Dropping RPM/Supercharger Clutch

[Faith Johnson]

Okay, so I have noticed that after about 30 minutes or so of driving the boat, the RPMs fluctuate between 6k and 7k. Speed drops by 15 mph. Spark plugs are good, oil is NOT overfilled, it's at the first tick on the stick. Could it be the supercharger clutch? If so, how do I know? If so, I need some guidance on how to change this bad boy. The shop is out a month on repairs. This forum has never steered me wrong. Feel free to state out of space claims. I just want an open discussion so no one else has to deal with this. I will admit, I have jumped some waves and heard the cry of the engine, a few too many times.

 

[Neutron]

Okay, so I have noticed that after about 30 minutes or so of driving the boat, the RPMs fluctuate between 6k and 7k. Speed drops by 15 mph. Spark plugs are good, oil is NOT overfilled, it's at the first tick on the stick. Could it be the supercharger clutch? If so, how do I know? If so, I need some guidance on how to change this bad boy. The shop is out a month on repairs. This forum has never steered me wrong. Feel free to state out of space claims. I just want an open discussion so no one else has to deal with this. I will admit, I have jumped some waves and heard the cry of the engine, a few too many times.

Usually when a S/C clutch goes you wont get that boat much over 20mph. And it doesn't fluctuate. My guess that its in the pump area.
When a cluch fails you can check by removing the intake boot and check with your fingers(not running lol) it should only spin freely one way and lock the other way. When the cluch goes it will spin both ways.
Put a blow off valve to prolong the cluch life anyway. With a new clutch or the current one

 

[Faith Johnson]

When you say pump area, can you elaborate? I just changed the impeller and the sleeve and still cavitate for about 5-10 seconds. Could it be related? I’m about ready to trade this thing in lol

 

[Neutron]

When you say pump area, can you elaborate? I just changed the impeller and the sleeve and still cavitate for about 5-10 seconds. Could it be related? I’m about ready to trade this thing in lol

Yes it definitely could be related

 

[TeenGee]

If your clean-out port fills with water, the cavitation could be caused by air getting sucked past the plug and into the pump. Check out this thread:

https://jetboaters.net/threads/another-clean-out-plug-thread.43036/

 

[David Martin]

Like everyone else says eliminate any possible just pump problem/cavitation only then move on to clutch test hear is a good video in the fairly straight forward test
Bing Videos

 

[Neutron]

Like everyone else says eliminate any possible just pump problem/cavitation only then move on to clutch test hear is a good video in the fairly straight forward test
Bing Videos

Not even close to what he is working on. Seedoodoos S/C are stuffed in the back. His is right in front when you open the engine compartment. Two hose clamps and it pops off and you feel if the fins move both ways or not. 10 min check

 

[FSH 210 Sport]

Okay, so I have noticed that after about 30 minutes or so of driving the boat, the RPMs fluctuate between 6k and 7k. Speed drops by 15 mph. Spark plugs are good, oil is NOT overfilled, it's at the first tick on the stick. Could it be the supercharger clutch? If so, how do I know? If so, I need some guidance on how to change this bad boy. The shop is out a month on repairs. This forum has never steered me wrong. Feel free to state out of space claims. I just want an open discussion so no one else has to deal with this. I will admit, I have jumped some waves and heard the cry of the engine, a few too many times.

First thing to check is the clean out plug seal. Your boat is four years old now and if you have been boating in salt water, not been removing and dressing the plug seal the seal could definitely be suspected for cavitation.

One of the salt water 210 FSH owners here a couple years back was having cavitation issues, he pulled his plugs religiously but due to the bimini laying on the stern area he’d just reach in and remove the plug, and hadn’t looked at them in a while. I asked him how the clean out plug seals looked and he pulled them and they were shot, he replaced them and no more issues.