M20c throttle cable rigging or other issue?

[Jcmtl]

When i pull the throttle, i easily hit 1000rpm but getting to idle (around 700rpm) really requires pulling hard on the throttle and even then, it creeps back up to 1000.  Im worried it will snap one day.  It makes landings a little long.

is this a simple fix?  How?

Any advice is appreciated.

[EricJ]

It sounds like something is interfering with the throttle travel at the closed end for some reason.    It should be inspected to sort out the problem.

 

[carusoam]

4 hours ago, Jcmtl said:

When i pull the throttle, i easily hit 1000rpm but getting to idle (around 700rpm) really requires pulling hard on the throttle and even then, it creeps back up to 1000.  Im worried it will snap one day.  It makes landings a little long.

is this a simple fix?  How?

Any advice is appreciated.

That is bad…

As in… not normal… so anything could happen next…

A few things you can do on the way to getting this fixed…

1) know the OPP route for getting new control cables…

2) search around here for McFarlane 

3) Expect that you may have to box it up and send it in as “technical detail for producing a new one”

4) They probably have a matching one for your needs on the shelf…

5) About control cables…

They wear, and fall apart, and misbehave, and often break at low power settings…

6) Have you or your mechanic inspect the cable from one end to the next to make a plan…

7) Post the pic of what is falling apart…

8) Most mechanics have seen these before… it’s not usually Mooney specific…

9) Check the age of the cable…

10) Good progressive maintenance has these swapped out at engine OH…. Every 2k hours or so…

PP thoughts only, not a mechanic…

All stuff I heard around here…

Best regards,

-a-

[Jcmtl]

Here is a picture.  This is with the throttle as far back as it will go without effort. However its not totally at idle, i have to force the extra little bit. 

[carusoam]

Nice pic…

Let’s see if @M20Doc is cruising by… (M20C, sticking throttle control…)

Best regards,

-a-

[Guest]

It sounds like you need to re-rig the throttle control.  Likely the aluminum cable mount is bending slightly as you try to force the throttle arm to contact the idle stop on the carburetor.

Clarence

[Guest]

1 hour ago, Jcmtl said:

Here is a picture.  This is with the throttle as far back as it will go without effort. However its not totally at idle, i have to force the extra little bit. 

In you picture the cable clamp is the wrong part number and your fuel pressure hose is the wrong type.  That hose is meant for instrument air, not fuel or petroleum fluids.

Clarence

[Jcmtl]

2 hours ago, M20Doc said:

In you picture the cable clamp is the wrong part number and your fuel pressure hose is the wrong type.  That hose is meant for instrument air, not fuel or petroleum fluids.

Clarence

Thanks.  I've noticed on here that quite a few people have the wrong clamp. 

Regarding the cable rigging, i guess it's a matter of moving the throttle arm on the carb closer to that smaller (the one that hits the stop)?  I'll have my mechanic look at it.

 

[carusoam]

The power of MS in action…

A twofer…

1) Original question gets an answer…

2) Something you didn’t know about gets pointed out as well…

fuel going in a rubber tube meant for air… will probably swell over time, and possibly release material back into the line…  something best avoided…

Now, you have some expertise you can share…  each time you see that wrong clamp being used… you can speak up and help the next guy…

Everybody gets assigned an MS task… really, they take on a unique task themselves….

Doc covers tons of mechanical issues every day…

Dan points everyone towards the value of a real CO detector…

JCM got proper clamp for the M20C throttle cable…

I got ‘welcome aboard!’ Duty…

Go MS!

Best regards,

-a-

[Guest]

31 minutes ago, Jcmtl said:

Thanks.  I've noticed on here that quite a few people have the wrong clamp. 

Regarding the cable rigging, i guess it's a matter of moving the throttle arm on the carb closer to that smaller (the one that hits the stop)?  I'll have my mechanic look at it.

 

Moving the rod end on the cable or the arm on the throttle shaft, or a bit of each as required.

Clarence 

[Jcmtl]

On 4/24/2022 at 8:16 PM, M20Doc said:

In you picture the cable clamp is the wrong part number and your fuel pressure hose is the wrong type.  That hose is meant for instrument air, not fuel or petroleum fluids.

Clarence

On the pre 67 parts manual, it calls for the AN742, but on the 68+ parts manual it's the MS21919 with the rubber insert.   Is one clamp better than the other, are they interchangeable?  I have a 68.

Edited May 4, 2022 by Jcmtl
more precision

[Guest]

3 hours ago, Jcmtl said:

On the pre 67 parts manual, it calls for the AN742, but on the 68+ parts manual it's the MS21919 with the rubber insert.   Is one clamp better than the other, are they interchangeable?  I have a 68.

Personally I’d use the AN742 series clamp.  The MS21919 series clamp with the rubber insert is prone to deteriorate when exposed to oil.  The steel AN742 provides a firm grip that won’t allow the cable to slip.

Clarence