stern drives...
 

stern drives:

lot of guy are quick to tell you "stern drives are junk","stern drives will cost you a fortune to maintain","stern drives allways break","stern drives,the drives are weak","stern drives,if the bellows leaks,the boat will sink on the spot"...well...from my experience,none of the above is true...far from it...


below,is a merc "alpha 1 gen II" drive,this drive is 11yrs old,the hydraulics - trim cylinders and all lines are original,the drive has never been "apart",water pumps have been replaced,this is the second time i've replaced bellows on this boat.the engine's also original,and the boat's wet stored,for the season - april to october,every year...

drives,the need to be removed every fall,upon winterizing the boat - do not skip this process - pull the drive ! there's no way to lube the fitting on the u-joint,without removing the drive,there's really no better way to inspect the drive shaft bellow,without removing the drive,and,last but not least,there's no way to lube the input shaft for the drive,with out removing that drive...again,do this,regardless of what mfg or type drive you have...

bellows:should be replaced every 5yrs.inexperienced people will tell you if the drive shaft bellow leaks,you're gonna sink,on the spot - WRONG ! way wrong ! on a merc,the water will trickle out of the "weep hole",only a small amount - as you can see in the pictures,the o -rings around the shaft these will seal the water at the gimbal bearing...
shift cable bellow:inexperienced people will tell you,it will sink your boat on the spot as well,again,wrong,way wrong ! the hole's slightly larger than the shift cable's outerjacket - small amount of water...
exhaust bellow:this will sink you on the spot,is what's said by the know it alls again - wrong,and again,way wrong ! the ehaust is sealed from water - the bellow just connects the exhaust to the drive...

drives:
the gaskets and o rings need to be repalced,when the drive's pulled - do not use a sealer,silicone,or weather strip adhesive to hold the gaskets/o rings.use a non metallic grease
be sure and use a "spline lube" for the input shaft,again,use appropriate spline lube...use a light coating of grease,non metallic grease,on all the bolts and tilt pins,along with the gaskets and o rings - this will help seal,as well as allow you to remove everything again,with little effort...

note the picture of the drive - that's all the dates,i've pulled this drive - scratched onto the housing - quite a while huh ? the drive's a 2000 - note the picture of the hull ID number...
again,this drive's 11 seasons old,not bad,huh ? this is typical of maintained properly stern drive power systems,they honestly are a pretty trouble free system.the horror stories usually come from old,unmaintained drives.

last word on bellows:
bellows will allow water to enter the boat,however,that water will not enter as much as the inexperienced people will tell you,the drive shaft bellow,if it's completley gone,a small amount will trickle through the "weep hole"-nothing extreme !
shift cable bellow,even if it's gone,the amount of water leaking in,is minimal...
why do boats sink at the dock,with leaking bellows ? bilge pump runs moure,no shore power/ charging system,battery becomes dead,boat sinks...

again,nothing wrong with stern drives,my own sea craft,is a stern drive powered boat,it's ran,and ran hard,a large portion of the boats i service and store,are stern drive powered boats,the results are similar,proper maintance practices are the key to a long life...i use and recomend mercruiser parts only,i avoid the cheap aftermarket parts.merc offers a "transom repair kit",this kit includes everything you need - drive shaft bellow,shift cable bellow,and exhaust bellow,water transfer tube,gimbal bearing,along with all required gaskets and o rings.i also replace the lower shift cable and the oil resevoir tube at the same time - all these parts need to be removed to perform a bellow replacement - there's no additional labor charge and the price is minimal.this whole operation takes approx 4hrs to complete - includes servicing the drive.the replacement gimbal bearings from merc are "perma lube",no anual greasing is required - i've got a few of these out there,with no problems...


questions ?

My sterndrive is 32 years old and going strong. Boat came with paperwork for all the stuff he has done to the boat since new in 79'. No major repairs on the leg. Freshwater though. :)

http://i224.photobucket.com/albums/d...raft/049-1.jpg

http://i224.photobucket.com/albums/d...t/000_0072.jpg

Pelican,
Thanks for the informative post. I've got a couple questions you might be able to answer.

