Gearbox no longer goes "clunk".

[sbillis]

I have a PRM 120 mechanical gearbox in my boat. Since it was fitted some twelve years ago when engaging either forward or reverse it has always gone "clunk". Just recently and once warmed up it has failed to go cluck when engaging forward although it still goes in to gear and does not appear to slip. It still goes "clunk" when engaging reverse.

 

If anyone is familiar with these gearboxes can they please advise me if to go silent when engaging gear is a sign of impending failure ?

 

Very many thanks.

 

Simon

[Tonka]

Have you checked the bilge as it may have fallen off

[Richard10002]

Have you checked the bilge as it may have fallen off

?????

 

it still goes into gear..... merely without the previously reassuring "clunk"

[Guest]

Might be worth disconnecting the remote, and using the lever on the side of the box to see how it behaves when engaging gear?

[Murflynn]

Just recently and once warmed up it has failed to go cluck ...........

have you checked if it is still laying eggs?

[Robbo]

Check your prop, the clunk may come from the free movement of the prop which may not be doing so anymore. Also check the gearbox oil and give it change if you haven't done so for a while.

Edited May 31, 2016 by Robbo

[Stilllearning]

Check your prop, the clunk may come from the free movement of the prop which may not be doing so anymore. Also check the gearbox oil and give it change if you haven't done so for a while.

It may be running low on oil.

[ditchcrawler]

Our box on our old boat use to clunk into gear, not long after stopping clonking into forward it stopped driving forward as well and we spent a couple of days on the Chesterfield getting a recon gearbox. That by the way is something I wouldn't do again, I would go for new with a full guarantee.

Edit to add

I think it still clunked backwards with drive. I am not up on box makes and numbers but it was a mechanical one, not hydraulic.

Edited May 31, 2016 by ditchcrawler

[Boat&Bikes]

I think your problem will be wear on the forward cone of the clutch mechanism. As the friction material starts to wear out the box looses its clunk due to the lack of instant grip, the cone slips into drive rather than grabs straight away. Another possibility is that the cable from your morse control needs adjusting. It's an easy check, just engage the box by hand via gearbox lever, if the box clunks into gear as previously then your cable needs adjusting. If it turns out to be the cone that has worn they can be replaced. I did my own on last boat but a workshop will replace if you prefer.

[MtB]

I used to have a boat with a PRM120 and in normal use it didn't clunk (or cluck) when engaging drive unless the engine tickover was bit fast.

 

My personal view is that silent engagement of drive is the desired and correct state of affairs. A clunk always felt to me as though the box was being mildly abused.

[Grebe]

Our box on our old boat use to clunk into gear, not long after stopping clonking into forward it stopped driving forward as well and we spent a couple of days on the Chesterfield getting a recon gearbox. That by the way is something I wouldn't do again, I would go for new with a full guarantee.

Edit to add

I think it still clunked backwards with drive. I am not up on box makes and numbers but it was a mechanical one, not hydraulic.

 

That was a long time ago Brian, 1998?

 

I seem to recall it was a 150 box that failed and the replacement was a recon 120 box.

 

Memories of Stockwith basin, Arthur and Roma Eastwood and meeting you come to mind.

Edited May 31, 2016 by Grebe

[ditchcrawler]

 

That was a long time ago Brian, 1998?

 

I seem to recall it was a 150 box that failed and the replacement was a recon 120 box.

 

Memories of Stockwith basin, Arthur and Roma Eastwood and meeting you come to mind.

That was it. He really did me proud, real first class service to get us on our way again. I cant think of anywhere that could have gone to more trouble to sort us out. I take it he has long retired now?

[Guest]

I used to have a boat with a PRM120 and in normal use it didn't clunk (or cluck) when engaging drive unless the engine tickover was bit fast.

 

My personal view is that silent engagement of drive is the desired and correct state of affairs. A clunk always felt to me as though the box was being mildly abused.

Technodrive do similar. Very similar box to the PRM mechanical.

[MtB]

Forgot to say, on mine the Teleflex/Morse control usually needed adjusting, as it was increasing the engine speed slightly before engaging a drive gear. This led to the disconcerting clunk. Adjusting it so the gear was engaged before raising the engine speed fixed it.

[sbillis]

Many thanks to all who responded. I will try the gear selector and then check out the oil levels when I am next at the boat.

 

Simon

[Guest]

Forgot to say, on mine the Teleflex/Morse control usually needed adjusting, as it was increasing the engine speed slightly before engaging a drive gear. This led to the disconcerting clunk. Adjusting it so the gear was engaged before raising the engine speed fixed it.

Interesting. I will check that on ours. Cheers.