life expectancy of a rebuilt engine

danny9696

Petty Officer 2nd Class
Joined
Jan 4, 2009
Messages
111
Hi all I am getting ready to buy a 94 150XR6 but I just heard that a rebuilt engine life expectancy is only about five years and a the originals usually run forever if properly maintained I was wondering if this is true, I have a ski boat and we don?t run her wide open very often but we tow a four man tube with the kids quite a bit, I was wanting to upgrade from the force 125 to this merc 150 XR6 to get a little more power but I got a little nervous after hearing that rebuilds don?t last as long, can anyone shed some light on this for me

Thank you

Danny
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: life expectancy of a rebuilt engine

Your question depends entirely on the rebuilder or refurbisher. If properly done to stock specs, properly broken in to Merc specs and properly maintained thereafter you can get as much as 1000 hours out of them, (same as new). Years have nothing to do with engine life, it's measured in hours and environment (salt vs. fresh).

If... the engine is in good shape, the transformation will be dramatic. That's a great motor you're getting.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: life expectancy of a rebuilt engine

You ask a seriously tough question.

It ALL depends on the quality of work done.

A TOTAL rebuild, or just having a new set of rings thrown in it, or somewhere in-between.

A TOTAL rebuild is as good as a new engine, the rest are definitely of a lesser quality.

The mechanic that assembles, the machinists that set the machining up, and of course, the operator, all contribute to the length of an engine lifetime.

Any fool can destroy a perfect engine, then again, an imperfect engine can last a considerable time with very careful operation and minimal load.

The quality of a build, or even a rebuild varies with the mechanic, there is NO reason a rebuild motor cannot last a goodly number of years, just like a new motor.

Proper break-in procedure is critical, new or rebuilt.

The operator has ultimate responsibility for how the motor is used, or abused.

You pretty much nailed it when you stated "with proper maintenance" as NO motor can be expected to last long if it is not properly cared for.
 

danny9696

Petty Officer 2nd Class
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Jan 4, 2009
Messages
111
Re: life expectancy of a rebuilt engine

Thank you very much for the info, second part is: I was told to brake this engine in with 32:1 oil mix for a tank of fuel or 10 hours not to run over 4000 RPM and to vary RPM, not to idle to long or stay at any certain RPM to long, I was also told by someone else that if I run a 42:1 mix it would help the engine live longer, I live in a high elevation and I only get about 3-4 months in the summer to use our boat I figure we get out about 24 days weather allowing, and put about 5 hrs a day on, I use the green engine store in the winter and I fog the engine after our last time out and use an electric blanket on the engine all winter, gear lube start of every summer and new impeller I always lower the engine and keep her covered ad in the barn in the winter if I can do anything else please give me any info, I boat on a bear budget so I need this thing to last,

Thank you

Danny
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: life expectancy of a rebuilt engine

From the Merc service manual....

attachment.php
 

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Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: life expectancy of a rebuilt engine

I use an electric blanket on the engine

I dont suggest this as you can cause the engine to "sweat" under the cowling, better to leave it cold.

As to the life of a rebuild, a rebuild is boring all cylinders,new pistons and related items and will last as long as a "new" engine because it is "new". A repair is only fixing damages and re-ringing. Usually this will last several years till the stock spec's are exceeded and will need "rebuilt".
 

danny9696

Petty Officer 2nd Class
Joined
Jan 4, 2009
Messages
111
Re: life expectancy of a rebuilt engine

No more blanket, I don?t have oil injection on the 150XR6, will the 32:1 work for the brake in? The engine is a complete rebuild all mercury parts and all Machine work has been done to spec, cylinders bored over to get them back to round and all bearings replaced, form what everyone has told me should last me a long while, now if it would just quit snowing I may be in business
 

j_martin

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Sep 22, 2006
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7,474
Re: life expectancy of a rebuilt engine

I dont suggest this as you can cause the engine to "sweat" under the cowling, better to leave it cold.

As to the life of a rebuild, a rebuild is boring all cylinders,new pistons and related items and will last as long as a "new" engine because it is "new". A repair is only fixing damages and re-ringing. Usually this will last several years till the stock spec's are exceeded and will need "rebuilt".

I disagree. The reason an engine sweats is because ambient temp rises, including dew point, and when the dew point is warmer than the engine which is still cold, there will be some condensation. If the engine is kept even a few degrees above ambient, that's much less likely to happen. It sounds like your engine is well loved.

A rebuild will last from 30 seconds to 20 years, depending..........:D You knew that.

If the oil injection is still on the motor, then 50:1 in the fuel tank will give you from 40:1 - 25:1 operating. It would be between 30 and 40 most of the time. If the injection has been taken off, then mix between 32 and 40:1 for break in. Maybe one tank of 32, then go 40. Use a dino tcw3 oil for break in. After it's thoroughly broken in, you could go to a synth blend if you wish. I run an 88 XR4 that's never been split on pure synthetic and it does well, but I guess it's not recommended.

I run an ounce of oil per gas in the fuel tank for insurance, so it runs at about 35:1 at WOT, and probably about 60:1 at idle. Those are the only 2 throttle positions I use. I carry a quart of oil just in case the oil-alert alarm goes off.

just my 02
John
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: life expectancy of a rebuilt engine

I agree with John.. 35:1 is a good break in mix for the first 10gals. If you have a 20 gal tank you can start mixing at 50:1 from then on if you're above 3500 feet. I run 50:1 at SeaLevel which is fairly well recognized as the defacto standard for mixing fuel.

Some like to run at 45:1 or even 40:1 and that's fine but anything more than that after break-in and you can lean an engine out. I also like to run a couple of degrees less advance during breakin. I think it makes for better break in. That's just a personal thing and I don't have any facts to support it except that my motors are still running.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: life expectancy of a rebuilt engine

I would suggest that you change your gear lube BEFORE Winter, reasoning, IF you have a leaky seal and water inside the case then changing BEFORE it freezes can prevent a cracked case.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: life expectancy of a rebuilt engine

I would suggest that you change your gear lube BEFORE Winter, reasoning, IF you have a leaky seal and water inside the case then changing BEFORE it freezes can prevent a cracked case.

If I've had a low hours summer, I just pull a sample in the fall. If the bottom 1/10 oz is clear, it's all good.
 

danny9696

Petty Officer 2nd Class
Joined
Jan 4, 2009
Messages
111
Re: life expectancy of a rebuilt engine

You guys are great, I think I will take both of your advice, and sample after a low use summer and change it befor winter,

Thank you again

Danny
 
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