Mercruiser has had some problems with electrolytic corrosion, particularly on the Bravo drives, haven't they? What caused the problem? Has the Mercathode system fixed it?

I'll be using the Bravo 1 drive that came with my 25 along with a shiny new 350 Mag MPI. This is my first sterndrive boat, and I want to get familiar with the potential problems so I can do appropriate preventive maintenance. Any info experienced sterndrive owners can provide is appreciated.
Dave

that was the older bravo III drives - not an "electrolysis" problem - galvanic corrosion - electrolysis,that's hair removal...
problem came from the prop shaft carrier,too much stainless steel...
since been corrected...
you need to be carefull with those older bravo drives/transom plates - the water transfer hose - there's a bushing,it will become restricted,from salt intrusion,end result is a low water/distrurbed water flow

The Volvo 280 outdrive is the best ever....

Ya mine has the original alpha I gen I with a ford 351w and I like it a lot. Didn't think I would like it as much as I do. Even the raised motor box makes a nice casting platform. Though it does seem to have an electrolysis problem, but I just change the zink every month or so.

Galvanic corrosion, right. Maybe that's why my hair is getting thinner, I have an electrolysis problem. :D


I'm setting up my Bravo with a 1.25" through hull water pickup and a strainer. That's how it was when I got it, but I'm junking the brass ball valve and using a bronze seacock. The water pickup in the transom plate is blocked off. Does that solve the problem?

Dave

You may want to tap something like this into your RW line so you can run the boat off fresh water when the need arises.http://www.yachtsofstuff.com/userPos...xs=mtg#install

I never really understood sterndrive hate, alot of it seems unwarranted. As with most things, preventative maintenance is key. Some people want closed transoms and running gear you can trim. I prefer being in a small boat you can simply press a button for a few seconds and change your draft. Although my buddy has 22' F.L. Tripp, if it hits bottom around here you just throttle up and push right through on the keel, unless of course it keeps getting shallower, lol.

dumb question - does the "trim indicator" work ?

running a thru hull - that avoids that potential problem...good move !

this is gonna sound really strange: just work with me...

flushing - sounds like a really good idea,right ?

in just about 20yrs,in this biz - i've never seen an engine failure,directly caused by an engine being raw water cooled.i've never seen a "clogged cooling jacket",never seen a block rusted through...

if the engine's filled with water - even sea water - there's an absense of air - no oxygen,right ?


the weak link on gas engines is the exhaust system - be it either stern drive,or inboard - these are the most common cause of an engine failure - some engine mfg's do not include the mainfolds in their fresh water cooling systems - some do - crusader,is a mfg that does...with all that,the risers,or,the manifolds are expelling sea water - meaning,these have a finite life.the normal accepted life is approx 5 years.flushing with fresh water will not prolong this - against popular belief...

it seems we're on this subject,so - i'm gonna run with this...

see next entry,for more info...

center consoles - seacraft center consoles - they've got a flush fwd deck - this is where you battle a big fish from - the engine box isn't a factor - you fight the fish from the bow - fish "pulls" the boat,plus,whoever's on the helm,you can see what's going on,to follow the fish - the boat handles a little easier from the "pointy" end...

this is how it's done...

stern drives - gas engines:


the smartest move you can make,is to pull the plugs and perform a compression test,anually.i normally do this at time of winterization.
run the engine,to normal operating temp,and pull the plugs - take a long look at the plugs - you're looking for either "rust stains",or a plug that's "snow white" - this is an indication,that cylinder's burning water - this shows up,way before any water is noted in the oil.mositure rises to the highest point - get in the habit of looking at the "breather hoses",from the valve covers - look for steam - this is another indication,the engine's burning water.a rusted,salt covered interior of the distributor is another - again,all due to moisture rising...
perform a compression test - what you're looking for is "uniformity",each cylinder should be within 10% of each other...

now,if you're compression is low,on a cylinder - odds are,it's caused by,that cylinder ingesting sea water,via the exhaust valve - end result a runsted valve,that has lost it's concentricity - it's not seating properly - this can be verified by a "leak down" test,with compressed air...

