Interesting actuator fact
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irritating nuisance
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From: Central PA
Interesting actuator fact
I’m rebuilding the LIM on my 85 SE and noticed something about the 5th and 6th port actuators. Only 1 of the diaphragm holes needs to be open. The only reason I can come up with is to allow the part to be universal instead of “right” or “left” handed, thus being strictly a cost-saving measure for mazda. Here’s a graphic so you know what I’m talking about:
I’m going to block the unnecessary holes (red on the actuator in the graphic above) on mine before final reinstall on the LIM. While not the most exciting mod, it certainly lends that sense of security knowing there is no way for air to escape, instead of relying on the gasket to create a seal. I think a set screw and some RTV would be ideal for 2 reasons: 1) It’s flush with the opening so it doesn’t change how it seated originally and 2) it can be easily reversed should it need to, (but I can’t fathom why). Even though there’s not a lot of psi to block, it’s a bean-counter induced weakness that can easily be corrected.
While it's unlikely for these to leak if properly torqued to a good gasket, the consequences would directly affect top-end power... Losing pressure past a gasket would delay port opening, prohibit full actuation or possibly prevent the port from opening at all, restricting power over 3800rpm.
If I’m missing something as to why these would benefit from NOT being plugged please let me know. I see no reason to not plug them up. This is more of a piece-of mind mod and not something I expect to feel (since my 5-6 were seized anyway
). There is no check valve in line from the split air pipe to the actuators, so they apparently vent back the same way. The holes definitely aren’t responsible for any normal venting and should be able to be capped without issue.
I’m going to block the unnecessary holes (red on the actuator in the graphic above) on mine before final reinstall on the LIM. While not the most exciting mod, it certainly lends that sense of security knowing there is no way for air to escape, instead of relying on the gasket to create a seal. I think a set screw and some RTV would be ideal for 2 reasons: 1) It’s flush with the opening so it doesn’t change how it seated originally and 2) it can be easily reversed should it need to, (but I can’t fathom why). Even though there’s not a lot of psi to block, it’s a bean-counter induced weakness that can easily be corrected.
While it's unlikely for these to leak if properly torqued to a good gasket, the consequences would directly affect top-end power... Losing pressure past a gasket would delay port opening, prohibit full actuation or possibly prevent the port from opening at all, restricting power over 3800rpm.
If I’m missing something as to why these would benefit from NOT being plugged please let me know. I see no reason to not plug them up. This is more of a piece-of mind mod and not something I expect to feel (since my 5-6 were seized anyway
). There is no check valve in line from the split air pipe to the actuators, so they apparently vent back the same way. The holes definitely aren’t responsible for any normal venting and should be able to be capped without issue.
Thread Starter
irritating nuisance
iTrader: (1)
Joined: Dec 2010
Posts: 252
Likes: 3
From: Central PA
If you use the set screws you can just unscrew the screws to revert back to unmodified.
Really don't need to swap the actuators to troubleshoot though, so it shouldn't be an issue.
Really don't need to swap the actuators to troubleshoot though, so it shouldn't be an issue.
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