Secondary Port Throttle Actuator vacuum leak - ZR-1 Net Registry Forums

boostedmaxPSI · 04-22-2012

Guys,

Something had been gnawing on me about the condition of the secondaries and how well they were working. I had addressed the vacuum leaks but I always felt something was fully opening/working.

So.... off comes the plenum again, for additional testing for peace of mind.

This time I hooked up a vacuum gage inline so I could see how much vacuum was being lost when I backprobed pin C17 to activate the secondaries.

First thing I noticed was the driver side secondary ports were fully open and the passenger side ports were only opening part way. In addition to the passenger ports not opening all the way, my vacuum gauge would drop below 5" and the driver side actuator would start to close partly.

I isolated the problem to the passenger actuator itself. Please see the attached video:

http://www.youtube.com/watch?v=yjtZA...ature=youtu.be

Notice how the vacuum starts to bleed off almost instantly. This does not happen to the driver side actuator however, the passenger side actuator will hold vacuum when you go above 15" vacuum. I assume this is because the internal diaphragm is laying over itself and sealing the internal leak.

Another observation is how the diaphragm pulls in at an odd angle. Seems like something is not centered internally to the actuator.

Thoughts?

I plan on purchasing two new GM units tomorrow. Who do you recommend that I source these parts from?

thanks
Frank

Z51JEFF · 04-22-2012

Quote:

Originally Posted by boostedmaxPSI

Guys,

Something had been gnawing on me about the condition of the secondaries and how well they were working. I had addressed the vacuum leaks but I always felt something was fully opening/working.

So.... off comes the plenum again, for additional testing for peace of mind.

This time I hooked up a vacuum gage inline so I could see how much vacuum was being lost when I backprobed pin C17 to activate the secondaries.

First thing I noticed was the driver side secondary ports were fully open and the passenger side ports were only opening part way. In addition to the passenger ports not opening all the way, my vacuum gauge would drop below 5" and the driver side actuator would start to close partly.

I isolated the problem to the passenger actuator itself. Please see the attached video:

http://www.youtube.com/watch?v=yjtZA...ature=youtu.be

Notice how the vacuum starts to bleed off almost instantly. This does not happen to the driver side actuator however, the passenger side actuator will hold vacuum when you go above 15" vacuum. I assume this is because the internal diaphragm is laying over itself and sealing the internal leak.

Another observation is how the diaphragm pulls in at an odd angle. Seems like something is not centered internally to the actuator.

Thoughts?
I plan on purchasing two new GM units tomorrow. Who do you recommend that I source these parts from?

thanks
Frank

Id check with Jerrys Gaskets first.

GOLDCYLON · 04-22-2012

I have a used pair of vaccum actuators that I no longer need they were purchased from Tom Henry Chevrolet in early 2011. Hows $100 for the pair plus shipping sound? I paid $125 each for these but they are one year used. Lmk. GC

GOLDCYLON · 04-22-2012

These pull at an unnatural angle as designed by GM. If they lengthed and centered the rod it would have been a better design. I am sending you a pic of mine attached to the actuator rod when we pulled them out of the car.

A26B · 04-22-2012

The actuator actually pulls straight with the "angled linkage" installation. If you turn it over & make the linkage "straight", the diaphram will pull at an angle, resulting in binding. FOr best operation, leave the actuator angled, the way it originally & intentionally came from MerCruiser.

Good pictures Daryll.

GOLDCYLON · 04-22-2012

Quote:

Originally Posted by A26B

The actuator actually pulls straight with the "angled linkage" installation. If you turn it over & make the linkage "straight", the diaphram will pull at an angle, resulting in binding. FOr best operation, leave the actuator angled, the way it originally & intentionally came from MerCruiser.

Good pictures Daryll.

True statement.

boostedmaxPSI · 04-22-2012

Quote:

Originally Posted by GOLDCYLON

I have a used pair of vaccum actuators that I no longer need they were purchased from Tom Henry Chevrolet in early 2011. Hows $100 for the pair plus shipping sound? I paid $125 each for these but they are one year used. Lmk. GC

When you apply vacuum to these units how does the center rod get pulled in? Did you notice in the video that I posted how the rod will make contact to the housing? I assume there is something off internally.

GOLDCYLON · 04-22-2012

Quote:

Originally Posted by boostedmaxPSI

When you apply vacuum to these units how does the center rod get pulled in? Did you notice in the video that I posted how the rod will make contact to the housing? I assume there is something off internally.

Correct it should not slap the housing as demonstrated in your video. They will slightly graze the edges somewhat center and hold vaccum. All these are are vaccum diaphrams when they age and wear they leak and set a CODE 61. We have all been there and done that.

XfireZ51 · 04-22-2012

I got an idea! Pull the throttle plates on the secondaries and we'll throw in a chip that has secondary injectors turn on at anything above idle. You can unplug the secondary MAP sensor and air pump.

Z51JEFF · 04-23-2012

Daryll,Ill take these if the OP passes.

