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Thread: mp3 or any m90

  1. #1
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    mp3 or any m90

    Ok I have the blower off the car and I was spinning it by hand and it was harder than normal to turn. So I thought chit my bearings are goin bad. So I decide to pull the oil fill plug to make sure there's oil in it and as I loosen it I get a big pressure release. So I check the oil and there's plenty in there. Then I spin the pulley by hand again and its free like normal.

    So the question is. Is anyone else getting a huge pressure buildup in the oil resevoir that would make the blower hard to turn?

    Is there seals between the rotors and front bearing plate?

    And last is there some type of vent or expansion chamber I could put on to vent the pressure buildup?
    ~Chris
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  2. #2
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    Hope it didn't spray on you. Stuff stinks like plastic shoes on a hot day at the chicken processing plant.

  3. #3
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    Quote Originally Posted by Stupid Canuck View Post
    Hope it didn't spray on you. Stuff stinks like plastic shoes on a hot day at the chicken processing plant.
    You know Tod, I'm not even going to ask how you come by that information

    Ira

  4. #4
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    I had the same thing happen last year with my MP2. I repalced the coupler, and after a few days thought I better check the oil level. When I did there was enough pressure to spray oil on the hood liner. I haven't checked it since then so not sure what happened.
    SCCoA Member#: 2515
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  5. #5
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    Last time I checked my fluid, some overflowed out. I checked it while the engine was still warm. I figured since the fluid was warm that it expanded a lot because the fluid level was all the way to the top. I could see how that could build up some high pressure in the case and hold it for a while.

  6. #6
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    Quote Originally Posted by BLOWN38 View Post
    Ok I have the blower off the car and I was spinning it by hand and it was harder than normal to turn. So I thought chit my bearings are goin bad. So I decide to pull the oil fill plug to make sure there's oil in it and as I loosen it I get a big pressure release. So I check the oil and there's plenty in there. Then I spin the pulley by hand again and its free like normal.

    So the question is. Is anyone else getting a huge pressure buildup in the oil resevoir that would make the blower hard to turn?

    Is there seals between the rotors and front bearing plate?

    And last is there some type of vent or expansion chamber I could put on to vent the pressure buildup?

    I think they are seals on the rotorplate and the snout. Some pressure will leak into the snout area, but should vent tru the snout seal. Sounds like the seals are doing a hell of a job. Is the front snout seal installed backwards?
    When I was spraying oil from the front snout seal at the shootout, I though about putting a breether system with an oil catch, just like the Autorotor guys have, and Kenne bell systems. But since it ended up being the spun hub everything is back to normal.

  7. #7
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    Yes, there is a little seal on the shaft for each rotor. They are hard to replace and don't wear out too often, so most people don't replace them ever. I think that Embree Specialty Machine will replace them. I am pretty sure that Magnum Powers doesn't. The tricky part is retiming the rotors to the gears with enough precision.

    If you have a lot of pressure in the gear section, it sounds like those seals might be going bad for you. Now that I think of it, they probably weren't designed to hold back the sort of PSI many guys here are pushing.
    God bless!!!

    Former Birds:
    1990 SC auto ... red outside, gray cloth inside ... ~225,000 miles ... Sold.
    1990 SC auto ... white outside, gray cloth inside ... ~150,000 miles ... wrecked.
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  8. #8
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    Quote Originally Posted by S_Mazza View Post
    Yes, there is a little seal on the shaft for each rotor. They are hard to replace and don't wear out too often, so most people don't replace them ever. I think that Embree Specialty Machine will replace them. I am pretty sure that Magnum Powers doesn't. The tricky part is retiming the rotors to the gears with enough precision.

    If you have a lot of pressure in the gear section, it sounds like those seals might be going bad for you. Now that I think of it, they probably weren't designed to hold back the sort of PSI many guys here are pushing.
    well if the seals are leaky wouldnt it not hold pressure.. if it can leak in cant it leak back out???
    Last edited by 92sclikenew; 01-11-2008 at 03:40 PM.

  9. #9
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    Let's say, just for example, that the seals start to leak over 10 PSI. (That's differential pressure, not absolute.) If you had 15 PSI in the rotor area and it bled into the gear area until the gear areas was pressurized to, say, 5 PSI, then when the rotor area was depressurized, the seals might be able to hold the 5 PSI in the gear cavity. See what I mean?
    God bless!!!

