Magnuson M90 really loud

boostbird90

Registered User
I just replaced the blower on my '90 sc with a reman unit from magnuson. Fired the car up and wow is it loud. Sounds like a vortech or procharger race unit at idle and when I took it for the test drive it howls like a jet ! Is this normal for this type or do I have a problem? I think it may have a boost leak because it is definately more sluggish when I roll on the gas. It makes 10psi with a 10% pulley on it. I'm gonna go thru the IC tubes and reseal everything but as for the noise Anybody run into this before???
 
Yes it has oil in it, and what gets me is it idles and runs really nice when its not in boost. Are there any IC gaskets out there worth using?
 
my ported early model sounded like that after i got it back from getting it ported and snout rebuilt full of fluild and 13 pounds of boost ran fine just loud as hell was awsome.
 
I didn't get the lower inlet tightened down very well one time and it made a noticeable scream at higher boost levels (7-10psi). Would idle quiet and run fine, but would leak under pressure.

I agree with Dave, you probably have a boost leak...or very sensitive ears. :p:)
 
one other thing....did they close the sound ports on the outlet side?

I don't think that's a typical service they perform, but that would make it loud too - but still, your max boost should be plenty higher than 10psi with the pulley.
 
As far as the sound goes I love it and don't want to fix the noise. Just don't wanna be driven it and it lock up or something stupid like that!?!? I sprayed it with carb cleaner on all the joints and made no difference then used a leak detector for gas lines (really soapy bubbly stuff) also then got it into some boost and no joy. so I'm gonna pull that one off and pull it apart and see if anything looks goofy. Any one know what the rotor to case clearence should be?
 
If you forgot to connect the bypass valve's vacuum hose it will whine like crazy because the bypass is always closed.

David
 
Sounds to me like the bypass is closed also. Check the vacuum line to the bypass actuator.
 
The bypass is hooked up and works. Went over and resealed all joints then took it out and got it warmed up then double checked for leaks, still the same. I'm gonna pull it off again and put the original one back on. See what happens. . . . . I'm thinking this blower maybe loose on the inside.
 
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