OPTIMAX GURUS...

[Broadhead100]

2005 Optimax 150XL. SERIAL# 1B105337

As some of you guys know I'm a fairly recent first time Optimax owner.. learning alot and trying to educate myself on the in and outside of these engines..

Looking for opinions on my current setup relative to current prop on the boat.

Here's my issue... traded a glass boat for a crestliner 2050 sportfish with this engine on it so i could fish bigger water... unbeknownst to me at the time I didnt realize this boat/motor combo wasnt coming close to peaking the RPMS. In fact as I have learned it is coming up pretty short.. WOT puts me right at or just under 5k at about 42 mph (gps) fully trimmed up.. in fact to the point where I start losing bite..the cavitation plate seems good... not running under water.. . logic suggested I'm simply over propped???

Current prop is a 14x19p aluminum and unsure of the brand.. was thinking perhaps I could simply find a 14x17 and increase rpms by 3 or 400 and call it good.. conundrum is I cant find that size and all prop calculators tell me I should be running a 15x17 which seems a bit counter intuitive to me... in theory a 15x17 will be pretty dang close to a 14x19 regarding rpm gains??? I see it as a wash...

Any thoughts? Should my opti 150 be turning the 14x19 at higher rpms? And am I correct assume at 15x17 will yield similar rpms??

For what its worth... the boat loaded should be somewhere between 2600/2700 lbs on average.. and for all intents and purposes runs good with no issues... get on plane fairly quick with no issues...

Perhaps I'm not fully powered? Did recently do a plug change and old plugs all looked the same.. no indication of dropped cylinder etc... did these 2005 optics have coil issues or was it shortly after?

Could really use some good advice from you guys...

Thx

[Broadhead100]

Anybody have any thoughts?

[leonreno]

You definitely need less pitch, what is the max rpm rating for that motor? What brand/model prop is on there now?

Here is a link to a good forum to help pick a prop, they are good here too, especially in the prop section, but 90% of these guys run bass boats.
https://www.bandofboaters.com/forum/...mance-handling

[Broadhead100]

Max is 5750.. current prop is a 14x19p aluminum.. no idea on brand... would at the very least like to see this motor running 5500 WOT.. I'll check out the link... appreciate it

[Broadhead100]

Started looking into few things on this motor.. was going to check reeds with mirror... pulled of top cover and this is what I see... plenum is extremely dirty.. this cant be normal can it?? What would cause this?

[lpugh]

I would start with a 15 4 blade Solas and go from there, The intake looks fairly normal, but check the drive belt carefully, looks like it may be shedding some rubber

[Broadhead100]

Thx Lpugh... never considered a 4 blade.. I'm assuming 15 pitch?

As for the dirty plenum...I thought same thing but drive belt shows no signs of shedding... almost thinking it may be particles from the insulator pads inside the cowl.. anyrate.. I spent the afternoon cleaning it up.. I'll keep an eye on it.. on another note.. discovered some oil residue seeping out from under the flywheel now as well.. in addition when I pulled the belt for inspection I checked the compressor for slop or play of which there was none but when I cycle it through a full revolution by hand it makes an audible chirp or squeak sound as it builds and releases compression... not sure if it is supposed to do that either?? starting to think I should have passed on this one..

The motor only has 115 hrs on it..

[SilverFox579]

Have an as new 14.5 x 17 Black Max, purchased new from European Marine, with less than 30mins run time PM me if interested.

When rotating compressor pulley by hand, it should not be releasing compression, you should note compression build with each rotation and get harder to turn pulley by 3rd time. The squeak is probably the reeds opening on intake stroke. If you've ever rotated an oil lubed piston style air compressor by hand you'll know what I'm talking about.

[Broadhead100]

Have an as new 14.5 x 17 Black Max, purchased new from European Marine, with less than 30mins run time PM me if interested.

When rotating compressor pulley by hand, it should not be releasing compression, you should note compression build with each rotation and get harder to turn pulley by 3rd time. The squeak is probably the reeds opening on intake stroke. If you've ever rotated an oil lubed piston style air compressor by hand you'll know what I'm talking about.

Thx silverfox... makes perfect sense... again having little knowledge certainly raises questions on my end... right wrong or indifferent.. appreciate your response. Check your PMs.

[Broadhead100]

This should be it... again motor starts and runs fine.. with cowling on at idle u can barely heat it.. much more evident with cowl off on hose in driveway.. everything is solid and tight.. no lash or play in the assembly..

[Broadhead100]

Don have u heard this noise coming from any opti compressors??

[EuropeanAM]

There is a distinct sound make by an Optimax Air Compressor that is not present on non-Optimax engines. Keep in mind that diagnosing "sounds" by keyboard and monitor is really not a good method.

[Broadhead100]

There is a distinct sound make by an Optimax Air Compressor that is not present on non-Optimax engines. Keep in mind that diagnosing "sounds" by keyboard and monitor is really not a good method.

Yea I get that... just didnt know if the distinct sound is obvious and easily identified as such..

More curiosity on my end as I learn this engine.. finding out they are pretty neat in design and function.

You have any thoughts on my rpms being so low relative to current prop on my boat?

Appreciate u chiming in here..

[EuropeanAM]

Don't put thought into the diameter of the prop- focus on the PITCH. I would agree that 19P is a bit steep for your rig, probably need to drop back to a 17 pitch (which will be a larger diameter than the 19's are).

Need to get that engine up in the 5500+ range at WOT for best results and longevity.

[Broadhead100]

Don't put thought into the diameter of the prop- focus on the PITCH. I would agree that 19P is a bit steep for your rig, probably need to drop back to a 17 pitch (which will be a larger diameter than the 19's are).

Need to get that engine up in the 5500+ range at WOT for best results and longevity.

That's exactly my thinking... thank you very much!

[SilverFox579]

Check your PMs.

Responded. Don makes a very good point about diagnosing noise by keyboard...yours sounds a lot different than mine but I've never had a reason to crank mine with cowl off.

[Broadhead100]

Hey Phil or Don... so either of you guys know off hand the torque spec on the flywheel nut on this motor? On anybody else?

[SilverFox579]

125ft lbs per my manual.

[Broadhead100]

Awesome... thx Phil... I need to get a manual

[SilverFox579]

Call or email Rhonda with engine serial number and she'll set you up.

If you want to order or price Mercury Engine Parts or Accessories