4.5hp seahorse problem

[adamonimac]

Hi All,

I've got a 4.5hp johnson seahorse motor that last time it ran stopped making water at the teltale at idle speeds. I'm assuming that the impeller needs replacing. So heres my problem. I've removed the 3 bolts holding the lower unit to the leg, but the lower unit wont move down more than about 4mm. I think that it has something to do with the shift linkage, but I cant see anywhere that looks like a join in the linkage that needs to be undone. Any advice / diagrams etc appreciated ! As far as I can tell its a 1982 model (J5RHCNR)


Thanks

Adam

 

[raczekp1]

Re: 4.5hp seahorse problem

http://www.boats.net/parts/search/BRP/JOHNSON/1982/J4BRHCNR 1982/GEARCASE/parts.html
its.82 model.
pul down LO litle harder and it shoul be relased

 

[Vic.S]

Re: 4.5hp seahorse problem

No problem likely with the shift linkage. It just pulls straight out of the mechanism at the top.

Likely trouble is that the drive shaft is stuck in the crankshaft.

More force needed but you might damage the water pump housing in releasing it so be prepared to replace that if necessary.

When you get it apart make sure you can get a good water flow from a hose up the water tube and through the engine ( take out the thermostat) The grommet at the top of the water tube is a PITA as it can obstruct and even completely cut off the water flow. Power head off to replace unfortunately.

Lightly grease the drive shaft splines when reassembling.

( consider replacing the drive shaft seal while you have it all in bits)

 

[adamonimac]

Re: 4.5hp seahorse problem

thanks for the replies guys, i'll try giving it a bit more force. hopefully nothing breaks! i'm assuming that the driveshaft has a sline that goes into the crankshaft. I guess it gets corrosion or something......
would wedging the lower unit with screwdrivers be the best way?

 

[Vic.S]

Re: 4.5hp seahorse problem

I'd rather use wooden wedges.

But if the shaft is firmly stuck at the top what will happen is that it will pull out from the pump and gearcase. As it comes the impeller key will damage the pump housing.
Luckily when it happened to me it had an after market impeller fitted with a plastic key. The pump survived, the key did not!

 

[adamonimac]

Re: 4.5hp seahorse problem

Thanks for your advice suys. After a bit more force (yes using wedges and a hammer) the lower unit finally came out. Seems that nearly 30 years of use in salt water by previous owners has taken its toll. The drive shaft is very pitted and needed to be sanded back to remove rust scale etc to get the waterpump housing off. Good news is that the water passages were not blocked (phew!) and it was just that the rubber part of the impeller had separated from its centre, allowing the drive shaft to turn without tuning the impeller. Have replaced said impeller with a new one and now have a very healthy stream of water from the tell-tale.

Cheers

Adam

 

[samo_ott]

Re: 4.5hp seahorse problem

Well that's a good happy ending!