Hey guys,

I am stumped on a problem with the ol' tub and am hoping you can help me out. The boat is a 1994 Mirage 217 Intruder with a 7.4 and a Bravo 1. I am all but certain that this is the 330 HP 7.4.

I finally got the boat out of storage this past weekend and encountered some trouble. The boat didn't really sound the same to me and, when taking off, I noticed it seemed to have less power out of the hole. Rather than the bow rising and settling down pretty quick, it took a little longer to nose-over. The boat was missing a bit at just off idle and seemed to be down on speed (it generally runs upper 60s mph and was running upper 50s on the speedo, not GPS), which I attribute to gas that is probably a little stale. I just changed the water/fuel separator and the plugs and nothing looked amiss. Anyway, the lake was really choppy and the boat had to have been airborne a couple times (I know, I know). After stopping and puttering around a bit, I went to take off again and the boat went nose high and was taking forever to get on plane, just as it was starting to get on plane, the engine hits 4000 RPM and free revs like it got kicked into neutral. I tried a few more times and, like clockwork, every time at 4000 RPMs it loses yank and free revs. Trim was set all the way down or up to about 3/4 the way down.

I figured I spun the hub in the prop, but I didn't. It has the plastic flo-torq adapter in an Apollo XHS 14.625x23, and the adapter looks like brand new. No signs of slippage internally or externally. Additionally, the bronze or brass splined input is also perfect. My only other thought was an engine coupler, but there was no burned rubber smell. The boat shifts perfectly with no odd noises and operates under its own power up to 4000, albeit a bit lazy on take off.

I am at a loss and have a trip planned in about a week. Any thoughts on where to look for my problem?

Thanks in advance for any insight you can offer!

Did you visually check that the outdrive is going all the way down ? It needs to or will usually cavitate the prop when planing.

No, I did not visually confirm, Just made sure the trim gauge reflected that the drive was all the way down. If the drive was up 1/4 of the way, would it cause the condition I am describing? I ask because I generally run wide open at all the way down to 1/4 of the way up (3/4 of the way down). I tried the drive in various positions according to the gauge on the helm, but maybe the drive wasn't responding. I can take it out this weekend and try again. It just seems like if it was the prop cavitating that it would happen sooner than when it was just coming on plane. It is odd that it is always at 4000 RPM.

The gauge is on the side of the drive. I would assume it is close to accurate. What about cone clutch slipping at 4k? Any different props to try? Might be interesting if it happens at different rpm with a different pitch.

Sounds like the clutch is slipping under load. Cold also be the cause of the speed loss as well. If there was a slight smell of rubber in the engine bay could also be the engine cupler going.

Thanks for the responses guys. There was no smell of burned rubber that I could detect. I am going to try a different prop when I get it back from the top shop this weekend. What all is involved in diagnosing and repairing a cone clutch problem? What other signs would point to it being the clutches?

If it's just starting to slip it could still shift fine but when you are trying to plain out its to much and that's when it lets go. Had it happen that way on my old 27 with a single 454. Then it stared to shift funny like it wasn't in gear then it would grab

I have never tried it but some one told me once to test it put it in gear then kill the motor. At that point put a socket wrench on the prop nut and try to turn it. If the shafts spins pretty easy then it's most likely bad. Don't know how true that is just what I was once told.

Okay, thank you for the advice. I will give it a try and see what happens.

​​​​​​​Clutches in outdrives do not slip. It engages the gears or it doesn't.