get in the habit of doing this,like i stated,anually

exhaust systems are the weak link...

take a look at these pictures - this is a 5.7 merc engine,it suffered an early death,due to it's exhaust system - normally,these engines,when they hydro lock - the small high torque starter,it will break the block - right where it mounts - this one,it didn't,it bent 2 rods - engine was replaced with a new 5.7 mpi merc magnum...at my shop - we do not use "remans",long blocks,short blocks,or offer rebuilds of gas engine,like these - it's repalced with new,complete,drop in engines,or the job's not done...

as you can see in the pictures,some one,used a silicone sealer on the riser gaskets - bad move - very bad...

Don't have one. Typically they never last long anyway when repleced.

Yep ! That'sa right :D

nice capt !!!

Pelican-
I suggested the flusher for the bravo because my boat has the same cooling setup and with the boAt on a trailer i now have a good system to run it in the driveway.
I agree about the block flushing not accomplishing much.
I've been down the manifold failure route-aint no fun. Was able to save the motor though with some quick action.

My 350 Mag MPI has closed cooling (including the manifolds) and came from the factory with a quick disconnect for running it on the hose.

Pelican
What is the most common cause of water ingestion, manifold failure? Do the manifolds rust out from the water jacket side, or from the exhaust passage side? Or is it riser gasket failure?

Dave

i think you might wanna check that cooling system again - i don't think merc manifolds are freshwater cooled.

the cooling passages will erode - the gasket surfaces erode too - mercs are not as prone to this,later model mercs - they use a "dry joint" system...

those MPI'S with the horizon package - like the one you have,is it new as in 2011 ? if so,it would be equipped with catalytic converters - to pass the emissions standard ...your engine cat equipped ?

That's a sweet setup. I'm jealous.
It seems like the only issue you will have will be keeping an eye on the risers.
Does that motor turn 325 horses?

I think the closed cooled models may have been available with cold manifolds or warm manifolds in different years. Check out the back of Mercruiser MPI Service Manual #31, you'll find water flow diagrams for engines with the manifolds cooled by the closed system. I vaguely remember verifying mine was piped like that, but I haven't looked in a while. It's sitting in my shop covered with a tarp.

Mine is a post-Horizon, Seacore model but not a 2011. I bought it last year. No Cadillac converter. :D


Nope, just 300 ponies. I think the only 5.7 engines direct from Mercruiser turning 325 HP are carbureted. I was considering one of those strokers like Island Trader got, but couldn't find one with closed cooling.

Dave

no carb'd engine are available from merc - can't pass emissions...

i have not seen one of those "seacore" engines - heard about them,but not seen.

the merc engines have a "dry joint exhaust system - meaning,no water is pumped through the mount point where the riser meets the mainfold - pretty durable set up - haven't seen any failures from them...

only problems i've seen - is the water pressure sensors - back of the engine- power steering cooler,is where it's located - seen a few of these go bad...other than that - nothing...
my own rig,it's got a 5.7mpi,horizon engine - it's an older engine - '02,and it's been 100% trouble free - it's got just about 500hrs on it...i've used quite a few of these on repowers,in both stern drive applications and inboard systems - all with similar results...


make sure you "wheel" that engine,so it just about "bumps" the rev limiter...


the bravo drives,they're a very good drive,very durable simple basic maintance on them...
i have not seen a bravo III drive,since the update,with any kind of corrosion problems - one client of mine has a crowneline,BIII drive - it's an '06 - no corrosion anywhere - it's a slipped boat...

side note:antifouling paint - you really should have a gap,of 1" around the perimiter of the transom assembly,where there's absolutley no paint - leave that area clean - failure to follow this,can result in a galvanic reaction,between the copper based antifouling paint and the aluminum transom plate...

Thanks for the good advice. I may have some more questions for you when I start installing outdrive and engine.

