300X thay are fast, rumor is they blow up

[Brad Zastrow]

I was real close to buying a multi-engine cat with four 300X's. I got cold feet after talking with guys and reading posts on OSO that these 300X's are blowing powerheads far too often. The one I was going to buy smoked 2 in testing. The old 300 Promax's are supposed to be very good. I have talked to at least 4 guys who own them and all love the power and all lost a motor or two or three. One guy even bragged they are fine after he blew one up after 2 hours, but now he has 40 hours on it. :eek:

Anyone?

[Vicious]

I know the old 300's I sold on the demo boat had 78 hard hours on them no problems, And the new owner has just over 230 hous acording to the ECU's he had reed's put in the motor's but thats it!! He is very happy with them.

[22VelocityProMax300]

Brad, I have just over 100hrs on my Pro max 300 and the only problem that I had was at about 8hrs I had a stator go out on me. Other than that the motor has been trouble free. I have wondered about one thing , I turn my motor to a max of 6200 with a merc chopper. The 300x turns higher at 6800 rpms, could this be part of their problem, maybe a 3.0 litre is on the border when they approach 7000. I am just tossing this out ,maybe its a coincidence. Frank

[Brad Zastrow]

The guys having problems seem to be the high RPM offshore stuff. But, I would think even the smaller boats would have the same problems. Or I am just talking to the few who have had problems??? Like I posted the "300" I have heard run forever with no problems. It is the "300X" I am hearing things about.

[BANJO]

I have 165hrs on my 300X and still running very strong. These motors rip, no complaints here.

[HERB]

I"m on my second power head but it has 150hrs and no problems.
My frist only lasted 40hrs. These motors have a lot of power.

[trbocharge]

The question that should be addressed is "why are they blowing up?"...........fuel delivery,ecu problems, design problems, part failure??????

Those who have experienced these failures please share your info on whyand what failed......

Thanks

[baja200merk]

wuts the dea?

[Scream And Fly]

Our experiences with them is that they are a reliable engine, but like any high-performance engine, there are going to be premature failures sometimes. This goes for the Pro Max 300 as well.

The 300X make serious power too - an impressive gain over the Pro Max 300.

Greg

[jerry]

jerry is gonna tell ya that if you put 4 of any motors a on the back of a cat , your gonna break **** big time . put 4 2.4s , 2.5s on a cat and they break . the 300x is a great motor but like every other outboard sometimes blow up unexplainably .
p.s you will go through gearcases like jerry goes through screen names !!!

[Dirk Pitt]

talk about a difference, I had pair of 300 promaxes, we made the switch to x's and wammo, picked up 16mph and I think theres more...............

[at100plus]

Dirk Pitt??? Isn't that Joe L's boat?

I love my PM 300 so far. I have about 90 hours on mine, not a single problem.

[300x Stoker]

If my understanding is correct, the computer stores lots of info. Someone should be able to tell us plenty. They warned us not to run up against the rev limiter. I wonder if that's what the offshore guys are doing who are having the trouble. I hope no one is trying to run them on cheap gas.

[ck1flyer]

I figure I have about 75 hours on my 300, it’s a 2000, ran only 2 summers. I have had no problems so far. Starts easy, idles nice, lots of power. I only run mine at 6,000 rpms, though.

-Craig

[scott reierson]

Brad,

You may already know this... but I read a post on OSO awhile back, that a 35 motion w/4-300 PM's barrel rolled. Just thought you might want to know. I think I saw the post about 2-3 months ago. Scott

[Liberator25]

I have a 24 foot Skater clone (Liberator) and run two 2003 Merc 330X motors. My props are 15x34 merc labbed 4 blades. The boat runs 112 mph @ 6500 rpms in 90 degree TX heat. Now that cool weather is here, I expect a little more. The motors now have 75 hours each and have not missed a beat. They start instantly, idle smoothly and suck gas like it's going out of style:D :D However, that's because I run them hard. Usually cruise between 5,000 and 6,000 rpm (6,000 is right at 100 mph). The motors like to run fast and they are pretty solid. Just my opinion:cool:

[Brad Zastrow]

This subject was brought up in a post on "Offshore Only" and guys were posting that they were blowing em up ( a lot). Here just the opposite. I wonder if it is the big water, bigger boat, wave jumping that is causing problems. Oh well, it spooked me big time.

