'75 1150 upper drive shaft bearing question

[monk-monk]

Im installing a new water pump assembly in my '75 1150...A few years back, i installed a pump assembly in my '72 1150, but i noticed something today, that i didn't notice on my '72 1150 so i have to ask...once i got the entire pump assembly out today (pump base included) i noticed a lot of circular slack in the upper drive shaft bearing...i can move the driveshaft like you would stir a pot...NOW, if i push down hard on the driveshaft and then spin it, it is tighter in the upper bearing...Here's the question: is this excessive circular movement in the driveshaft/bearing normal...i am familiar with the dynamics of the preload put on the driveshaft by the powerhead, thats why i pushed down on the shaft to see how it felt then...which, by hand, wasn't too bad...how much circular motion should the driveshaft have...wondering about the upper driveshaft bearing??

 

[emckelvy]

Re: '75 1150 upper drive shaft bearing question

The L/U's with a tapered driveshaft bearing are designed that way. Those with the bearing race on the bottom and tapered bearing on top, are supposed to have a preload pin. If that's how yours is, make sure the preload pin is free to move in the driveshaft, so it'll put tension on the tapered bearing.

Another, later design uses an upside-down bearing assy; the bearing goes on the driveshaft with the taper facing upwards. The bearing race is installed in the gearcase I.D. with its taper facing downwards. Free play is controlled by shims under the bearing race. This design does not have a preload pin.

Anyway, sure sounds like yours is the first type and I've noted these having quite a bit of play when you pull up the driveshaft, but when you push down as you said that play goes away.

Now, if you don't have a preload pin and there's tons of free play, maybe there's a problem and you should pull the pump base to see what's going on.

Otherwise, unless something seems terribly out of whack, I'd say you're Good To Go.

HTH..........ed

 

[monk-monk]

Re: '75 1150 upper drive shaft bearing question

Thanks for the response...here's what i do know: there is no preload pin on the top of the driveshaft, i do have the water pump base removed, thats how i noticed all the slack, i went to pick up the LU to roll it over and thats when i noticed all the circular slack in the shaft...im pretty darn sure the bearing race is tapered with the larger diameter of the taper facing upwards...i say this because i remember being able to pull up on the driveshaft which created even more slack between the bearing and the race...though i don't have a lot of "hands on" experience, i do have considerable knowledge of the LU components...I study this Merc stuff ardently...I will be reading my FACTORY MERCURY MANUAL to learn more...if i remember correctly, when merc did away with the preload pin it was because they change the "cut" of the gears (from straight cut to taper cut which the taper cut actually pulled down on the driveshaft...again, its that hands on experience thing..

 

[monk-monk]

Re: '75 1150 upper drive shaft bearing question

Sorry to post again so quickly, but the more i reveal, the better help i can receive...I just read the merc manual again and i understand...Merc reversed the installation of the tapered bearing/race when they did away with the preload pin...boy im having a strange suspicion about this set-up...and i do believe this is not the original LU...and i know for sure that whoever worked on this engine previously didn't have a clue as to what they were doing...just gonna have to study up...

 

[rodbolt]

Re: '75 1150 upper drive shaft bearing question

during the run of the inline 6 engines there were 3 basic drive shaft preload methods, one used shims under the pump base, a real pain when replacing the pump base, the other two used shims under the race,one used a preload pin the other a nut on the bearing bore similar to a later style alpha.
all 3 cases would interchange as whole unit from one motor to another.
dont ask how I know that one.

 

[monk-monk]

Re: '75 1150 upper drive shaft bearing question

OK, this set-up does have a shim under the water pump base...and what makes that a real pain when replacing the pump base rodbolt..??

 

[rodbolt]

Re: '75 1150 upper drive shaft bearing question

cause now I gotta WALK ALL the way over to my box, get my depth mics, get the manual, make some measurements,do some math, and see if I have to WALK ALL the way to the parts room look up a shim and hope I have it in stock then WALK all the way back.
see why its a pain. someone is paying 85/hr for my walking and parts lookup time.
that and the later style ya simply plop on the base with the correct seals and gaskets and go.
see? no walking.
it works well, just later designs were easier.
thats why sometimes the boat salvage yard ebay backyardigans will bite ya.
you look up all the parts Via the engine seriel plate,pull them have them hot and ready on the bench, gonna smoke this one and impress the service manager.
get it of and apart and go WHAAAAT.
then go tell the service manager you have NO parts to fit that antique unit on that 85 model inline 6 and its gonna be 4 days to get them for a simple pump job.
now all the parts go in a box,the boat gets moved back out and parked and the work order goes back in the stack and pray nothing is back ordered.
then the parts come in, parts doesnt telll you for 3 days they are in and now you have to break your schedule to get that rig back in the shop cause you have 3 more work orders open on the bench.
see what I am saying?

