Borg Warner makes a "klonk" sound when it goes in to reverse.

[Jacob Vetter]

Hi,
I have a problem with my Borg Warner gearbox. It makes a big noise "klonk" sound when i put it in reverse. The engine is a Ford Lehman 2725E.
I have changed the damper plate, changed the gear oil, but it does not help. No problem when i go in forward.
If anybody have a solution to this problem i would much appreciate to here from you
My ship is not a Trawler, but a 1984 Nauticat motorsailer 40 ft.

 

[Jacob Vetter]

Hi,
I have a problem with my Borg Warner gearbox. It makes a big noise "klonk" sound when i put it in reverse. The engine is a Ford Lehman 2725E. I have changed the damper plate and changed gear oil, but it still sounds bad when it goes in to reverse, not in forward though. I appreciate any comment

 

[rslifkin]

Can you tell if the noise is coming from the main portion of the transmission or the reduction housing on the back of it?

Also try spinning the shaft in both directions by hand with the engine off (and wiggling it back and forth if you can) to see if you can get anything to make a noise. If the noise turns out to be in the reduction unit, they're not particularly hard to open up. And if you can slide the shaft back far enough you can often pull the reduction housing off the trans without needing to pull the trans off the engine.

 

[Jacob Vetter]

Can you tell if the noise is coming from the main portion of the transmission or the reduction housing on the back of it?

Also try spinning the shaft in both directions by hand with the engine off (and wiggling it back and forth if you can) to see if you can get anything to make a noise. If the noise turns out to be in the reduction unit, they're not particularly hard to open up. And if you can slide the shaft back far enough you can often pull the reduction housing off the trans without needing to pull the trans off the engine.

Well, no noise from turning the prop. And to take it apart is difficult, because lack of space. This is not a Trawler, but a Nauticat motorsailer. Maybe the noise is because of to low rpm in idl? What rpm do you recommend?

 

[rslifkin]

Too low idle RPM will usually cause a rattle / clatter while in gear (from the damper plate and reduction gears when the idle gets too rough at low speed) not a single clunk. And that will usually happen in forward and reverse not just one.

 

[Mac2]

Not sure this applies, but I'm throwing it out there. I had the same issue with my lifted truck. The larger angle caused the u-joint to wear down quickly. I only knew it was worn when I put it in reverse and it made the clunk sound. I'm wondering if it could be a worn cutlass bearing, shaft saver, worn/loose bolt on shaft to transmission fitting etc. Like someone said already, figure out the area the sound is coming from when you put it in reverse.

 

[Jacob Vetter]

Not sure this applies, but I'm throwing it out there. I had the same issue with my lifted truck. The larger angle caused the u-joint to wear down quickly. I only knew it was worn when I put it in reverse and it made the clunk sound. I'm wondering if it could be a worn cutlass bearing, shaft saver, worn/loose bolt on shaft to transmission fitting etc. Like someone said already, figure out the area the sound is coming from when you put it in reverse.

The cutlass bearing is new, the shaft saver is new, no loose bolt on shaft, so i don´t know.. and about the sound, it is very hard to define from witch part it comes, within i would say..

 

[Mac2]

Just noticed you said this was a motorsailer. Any chance you have folding props?

 

[SteveK]

With the engine running, the gear shift cable removed tried hands on shifting? a stethoscope would be handy to pinpoint sound.
You could observe as well up close.

 

[Jacob Vetter]

Just noticed you said this was a motorsailer. Any chance you have folding props?

I have a Autoprop (Bruntons H9) on it..

 

[Mac2]

Just spit balling here: Not sure how that prop works, but I was thinking the "clunk" sound might be the blades turning as they switch directions in reverse, or the blades aren't functioning as they should. Not sure how far up the shaft that sound would travel.

 

[Jacob Vetter]

Just spit balling here: Not sure how that prop works, but I was thinking the "clunk" sound might be the blades turning as they switch directions in reverse, or the blades aren't functioning as they should. Not sure how far up the shaft that sound would travel.

Yeah, you could be right, but the sound comes from the gearbox, not from prop. But maybe the switch of blades is so hard on the gearbox that it makes the klonk sound? But all so when i put the gear in forward, it turns the aksel slowly at first, but in return it just crank in, it seems..? So i think there is a lack of pressure in the valve. I took the valve apart, and it was fine, so valve is working, but maybe not enough oil pressure?

 

[rslifkin]

If it engages slowly in forward like it slips rather than a firm engagement like you're getting in reverse than that's a problem. Make sure the shift lever on the transmission is going all the way into the forward detent and that the shifter is hooked up the correct way (Velvet drive transmissions have a distinct forward and reverse, they cannot be run in either direction like some others can).

 

[twistedtree]

Try to get a pry bar position such that you can pry the coupling fore and aft to see if there is any play. It may be related to a completely different transmission, but I have heard of the output flange nut working loose allowing the flange to slide fore and aft. In reverse the shaft will be pulling on it, and in forward it will be pushing.

