mariner 40hp forward slipping

[bigg20032000]

87 40hp mariner on water christmas eve all is fine. in water this a.m. when going to forward anything over quarter throttle it slips. thought it was the prop slipping changed prop same thing. took linkage loose an manually shifted .no help. WHERE DO I START LOOKING. any ideas

 

[Bondo]

Re: mariner 40hp forward slipping

87 40hp mariner on water christmas eve all is fine. in water this a.m. when going to forward anything over quarter throttle it slips. thought it was the prop slipping changed prop same thing. took linkage loose an manually shifted .no help. WHERE DO I START LOOKING. any ideas

Ayuh,.... Pull the lower unit, 'n check the splines on the drive shaft, 'n up in the crankshaft,......

 

[MH Hawker]

Re: mariner 40hp forward slipping

2 bad props

 

[bigg20032000]

Re: mariner 40hp forward slipping

tried brand new prop no help. pulled foot splines on shaft look ok . drained foot no metal in gear oil. motor is jumpimg completely out of gear when you throttle up but you can hear it clunk back in gear when you throttle down. i have a foot off of a 50hp mercury , will it interchange?????

 

[Bondo]

Re: mariner 40hp forward slipping

tried brand new prop no help. pulled foot splines on shaft look ok . drained foot no metal in gear oil. motor is jumpimg completely out of gear when you throttle up but you can hear it clunk back in gear when you throttle down. i have a foot off of a 50hp mercury , will it interchange?????

Ayuh,.... What about the splines in the end of the crankshaft,..??

 

[bigg20032000]

Re: mariner 40hp forward slipping

Ayuh,.... What about the splines in the end of the crankshaft,..??

look good too

 

[bigg20032000]

Re: mariner 40hp forward slipping

worse today. took foot back off i can not make it slip holding driveshaft and attempting to turn prop shaft with a long bar:blue:

 

[racerone]

Re: mariner 40hp forward slipping

This certainly points to a bad prop.--------Very difficult for a clutch dog to " slip " on these Mercury motors.-----Can you test it by manually shifting it with cable disconnected at the motor ?-------Was the lower unit off for waterpump work when this problem started ?

 

[bigg20032000]

Re: mariner 40hp forward slipping

well after I got a small bore light an inspected the crank splines again they don't look so good. think its time to go boat shopping.

 

[bigg20032000]

Re: mariner 40hp forward slipping

is this a repairable fix or will the crank need to be replaced

 

[Bondo]

Re: mariner 40hp forward slipping

is this a repairable fix or will the crank need to be replaced

Ayuh,.... It's now a Parts motor,....

 

[bigg20032000]

Re: mariner 40hp forward slipping

ok got thing apart an the splines are good in the crank an on the driveshaft so it must be { in the foot????????? }

 

[bigg20032000]

Re: mariner 40hp forward slipping

adjusted linkage now I have reverse but still slips in forward. water pump output does not change when it slips so that is telling me that it is defiantly not in the crank / driveshaft but in the foot. am I correct in thinking this?????

 

[1nebel0]

Re: mariner 40hp forward slipping

Sound to me like a linkage adjustment... disconnect the shift cable and stick it in gear on the motor to insure full engagement...that will tell you that your adjustment is incorrect.....

 

[bigg20032000]

Re: mariner 40hp forward slipping

Took linkage loose put in water shifted by hand still slips over quarter throttle noise coming from foot. Reverse ok

 

[oldman570]

Re: mariner 40hp forward slipping

Time to remove the LU and do a pressure test looking for any leaks. Then look the prop over real good to make sure it is the correct fit on the prop shaft. If all checks good, then it is time to pull the prop shaft and internals to check for ware of the clutch dog and the gears. When doing the internal work, it is a good time to replace the seals and gaskets to save another teardown later, if one of them leaks.
JMO
Oldman570

 

[MH Hawker]

Re: mariner 40hp forward slipping

I would drain the LU oil before I would tare into it. Do you have chunks in the LU oil. If you are losing the gears it will have chunks in it. The oil will tell you a lot. It may have a magnetic lower drain plug. or if you see a lot of glitter in the oil that's fine metal particles, but normally by the time it wont pull any more the gears are stripped out and you have chunks of metal.

 

[bigg20032000]

Re: mariner 40hp forward slipping

I can get a good LU with prop for $375.00 is this a good deal versus a rebuild???

 

[MH Hawker]

Re: mariner 40hp forward slipping

Thats not a bad price, but make very sure thats what you need.

 

[oldman570]

Re: mariner 40hp forward slipping

The price is fair for a good working LU that fits your setup. Before handing any money over you should make sure it will fit, have a pressure test done, turn the drive shaft and prop shaft while in all gear positions and feel for any rough spots while turning, check the shifting into all gears while turning the drive shaft. A set of new gears will cost about as much for your LU, not to mention the seals, gaskets, bearings, and other parts to do a total rebuild of yours.
JMO

Oldman570