used lower unit 1974 Evinrude V4, how to check?

[zj-jeepster]

Hi all,<br />I just got a used lower unit for my 1974 Evinrude 85HP V4 hydro mechanical assist shift lower unit and I'd like to know how to do a quick and dirty check for the mechanical aspects of it. I will later check for seals with pressure testing, but for the time being I just want to quickly check the innards for possible existing damage.<br /><br />Lube appears chocolate brown in color.<br /><br />When I tried to turn the drive shaft I had to use both hands and it's kinda hard to turn. I can hear a slight rubbing sound.<br /><br />When I tried to move the shift rod it doesn't want to move. Hydro mechanical assist shift means the motor should be running to be able to shift? I'm thinking the oil pump in the lower unit helps this?<br /><br />Prop shaft turns very easily and true and tight so I guess it's in neutral.<br /><br />Any help would be appreciated.

 

[merc16]

Re: used lower unit 1974 Evinrude V4, how to check?

zj jeepster,<br /><br />that chocolate brown gear oil, thats old gear oil buy youself some new gear oil and change her up.and as for you not being able to shift the engine has to be running and gears,driveshaft, and clutch dog have to be moving for a smooth shift.yeah the driveshaft might be a little hard to turn but thats normal considering it has to turn an impeller squeezed in a housing and a pinion gear in the gearcase just remember, NEVER TURN YOUR DRIVESHAFT COUNTERCLOCKWISE!!! THIS COULD FLIP YOUR IMPELLOR BLADES THE WRONGWAY!!! ALWAYS SPIN IT CLOCKWISE. overall with a little tlc your lower unit sound like its in good working order.

 

[zj-jeepster]

Re: used lower unit 1974 Evinrude V4, how to check?

merc16<br /><br />Dude, thanks for your encouragement Ok i'm kinda really relieved now. I don't remember which direction I turned the drive shaft. I think I tried both directions like a newbie would. I do want to learn the water pump with this backup unit anyway so I'll have to get some new gaskets/impeller and study my manual some (much) more. Thanks again.

 

[zj-jeepster]

Re: used lower unit 1974 Evinrude V4, how to check?

Ok,<br />I'm looking in the OMC manual and it looks like the picture of the impeller on page 6-3 is wrong. I think it should show the blades going the other way. Is that a misprint or am I looking at it wrong?

 

[Solittle]

Re: used lower unit 1974 Evinrude V4, how to check?

Look at the flywheel. The guides for rope starting will show you which way the crankshaft and the driveshaft are turning.

 

[ledgefinder]

Re: used lower unit 1974 Evinrude V4, how to check?

Clockwise, looking down from the top, is the 'right' direction. The driveshaft of a lower unit with a new impeller is impossible to turn with your bare hands, so the fact that this one is tough to turn is good. <br /><br />You can shift the hydro-assist mechanical (1973-77) V4 lower units without the pump, but it takes a REAL stout pull on some of them, and that's not a negative sign. It's easy if you're doing it with the leverage provided by the remote control & linkages, but can be tough if your just push/pulling the end of the shift rod.<br /><br />I've had some problems with pitted, salt-water corroded driveshafts on these (though they're way better than the older non-stainless Mercs). If it's been in salt, look carefully here. These can make it tough have a good surface for the seals under the water pump. <br /><br />I also have had a run of leaking shiftshaft seals. This is by far the easiest seal to change out, so not really a problem. Post back if you have trouble with that donut.<br /><br />If you drain the fluid (takes a couple hours for it all to drip out), then remove the impeller, you should be able to spin the LU freely. If the bearings or gearset is getting noisy, you'll hear it. <br /><br />For me anyway, a running water test is the only way to really verify that the LU is leak-free. Pressure testing is a great way to find where leaks are, and worth doing as a test anyway, but I've had a couple LUs that did fine on pressure tests but leaked in use. I'm now letting the pressure sit for 30 minutes to overnight - seems necessary to pick up slow propshaft seal leaks when there's still some LU fluid around.<br /><br />Only other non-obvious thing I can think of is to use some gasket sealant on the LU/midsection mating surfaces. Leaks here are usually just cosmetic, but if bad enough the exhaust housing water level can get pretty low.

 

[zj-jeepster]

Re: used lower unit 1974 Evinrude V4, how to check?

thanks guys<br />ok, clockwise rotation, the piture in the OMC manual is wrong. it should show the blades going the other way. I'll be playing around with this spare unit then. hope I don't make it worse. will be studying the manual with a magnifying glass. there's so many special tools needed, I'll just do the easy stuff.<br /><br />I'm gonna start a new thread about my existing lower unit.

 

[zj-jeepster]

Re: used lower unit 1974 Evinrude V4, how to check?

ledgefinder<br />that was an awsome post. I thank you so much for your time and patience to share your expertise.