Think i blew the 250 xs up

[harrells]

Up date. A locked up gearcase, this is #5 in three years. First one to lock up while haulin ass. Got a new one on order. Just relieved it wasn't the air pump. Looks like it over heated sucked in the drive shaft seal, spun the carrier bearing and trashed the gearcase housing. Can't figure out why, because I just changed the gearlube less than 10 hours ago with merc racing lube and made sure I drained at least 2oz. out after filling. I don't run it as high as most allisons, it's about 1/4 in. below pad. Do I need to drain more than 2oz? Now who here can turn my new 3.0L non-ratcheting gearcase into a ratcheting gearcase, or do I have to get a modified 2.5 L gearcase. I am not liking how the boat reacts when the prop stops spinning at high speed. It's a good thing my wife wasn't with me when it happened, she probably would never ride in it again.

 

[GotMyAlly]

Man, you have even worse luck with gearcases than Duane.

I didn't know that was possible..........

 

[robo]

Damn!

 

[Dave Hensley]

I think I would look into the oil expansion tank. Check Todd Defillips. He is the guru on the 3.0 liter stuff. Post here as ToddD.

 

[champ198]

Ha! We're tied. I've hit objects twice knocking skegs off and bending prop shafts and grenaded the sporties the other times due to seal failures. One lower locked up during a night tournament when I was hauling a 6lb bass back to weigh in where I would have won big fish. I thought I'd hit something massive as the lower locked and shut the engine down.

Water easily gets in the sportmasters if you run them hard for long distances on these Allisons where you're at least 1/2" above pad or more. They get hot, oil and air expand, and then cool. Could overfilling be the culprit? Possibly as the instructions for filling say to fill to the vent but that's always too much. Jeffro his dad, Neal, and Todd helped me at the Clifton rally save my current lower because it had clear water running out of it and we replaced the shift shaft seal at the rally before I put in.

 

[Jr in Jax]

Has to be something 3 litre related since I regularly run my sportmaster 3/8" above for 50-60 miles at a time above 6K. I have lost several drive shafts due to rust and have a speedisleeve on my current one. I do have my Sporty resealed almost every year.

 

[GotMyAlly]

The 2.5 sportmaster has a vent. The 3.0 does not. If the fluid expands beyond the capacity of the case, it pushes out seals.

 

[Dave Hensley]

Todd Defillips expansion mod. Him and Chaz have it figured out.

 

[Jr in Jax]

The 2.5 sportmaster has a vent. The 3.0 does not. If the fluid expands beyond the capacity of the case, it pushes out seals.

Thanks much, I was not aware of what everyone was talking about. It would seem that Merc would make a blind gas pocket somewhere in the top of the gearcase to cushion fluid expansion. Could exhaust gas be heating the internals/lube up also?

 

[harrells]

Dave, Thank's for the heads up. Talked to Todd Dephillips today, i'm gonna pull all the merc seals out of the new case, and he is sending me the billet seal kits for the drive shaft and the shift shaft. What a great guy to talk to and deal with. I would highly recommend anyone with a 3.0l sporty to do the same. His web site is www.wickedpowerboats.com.

 

[Dave Hensley]

Yep. Todd and Chaz are elite Merc gurus.

 

[SLOmofo]

Have done that. Gary the only problem I see with that in a lake motor that sees prolonged runs at higher temps is that if you don't have a tight fit between the cast sleeve and the aluminum block register it doesn't cool very well. Guessing there are chemicals and compounds that might be used to fill in but the glue the factory has been using, Loctite retaining compound, isn't the answer. My research is not scientific. I could be wrong. I have just seen the before and after several times.

F'ing bean counters. GLUE!?!?! Unless the glue compound is very conductive for heat, thats just dumb in my book. Just as dumb to not have enough interference fit. Yes I have pinned a sleeve on an engine of mine.

 

[SLOmofo]

I to have a junk merc sportsmaster that puked all the oil out and seized the input shaft bearings. This time it's getting a tube up to the cowl and a catch can.

 

[Dave Hensley]

Gary we have just seen the result of a company that was great at engineering and innovation lose it's patriarch and it's leadership. The almighty dollar is all that counts. Keeps us hot rodders busy trying to make their junk last.

 

[harrells]

I'm Thinking a class action law suit is in order if I have to replace another gearcase. This is really pissin me off!!!

 

[Tim Powell]

My service manual calls for 28 oz. My sport master held 38 oz until it came out of the vent. Ive always let 2-3 oz drain out to keep the seals from pushing out.

Now days instead of wasting the oil, since I know this case holds 38 oz, I just pump a bottle (32 oz) of lube in and call it good. I also crack the vent to release the pressure after the first couple trips

No issues so far and I run 100 miles round trip almost every weekend from April to Oct.