    Former Birds:
    1990 SC auto ... red outside, gray cloth inside ... ~225,000 miles ... Sold.
    1990 SC auto ... white outside, gray cloth inside ... ~150,000 miles ... wrecked.
    1989 Base auto ... Crystal Blue metallic outside, dark blue inside ... ~160,000 miles ... Sold.

  10. #10
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    Quote Originally Posted by S_Mazza View Post
    Let's say, just for example, that the seals start to leak over 10 PSI. (That's differential pressure, not absolute.) If you had 15 PSI in the rotor area and it bled into the gear area until the gear areas was pressurized to, say, 5 PSI, then when the rotor area was depressurized, the seals might be able to hold the 5 PSI in the gear cavity. See what I mean?
    got ya i was thinking more stupider

    i wasnt thinking underpressure leaking???? my bad...

    i just thought as if they would leak any time..

    cuz like you said if it takes 10 psi for the seals to leak,well soon as the psi in the gear area is under 10 psi it wouldnt leak back out.. and then you would have pressure when you take out the oil plugfully understand....

  11. #11
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    Quote Originally Posted by BLOWN38 View Post
    Ok I have the blower off the car and I was spinning it by hand and it was harder than normal to turn. So I thought chit my bearings are goin bad. So I decide to pull the oil fill plug to make sure there's oil in it and as I loosen it I get a big pressure release. So I check the oil and there's plenty in there. Then I spin the pulley by hand again and its free like normal.

    So the question is. Is anyone else getting a huge pressure buildup in the oil resevoir that would make the blower hard to turn?

    Is there seals between the rotors and front bearing plate?

    And last is there some type of vent or expansion chamber I could put on to vent the pressure buildup?
    It's actually very common. The pressure buildup comes from two things...compressed air getting past the seals that isolate the oil filled gear case from the rotors, and from heat causing the air in the gear case to expand.

    The reason the pressure doesn't just bleed off is because of how the lip of the seal works...it sort of a one way thing and designed to keep oil in the case, not stop something from entering the case. The higher the trapped pressure, the more force there is pressing against the lip of the seal inside of the gear case.

    I had constant front seal leaks and thought that adding an expansion tank with an air breather to relieve the trapped pressure was the answer. Unfortunately, once I created an easy path for the trapped air to escape, this caused even more leakage of air into the gear oil case and quickly blew half the oil out of the gear case right thru the expansion tank and breather, and soaked the motor with a nice oily mist.

    The best solution is replacing either the entire rotor pack with one that has less miles (like from a GTP) or having the seals and bearings replaced by someone like ESM/High Speed Labs, and install a viton snout seal with a real retaining ring, not the flimsy stamped wire the factory uses.

    David
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  12. #12
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    Ok guess I'll have to get a newer rotor pack with coated rotors, and just open the fill screw to vent the pressure after some hard runs until I get the new pack.

    Cause I just put the new snout seal in the double lipped one and it was still leaking, but not as bad and I guess able to hold more pressure in the oil/gear reservoir.

    I was thinking of making an expansion tank like you said David and Ricardo, but since you said it still pushes oil out i'll just manually vent it after a run.

    How does the reservoir on the AR's work? Does It vent pressure at all or just give it a place to expand?
    ~Chris
    SCCoA Member #1826
    Bettie Riding jack stands
    SCARlit on drag duty now

  13. #13
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    The expansion tank on my AR vents air and a small spray (aprox 2" dia. pattern) of oil mist onto the underside of the hood when running it hard. It doesn't seem to have nearly as much air leakage as the M90 does. If you vent the M90 case it will leak much more air and a lot of oil along with it.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  14. #14
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    Quote Originally Posted by David Neibert View Post
    real retaining ring, not the flimsy stamped wire the factory uses. David
    Where can I get one of these?

    MP? How much?

    Do you have the size, I can just call a bearing place and get one.

  15. #15
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    Quote Originally Posted by 90blkbrd View Post
    Where can I get one of these?

    MP? How much?

    Do you have the size, I can just call a bearing place and get one.
    I got mine from Magnum Powers....shouldn't cost more than a couple bucks including the postage. Sorry I don't know the size or you could just get one from a bearing place.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

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