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Manifold Butterflies Shaft

PostPosted: Sat, 01 Aug 2020 11:43 +0000
by Gravy72
Dont ask me why however I need to remove the butterflies (Flutter valves) shaft on my 2005 Hilux KUN26R to make a repair. No problem with removal of the butterflies, cannot get the shaft to slide out of the manifold despite it being free to rotate.
Appreciate if someone can assist. :(

Re: Manifold Butterflies Shaft

PostPosted: Wed, 05 Aug 2020 1:00 +0000
by Gravy72
For those that may end up in the same predicament this is a radical solution. :evil:

On the left hand end of the manifold there is a dimple where the shaft is supported in a drilling, carefully drill into the dimple using a diameter drill that will facilitate the hole being tapped for a threaded plug. Ensure you dont drill into the shaft.

You should now have access to the end of the shaft. Soak in WD40 each section of the shaft where it is supported in the manifold partitions for at least 12 hours.

Take a suitable diameter pin punch and hammer strike the end of the shaft that you have exposed by the drilling process. The shaft will begin to exit the manifold exposing the areas that had been contained within the partitions. You will probably see carbon scale build up which has prevented you from removing the shaft previously.

Using fine grade emery tape remove these carbon scale deposits, then using a suitable diameter rod of sufficient length drive the shaft from the manifold.

Whilst the shaft is removed thread the manifold dimple drilling and install a threaded plug.

Ensure you liberally lubricate the shaft during re installation pushing and pulling it to clean the partition holes.

You will be surprised how much carbon scale you will find has been deposited onto the shaft and into the holes.

I hope others do not have to take this radical approach to what should be a simple dismantling process.

Re: Manifold Butterflies Shaft

PostPosted: Thu, 06 Aug 2020 8:48 +0000
by martynvella
Have often wondered what those flaps are actually there for as well as the throttle like butterfly by the EGR inlet.
Any ideas?

Re: Manifold Butterflies Shaft

PostPosted: Thu, 06 Aug 2020 11:04 +0000
by Gipsy
The butterfly valves are there to shut the engine down primarily. Sometimes a diesel will run after shutting down but these valves make it more instantaneous. Someone else may have additional info.

Re: Manifold Butterflies Shaft

PostPosted: Thu, 06 Aug 2020 2:33 +0000
by martynvella
Thought shutting down the injectors would do that rather instantly but i guess there are instances when the engine is running on oil like a rollover or blown turbo seal where that back up would be very handy.

Re: Manifold Butterflies Shaft

PostPosted: Thu, 06 Aug 2020 2:39 +0000
by Gipsy
Yes mate that's probably the main reason for them in case of a runaway engine, shutting off the air supply and choking off the fuel/air ratio. I would be interested to hear if there are any other reason for the butterfly valves.
By the way, a runaway engine is very exciting in a trans sonic 600+mph jet aircraft and the only way to stop it is shut off the fuel or find a mountain to slow the progression. It happened to me on a test-bed once and it was very frightening until the fuel ran out. :o
An engine flame-out is more common and normally ends in an ejection seat exit and a sudden stop when the aircraft hits the ground! :?