Proper orientation for 470 camshaft seals?

[natemoore]

Read this excerpt from the #8 manual.

"1. Apply Loctite 8831 to outside diameter of all oil seals....

2. Both water pump seal lips face water side....

3. Fill space between water pump oil seals...

4. Install crankshaft seal with seal lip toward engine block.

I've received conflicting information, and the mechanic who installed these on on my engine did one facing in and one facing out, so that was no help.

Based on the way the front crank seal is installed--and it can only be installed on way--the author of the #8 manual calls the side of the seal with the garter spring the "lip."

Without getting bogged down in terminology, I've provided two drawings. The first is how I interpret the manual. The second is the alternative (and I believe incorrect) installation.

Do you agree?

 

[stonyloam]

Re: Proper orientation for 470 camshaft seals?

The oil seal lip and the water seal lip should face in the opposite direction. Remember with the oil seal you are trying to keep oil under pressure in the engine (lip toward the block), and with both cam seals you are trying to keep water out of the engine (away from the block) The cam seal is high above the normal oil level, so oil getting into the coolant is not a problem. It is designed so that when the outside seal wears and begins to leak, the coolant under pressure leaks past the first seal, and dribbles (under little pressure, easiest path) out of the weep hole, and does not go past the second seal into the engine. Hope that helps

 

[natemoore]

Re: Proper orientation for 470 camshaft seals?

The oil seal lip and the water seal lip should face in the opposite direction. Remember with the oil seal you are trying to keep oil under pressure in the engine (lip toward the block), and with both cam seals you are trying to keep water out of the engine (away from the block) The cam seal is high above the normal oil level, so oil getting into the coolant is not a problem. It is designed so that when the outside seal wears and begins to leak, the coolant under pressure leaks past the first seal, and dribbles (under little pressure, easiest path) out of the weep hole, and does not go past the second seal into the engine. Hope that helps

I asked this question in the "visiting machine shop tomorrow" discussion and got an answer that confused me and seem to contradict the manual, that's why I started a new thread.

It does seem like the side with the garter spring faces whatever you're trying to keep in (oil, coolant, etc), as I postulated in the other discussion.

Thanks.

 

[stonyloam]

Re: Proper orientation for 470 camshaft seals?

Looking at the photos in both the Clymer and Merc manuals, and Dr bowtie's id your drawing #2 would be correct. Better make sure

 

[totx]

Re: Proper orientation for 470 camshaft seals?

Looking at the photos in both the Clymer and Merc manuals, and Dr bowtie's id your drawing #2 would be correct. Better make sure

Agree... Merc manual have the metal side facing out on the picture.

Actually I think this is a dual lip seal, confusing...

http://www.alliedbearings.com/prodhighlights/crseal_types/crseals.html

 

[guyaverage]

Re: Proper orientation for 470 camshaft seals?

The oil seal lip and the water seal lip should face in the opposite direction.

NO !!! :redface:

If you are using double-lip seals (like what Amarket sells) then the seal is identical in both directions and it wont matter how you install them.

However, if you are using stock, Mercruiser (or similar) single lip seals, then BOTH seals face the water pump side.

Seem counterintuative, but thats the way they get installed.

The theory here is, if the first seal (water) fails, as the pressurized coolant flows past, the second seal (oil) will prevent the pressure from pushing the coolant into the crankcase, and instead will vent through the weep hole. If the oil seal lip is facing the crankcase side, it will be at a severe handicap in keeping any pressurized coolant out. The spring (lip) side needs to face the side of highest pressure, which in this case would be the coolant side if the front (coolant) seal were to fail.

 

[stonyloam]

Re: Proper orientation for 470 camshaft seals?

The oil seal lip and the water seal lip should face in the opposite direction.

Sorry, should have said crankshaft, not oil. Right both cam seals face in the same direction, away from the block.

 

[natemoore]

Re: Proper orientation for 470 camshaft seals?

NO !!! :redface:

If you are using double-lip seals (like what Amarket sells) then the seal is identical in both directions and it wont matter how you install them.

However, if you are using stock, Mercruiser (or similar) single lip seals, then BOTH seals face the water pump side.

Seem counterintuative, but thats the way they get installed.

The theory here is, if the first seal (water) fails, as the pressurized coolant flows past, the second seal (oil) will prevent the pressure from pushing the coolant into the crankcase, and instead will vent through the weep hole. If the oil seal lip is facing the crankcase side, it will be at a severe handicap in keeping any pressurized coolant out. The spring (lip) side needs to face the side of highest pressure, which in this case would be the coolant side if the front (coolant) seal were to fail.

These seals may appear to have two lips, but one is just the dust lip. Only one side has the garter spring.

Look at the first drawing. The pressure of the coolant presses down on the sealing lip, whereby assisting the spring in keeping the rubber tight against the shaft. Same principle as a brake cylinder. The brake fluid pressure presses the cup tighter against the cylinder wall. The greater the pressure, the more tightly is seals.

I think we are all saying the same thing. The spring goes toward the high pressure side, i.e., toward the block for the crankshaft, and toward the water pump on the camshaft.

My #8 manual does not have any detail pictures of the seals installed, but it sounds like there is some Mercury manual leading people astray, hence all the cam seal issues.

So, the first drawing is correct, agreed?

 

[dr_bowtie]

Re: Proper orientation for 470 camshaft seals?

yes the spring side goes towards the higher pressure side....That would be the fluid you wish to contain....