96 Yam 4st 50hp lower unit siezed on

[terrygeorge]

Please can anyone offer any advice on how to remove a siezed lower unit from the above engine.<br />All 5 (including hidden one !) bolts out - presume splines are siezed...<br />Any help much appreciated.<br />Terry

 

[BillP]

Re: 96 Yam 4st 50hp lower unit siezed on

I have a 1996 Mariner 50hp 4 stroke which is supposed to be made by Yamaha and the same.<br /><br />The shift rod may be holding the lower unit on. Mine disconnects under the cowl at the front of the engine. The foot won't come off without disconnecting the rod.

 

[terrygeorge]

Re: 96 Yam 4st 50hp lower unit siezed on

Thanks Bill - no, I am assured this shift rod is on a spline and comes away with the leg.<br />It would seem the drive shaft is siezed into the crankshaft...and so far we have had no success in moving it.<br /><br />Terry

 

[BillP]

Re: 96 Yam 4st 50hp lower unit siezed on

I think you need to look under the cowl or at a manual and verify the shift rod connection. Our 50hp 4 stroke motors are supposed to be identical and I had to disconnect the rod to get my lower unit off. The shift rod raises and lowers to do the shifting...splines aren't logical in this application.

 

[terrygeorge]

Re: 96 Yam 4st 50hp lower unit siezed on

Thanks Bill<br />No, I have a pair of engines and have spit the other one very easily. The shift rod is splined just above the gearbox. The spline into the crank , which is siezed, is less than 2 inches long, but remains solid so far !!<br />Thanks for your help<br /><br />Terry

 

[rodbolt]

Re: 96 Yam 4st 50hp lower unit siezed on

hello<br /> wow I wish I could help more. so far I have not personally seen this. I do know of another dealer that is a friend that had one like that. he found the splined shaft goes through the oil pump and the to the crank. the drive shaft splines are driven by the crank splines and drive the oil pump. anyway what he found was the spline had burrered and would not release from the crank/oil pump . he used thin steel wedges and a hammer to remove it. it worked out for him so good luck.<br /> . keep us posted as to your progress.

 

[terrygeorge]

Re: 96 Yam 4st 50hp lower unit siezed on

That should have been split - not spit - the other one !<br />We have used pinch bars etc to exert extreme pressure on the gearbox housing/drive shaft housing joint, which has opened a couple of mm - but no more. Suspect this is damaging water pump housing, but engine is dead without being able to split it.<br />The drive shaft is slightly accessible at the top of the leg where it enters the powerhead - have been tapping this with pressure on, all to no avail.<br />I have now drained the engine oil and next move is to invert the engine complete and try and let some diesel penetrate into the driveshaft/crank joint....will keep you posted.<br />Thanks for your interest<br />Terry

 

[phatmanmike]

Re: 96 Yam 4st 50hp lower unit siezed on

disconnect the shift linkage...as told above

 

[BillP]

Re: 96 Yam 4st 50hp lower unit siezed on

Ok, I guess the motors are different. Try heating the crank (maybe just heating the flywheel will work). I use a heat gun and then put ice paks on to cool the parts. This gives the most expansion/contraction and has worked for me on really tough motor parts. After a few cycles it may pry off.

 

[BillP]

Re: 96 Yam 4st 50hp lower unit siezed on

What happened? Did you get the lower unit off?