Bypass Valve Actuator Replacement

[bogey]

I was working on the car to changing oil (Penzoil Platinum Full Synthentic 5w30, for those who will ask) and was checking over the engine bay when I noticed the arm of the bypass actuator was rather worn and at a weird angle.

Closer inspection showed the rod had detached form the spot weld in the cup and the end that goes through the pivot hole was rather worn and deformed. Fortunately the rod is softer metal than the bypass lever which was not worn. (Gee, do you think they thought of that when they made it?)

Photos of the offending rod are here: http://www.thebogarts.net/imagelib/photo_list.asp?folder=Misc

Fortunately when I visited with Tom in July, he provided me a spare actuator that I decided to install today. Installation of the item should have been fairly straight forward, but was a real PITA due to tight quarters and large hands. But it is installed now.

I notice that the car seems to snap into boost a bit faster and the "middle" ground where the bypass is partially open seems to have gone away.

Thank you Tom for proactively providing a replace the actuator in July. As we suspected, it did indeed need replacement. Also, pressing out the stop was quite simple with a socket and hammer.

[Tom @ Fast Forward]

A new marketing slogan "FFS, We're so good we fix it before it breaks". ;)

When you were here it looked like it was near death. Glad I forced you to take one home with you. :) Seriously, sorry it broke. It does happen from time to time.

[mx5jmcb]

Its weird...

My first problem with the actuator was it blocking at an angle were it would not close the valve until i reached around 5500rpm.

Tom sent me another bypass which i installed and all was good (for about 2 months) until last week were i started hearing a rubbing noise from the blower. At first, it sounded like the eaton was going towards failure, had a bad bearing or something. Then i played with the actuator arm for the heck of it and the noise stopped as i opened the valve. It ends up the rubber inside the actuator had moved somehow and caused a leak meaning it wasnt holding vacuum anymore. Basically it was shut all the time. This explains the noise at idle and the slight wining noise when i gave it a little gas. I also had no transition feeling from when the actuator shuts and boost kicks in.

So i went back to the old actuator which still seems to work. Im wondering what the deal is with those actuators, i know a few of us have had issues with them and i did notice the slight wear on the actuator arm (not as bad as yours Bogey but getting there), Tom maybe you could help us out on this one...i hate having to carry spares.

JM

[mx5jmcb]

Installation of the item should have been fairly straight forward, but was a real PITA due to tight quarters and large hands. But it is installed now.



True that ... hehe such a simple task but that bolt under the actuator is just a damn pain, i've done it twice so i guess next time wont be as bad. It took me a good while, good thing i has a magnet to get that bolt back when it fell.

[bogey]

The bolts are a bit tough to get to, but the biggest problem I had was getting the new actuator arm through the pivot hole. I do not have the clearance below to really rotate the actuator housing low enough to line up the keyway. When I did get it together, then the other metal flange would not rotate back into position because it hit the end of the rod.

I have to remove the throttle bracket and rotate the flange the other direction to get it back in position.

I wonder why the rod is barely attached to the metal cup. I think they could be attached better than the tiny spot weld.

[mx5jmcb]

Im assuming you have an ABS model NA...probably a bit more squeezed than mine.

[bogey]

No ABS. Just too many lines and things to work around.

[bogey]

Well, the actuator install survived 4 days. The car ran great until yesterday when it suddenly started to run rough and went lean.

I checked everything over today assuming it was a vacuum leak and found the actuator was leaking like a sieve. The rubber diaphram has a major rip in it.

Tom is sending me a new one. I guess I get to try again.

[Tom @ Fast Forward]

You sure are hard on parts. :)

[mx5jmcb]

The actuator was a PITA on my last track day.

It was sticking open all day long to the point were i said the heck with it and just went home. I tried to adjust it at another angle put it would still stick open.

I have a feeling changing to yet another actuator wont solve the problem Tom, there is clearly something wrong with one of those moving parts. Would be nice if you could look into the problem.

JM

[Tom @ Fast Forward]

There is a silver "U" shaped ring. If you have removed or even loosened the two bolts that mount the actuator, you have to be very careful when you tighten them back up to center that ring on the shaft. The holes through it ar very tight tolerance to the shaft. If the silver ring touches the shaft, it will stick and not turn. I would suggest that be your first place to look.

[bogey]

Received replacement actuator and installed. Car running great again. Thanks!

[Tom @ Fast Forward]

Make sure that when you re-installed it, everything moves freely.

[bogey]

Its all good.

[tony soprano]

The actuator was a PITA on my last track day.

It was sticking open all day long to the point were i said the heck with it and just went home. I tried to adjust it at another angle put it would still stick open.