04-22-2012	#1
boostedmaxPSI Join Date: Apr 2012 Location: TEXAS Posts: 171	Secondary Port Throttle Actuator vacuum leak Guys, Something had been gnawing on me about the condition of the secondaries and how well they were working. I had addressed the vacuum leaks but I always felt something was fully opening/working. So.... off comes the plenum again, for additional testing for peace of mind. This time I hooked up a vacuum gage inline so I could see how much vacuum was being lost when I backprobed pin C17 to activate the secondaries. First thing I noticed was the driver side secondary ports were fully open and the passenger side ports were only opening part way. In addition to the passenger ports not opening all the way, my vacuum gauge would drop below 5" and the driver side actuator would start to close partly. I isolated the problem to the passenger actuator itself. Please see the attached video: http://www.youtube.com/watch?v=yjtZA...ature=youtu.be Notice how the vacuum starts to bleed off almost instantly. This does not happen to the driver side actuator however, the passenger side actuator will hold vacuum when you go above 15" vacuum. I assume this is because the internal diaphragm is laying over itself and sealing the internal leak. Another observation is how the diaphragm pulls in at an odd angle. Seems like something is not centered internally to the actuator. Thoughts? I plan on purchasing two new GM units tomorrow. Who do you recommend that I source these parts from? thanks Frank __________________ 1966 Mustang GT tribute 1988 Callaway Twin Turbo Aerobody (FOR SALE pm me for more info) 1991 Callaway CR1 SuperNatural 475 Aerobody 1992 Callaway SuperNatural 435 Aerobody (sold) For Sale:

04-22-2012	#3
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,155	Re: Secondary Port Throttle Actuator vacuum leak I have a used pair of vaccum actuators that I no longer need they were purchased from Tom Henry Chevrolet in early 2011. Hows $100 for the pair plus shipping sound? I paid $125 each for these but they are one year used. Lmk. GC __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V Last edited by GOLDCYLON; 04-22-2012 at 06:21 PM.

04-22-2012	#4
GOLDCYLON Join Date: May 2007 Location: Peoria, AZ Posts: 9,155	Re: Secondary Port Throttle Actuator vacuum leak These pull at an unnatural angle as designed by GM. If they lengthed and centered the rod it would have been a better design. I am sending you a pic of mine attached to the actuator rod when we pulled them out of the car. __________________ GOLDCYLON - 91 ZR-1 #2014 GOLDCYLON - 90 ZR-1 #2794, 4L60e (Formerly Schrade's) GOLDCYLON - 11 CTS-V Arizona State Director 91 WHITE/BLACK #2014. 380 P&P&PCed,Ported Heads, Jeal Long tubes, Corsa Exhaust/FIKSE FM-5s /LED TLs, LED Headlights, Front Wilwood 6 piston narrowlite calipers and rear Wilwood caliper street shop mod,CNCed Coolant Pipes,TPI Cvr,Filter cover,Stainless Bolts, DRM/DOM PROM /ZFDOC mod build #102,DRLs,BMAD with stainless Debris Screen,Coplan Air Blaster, Pioneer APP Radio 4,Brey-Krause HB,Sub Bar,Fire extinguisher seat mount,DRM Coilovers,LEDs everywhere,Compass mirror (orange),V1 DIC hidden display, Homelink sun visor, Carbon Fiber top x3 and APSIS Carbon Fiber interior, APSIS CF Steering Wheel/NAPA Leather, Banski trailing arms, Guldstrand front suspension,urethane bushings from Prothane (total suspension) ZFDoc drive shaft safety loop, raptor shift light (orange),AO engineering louver front plate, Console seat cushion, 96CE seats with black custom Sheepskins, ss billet catch can,Viper remote entry/alarm,Cragar Rear Louvers,LED side louver lights, Dewitts Radiator with SPAL fans and a Woods 160 T-Stat 90 RED/BLACK #2794. 4L60e Automatic Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless Headers, Corsa Exhaust, SAN Secondaries and Haibeck PROM, Exotic Muscle Coil overs, LED Interior Lights, LED Tail Lights, LED Headlights, 94 Sport seats with black custom Sheepskins , Cragar rear louvers, GS Front calipers, Banski Trailing arms, APSIS Carbon Fiber steering wheel, Front and Rear Baer Eradispeeds, DRLs, Guldstrand front suspension,urethane bushings from Prothane (total suspension), Dewitt's Raditor with Dual SPAL fans and a Haibeck 170 T-Stat 11 RED/GREY CTS-V Last edited by GOLDCYLON; 04-22-2012 at 06:22 PM.

04-22-2012	#5
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,394	Re: Secondary Port Throttle Actuator vacuum leak The actuator actually pulls straight with the "angled linkage" installation. If you turn it over & make the linkage "straight", the diaphram will pull at an angle, resulting in binding. FOr best operation, leave the actuator angled, the way it originally & intentionally came from MerCruiser. Good pictures Daryll. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

04-22-2012	#9
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,709	Re: Secondary Port Throttle Actuator vacuum leak I got an idea! Pull the throttle plates on the secondaries and we'll throw in a chip that has secondary injectors turn on at anything above idle. You can unplug the secondary MAP sensor and air pump. __________________ [SIGPIC][/SIGPIC]Former Membership Chairman Former ZR-1 Registry - BOD 1972 Corvette 4speed base Coupe SOLD long time ago 1984 Corvette Z-51/4+3 SOLD 1992 Corvette ZR-1 Aqua/Gray #474 SOLD 1992 Corvette ZR-1 Black Rose/Cognac #458 2014 Honda VFR Interceptor DX

04-23-2012	#10
Z51JEFF Join Date: Dec 2007 Location: Fremont,Ca Posts: 3,080	Re: Secondary Port Throttle Actuator vacuum leak Daryll,Ill take these if the OP passes.