[Liberator25]

Just a couple of thoughts. They are fully warranted for one year and extended warranty is offered. Should you take the plunge, this should offer you some comfort.

The X motors are a pretty well proven design, they are based on the PM 300 and then "tuned" with a little hand grinding on the exhaust chest and a few other tweaks to get them up to 330 HP. Each one is run on a dyno before they leave the factory and while bad things can happen, and do, this is a product that Mercury has a lot at stake in and has done everything reasonable to ensure they are reliable. The X's are a more reliable package than the 2.5's due to them bringing the power on at a much lower rpm. All said, I bought mine with complete confidence.

[gggforce34]

100 hrs still running strong. major destgn flaw. Your 300x will injest its belt if it breaks at WOT. Merc pulled 18'' out of the reed cage of my buddies 02 300x. The belt caused the motor to blow. Also the belt cuts a groove in the shroud when the r's are spooled up. this causes small particles of plastic and belt to be injested by the motor. Remember the intake on the plenum is on top of the motor in direct line with the belt. I think this is why the 300x blows up. gggforce...

[JOSEPH SHULMAN]

We have two in one season, confirmation!!!!

[Viper GTs]

Brad, I ran mine for 5 years...HARD...1 alternator and belt and thats it!!! Al

[Superbender]

7yr old post, they're all no good buy them, give me your old 300x install verados and you will be good to go:D

[Liberator25]

I Now have 300 hours on both motors (300X) and have had the following experience. They run a little less strong than when new ... top speed is down to 105. Over the years I have lost both lower units and left motor powerhead. Serious $$ each time ($5K for each lower and $8K for the powerhead). However, I used to run a 383 Chevy stroker with a 125 shot of nitrous and I popped 3 outdrives ($10K per) in one year!!! Outboards in general are more reliable in a high performance application. I haven't been freaked out by the reliability, actually I consider it pretty good for a go fast boat that is operated near the top of the performance envelope most of the time. Gentle use would make these motors last MUCH longer, but hey, that's not why I bought 'em. Verado's are interesting, but HEAVY. I'm still happy with my motors ... 7 years later.:cool:

[JamesGang]

I have 4 of them. Best engines I've ever owned. Wish you could still buy them new. Who cares about gas mileage, they push unbelievable.

[Skatin]

I Love my pm 300's not X's. No problems at all.

[mikesufka]

Not sure if anyone cares, but I really like my 300XS's that I bought this spring. Fuel economy is incredible and I picked up a few miles an hour. This is after owning a pair of 300 Promax's. Same boat. 30 foot Spectre.

MDS

[river rocket]

I have a 300x with 384hrs and still going strong. No issues to date.

[WILDMAN]

You ready for a new 30 Liberator yet?



I Now have 300 hours on both motors (300X) and have had the following experience. They run a little less strong than when new ... top speed is down to 105. Over the years I have lost both lower units and left motor powerhead. Serious $$ each time ($5K for each lower and $8K for the powerhead). However, I used to run a 383 Chevy stroker with a 125 shot of nitrous and I popped 3 outdrives ($10K per) in one year!!! Outboards in general are more reliable in a high performance application. I haven't been freaked out by the reliability, actually I consider it pretty good for a go fast boat that is operated near the top of the performance envelope most of the time. Gentle use would make these motors last MUCH longer, but hey, that's not why I bought 'em. Verado's are interesting, but HEAVY. I'm still happy with my motors ... 7 years later.:cool:

[Ospreyproduction]

They all blow up! I've blown 300x's and 300 pro max's.