 

[monk-monk]

Re: '75 1150 upper drive shaft bearing question

Yeah, surprise, surprise...so if the new pump base isn't the same depth as the original pump base, then you have to recalculate the shim thickness...I've read about that in the manual...push up, push down, measure this, measure that...gonna have to go back and read my manual...need to know where to measure what, and in what position to have the driveshaft...Im not one bit scared, i have the tools and the mechanical knowhow, plus i have the power of iboats behind me...tell me more...Here's my motto: educate, prepare and apply...a well planned job is half over!

 

[rodbolt]

Re: '75 1150 upper drive shaft bearing question

however, if and only if, the original base was shimmed correctly and wasnt melted between the bottom part that sits on the shim and the gasket surface you can measure the old distance,the new base distance, do the math and its out the door.
I havent touched an inline 6 in at least 6 years and with any luck never will again.
in my salt pond area they are getting to old to take apart.

 

[monk-monk]

Re: '75 1150 upper drive shaft bearing question

I understand...now see, thats the stuff that makes the difference...what novice would recognize (or think to look for) a worn pump base when doing calculations...i thought about this while awaiting a reply...i figured i'd just take my depth gauge and do a comparison between the gasket surface and base of each unit...add, subtract blah blah, but if the old base is worn, then good luck with that...it'll never be right...my Merc manual tells all about this...starting from scratch...im not going to "play" off of anything...thanks so much for the help...it's amazing how someone can "jump start" another person mind..

 

[rodbolt]

Re: '75 1150 upper drive shaft bearing question

base wont wear unless the bearing spins, in which case you have a lot of other issues.
they can melt, depends on how bad its melted.
would also depend on if I had owned it or been the last person to change it as to which way I would go.
I mean if its worked for 20 years you have owned it dont change it. if its new to you and you dont know who or what worked on it last do the procedure.
I have changed many corroded upper drive shaft housings on OMC and Yamaha without dissasembling the drive to shim it.
simply measure the old housing,measure the new one. do the math and change shims as nessasary.
trick is with old gearsets, you really really dont want to move the pinion gear to a different wear pattern on the fwd gear.
but sounds like your reading and on the right path.
good luck.

 

[monk-monk]

Re: '75 1150 upper drive shaft bearing question

rodbolt...you have helped me a bunch...now im gonna help you...never say bad things about these old Mercurys for they are very workable motors...i might be wrong, but from your text, it sounds like you're working under a lot of pressure...it's how you make a living apparently...time is money no doubt...i live that world too in electrical work...but if you worked on these old Mercs as a hobby, just took your time with things, it would give great results...i had a guy tell me, "never try to remove that water jacket cover cause the bolts will break"...well, i put a wrench on them and moved them ever so slightly...then i sprayed them with WD-40...i moved those bolts back and forth and kept spraying penetrating lube in there, for days...BUT i got everyone of them out...it's patience...BTW...the water jacket cover had to come off to be able to press in a new cylinder sleeve..that surface is the "true" surface to squarely press in the sleeve..Now i have a sweet '72 1150 that runs like a champ...Thanks for the help...means a lot...

 

[rodbolt]

Re: '75 1150 upper drive shaft bearing question

never said bad things.
however in my area you would have broken all the water cover fasteners,most the exhaust cover fasteners and ALL of the ex diverter plate fasteners only to find the diverter surface to badly corroded to repair.
trust me my area is tough on outboards and the average life span is about 6 years before the corrosion monsters eat ya. happens to ALL brands.
I worke on those inlines any many years even worked on some of the old direct drive dock busters.
however I dont like them anymore as they got to old and harness's,switch boxs,points caps,rotor shafts,and trigger assy's simply got to expensive.
but to those that have one and they work they are quite nice.
I had a 1500 on a 17 cajun that was sweet.
I got it cheep cause no one, ot even me could figgure out why the only way it would start cold is spray WD-40 down each carb throat before cranking.
do that and it lit right up, dont and it would crank several minutes.
my cure was to knock out the bypass nipples from 3 old jonnyrude crossflow transfer port covers, drilled all 3 carb flanges and pressed the nipples in, added a fuel primer solinod from a jonny rude and it was the fastest starting old inline you ever saw.
its also why later inlines got just that treatment from merc.
another trick was to block off the backdrag hose to aid in upper midrange leanouts on light hulls with big props the inline jonnyrudes had the same issues with their backdrag carbs.
other than that,keep a fresh water pump in it, some years mine got 2 a year,keep the fuel system absolutly clean and they ran very very well.
until the ex divider corroded through and sprayed saltwater into the ex ports or the ex diverter plate disentergrated and did the same thing.
other issue here was the tops of the cyl jugs would corrode out from under the water cover gasket.
only real fix was to remove the cover,remove the power head and redeck the block/jug surface.
not saying anything bad about old mercs or electric shift jonnyrude or hydro electric shift jonnys or even hydro-electric OMC stuff. other than its dirt old,not worth fixingin my area and parts are tough to obtain here.
anything I remember I will post and I do still have most the old manuals someplace from years ago working for a merc dealership that eventually closed up and the owner gave me all the merc,mercruiser and suzuki manuals.