Mariner 135 slipping or missing?

[dozer1013]

The engine is an 86 Mariner 135 (ob106463)

When in gear at low RPMs, there is a distinctive "THUNK" sound which can be felt as well as heard.
It repeats every second or so
It's like something is slipping or missing maybe

It only happens just after putting it into gear.
It does not happen when idling or once the RPMs are increased.
It starts and idles fine and gets up on a plane and runs at high speeds fine

Anyone experience this before or have any ideas what I need to check?

Thanks!

 

[Bondo]

Re: Mariner 135 slipping or missing?

The engine is an 86 Mariner 135 (ob106463)

When in gear at low RPMs, there is a distinctive "THUNK" sound which can be felt as well as heard.
It repeats every second or so
It's like something is slipping or missing maybe

It only happens just after putting it into gear.
It does not happen when idling or once the RPMs are increased.
It starts and idles fine and gets up on a plane and runs at high speeds fine

Anyone experience this before or have any ideas what I need to check?

Thanks!

Ayuh,.... Check, 'n adjust the shift linkages,...

It sounds like the dog-clutch is slippin' outa gear,...

 

[dozer1013]

Re: Mariner 135 slipping or missing?

Ayuh,.... Check, 'n adjust the shift linkages,...

It sounds like the dog-clutch is slippin' outa gear,...

ok so that sounds like it might also explain some grinding in low RPM forward gear? when i say low I mean right out of neutral like before it feels like forward is engaged. It's done that since I've had the boat (about 5 mos) but the thunking is new

And excuse my newbie-ness, but how do you adjust shift linkages?
Is it a big deal job?
I'm somewhat mechanically minded but pretty new to boats

Thanks!

 

[Silvertip]

Re: Mariner 135 slipping or missing?

If you are "easing" the throttle/shift lever into forward or reverse stop doing that. This is one case where "slam-bam" is the proper technique. There is no typical clutch mechanism other than "dogs" made up of a male and female gear-like assemblies. In neutral these two parts are separated. When you shift, the two assemblies are forced into "mesh". By being gentle, these mating parts wear and chatter and eventually the two assemblies will not stay in mesh under power.

Your best bet for adjustment is to obtain a factory service manual for your engine. But failing that, you disconnect the shift cable at the engine. You then make sure the actual lever it is attached to is in neutral and that the control box shift/throttle lever is in neutral. It wouldn't hurt to wiggle it a little to ensure this. You then bring the attachment end of the cable up to the shift lever where it was previously attached. If the two points do not mate up exactly without pulling or pushing anything, you must adjust the trunion (the threaded piece) that secures the cable to the engine block. When properly adjusted the cable end and shift lever should mate up exactly.

 

[dozer1013]

Re: Mariner 135 slipping or missing?

If you are "easing" the throttle/shift lever into forward or reverse stop doing that. This is one case where "slam-bam" is the proper technique. There is no typical clutch mechanism other than "dogs" made up of a male and female gear-like assemblies. In neutral these two parts are separated. When you shift, the two assemblies are forced into "mesh". By being gentle, these mating parts wear and chatter and eventually the two assemblies will not stay in mesh under power.

Your best bet for adjustment is to obtain a factory service manual for your engine. But failing that, you disconnect the shift cable at the engine. You then make sure the actual lever it is attached to is in neutral and that the control box shift/throttle lever is in neutral. It wouldn't hurt to wiggle it a little to ensure this. You then bring the attachment end of the cable up to the shift lever where it was previously attached. If the two points do not mate up exactly without pulling or pushing anything, you must adjust the trunion (the threaded piece) that secures the cable to the engine block. When properly adjusted the cable end and shift lever should mate up exactly.

Good to know about the "slam-bam" technique because I indeed had been easing the throttle into gear

Thanks for the tips, I have a friend who has the manual so I'll borrow it and check it out keeping your suggestions in mind