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View Full Version : Found new source of vacuum leak.



Mike Puckett
12-04-2008, 09:52 PM
I decided to put the MP2 blower I've acquired on my SC and compare it to my current S-model blower. The swap over seemed normal enough but when I started it up it didn't want to idle, I only had 10" of vacuum, and my a/f meter read super lean except when I drove it around. It acted just like when I cracked my IC. Spraying brake cleaner at all the connections showed nothing. I pulled the blower back off and while checking it over noticed that the gap where the intake bolts to the back of the blower seemed to be a bit wide. I took an .25mm feeler gauge and slid it right thru the connection. No wonder it's running lean, it's got a terrible leak right there. The gap was so wide 518 anerobic sealer wouldn't even set up and harden. It turned out that both the back of the MP2 and the MP intake manifold weren't flat but bowed slightly. I used a big wide flat file and flattened the intake manifold surface and then taped off the inlet on the MP2 to keep the metal filings out and flattened it as well. Then I used some silicone between the surfaces to seal them. Now I wonder if my S-model is flat. There was a little puddle of oil under it when I first pulled it off. Anyway, the car's back to running normal again but I never thought to look there for a vacuum leak. It felt kind of strange but I can stick my hand all the way thru the intake manifold and touch the back of rotors.

WhiteThunder
12-04-2008, 10:07 PM
Mike,

I had a similar problem. Where the MP intake bolts to the back of my ported 94 supercharger there wasn't a good seal. After the supercharger was ported, there was a thin area between the top of the rectangle and the two rotor bearings.

A smoke machine found the problem. Shot the smoke into the throttle body and we could see it drifting up from the back of the supercharger. Took it apart, reapplied the anerobic sealer. Seems fine now.

eddie
'90 5-speed SC (blown Spec clutch right now)
'97 LX sport

89XR7TD
12-04-2008, 10:23 PM
Just wondering how the car feels now from before Mike?

Lounder whine-More top end?

Good info for others Mike!

Tom

Mike Puckett
12-05-2008, 12:12 AM
I'll have to wait for that. It's been pouring rain all afternoon and evening and the streets are soaked so all I'd do is spin the tires. I'll have to try it out tomorrow. I'm concerned how it'll affect the tune but hopefully not much. It's got the MP cast outlet adapter on it, too instead of my 3/4" raised adapter.

Mike Puckett
12-05-2008, 07:20 PM
I got it out on the road just now and all is well. It's idling high but I like it like that. More power, I can't tell but plenty of power and a bit more responsive indeed, easily spin the tires in 3rd but it's cold out. Louder whine? Oh yeah!:cool:

89XR7TD
12-05-2008, 11:34 PM
Sounds very good!!!!

Oh, one question Mike, when you had the major vac. leak there,it wouldn't idle or even stay running while giving it gas either right or it would run but run like poop?I had similar problem but mine wouldn't idle or stay running with giving it gas. Just wanted to see if we had same problem?

I have yet to run it with the MP2 stuff on is why I ask how your car felt after the switch:confused:

Tom

Mike Puckett
12-06-2008, 12:15 AM
When it was cold I had to keep giving it gas to keep it running. After it warmed up a few minutes it would idle on its own but was unstable, up and down and almost stalling. When I drove it, it seemed fairly normal, just had a balky idle.

90MN12
12-06-2008, 04:34 AM
mike, so are you gonna take to the dyno and/or track to compare the blowers?

I think that's funny. when I had mine installed, it had a really bad idle problem and at first had hard starts without using the gas. had to have idle high to keep on. but coupler was bad, making noises. with the above thought it be better to rebuild asap so only test drove and had mechanic install original stuff back. dam that test drive was bad a$$. felt a big difference over stock.

Mike Puckett
12-06-2008, 10:39 AM
The 1/4mi tracks here are closed until Feb or Mar next year. I'll probably put it on the dyno in Feb just to check the tune and adjust if needed. I forgot to check my boost levels so I don't know if it's boosting more than the 14psi the S-model gives me. I'll stick with the 5% pulley. In the meantime I've got some more weight to pull out of the car and I need to swap out the tranny during the off season. 3rd gear synchro is gone.

89XR7TD
12-06-2008, 05:25 PM
The 1/4mi tracks here are closed until Feb or Mar next year. I'll probably put it on the dyno in Feb just to check the tune and adjust if needed. I forgot to check my boost levels so I don't know if it's boosting more than the 14psi the S-model gives me. I'll stick with the 5% pulley. In the meantime I've got some more weight to pull out of the car and I need to swap out the tranny during the off season. 3rd gear synchro is gone.

Goodluck when the track does open up:)

Tom