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Crankshaft Oil Seal

nippaero

nippaero

Well Known Member
I had an old timer at the airport today tell me that it was ok to cut the Oil Seal to make it easier to fit on the crankshaft. Anyone ever hear of this? Sounds like you would just be asking for a leak down the road.
 
I sure wouldn't do it!

I found it relatively easy to do. I just wrapped a plastic grocery bag over the prop flange which made prying the seal over a WHOLE lot easier. It wasn't a big deal at all.

Standard excuses: YMMV, Batteries Not Included, May Cause Erectile Dysfunction, talk to your family doctor, etc....
 
heating up the new crank seal in a pot of hot water makes it easier to stretch over the crank flange.
 
I'm assuming you are referring to a Lyc O-320/360.

There are two seals available - one a single piece that has to stretch around the prop flange and the other a split seal (as in already cut to save you the trouble). Properly installed, they both do fine. Personally, I've used the stretch method (see http://www.lycoming.com/Portals/0/t...I 1324C (05-26-2009)/Crankshaft Oil Seals.pdf ). What has worked for me is to heat the seal in boiling water and to use a couple of 1/4" extensions about 8" long to work the seal around the flange. (Some care needed here to avoid chewing up the seal.) I've seen the Lyc tool referred to in the Service Instruction and it's a really nice (as in $$$$) tool. EAA has an article on how to make such a tool - I think it should work fine but I haven't personally made one of these yet ( http://spirit.eaa.org/experimenter/articles/2012-02_sealtool.asp )

Bottom line, if I could avoid it, I wouldn't use the split seal.

Dan
 
Seal

Also hook the spring around the crank first then put seal over flange trhen install spring on seal next put polybond on seal then install in front of case.
 
Having just done this 2 weeks ago, the springs on the new seals are not the hook type. If you look at the spring carefully you will see were one turn of the spring appears missing, that is the point where one end of the sprint is screwed into the other end. You have to grab it on both sides of this space and twist in opposite directions to get the sprint apart. I found out the hard way by trying to stretch it over the flange and that is when I found out how the new springs are joined at this joint.


Thanks

Ray
 
The Lycoming service bulletin says to use Dow Corning 737 Neutral Cure for the sealant. I cant seem to find it on Aircraft Spruce. Is there another sealant that works?
 
nippaero said:
The Lycoming service bulletin says to use Dow Corning 737 Neutral Cure for the sealant. I cant seem to find it on Aircraft Spruce. Is there another sealant that works?
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For years, I have heaard of folks using PlioBond for this.
 
Not to start an argument....well maybe, But......hold on a second....ok, let me put this on, ok, so why does Lycoming want you to use contact cement for this, because that's all they had 50 years ago? just asking, there are a lot of excellent modern sealer-adhesives out there that have great qualities for this aplication. sorry, just asking.
 
Seal

bret said:
Not to start an argument....well maybe, But......hold on a second....ok, let me put this on, ok, so why does Lycoming want you to use contact cement for this, because that's all they had 50 years ago? just asking, there are a lot of excellent modern sealer-adhesives out there that have great qualities for this aplication. sorry, just asking.
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Maybe cause it works ? What's also nice is its easy to clean when it comes time to replace the seal . I've done a handful ( maybe 12 ) I've never seen failure at the glue joint .
Might be better stuff, but by the time I pull the cowl ,remove the spinner and prop , maybe a prop spacer and flywheel I'm not in the experimental mood 😓
 
I recommend the Dow Corning 737

nippaero said:
The Lycoming service bulletin says to use Dow Corning 737 Neutral Cure for the sealant. I cant seem to find it on Aircraft Spruce. Is there another sealant that works?
Click to expand...

I've had to replace my seal several times using the old Lyc spec. calling for PlioBond which was available from the local hardware store. I never had much luck getting it to seal for more than a couple hundred hour. The last time I replaced the seal I saw that Lyc spec changed to the Dow Corning 737 sealant. Used it and it has held up very well so far. While PlioBond is a contact cement type product that requires applying to both surfaces, letting tack up then install seal, the 737 is a one part adhesive sealant that you apply to one part (the seal) and then install.
 
Crank Seal

I have replaced dozens of these and use Hylomar sealant with 100% success. Have always used boiling water & the special tool. More recently started using the plastic grocery bag over the prop flange instead of lubricant and that works the best. Be sure the seal part numbers are correct for your case. Some 1 piece seals have a small ridge around the outside perimeter that mates with a small groove in the case. (My IO-320 B1A late style case is like this). I'm fairly sure that if your engine uses a split seal without the outside perimeter ridge you also need the steel retaining plates that bolt on to the front of the case.

Don B

RV 9 Rebuild in Progress
 
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nippaero said:
The Lycoming service bulletin says to use Dow Corning 737 Neutral Cure for the sealant. I cant seem to find it on Aircraft Spruce. Is there another sealant that works?
Click to expand...

PlioBond is commonly used.

We have an old coffee pot with about an inch of oil that is used to heat and lube the seal prior to installation. The plastic bag idea above will be added to the process. Good tip.
 
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