Silicone over grate bolts

[njmr2fan]

I went under the boat today (I don't know why, as I told my wife) But while I was under there I saw that the silicone I replaced in the bolt holes for the intake grate are clean gone. What would be a better choice of Sealant that will stay in there? I can't belive it's all gone. Clean!

 

[Murf'n'surf]

RTV silicone would hold better.

 

[Scottintexas]

unless it's giving you problems I wouldn't worry about it,

 

[njmr2fan]

There are no problems at all. I just thought if they were sealed and smooth from the factory I should probably keep them that way.

 

[Murf'n'surf]

Silicone won't stick to silicone so you'll need to clean off the old stuff really well if you want it to stick.

 

[njmr2fan]

There is no silicone left. Everything is CLEAN, I may need to only wipe out the area with some acetone or alcohol.

 

[dansshin]

Do I need to check this on mine? What is grate bolts?

 

[njmr2fan]

The intake grate is bolted to the bottom of the hull. All the bolts holding it on are usually covered in silicone and smoothed over so there is no disturbance to the water entering the impeller.

this isnt the best photo but you can see that one bolt is under silicone and the rest are uncovered already.

 

[dansshin]

So it comes from factory covered with silicone? I never even knew this would even make a difference. I'll have to check mine to see what it looks like.

 

[dansshin]

Just looked on mine and on passenger side it looks fine except the two bolts in the center and some peeling but on driver side few have silicone missing. So you are saying all 8 bolts need to be covered with silicone? What issue would this cause when silicone is gone?

 

[Scottintexas]

@dansshin the thought is that the water flow into the intake needs to be smooth, if it is disrupted it causes turbulence/air bubbles and the pump doesn't get loaded with water evenly causing cavitation, the facts of how much disturbance causes a problem is debatable,

my opinion is it's either to look nice or to seal to prevent water penetrating around the bolts. most of the bolts are after the intake so any disturbance would be minimal to the intake,

If you not experiencing any issues I wouldn't worry about it, if you notice a lack of power vs rpms it would be a place to look at,

 

[dansshin]

My throttle on the right side seems to be little off, not sure if it's related to this. I have to push that little further than one on the left. Also right one seems to slip backwards after I let go where as the left one seems to be stay in place. Putting silicone on there seems to be simple enough so I'll try that.

Just from visual perspective peeling coating seems to be more alarming. I noticed @njmr2fan grate has some peeling as well as my passenger side grate unit. That's not an issue?

 

[tdonoughue]

@dansshin , sorry, but those will be unrelated issues. The mismatch between the throttles is an adjustment you make in the engine compartment (there is a thread around here that has a video and everything on the fix--it is an easy one). The falling throttle is a different issue--more complex to fix. Also a thread on here on that throttle drop. Neither will be affected by the silicone on the outside of the boat.

I think about 1/3 of mine still have the silicone on them. I have noticed no ill-effects. And peeling? I think about 1/3 of the coating is off of my grates. Again, no ill effect.

 

[tdonoughue]

https://jetboaters.net/threads/dual-motor-rpm-differences.3533/#post-59113 is the one on matching the throttle RPM...

 

[tdonoughue]

The throttle drop thread: https://jetboaters.net/threads/throttle-dropping-check-here.299/

 

[dansshin]

@tdonoughue I've seen that video. I noticed difference between the two on mine varies from time to time although right one falling back seems to be consistent. Do you still think is caused by that adjustment being off?

 

[dansshin]

@tdonoughue Thank you for the information and link to these threads!

 

[tdonoughue]

Probably so. Mine drops as well, but not enough for me to go through all of that to fix it. I also think my throttles are off a bit, but again not enough that it has bugged me enough to go tweak them. But whatever difference it is is fixed--it does not vary on mine.

 

[dansshin]

Yeah, so I've noticed that to get the rpm gauge to be at the same reading sometimes both throttle feels like it's in approximately the same forward position and last time I was out I notice I had to push the right one bit further than left for same RPM. It's possible that whatever is causing the adjustment to be off has caused the right one to be off bit further now, I'm not sure.

 

[Ronnie]

All of my (4) jet boats I bought used, none came with those bolts covered in silicone and all worked perfectly as far as I can tell. The same is true of the many pwcs I've had and some were purchased new.

I don't think you are preventing any important water flow by putting silicone on any bolts behind the intake opening and if the remaining bolts are seated correctly putting silicone over them won't make any appreciable difference in performance. It would not be worth the effort too me anyway.