Why so many blown motors?

[Devins]

I have just started looking for a "real" bass boat to replace my all-electric reservoir rig. While looking at ads for used boats, one thing I have noticed is the large number of boats that have replacement or blown motors.

Why do so many bass boats blow their motors? Is it usually lack of oil? Running too hard? What kind of routine maintenance will prevent it?

[Jig Man]

Breaking in a new motor slowly by factory recommendations and letting them warm up before take off goes a long way toward keeping a motor going.

Around here some guys break a motor in from the ramp to the nowake bouy.  Then it is wot and before long repower.

[Bull Hurley]

cheap gas containing ethanol

[SoFl-native]

Lack of maintenance and age.

Applies to women as well.

[fishizzle]

Cheaper parts in manufacturing and lots of aluminum and plastic.

[done]

Lack of maintenance and age.

Applies to women as well.

ROFL ;D Nice. Yeah I have to say breaking in my motor was ANNOYING but I have seen what happens when you do not do it properly and that could be some of it. I have seen the threads here on Ethanol and remember the fun time we have in WNY with lawn mowers and snow blowers when they made it mandatory for a bit. So I avoid it. Maintenance is a common issue as well. Speaking of which I REALLY need to get mine in for a tune up and check up.

[Devins]

Thanks for the replies.  There seems to be several possible causes.  I have been surprised by the number of boats, even only 6 or 7 years old, with blown or replacement motors.  I would think that they should hold up longer than that.

[bilgerat]

As a guy who makes his living as a marine (diesel) mechanic, let me tell you these myths about maintenance and proper break in procedures are just a bunch of bull.....go ahead and run 'em full bore :

[Way2slow]

A lot depends on the motor.

The early DFI motors (all makes), were rushed to market and suffered a number of engineering design problems.

Mercs had some problem with plastic oil pump drive gears

Some where because the early Oil injections were not that reliable and people still try to running the original pump system 15 - 20 years later.

The mid 90's OMC's had problems with the ring locator pins coming out because of a design change and the fact the port side runs hotter than the starboard side. They also had issue's with the top main bearing retainer coming loose when they went to the lighter rods and pistons. A field mod came out for that but many didn't get it.

The vast majority are due to operator ignorance. Old gas and modern outboards don't mix but people constantly leave their boats sitting for months on end and think they can just go to the lake with that same gas that's in it and the gummed up, dirty carbs that it causes. The loss of octane causes detonation that destroy pistons, the dirty carbs leans a cylinder and melts the center out of the piston. Then you have those that think a water pump should last the life of a motor and fry the power head because they didn't think it was necessary to replace it every few years. Throw in those that don't even know what decarbing a motor is, much less do it every 50 hours and you have your answer.

10- 15% are probably because of manufactor design problems, the rest are because of the idiots (I guess you could say the unknowing) operating them.

[frogtog]

My break-in procedure, Start motor, let idle for ten minutes, point boat up river and WOT for about 50 miles. If it holds up then you have a good motor. Caution: this method is not for the weak at heart or wallet

[Way2slow]

My Break-procedure on a powerhead that is bored and installed new pistons.

Two hours in the tank at 2,000 rpm on 40:1 gas/oil ratio.

One hour on lake varying between 3,000 and 3,500 rpm, trying to never stop so heat stays in motor.

One hour varying between 3,500 and 4,500 rpm, again, not stopping so heat stays in motor.

One hour cruising at 4,500 and kicking it up to 5,500 for short 15 - 20 second burst, extended those to 30 - 45 second burst toward end.

One hour at 4,500 - 5,000 kicking it to WOT for 15 - 20 second burst and extending those to 30 - 45 seconds toward end of hour.

For the next four hours, I pretty much cruise at 5,000 or so rpm and start making short WOT runs and gradually extending those to a couple of miles at the time.

After I get 10 hours, I run it pretty much how I please, at WOT for as long as I please.

During the break-in I'm doing plug and piston checks dozens of times to make sure my mixtures are right. Especially everytime I take it to a higher RPM. I also run EGT's in my motors so I'm constantly monitoring those.

If it's a motor I have plenty of piston clearance and primarly just replaced the rings, I take it easy for the first hour, working into WOT runs toward the end and then run the crap out of it.

[South FLA]

Cool link on keeping you existing motor running well

http://www.themarinedoctor.com/decarb.htm