Pressure inside the Eaton 90 oil chamber...

KMT

Registered User
I'm sure many owners have had the experience of removing the fill plug on their supercharger and finding air/oil wanting to escape because of retained pressure inside.

...is that pressure from heat/expansion related strictly to the cavity and contents, or is it perhaps from boost that somehow managed to bleed over into the cavity over time...?
 
I'm sure many owners have had the experience of removing the fill plug on their supercharger and finding air/oil wanting to escape because of retained pressure inside.

...is that pressure from heat/expansion related strictly to the cavity and contents, or is it perhaps from boost that somehow managed to bleed over into the cavity over time...?

Both...the seals between the rotor pack and gear oil case, seem to act like a check valve allowing air to enter, but not exit back into the rotor pack.

I grew tired of blowing out snout seals and got the bright idea to vent the gear case. Bad idea...once I supplied a path for the air, it leaked even more and sprayed oil mist everywhere.

Solution for me was a viton snout seal and replacing the flimsy bent wire seal retainer with a real snap ring.

David
 
>Both

Sounds logical, thanks, David.

Would it perhaps follow that a lack of retained pressure would indicate an issue needing attention...?
 
Sort of, but from what I hear, you need alot of special equipment or a massive horse shoe in the you know where to make sure the timing of the rotors are perfect.

You need to pull the rotors out and replace the bearings etc on the front plate, and rotor timing is very exacting. If its bad, your probably better off digging up a newer rotor pack.

Frit
 
I had so much pressure in mine early this season it actually mad it hard to turn the rotors. I thought damn my blowers going bad so I removed the fill plug ton of air came out made sure there was oil there then turned the pulley and it was ok.

Had to send teh blower to Embree to have the rotor seals replaced alls good now. Still gets air in the reservoir but not like before.
 
Make sure the fluid level is up to the right level. the SC fluid is supposed to be of a type that doesn't expand with heat to limit pressure gain in the housing. If there is excess air in there from low fluid levels the pressure can be higher.
 
So in other words if there is a little pressure thats ok but if there is a lot of pressure then the rotors should be sent out to have the seals replaced.:confused:Or should there be no pressure at all?
 
I think there is always going to be some pressure...especially when hot. The oil in the gear case isn't supposed to expand, but the air in the case will.

I don't know that having pressure in the case is all bad, because if it's already pressurised it will reduce or eliminate the amount of air leaking past the rotor pack seals. Basicly...the air won't enter the case if air in the case is of equal or greater pressure.

David
 
Essentially nothing to worry about as long as there isn't so much pressure it blows oil past the front nose seal.
 
Nice - ummm, color.....
m90-1.jpg
 
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