There's some info on the Mercruiser web site saying the 2011 regs apply to new boats, not repowering boats manufactured before 2010. As of last February, they were still offering a carbed 5.7 crate engine at 325 HP as a repower option. Not a complete drop-in, just engine, ignition system, and fuel system.

http://www.mercurymarine.com/media/m...nformation.pdf

Don't know if it's still available.
Dave

that's not a new motor - merc reman,is alot different than new motors...

merc offers no carb'd new motors

Great info.
I also have a stern drive on my Tsunami,and also on my last boat.The whole sterndrive bashing is kind of like the bashing Bayliner took.Most of it is done by people who never owned either a stern drive,or a Bayliner.
No doubt that in salt water stern drives require more maintenance,and proper care needs to be given to the drive.Because of the salt corrosion problems parts may need to be replaced more often,and you can't tilt the drive completely out of the water like an outboard.
I'm ten years into pretty hard use with sterndrives,and can count on one hand,any problems that required any serious work.
Like anything else you have to maintain them,bellows need to be inspected and changed periodically,gimball bearings need to be greased properly,as well as the u-joints.Exhaust manifolds need to be changed occassionally,especially in salt water.In fresh water they last for years and years.

I know that most of the members on this site are salt water boaters,but on the great lakes where guys like me and Floorboy fish,I/O's(and inboards) are much more common.I like the big high transom when we're fishing in snotty stuff and the waves are rolling up the rear.I also like the open transom for netting fish(we only troll),nothing in the way.
I also like the fact that I can do almost all the work myself,as it's a simple 350 GM engine.I don't have to worry about a computer or printed circuit crapping out and not being able to fix it myself.
Even the drive doesn't require a rocket scientist to work on it,and even if it blows up,companies like SEI make great good quality after market drives for cheap money.
I guess if I was fishing the salt,and I had to decide on a power package,I'd go with outboard power.But,I wouldn't be scared off from going with a fresh water cooled I/O.

I can't even begin to imagine what it costs to fix a modern four stroke outboard,never mind trying to fix it myself.I shiver just looking at it when the cover is off.They are a marvel of engineering and nice,but way beyond my skills.
Both have their pros and cons.

http://i2.photobucket.com/albums/y7/easy2/IMG_1916.jpg

"It's a simple 350 GM engine"

My primary reason for preferring an I/O. If a problem develops, that old style car engine will warn you well before it quits, almost every time. The rest of the time, a good set of spares and some repair knowledge can get you home from way way out in the boonies.

THX ! Some great advice.

I have a 1975 23' with a 2003, 350 300HP MAG MPI - freshwater cooled manifolds and dry joint risers - with a Bravo 3.

Awesome set up. Incredible power. Great response. Fair on fuel consumption.

Saltwater run and in water for 7 months.

There is more maintenance on the drive than any other outboard I've owned. That's if you like things to be 'right' which I do.

During each boating season, while in the water, I must do a barnacle scrape from all the exposed metal parts and a few of the drive areas. This is done 2-3 times a season.

The transom mount, the gimbal and the drive need to be sanded pretty well each season to remove the loose antifouling paint and random barnacles, then I will prime any exposed metal areas with primolux and then trilux ( not the spray - I brush it on from the can - a flux brush gets in to the crevices in the mount ). This has enabled me to keep my drive, gimbal and mount - MINT! each season. It's a decent amount of work but I feel worth it. Probably 6-8 hours a season

As for corrosion, I epoxy/barrier coated my SS trim tabs and anti foul them - this helped to reduce the amount of NOBLE metal in the water a lot. I keep the mercathode in as best shape as I can, it's tough to clean the element without damaging it.

I do all my own maintenance and the one jobI want to tackle is the bellows. Never did this project before - I do hear it is difficult at best - a real 'hand-bleeder'.

In a perfect world, I'd have a 4 stroke Yamaha outboard. IMHO - it can't be beat. No metal exposed to the saltwater for 7 months...

it's best not to sand the original paint,on any of those parts - use a scotch brite pads - just simply "dull" the surface...as far as scraping is concerned - another bad move - you will damage the paint...
pressure washing,usually takes off any loose antifouling paint...


if your power set up is "fair" on fuel consumption - i suggest you take a look at the prop on the boat - make sure that engine is just about "bumping" the rev limiter,with the boat loaded,in the way it's normally ran,and full throttle - if the engine's running overloaded - not reaching it's reccomended rpm,it's gonna consume way more fuel than it needs to...

trilux is the best product - it's formulated for use on aluminum

Agreed. On a new drive - and I HATED to paint it the first time, I would use a Green scotch scrubber. But, once you have painted it, you can use either or. Either way, I'm not talking aggressive sanding - light with 120 or so - I want to remove the oxidized paint. Where metal shows, I sand it to bright aluminum so the primer has a better chance to stick.