I have a feeling changing to yet another actuator wont solve the problem Tom, there is clearly something wrong with one of those moving parts. Would be nice if you could look into the problem.

JMI'm having the same problem. I finished up my install a couple of weeks ago but hadn't had the opportunity to actually drive the car until last weekend. I wasn't seeing any boost at all. At least not that the PC Pro was recognizing.

After checking various gaskets, vacuum connections, and fasteners, I focused on the bypass valve. Sure enough, I noticed when I shut the car off that the bypass valve remained open. I had to close it manually. I can't tell if it's binding or if there's an issue with the diaphragm. JM, were you seeing any boost at all when the bypass was stuck open?

I'll take a closer look at things this weekend and see if I can figure out what's going on. Tom, I'll give you a call if I'm stumped.

[mx5jmcb]

I'm having the same problem. I finished up my install a couple of weeks ago but hadn't had the opportunity to actually drive the car until last weekend. I wasn't seeing any boost at all. At least not that the PC Pro was recognizing.

After checking various gaskets, vacuum connections, and fasteners, I focused on the bypass valve. Sure enough, I noticed when I shut the car off that the bypass valve remained open. I had to close it manually. I can't tell if it's binding or if there's an issue with the diaphragm. JM, were you seeing any boost at all when the bypass was stuck open?

I'll take a closer look at things this weekend and see if I can figure out what's going on. Tom, I'll give you a call if I'm stumped.

Here's what happened....

The first time the bypass issue happened, it was stuck open. The car had no boost and no power until i hit about 5500rpm at WOT were it started boosting. Im not actually sure if it ever closed but nonetheless it started pulling. After seeing that the bypass valve was responsible for that, i took it off and put another one Tom had sent me.

After about a month, the other one developped a rip and was stuck closed. I took that one off and tried the first bypass valve that i had taken off and apparently for some reason, it still worked. A few weeks after, it too developped a rip and was stuck closed. If i were you, i'd take the one you have out, make sure the diaphragm moves properly and at the same time give a little suction on the bypass tube to see if the rod moves freely. The diaphragm inside might of twisted like mine and will not work because of this. If you would of told me that the bypass stuck closed, i'd tell you to replace it but since its stuck open, it might be still good.

Tom sent me another bypass and this time i took special precautions to make sure that nothing interferes with it moving. I've relocated some of my vacuum and fuel injection hoses far out of the way to be 100% sure they never touch the bypass which i dont think they did anyways and i was careful to center the metalic ring that goes around the valve mechanism. Hopefully, its the last time i get a failing bypass.

Im getting a little too good at taking them apart!

[Tom @ Fast Forward]

The key to success is to ensure that it operates freely. If there is any drag on the valve, you can have problems. Things I have seen that cause it are exterior things rubbing on the crank arm, the silver bracket not properly aligned on the shaft and the centering colar (inside the silver bracket) not properly aligned.

[tony soprano]

Thanks JM, Tom:

Hopefully I'll get some time to check it out tomorrow. I'll apply vacuum at the bypass valve and see if I can determine why it isn't closing. At idle (high vacuum) the bypass is pulled completely open, like it should be. Yet, when I turn the car off, the valve only closes about half way. I can lightly push on the lever that the actuator connects to and it will close, but it won't do it without assistance.

[tony soprano]

Well the bypass valve is definitely sticking wide open but I don't know exactly what the culprit is. Everything is routed away from the actuator arm so there's no interference with other parts. I started the car today and watched the bypass valve operate as I alternately attached and removed the vacuum line from the nipple.

At idle, the vacuum pulls the bypass valve wide open, just as you would expect it to. However, when I removed the vacuum line from the bypass valve it doesn't budge, it remains wide open. :confused: This of course explains why I'm seeing absolutely no boost.

Without a vacuum source attached, I'm able to manually move the linkage to close the bypass valve. It doesn't seem to bind as it takes minimal effort to close, but it won't close on its own. When the system is working properly, what actually closes the valve in the absence of vacuum? Is it simply the diaphragm springing back to its uncompressed state or is there some kind of return spring on the internal throttle-blade that the bypass actuates? A combination of those two? Whatever it should be, it isn't happening for me.

Thoughts?

[Tom @ Fast Forward]

There is a spring inside the actuator behind the diaphram. If, while it is stuck, you just loosen the two screws that mount it to the actuator and it closes, that silverbracket is binding. Take a close look at the colar. Is it dragging on that bracket? Maybe you just need to loosen the set screw and re-center that colar? If neither of those, I will be happy to replace the bypass actuator.

