Crankshaft seal - quick easy question
#3
Elite Member
Thread Starter
iTrader: (6)
Join Date: Sep 2007
Location: CA
Posts: 2,017
Total Cats: 13
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Don't you need grease on the inner lip (pink circle)?
I believe there's a spring inside the seal and applies constant pressure circumferentially to the shaft. It needs a grease so it doesn't spin dry. Is this not right?
I believe there's a spring inside the seal and applies constant pressure circumferentially to the shaft. It needs a grease so it doesn't spin dry. Is this not right?
![](https://www.miataturbo.net/attachments/engine-performance-56/125637-crankshaft-seal-quick-easy-question-smallnosecrankdamage21359143886_zpsf0d2ff0f.jpg?dateline=1413318647)
#6
Elite Member
Thread Starter
iTrader: (6)
Join Date: Sep 2007
Location: CA
Posts: 2,017
Total Cats: 13
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Quote from honda-tech:
Oil seals will machine a slight groove into the shaft it is sealing.
If you replace the seal and the oil still leaks, either the shaft needs to be machined(unlikely) or you can take the garter spring off the seal and tighten it to put a better clamp on the seal to shaft interface.
https://en.wikipedia.org/wiki/Garter_spring
Of course this all means nothing if you put the seals on dry, that would cause the seal to burn if there was no lube.
Oil seals will machine a slight groove into the shaft it is sealing.
If you replace the seal and the oil still leaks, either the shaft needs to be machined(unlikely) or you can take the garter spring off the seal and tighten it to put a better clamp on the seal to shaft interface.
https://en.wikipedia.org/wiki/Garter_spring
Of course this all means nothing if you put the seals on dry, that would cause the seal to burn if there was no lube.
#12
Elite Member
Thread Starter
iTrader: (6)
Join Date: Sep 2007
Location: CA
Posts: 2,017
Total Cats: 13
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
So how does a seal prevent leakage around a spinning shaft? You don't think the inward radial force of the garter spring can score the crank? Does it not hug the spinning shaft?
Serious question. I don't understand how a seal works.
Serious question. I don't understand how a seal works.
#14
Elite Member
iTrader: (21)
Join Date: Jun 2007
Location: Rochester, NY
Posts: 6,623
Total Cats: 1,277
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
The seal does "hug" the shaft, and that is how it seals. It just doesn't do it very tightly, and certainly won't mar the shaft at all in normal conditions. There are charts that I use to size the seals depending on how tight a seal I need vs. the friction/heat a tighter seal creates.
#15
Elite Member
Thread Starter
iTrader: (6)
Join Date: Sep 2007
Location: CA
Posts: 2,017
Total Cats: 13
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
After reading about this, I believe you guys are mistaken.
Google "groove crank seal" and you'll find pages and pages where this has happened. It appears Speedy Sleeve is a product that can remedy this...or just place it in deeper.
Google "groove crank seal" and you'll find pages and pages where this has happened. It appears Speedy Sleeve is a product that can remedy this...or just place it in deeper.
![Giggle](https://www.miataturbo.net/images/smilies/gay.gif)
#17
Cpt. Slow
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (25)
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,360
Total Cats: 1,184
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Yeah, that's actually no joke.
And the seals are oiled. If there was no oil behind it, you wouldn't need a seal. It's good practice to put a little oil on all surfaces and it'll stay lubricated until the motor makes it's own oil pressure.
And the seals are oiled. If there was no oil behind it, you wouldn't need a seal. It's good practice to put a little oil on all surfaces and it'll stay lubricated until the motor makes it's own oil pressure.
#19
Senior Member
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (2)
Join Date: Oct 2013
Location: Goleta, Southern California
Posts: 520
Total Cats: 27
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I grease all cam crank seals on the inner lip during install. I also use permatex non hardening stuff on the outside, although never had a factory seal leak around the outside.
Oil vapor and splash takes care of lubrication after start up. Yes the seal touches the shaft. This is not Archimedes scroll days fellas. Yes I've personally seen seals wear groves in steel. I once ran an aluminum pulley (different application) in which the pulley made the contact with the seal. Lucky it was only a prototype pulley because the aluminum had a significant groove where the seal was riding after about 5k miles.
To answer the question, if there is some oil or grease on it, it's fine. You see some of these guys do nothing at all and have no ill effects. You are fine. Also, I've never been able to pull a crank seal without damaging so if you must redo it, buy a new seal.
Come to think of it, I've pulled seals out of the box that were pre greased.
Oil vapor and splash takes care of lubrication after start up. Yes the seal touches the shaft. This is not Archimedes scroll days fellas. Yes I've personally seen seals wear groves in steel. I once ran an aluminum pulley (different application) in which the pulley made the contact with the seal. Lucky it was only a prototype pulley because the aluminum had a significant groove where the seal was riding after about 5k miles.
To answer the question, if there is some oil or grease on it, it's fine. You see some of these guys do nothing at all and have no ill effects. You are fine. Also, I've never been able to pull a crank seal without damaging so if you must redo it, buy a new seal.
Come to think of it, I've pulled seals out of the box that were pre greased.