[JamesGang]

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> Hey Wildman

I’m trying to figure out if you’re a hell of a salesman, have a stutter, both, or is that a new sales technique that works in an off economy?

[WILDMAN]

Nope, just an old customer that I talked to a while back. If you noticed, he has a 25 Liberator now.

[at100plus]

I had zero problems with my 98 PM300, best motor I ever had. If I can find one of that vintage I may put one on my current boat soon.

[Stoker1]

System glitch. Happens a bit.

[Liberator25]

You ready for a new 30 Liberator yet?

Long time between posts, been doing lots of other things. I recently got my Private Pilots License and while I haven't forgotten boating, flying is VERY COOL!! My current plan is to get an airplane next year ... not a bigger boat. But you never know, things can change. I still haven't been outrun ... of course that's just a function of $$. If the right guy decides to spend the right amount, I'll be number 2 but only for a short while ... then it's off to see Chuck Goodman and his magic Nitrous Systems ... never did learn my lesson about that:eek: ... I understand he's fixed the GET HOT AND SIEZE problem when you turn off the juice. Only if needed.:D

[JamesGang]

Just kidden with ya. This morning when I saw your post it had the same thing 3 times in a row.


Nope, just an old customer that I talked to a while back. If you noticed, he has a 25 Liberator now.

[hydrostream1]

I have 300 plus hours on my 300pm,tough motor.Run good fuel,fuel separator filter like racor.Prop it on the high side.I`m building an x motor now,the sportmaster lower needs the 3 seal top plate and double shiftshaft seals to prevent water from getting in,thats one reason why alot of the lowers fail.

[parkerkyb]

I have 130 hrs on 300 x and no problems.

[Liberator25]

I Love my pm 300's not X's. No problems at all.

I've thought about the trips route once or twice, but never pulled the trigger.

How fast does your boat run and how much of that do you attribute to the third motor?

My boat used to run 112, but with hours it's now down now to 105 (slowing down like I am:D).

I am guessing here mind you, but I'm thinking that a third motor on my boat should put me in the 120 to 130 range. Does that sound about right to you?

I'll bet that boat of yours gets a lot of attention ... any self respecting gear head would have to be very interested and probably would talk your ear off ...

[Skatin]

I love having trips but don't do it if you are just looking for speed. You can get an easy 5-10 mph but you get there a s*&t load faster. I mainly did it for looks and just because you don't see any like it. I got it to 123-125 but it has more in it with setup and tuning. I need new props but I just don't have the money right now!! Stock market Bull**** and Obama care are painting a muddy future right now so I'm holding back on everything till there is light at the end of the tunnel. Till then I will just enjoy the boat as it is!!

[Liberator25]

I see you have the cover off the center motor so the steering yoke bolts are visible ... the covers are on the two outers so the bolts aren't visible. I had my two covers on and couldn't see my bolts and at about 100 I felt the back end wiggle a little. That was a new sensation for me and it made me put the boat back on the lift and shake everything down ... I couldn't find anything that "felt" loose, so back to the lake I go. I had a boat full of guys and at about 80 or so (we were on our way to a long straight section where I could air it out) when the boat suddenly turned hard left. Threw the guy in the right rear seat out, slid the left rear seat guy hard to the right and the left front seat guy wound up in my lap. I have never seen or felt a turn that hard ... it was unbelieveable. Still didn't know what had happened at this point. Fished my buddy out, and while we checking all our parts, I leaned on the steering wheel and the right motor moved but the left one did not. It had sheared off the last of two remaining bolts (the other 4 had worked their way out over time and were nowhere to be found). When the left motor broke free of the steering yoke, it did what it wants to do ... turn hard left ... that's when all hell broke loose. I share this with you because my covers are OFF and stay OFF ... I check those 6 bolts on both motors EVERYTIME. It is a miracle that it didn't flip and throw all of us out, but that was some incredible hook. Here's a pic to illustrate:eek:
222771

[Skatin]

Ouch that doesn't sound fun at all. Glad nobody was hurt. I have the cover on now. That pic was taken while I was still in the process of installing everything. I generally locktite everything but I will check them to make sure.