[mx5jmcb]

Had an issue with the bypass actuator yesterday.

The bypass plate that's inside the blower closed and stuck their and i had to pop it open it with a pair of pliars. Did not pull on it that much in order to avoid damaging it but it was stuck closed so that might explain the bypass valves sticking and ripping. When i push the valve complete closed i can feel that it sticks a bit.

It seems to stick when i give the throttle specific inputs...last time i headed to the track, the bypass stuck closed always on the same turn were i had to brake and stab the throttle. It happened like at least three times at the same place on that track!


Is there anyway to block it before it reaches the point were it sticks?

[Tom @ Fast Forward]

That sounds like the collar is mis-adjusted. loosen the set screw and see if the bypass still sticks. There should be some side play.

[tony soprano]

There is a spring inside the actuator behind the diaphram. If, while it is stuck, you just loosen the two screws that mount it to the actuator and it closes, that silverbracket is binding. Take a close look at the colar. Is it dragging on that bracket? Maybe you just need to loosen the set screw and re-center that colar? If neither of those, I will be happy to replace the bypass actuator.Eureka!! I loosened the two button head screws that sandwich the silver bracket against the actuator bracket. As soon as I released tension on those two screws, the bypass valve closed right up. I manually operated the bypass valve without the car running and it closes right up now when I release the actuator arm. I'll spend some time making sure that silver bracket is positioned just right before I cinch down on the two mounting screws.

For future reference, when you speak of loosening the set screw to re-center the collar, are you speaking of the nut at the end of shaft that the bypass blade is connected to? It also looks like it wouldn't be a bad idea to occasionally lube that white bushing that's captured by the silver collar. I figure anything that allows the bypass valve to open & close easier will extend the life of the bypass valve diaphragm.

Thanks for the troubleshooting Tom!

[Tom @ Fast Forward]

GREAT. Problem solved.

The set screw on the collar is somewhere around the perimiter of the collar. Don't mess with the nut on the end of the shaft.

[tann3r]

I noticed some occational stumbling on startup. It turns out that the set screw onthe collar was loose. I'm not sure if it was binding, but at idle I could see the collar turn. Not thinking anything of it I just tightened it down. after reading this thread and feeling a lack of boost, I went out to check and my bypass was partially open with the car off. I loosened the set screw on the collar and it snapped close. I centered the collar and tightened the set screw so I'll keep an eye on it.

Is there a particular orientation for the set screw or is the collar there as a spacer? I noticed that the collar had a but of wiggle room rotationally.

Would a sticking bypass cause a high idle? I just readjusted my idle so it may be the computer working it out, but w/ the IAC unplugged it idles at 800rpm.

[tony soprano]

Tom, were there some design revisions on the bypass assembly? For the life of me, I can't locate a set screw on, or around, that silver collar. On my bypass assembly, the only fasteners orienting the position of that silver collar around the bypass blade shaft are the two button head screws that bolt to the side of the supercharger. When those two screws are loosened, the collar is free to be centered around the shaft. I can try and snap a pic to show what I'm talking about if it will help.

[Tom @ Fast Forward]

The butterfly inside the SC has side to side play when the valve opens. The collar is supposed to keep it centered. The setscrew fell out of the collar on my 99 a couple years ago and I have had no problems. The early BRP hotside superchargers didn't even have collars from Magnuson. In any case, the setscrew should be someplace around the perimiter as in this picture.


http://www.FastForwardSuperchargers.com/Install/Collar.jpg

[tony soprano]

The butterfly inside the SC has side to side play when the valve opens. The collar is supposed to keep it centered. The setscrew fell out of the collar on my 99 a couple years ago and I have had no problems. The early BRP hotside superchargers didn't even have collars from Magnuson. In any case, the setscrew should be someplace around the perimiter as in this picture.Ah, that's the collar. Like they say, a picture's worth a thousand words. I've been unclear on what the collar actually was. I thought you've been referring to the silver bracket that wraps around the bypass shaft and captures the nylon bushing that the shaft rides in. The set screw on my collar must be right at the bottom of the shaft because I haven't seen it while operating the bypass valve through its normal range of motion.

My particular problem was that silver bracket was either misaligned with the bypass shaft or torqued down enough to compress and/or bind the bushing that the shaft rides in. I probably won't be able to drive the car until this weekend but it's going to be nice to see what boost is like!

[Tom @ Fast Forward]

Personally, I think the hole in that silver bracket could be an 1/8" or more larger in diameter and those problems would go away. It is just too close tolerance. And I don't see a need for it to be that small.

[jacky1982]

Thanks! That's great!

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