1BO27977 150 optimax. Exhaust tuner?

[Shuck Grass]

What are the symptoms of a broken exhaust tuner? I hear rattling when WOT and have a hard time getting on plane.

[aussiejake]

Rich at low rpm to the point of fouling plugs.
Noisier than normal when on the plane....but you tend to get used to the noise.
You can sometimes hear the tuner hit the inside of the leg when you tilt the motor up for transport
Best check is remove the leg and look up inside with a flashlight to see if the tuner has fallen off.

[leonreno]

Your symptoms seem about right for a loose tuner, but could be other things too. But it’s a fairly easy check as stated above.

[JOE54]

some you can just shake mtr back and forth and they rattle clunk

[EuropeanAM]

All good info above. Removing gearcase and reaching up into the midsection with a long screwdriver is probably the most reliable check at your disposal.

[Shuck Grass]

What would replacement of exhaust tuner cost and what else should I check or have changed while this is getting fixed?

[leonreno]

Usually you can reuse the tuner you have, it’s the nuts that come loose, only difficulty is the power head has to come off, that’s where the main expense is.

[Shuck Grass]

I have been trying to find a video of the tuner being replaced. I have found nothing. Also, is there a better fastening system then what was done in 05? Thanks again for the replies.

[JOE54]

pull gearcase /powerhead ,disassemble exh housing,you can install loc wire in nut , double nut without nylon lock nuts(homemade locnuts) ,marring threads on studs and nuts ,_vise grip work good

[EuropeanAM]

I have been trying to find a video of the tuner being replaced. I have found nothing. Also, is there a better fastening system then what was done in 05? Thanks again for the replies.

+1 to Joe's comments, above.

Later models (and replacement tuners) use flange BOLTS rather than nylock nuts. I have to say that nylock nut thing is perhaps one of the silliest engineering "oops" I've seen in years.

I also like to utilize the GASKET for the tuner which was found in earlier-model EFI and CARB 2.5L models. To date... haven't had one fall off a second time when using "real" hardware and the gasket (combined with red liquid loctite).

NOTE: Don't rely on "videos" for repair of your outboard. I can't tell you the number of times I've had to fix an engine that utilized a "tube" video in an attempt to self-repair. There are more of them with serious errors than there are "good" ones.

Utilize a FACTORY SERVICE MANUAL as your guide for repairs. Best investment you can make in your engine.

[JOE54]

+100 on RED ^^^^^^