When you paint a never before painted drive with antifouling - no matter how you prep it, there will be areas that will come off in 'sheets' - 1/2" or so after a season... These need to be feathered and a scotch pad ain't gonna cut it. Whenever possible, don't use sandpaper, but at some point, it will be needed.

Since the subject came up recently, I've got a question for the experienced stern drive guys. I disassembled my Bravo transom assembly this evening. It was apparent that the seal on the upper swivel pin was bad. The steering arm and swivel pin were pretty badly rusted. I intend to replace both.

So my question is whether I should go with the stock swivel pin or get a stainless one. I'm concerned that using stainless could shift the point of corrosion from the pin to the aluminum gimble ring. If that's the case, next time around I would be replacing a gimble ring instead of a swivel pin.But what do I know? The lower swivel pin is stainless, so maybe it's a non-issue. Anyone got experience using the stainless upper swivel pin on a salt water transom assembly?

Thanks,
Dave

that's not true - the antifouling paint,it will come off - as far as the paint on the drive it self - it will not - granted,it will "wear",in the skeg area,from hitting the sand,but that's it - the drive in the pictures i posted - that's the original drive,the paint has never peeled on that drive,or any other drive i service - again,the paint i'm referring to,is the paint,on the drive,from the factory.and again,pressure washing,is definatley the way to go,followed by scotch brite pad - granted,a few barnacles may cling,especially,if the boat hasn't moved for a while - most of the time,these can be pressure washed off...

it's best not to "disturb",the original paint on the drive,the trim cylinders and the transom assembly - this can and will allow corrosion to get a "foothold",it also leads to the original paint popping off - which will lead to the entire drive needing to be stripped,chemically etch primed and refinished - the only way to repair that situation permenantly...

only ones i've ever used,are the standard pins from merc...

Pelican,

I will defer to your judgement - you definitely seem to have a lot more experience with mercruiser I/O's.

I am very happy with the condition of my set-up... Just not the work each spring to get it there...

Wish I had a boat lift !

There is a closed cooling system and a half system. The half system flows fresh water through the engine only the full system does the manifolds also with block off gaskets at the risers. On a full system salt or raw water only passes through the risers and out the exhaust. You can plmb the mercruisers either way. :D

I have a question in regards to the alpha one gen 2... I have changed my ujoints and Gimbal bearing due to a knocking. It doesn't happen at full trim or at any turn angles, just when it's in gear. The previous owner said it has been that way for a couple years. It's not a severe banging, just a clicking when the boat is placed in gear. Any ideas?
Thank you in advance.

71 Seafari, Mercruiser 140. Current motor block indicates it was manufactured in 1986/7, but has all 1971 electrical and ignition stuff. Original transom group and original M/R outdrive. Installed all new seals last fall, all new bellows, new lower cable, new hoses, new manifold and new exhaust riser/elbow.
We live in Florida, so "winterizing" is unnecessary. HOWEVER, after many years in the marine industry, I have an annual "maintenance list" for a sterndrive.

JANUARY 1
Remove drive
Change water pump impeller, inspect pump housing and wear plate.
Remove propeller
Inspect seals, bellows, u-joint, drive shaft
Lubricate, lubricate, lubricate
New outdrive gaskets and o-rings (never re-use)
Change Lower unit oil.
Clean and re-grease prop shaft

I would say that with proper flushing, raw water cooled manifold, risers/elbows, and t-stat housings are good for 6-7 years. But ya' gotta flush the motor for a period of time AFTER it gets to full operating temperature. Salt-away isn't enough, nor is 5 minutes running at idle with a cool motor. But eventually, these pieces WILL need to be replaced