Tighten the pylon on Prostar

[LoopSki]

My pylon on my 2017 Prostar is noticeably loose and moves and alot. What tools do I need and how to tighten it up? I noticed that there are two lug nuts on each bolt. I got nowhere with a crescent wrench

[skihacker]

I believe they're 19mm or 3/4 inch, all 4 are double nuts locked together, loosen the outer ones and tighten the inner ones with an open end wrench then re tighten the outer, mine still creaks a little when a bigger skier is back there tho.

[loeweb]

@skihacker Any clue when they went to a double nut setup?

[skihacker]

No idea, mime is an 18, the first year i had it it started creaking and I've been snugging the hardware once a year ever since.

[loeweb]

my '88 has one nut, so we've got it narrowed down to 30 years!

[Horton]

You need a 3/4" deep socket with an assortment of extensions. Back off the four outer nuts just a little bit then CRANK the four inner nuts and then retighten the outer nuts. You will have to temporarily remove the blower motor. Just set it aside and then put it back on when you're tightening the outer nuts.

 

 

[Kelvin]

My neighbor's 15 Prostar had loose bolts on the plate attached to the bottom of the boat. We had to completely remove the pylon and the aluminum bracket just under the floor to get to these loose bolts. Fairly involved process to tighten the pylon.

[LoopSki]

Got the two top ones done , having a beer break than attempting the bottom ones. Dont have the proper extension . I am really surprised how loose they were. The nut holding on the blower was hand tight.

[blagrata]

My 18's pylon was a little loose.... mainly creaking. The dealership had to replace some grommet or seal that they said shrunk after manufacturing (maybe over winter). I can't remember the details though...it did fix the creaking

[LoopSki]

Mine is creaking too

[LoopSki]

Pylon is good now but the blower is twice as loud now. Wtf?

[Horton]

@LoopSki not recommended by MasterCraft but just disconnect it.

[Broussard]

People actually run that air intake blower? :o

[RichardDoane]

There’s a bracket at the base of the pylon that has bolts going up through a tracking fin with 9/16 nuts. You need to get under the boat and hold the counter sunk heads with an Allen wrench. That way when they are tight and the two u-bolts are tight it will not creak.

[bishop8950]

Yes, check the bracket @RichardDoane points out. If the pylon is really loose, that could be the problem.

[RichardDoane]

It’s best to loosen the jam nuts and the u bolts, then tighten the base bolts through the tracking fin, and then tighten the u bolts last. The blower fan is important for combustion air and venting and though noisy is important. Especially in hot temps and at altitude.

[DW]

@loopski - did you tighten the blower more than previous? If yes, that created a noise path or amplifier as the blower vibrations simply act like a tuning fork. Loosen slightly or go with nyloc nuts so they don't fall off when you leave them slightly loose. Also, you could add a rubber washer between motor and mounting surface. One thing about a noisy blower, you don't forget to turn it off...

[Broussard]

@DW That motor runs when the entire time the engine is on to bring air from the bow scoop into the engine box.

[ScottScott]

I have it from a very reliable source that the blower in reference was put in as they found a slight loss of horsepower with warm air temps pulled into intake. In most cases its not an issue as it's a very slight loss that would likely only be noticeable at high altitudes, and rare other situations. Our 5.7 does fine without, even with some shorter setups.....in Florida. Maybe a bigger/short line skier would notice with/without.....maybe. the context I was told suggested to me that it would be in just the most demanding situations it could make a difference.

[Broussard]

@ScottScott Correct. I drove the prototype boat which was a 2014 ProStar with a 6.2 liter engine. The boat actually had an intake fan which drew air from the front scoop and pumped it into the engine box. It actually had another blower in the rear to expel hot air from the engine box out through the center cupholder. These were put in to increase performance by cycling fresh cool air into the engine box during summer. Turns out running higher octane fuel also did the trick.

 

These principles have been incorporated into the redesigned engine box for the 2021 ProStar.

 

Beginning in 2015 the factory began installing intake blowers and removed the center cupholder replacing it with a vent.

[skimtb]

2021 engine box is smart.

[LoopSki]

Pylon keeps coming loose. Have tightened it twice now , will be a third time today. Figured out the loud blower. Just moved it a bit. What keeps causing it to come loose? My kids tube alot. Thinking thats doing it.

[Broussard]

Tubing puts a lot of stress on tow points. What's your address? I'll mail you a box cutter. Should solve your issue.

[LoopSki]

I know tubing sucks but at least I get some of the kids out on the water. My kids friends that go to school with are not used to lake life and water skiing and such so to get them out is pretty much the only way with the tube

[blagrata]

@LoopSki Do you have the grab/tow bar on the back? That's where I tow a tube from. I had to get one of those ropes that has the big inflatable egg halfway back to keep the rope out of the water... but otherwise the tow point works great.

[ALPJr]

Pulling a tube should not loosen a properly installed pylon.

[keithh2oskier]

@LoopSki seems your boat is defective. I'll swap you for my 196. I pulled the kids on a tube last night and my pylon is tight.