and the quad seal. Always replace these as a set. Unless you really like removing inner primary covers.
I recommend replacing all the seals when an inner primary is removed.
Big seal
Pulley spacer
Quad seal
Mainshaft/main drive gear seal
Shifter shaft seal
Starter jackshaft seal
Inner primary seal
What 89FLHT said about the upgraded pulley/lock/spacer/nut is very important. If you have the original pulley on the bike, you should toss it into the scrap pile and get the upgraded setup.
I am learning more about this as we go but I am do not know enough about it to even attempt myself. Other riders have told me how easy it is to replace these things but when the time comes to ask for help no one is around to lend a hand. This is why I am over 2k in out of pocket cost and am on the third shop trying to track it down and make it stop. My bike is old and I get that but it only has 20k miles on it and I do not abuse it. Very frustrating and I am tempted to see if the dealer will give me enough on it to get out the door on a Sporty, not my preference but at least I won't have to make a trip to the shop every other month.................
Venting complete, thanks for everyone's ear.
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Seasoned HDF Member
Joined: May 2008
Posts: 21,173
Likes: 12,740
From: South Carolina
Don`t " Just ride it"-Fix it.
A leaky 5 speed is not rocket science. If your mechanic can`t fix it, you need a new mechanic, not a new bike.
Are you sure it is not engine oil leaking from a rear cylinder, and running down to the transmission?
Are you sure it is not primary fluid?
Make sure the transmission is not overfilled, and the vent tube is not kinked or obstructed.
A leaky 5 speed is not rocket science. If your mechanic can`t fix it, you need a new mechanic, not a new bike.
Are you sure it is not engine oil leaking from a rear cylinder, and running down to the transmission?
Are you sure it is not primary fluid?
Make sure the transmission is not overfilled, and the vent tube is not kinked or obstructed.
Last edited by Dan89FLSTC; Sep 3, 2010 at 04:48 AM.