Along the same lines, check your engine mounts. Get eyes in the whole thing and have someone shift fore and aft to see if you can spot any movement.

 

[Xlantic]

Maybe you are shifting too slowly. You need to do it with decision.

 

[long-cours.62]

Are you sure all is well fixed in the propulsion line ?

 

[SteveK]

There is a duplicate thread started here
Borg Warner gearbox problem
perhaps a mod can combine

 

[Jacob Vetter]

Are you sure all is well fixed in the propulsion line ?

Yes, everything is well.

 

[Jacob Vetter]

Maybe you are shifting too slowly. You need to do it with decision.

I have tried both, slowly sliding in and with decision, it makes a klonk anyway..I am beginning to think it is the prop. I have a masive Brunson H9 Autoprop installed and maybe the gearbox makes the noise when turning the blades..?

 

[Jacob Vetter]

Now i found out that if i push the gear into forward and to neutral and then to forward again there is no problem, the same goes for reverse, but the first time it goes from neutral to either forward or reverse it makes a big klonk sound, ..so must be the prop.

 

[SteveK]

Shifter cable slack/play at neutral at helm end?

 

[Nick F]

Its the prop! When you go into reverse the blades swivel about 180 deg until they hit a stop. However, this does not explain why it does not happen when going forward . . .

 

[Jeff F]

Its the prop! When you go into reverse the blades swivel about 180 deg until they hit a stop. However, this does not explain why it does not happen when going forward . . .

Agreed. I'd bet that if you get the boat moving in reverse and then shift into forward you'd experience a similar clunk.

I don't think I've driven a boat with a Brunton prop, but with other feathering props like the Max Prop this is quite noticable.

ETA: if you shift to neutral long enough for the shaft to stop turning before shifting into reverse this should disappear.

 

[tagillette]

My neighbor had this turned out to be a loose sink sliding down the shaft and hitting strut

 

[Jacob Vetter]

Shifter cable slack/play at neutral at helm end?

Good point! Today i changed the Morse control settings to "long stroke" it was in "standard stroke", unfortunately it did not help either (maybe a little better..). But I dont think it is a adjustment thing anymore, it seems like it must be a combination between a heavy autoprop (old) and an old gearbox (1973) I think a new fixed blade prop and a new rebuilt gearbox will do the trick..i hope. But it is strange that first time it goes from neutral to either forward or reverse it makes a big klonk sound..

 

[Jacob Vetter]

My neighbor had this turned out to be a loose sink sliding down the shaft and hitting strut

Agreed. I'd bet that if you get the boat moving in reverse and then shift into forward you'd experience a similar clunk.

I don't think I've driven a boat with a Brunton prop, but with other feathering props like the Max Prop this is quite noticable.

ETA: if you shift to neutral long enough for the shaft to stop turning before shifting into reverse this should disappear.

Its the prop! When you go into reverse the blades swivel about 180 deg until they hit a stop. However, this does not explain why it does not happen when going forward . . .

Well, i found out that if i push the gear into forward and to neutral and then to forward again there is no problem, the same goes for reverse, but the first time it goes from neutral to either forward or reverse it makes a big klonk sound. The blades of an autoprop does not have a stop, they can turn 360 degree endlessly..

 

[rslifkin]

If the gearbox is operating normally and the auto prop is working and in good condition, I'd just leave it alone. The clunk from the blades changing position isn't harmful or abnormal if everything else checks out. It's just something to live with.

 

[Jacob Vetter]

If the gearbox is operating normally and the auto prop is working and in good condition, I'd just leave it alone. The clunk from the blades changing position isn't harmful or abnormal if everything else checks out. It's just something to live with.

Yes i hope you are right! but it sounds bad and like something is not right. + sometimes it just goes into gear almost without a noise (but only when i put it in to the same gear again, and unfortunately not always..)

 

[twistedtree]

Is this something new, or has it always made this noise?

Is there any possibility of hanging a camera down on a boat hook and filming the prop and shaft when this is happening?

And I can't recall if you already did this, but have someone watch the shaft and engine while you shift to see if there is any fore aft movement in the shaft or engine/gear assembly

 

[Jacob Vetter]

Is this something new, or has it always made this noise?

Is there any possibility of hanging a camera down on a boat hook and filming the prop and shaft when this is happening?

And I can't recall if you already did this, but have someone watch the shaft and engine while you shift to see if there is any fore aft movement in the shaft or engine/gear assembly

It has allways been so!, We changed the gearbox, but it still makes the noise. I have talked to Brian from American Diesel, and he told me that max. RPM with load in forward should be 2350 RPM, but I can only reach 2000 RPM so my prop is to big, and that might have an impact on the gearbox. I dont have an gopro to do the water shot, but when i look at the gearbox and shaft, everything looks normal.