The Sterndrive I/O- A repair shops dream!

[craze1cars]

Re: The Sterndrive I/O- A repair shops dream!

So the question is...Why are these things so archaic and complex? I feel that it is lack of competition. Let's work together to make a long list of all the sterndrive manufacturers today:<br /><br />Mercruiser, Volvo.<br /><br />OK, I'm stumped now. Can anyone add to this list? It's always cheaper to run your old, paid-for tooling than to invest in new development and research. As long as the "big two" don't push each other, we're stuck with the status-quo.<br /><br />Anyone out there willing to form a company and give them some competition? That would likely solve the problem after some time.<br /><br />Jetdrives are still out there, and I think a good alternative. But they're a little more expensive and harder to find.<br /><br />Thus ends my useless opinion...

 

[rodbolt]

Re: The Sterndrive I/O- A repair shops dream!

just what are you going to use as the pump prime mover to create 250 HP with a shaft speed of less than 2500 RPM? much over a prop shaft speed of 2500 RPM and speacial props are required. <br /> as far as the bubble theory its out<br /> if people would maintain a stern drive properly we would have far fewer failures. failure is rarely sudden. it is usually a result of neglecting preventative maint. so far this year I have scrapped 4 engines. all of them I warned last summer of impending riser/manifold failure. all of them told me it always works and has given no problems. 4 failed so far and another will by october. usually if you wait till a riser fails it takes the engine with it.if its a saltwater cooled engine over 3 years old I wont even bother to pull the valve covers. but I gotta see this light weight prime mover with no cooling system that will weigh less than what we have now and still make over 250 HP at the prop shaft at less than 2500 RPM on the shaft.

 

[bigbrownbuku]

Re: The Sterndrive I/O- A repair shops dream!

preventative maintenance is key. o and jerryb you described a 270/28/290 volvo drive my favourite drive, very reliable, easy to work on(IF its been maintained)<br /><br />i dont see how moving the shifting inboard would improve anything. requires a much larger gearbox topside. merc tried their hand at all the things you describe and called it a "tr" drive. good luck with those.

 

[Lou C]

Re: The Sterndrive I/O- A repair shops dream!

Although is it true that sterndrives are complex, keep in mind that the complexity is offset by being able to use simple engines.<br />Take a 'modern' outboard, any one, E-Tech, Optimax, HPDI, and the four strokes from Yam, Honda, and Zuki. Nothing simple about them if you take a good look under the cowling.<br />Even a carbed old style V-6 OB has 6 carbs, that's right 6. Compare that to an IO, you get a single Rochester Q-Jet. And as far as lubrication, with a 4 cycle inboard you get a time proven pressure lube system (same true of 4 stroke OBs). 2 stroke, well since they moved away from premix there have been 'issues' with some of them, let's say.<br />so if you won't maintain the package, either one will cause trouble eventually, but people do love to complain about sterndrives. I'm sticking with mine for now!

 

[qystan]

Re: The Sterndrive I/O- A repair shops dream!

Comments from our boating fraternity here is that sterndrives are extremely bad news. Most older boats are lying around with their drives missing.<br /><br />Having bought a used boat (money pit) with an Alpha Gen 1 coupled to a 5.7 for one and a half years and worked on the engine and drive to fix a huge myrid of problems. The unfortunate fortune to disassemble the upper and lower units to change seals and bearings gave me a chance to see its internals, it is quite a simple design. <br /><br />The lower is no different from any outboard, save for the shorter drive shaft, in that respect, its reliability is no worse.<br /><br />The upper unit is not much more that an angle gearbox, gear designs are no brainers. Again, no reason that this should give too much trouble.<br /><br />The added upper unit does makes it more complex than an outboard and with more parts we will see lower reliability. Same for the 5.7 vs a 2 stroke. <br /><br />The basic law: more parts equate to lower reliability, this is worse than Murphy's Law- this is a guaranteed case.<br /><br />From the condition of the units I got that were supposedly maintained by mechanics, I'll say the chief cause of the failures is either lack of preventive maintenance or shoddy workmanship.<br /><br />Preventive maintenance usually hits most people to mean annual oil changes. It goes much further; changing out seals, bearings and wear items at intervals before failure is the key. Much like auto maker specifying intervals for timing belts and other stuff which cause secondary failures or have dire consequences if it fails. In this respect, Merc failed to provide intervals for these items, the only thing we see is for oil changes and greasing. Change all the oil you want- when water gets in the drive, its is gone before you get to the next interval. <br /><br />The designs should be maintenance friendly to keep repair times down- easy or user replaceable. It will encourage proper preventive maintenance as we will not 'miss the boat' for too long. In th elong run its good for both Merc and us. No loss for Merc as they will still sell their parts, get a better product reputation and for us - peace of mind.