First post tranny knock with ac on

[Scuzzy883]

Hey all finally became a member. Been using TRS for years seeking advice iv owned 4 different rangers. my current one is a 91 4.0 5 speed 4x4 I got a really weird issue with the tranny.

When I turn on the ac compressor I hear knocking in the tranny does not change speed ever just a consistent knock. When I turn it off it stops. The noise can not be heard in the motor bay. I'm not sure where to look for this. Any suggestions in the right direction. Thanks all. I appreciate it.

 

[rusty ol ranger]

Id get a mechanic stehascope and check to make sure its not coming from the motor or accesorys. I see no possible way for AC operation to affect the trans.

 

[Scuzzy883]

Id get a mechanic stehascope and check to make sure its not coming from the motor or accesorys. I see no possible way for AC operation to affect the trans.

That's what my thoughts were but I put my hand on the tranny and I can feel the clunking I pit my hand on psp feels fine ac compressor feels fine alt feels fine. I'll see if i can snap a video today.

 

[rusty ol ranger]

That's what my thoughts were but I put my hand on the tranny and I can feel the clunking I pit my hand on psp feels fine ac compressor feels fine alt feels fine. I'll see if i can snap a video today.

Does it only do it at idle? Is the idle RPM low?

 

[Dirtman]

There's no connection between the AC system and a manual transmission. Only two things happen when the AC compressor engages, engine load increases, and as a result the idle should go up. So if the noise isnt directly an issue with the AC system (compressor about to die) then the noise must be a result of the engine load. Like rusty said, get a stethoscope and start poking around.

 

[sgtsandman]

 

[rusty ol ranger]

There's no connection between the AC system and a manual transmission. Only two things happen when the AC compressor engages, engine load increases, and as a result the idle should go up. So if the noise isnt directly an issue with the AC system (compressor about to die) then the noise must be a result of the engine load. Like rusty said, get a stethoscope and start poking around.

Im wondering if its a main knocking. Athough that would change with RPM

 

[Scuzzy883]

New video · Thursday, May 21, 2020 🎬

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Here is a link to a video I took.

The rpm does drop at idle and you can feel it big down when driving it around.

What do y'all think.

Rusty you maybe right

 

[pjtoledo]

I'd look at the AC compressor and it's clutch.
the instant on-off, and the relatively lite tick sound doesn't point me to tranny issues.
if the AC is putting small shock loads on the crankshaft it feasible they are sent on thru to the tranny input.
step on the clutch, any changes?
sounds bounce around at times, the source isn't always where you hear it.

 

[Uncle Gump]

As PJ said... any change when you step on the clutch?

Does the tick change speed if you rev the engine? Seems your first post says it remains consistent... is this true?

Sure sounds like a lifter tick to me. Have you actually put a mechanical oil pressure gauge on the engine to see what the oil pressure is?

 

[Dirtman]

Im wondering if it could be the throwout bearing just on the verge of failing and reacting to the engine load when the AC compressor engages?

That or wizards?

 

[Scuzzy883]

Yes when I step on the clutch it goes away, it seems like the clicking goes away above 1000 rpms. At first I thought it was constant. But the sounds is faint you have to really hear it. On the revs to catch the change.

The throw out bearing may be it the clutch does feel a bit funny. Not sure if it's just I got used to my other clutch. The catch point seems off.

 

[Uncle Gump]

Im wondering if it could be the throwout bearing just on the verge of failing and reacting to the engine load when the AC compressor engages?

That or wizards?

Looks like we have a winner...

Probably time for a clutch job... don't buy the cheapest stuff you can find. You will be tempted...

 

[Scuzzy883]

Looks like we have a winner...

Probably time for a clutch job... don't buy the cheapest stuff you can find. You will be tempted...

Any suggestions on a clutch kit worth buying?

 

[Dirtman]

Luk is usually pretty good.