[Still Crazy]

I see you have the cover off the center motor so the steering yoke bolts are visible ... the covers are on the two outers so the bolts aren't visible. I had my two covers on and couldn't see my bolts and at about 100 I felt the back end wiggle a little. That was a new sensation for me and it made me put the boat back on the lift and shake everything down ... I couldn't find anything that "felt" loose, so back to the lake I go. I had a boat full of guys and at about 80 or so (we were on our way to a long straight section where I could air it out) when the boat suddenly turned hard left. Threw the guy in the right rear seat out, slid the left rear seat guy hard to the right and the left front seat guy wound up in my lap. I have never seen or felt a turn that hard ... it was unbelieveable. Still didn't know what had happened at this point. Fished my buddy out, and while we checking all our parts, I leaned on the steering wheel and the right motor moved but the left one did not. It had sheared off the last of two remaining bolts (the other 4 had worked their way out over time and were nowhere to be found). When the left motor broke free of the steering yoke, it did what it wants to do ... turn hard left ... that's when all hell broke loose. I share this with you because my covers are OFF and stay OFF ... I check those 6 bolts on both motors EVERYTIME. It is a miracle that it didn't flip and throw all of us out, but that was some incredible hook. Here's a pic to illustrate:eek:
222771

I also run without the skirt:iagree:. Every couple of times I go out, I tighten every mount, jackplate and steering bolt. Also beware of that rubber air horn on the throttle body. I had it migrate up the TB and jam the butterfly open at WOT. Had to kill the engine with the lanyard or hit a dam. Talk about a hook!

[Liberator25]

Hey Wildman ... I still run the boat now and then, but my new "thing" is airplanes. I just bought a Piper Dakota that was stripped to bare metal and rebuilt. Love that flying thing ... learning to fly was like going back to college ... lots of $$ and time, but well worth it. My toys are growing but I still like the old ones ;-). Everytime I run my boat I get this wonderful smile on my face. 100 MPH is the holy grail of go fast boats and CATS are the only way to get there safely ... IMHO.

Gotta love this stuff.

-
0

[lowlifeAE21]

On my 21 skater I had a 300x that had 430hrs and still pushed the boat to 104mph with a 30p performance prop, since then the boat has switch hands twice and still no issues and motor must have more then 500hrs!!!

[Liberator25]

I running 15x34 labbed cleavers that I bought off an off shore racing team that had about 30 sets of props ... I also have a set of 32's but they never seemed as fast. I know the 34's are keeping me off the rev limiter ... never thought about 30's. I wonder what most guys with 25 lib's run with the 300X motors?

[WILDMAN]

I'm rigging one now with 300xs's and 34x15 cleavers.

[Liberator25]

I'm rigging one now with 300xs's and 34x15 cleavers.

Guess I'll just stick with the 34's. Still love the boat ... hasn't been outrun yet, but that's probably because the guy with the right amount of money just hasn't decided to outrun me ... of course that would result in reaction (Chuck Goodman or trips or repower with a turbine ... he yaw!!!! ... havin fun now). Wife still is recovering from buying the plane, so I hope nobody outruns me anytime soon.

;-)

[tom kennedy]

Hello has anyone taken 300pms an put on svs system?? vs getting 300x motors . any coments would be good thx guys

[tom kennedy]

An no i not looking for 300x the soopms are working great

[tom kennedy]

300 pms

[Toffen]

Hi!

I did add a SVS and modified the ECU on a PM 300 some years back. I think I gained 1-2 mph, but accelleration was far better.

Cheeers, Toffen