OK, for all those old farts who still remember who I am
I gave my previous 95SR to my son, and just found another one almost exactly like the first one-go figure. My question is I remember the danger of having that butterfly valve on the 3.5 dual cam motor go south, into the manifold and trashing the motor. Question is, how do you inspect it externally without having to disassemble the whole intact manifold? From what I can see near the vacuum pot at the front of the manifold, there doesn't look like any slop in the rod where it enters the manifold thru that front bushing. Should I conclude someone already replaced it?
Thanks in advance guys, been a while

Seer <img src="/forums/images/graemlins/cheers.gif" alt="" />

Good question.

Welcome back.

John B.

Hiyas Johnny :)long time no see hey I see you got a 95SR yourself. When you look close at that front bushing, how much of a gap do you see between the bushing and the housing? I have to push on the actuator pretty good, to even open up a visible gap and then its about very thin paper width. I'm not seeing any slop in the fitting either radially or longitudinally so I *think* this one has been replaced but then again, I've never seen a 'bad' one so, was hoping someone who HAS would jump in here. I hate to spend all day dismantling that thing if I don't need to LOL.

Seer

The one in my truck has been disabled, and I've never really looked at it.

However, I have another old one sitting right here that RyanY gave me. When you turn the actuator, there is some slop, but when I apply vacuum to the fitting, it stays closed, but doesn't completely seal the short runners off. It comes close, but I can push it further closed with a finger.

Looking closer, I can tell something about the condition of the bushings in the shaft on the loose piece here. By just starting the rotation at the bell crank, I can tell it's not rotating in an exact circle...bad bushing.

There's no part number I can see on it to be able to tell if it's new or old although I know this one is an old model.

If you wanted to tear it down and or replace it, you need three gaskets for the assembly, plus a couple more for the EGR, according to the manual. Ryany also suggested knife-edging the leading edges of the butterfly valves and at least checking how all the intake lines up in case anything is grossly off that might require some machining.

There are 12 Phillips head screws that hold the valves to the shaft. These could fall out, I'd suppose, and they're right in the intake path. There are 7 bushings, or at least seven support points for the shaft. I guess there could even be two piece bushings or something in there. I can see play in them by lifting up on the valves.

If nothing else, think of the recycling value of the large piece of aluminum left over when you replace it with the new improved part. Which costs $375. Plus shipping.

John B.

What is the "improved" portion of the new part? What about removal of the butterfly? It has been mentioned, what happens to low-end performance?

My understanding is that the revised part has more robust bushings, but, not having seen one, I couldn't say for sure.

No one seems to notice any difference between a functioning part and one that has been disabled, at least from just running it on a butt-dyno. In theory, the engine should have a flatter torque curve, more torque in lower rev ranges and slightly better fuel economy. That hasn't been clearly demonstrated, however.

The only true way to know is to run a before and after dyno session.

John B.

I can feel the diff, easy. It's flat on the top end with the actuator disabled, and it has a happy soaring top end with the actuator working. You can feel the changeover at 3000, when the long skinny runners start running out of breath, and you can feel the change in the slope of the torque curve as the short fat runners come into play and the engine really starts to breathe. It's worth having working, IMHO. Worst case, I'd wire the actuator at halfway open...

The new model has different material in the bushings that is more resistant to wear and deformation under side load. I always wondered why you couldn't just machine some new bushings out of delrin or something similar, and counterdrill the inner side of the front and rear bushings and put an oring on there. The other real problem with worn bushings is the intake leak at the bushing, leaning out that cylinder. If you disable it for a wiggly shaft, seal the bushing with rtv.

I think mine has issues...so let me describe what I see/hear. Maybe others can chime in.

If I remove the engine cover and then start the car, the following happens. Where the rod goes into the plenum, I hear what sounds like a vacuum leak or air being sucked in. When the plunger pulls back (which it seems to do every 30 seconds or so) the air suction sound disappears and I hear a clicking, like a loud tick. I hear this same sound when driving (near an object or wall where the sounds bounce).

As of right now, I can tell the car has low power around 3K RPM and around 4K it comes alive. I think this means the valves are working.

vacuum leak at the shaft. Vac leak gets partially cut off when the arm torques the shaft in the sloppy bushing bore. Tick is probably the butterfly fluttering on the shaft on the stretching and about to fail butterfly plate screws.

The low power is a leaned out cylinder at the shaft vac leak. As the rpms rise and the leak becomes less as a proportion of total air flow, the mixture becomes ignitable and power comes back up to proper levels. You often get a vac leak misfire at idle that disappears as the rpms rise for the above reason.

Fastedddy,

As usual you nailed what I described! Given the vac leak at the shaft...does this mean time for a new plenum? Any "fix" short of plenum replacement?