motor cavitating

[mark]

I have a 07 2530 with twin 150s. This summer I noticed that my port side engine would all of a sudden start to cavitate while running. It could be running fine for long periods of time (an hour or more) and all of a sudden the rpms start running up and down, probably 500 rpm or so. No real change in anything as far as people moving around or sea conditions. Checked the prop,all good, motors trimmed all the way down. I dont know if the motor could have an electrical issue causing this mabye but it sure sounds like it is cavitation. Thanks in advance for any ideas as to what could cause this.

 

[Bryan 2530]

I have the same boat with twin 200's.

This summer I had the same issue while running offshore and found that by moving my ice cooler to the port side the problem stopped. Weird though, same boat, same side, different coasts.

That was the only time it happened to me. My motors are on the bottom hole. Brad V raised his one hole with some good results. Maybe he could chime in.

Do you guys think a motor that is too low could cavitate? I would assume so. I also have three bladed props.

 

[BradV]

id check where your motors are mounted and see whats going on with that. i wouldnt imagine having them too low would cause them to cavitate. what were the sea conditions like? I know running in some big seas ill blow out. The only other thing could be you ran over something in the water. Or something else that has been mentioned on some of these boards is that if you have a thru hull transducer or anything obstructing that particular motor for whatever reason. Im trying out props this week on my boat so ill post them and let you know.

 

[Hard Core]

I have the exact same issue with my '07 2510XLD with twin 150's, always the port engine, and always triggered by rough seas.

I suspected my swim deck mounted 32g livewell, so I switched to the built in live well (also the same weight, but amidships), and the problem was dramatically reduced. I can't recall having this problem up in Oregon, but I didn't run the livewell too much.

After an exchange with Eric in Parker's engineering department, he asked me if any through hulls were inline with that engine. Yes, the factory mounted livewell/washdown through hull is right in line with it, all my other stuff is centerline.

I think the primary cause in my case is the bubble stream created off the bait pump through hull, I will confirm this in my next trip. Parker will hear about this if this is the case.

For the others experiencing this issue, do you have a simliar washdown install location?

Barnes

 

[Hard Core]

Photo of my bilge area facing aft.

 

[mark]

I would like to hear what you find out Hardcore. I talked to my mechanic when I had my motors serviced this winter and he talked me into re-hubbing my props. I dont know if it helped yet as the boat is stored away till spring but I was a little leary about that being the problem. As far as adding weight to the port side I have a 8 horse kicker mounted on that side of the bracket so if anything I might be to heavy on that side already.
I guess I will have to wait to see if anything has changed.

 

[Bryan 2530]

For the others experiencing this issue, do you have a simliar washdown install location?

Yes, thinking back, it seems to be a little better when the seacock is closed. I'll have to pay more attention this year.

 

[gw204]

I talked to my mechanic when I had my motors serviced this winter and he talked me into re-hubbing my props.

An easy way to tell if you're spinning a hub is to put some sort of mark on the prop shaft sleeve and the inner hub of the prop itself. Then run the boat (and run it hard) and check the orientation of the marks. If things have changed, you need to rehub.

 

[Maguro]

I had a problem witch I thought was one motor cavatating, but it turns out my lower unit was sliping gears. I have a 05 2820 with about 600 hours. It was a good thing that I bought the extended warratie

 

[MaxOut]

Hey (Hard Core) I would have the Coast Guard do an inspection of that bilge. All through hull pick ups require double clamps and a sea cock. Just a good practice. Good luck on your cavitating issue. :wink:

 

[grouperjim]

you have a bronze thru-hull scoop mounted directly in front the port motor. this means the water is cleaner coming of the stern on the stbd side. and yes, that is where the factory put it.

there are low profile pick-ups that you can use, the difference is they don't pick-up very well while running unless you turn on the applicable livewell/washdown pump.

 

[tara11]

Do not want to sound dumb, but what is that thing and what does it do, I have never seen one and have no idea what it does ? Thanks, and it could use more hose clamps

 

[Bryan 2530]

Hey (Hard Core) I would have the Coast Guard do an inspection of that bilge. All through hull pick ups require double clamps and a sea cock. Just a good practice. Good luck on your cavitating issue. :wink:

Yes and while there at it, fix that right angle water intake hose. IMO, very poor aftermarket rigging.

He does have a seacock there if you look close.......... you guys are brutal.

 

[MaxOut]

Hey (Hard Core) I would have the Coast Guard do an inspection of that bilge. All through hull pick ups require double clamps and a sea cock. Just a good practice. Good luck on your cavitating issue. :wink:

Yes and while there at it, fix that right angle water intake hose. IMO, very poor aftermarket rigging.

He does have a seacock there if you look close.......... you guys are brutal.

This advice could save a life (or a boat) I am not afraid to give it. Not trying to be too critical but it stood out to me. That looks like a 1 1/4 - 1 1/2 inlet and would fill the boat at a much greater rate than that little bilge pump could keep up with (assuming the piece of Sh#! Rule float switch decides to work). Don’t take my text "tone" the wrong way I am only tiring to offer some advice. No one has to agree or act on it. :lol:

It sounds like your cavitation issue may very well be the port P/U and you may be able to add a manifold on the center one and get rid of that one? At the same time sure up your other connections. If you paint your bottom it would be easy to glass over the old inlet hole, repaint with barrier coat and anti-foul. Maybe make a temporary plate, remove pick up, install plate and test drive before you make a final decision. Good luck!

 

[Frank S.]

hi mark,
I also have a 2530 (2005); I purchased it used in 2006 from an older gentalmen who was a mercedes benz engine specialist. When I purchased the boat it had 170 hours and was less than a year old but I noticed it had Mercury props which I questioned and his response was exactly what you were describing. When I asked him why he went Mercury for the props he said he did the mathmatical computations (which I must admit impressed me) and Mercury made that prop. I will check to see what they are in a day or so, but I can say that I have never had a cavation problem and I currently have about 600 hours on my twin 150's.
frank s.

 

[Hard Core]

FYI, I installed Permatrims last week in PV on both engines, and cavitation issues are gone, plus I'm really happy with trim angle improvments the plates provide.

I'm 99% sure it is due to the bait/washdown pickup being directly in line with the port engine. This was a mistake Parker made, probably doing it there for single installs is fine. I sent that to Eric at Parker, and he never replied...

I have bronze seacocks on all fittings including the tuna tube pump. Additional hose clamps, good catch, but the USCG doesn't care because the boat's in Mexico!

 

[DaleH]

Sometimes, despite the best effort, there just isn't room for 2 clamps .

As an aside, for any water clamps or thru-hulls, I always use AWAB clamps, as they're far superior to typical hose clamps with the cuts in them.

If you can use 2 hose clamps, DO NOT Put them on the same way ... have one screw positioned so you tighten it from the left (or up) and then tighten the other from the right (or down). Two clamps oriented opposite each other will hold MUCH tighter than 2 oriented in the same direction.

AWAB clamp shown, note how the band is NOT perforated:

 

[HM5]

I echo Dale's comments here. I found all the double clamp situations on my 2003 oriented on the same side, and $pent a lot to replace with the better clamps. Looked like it came oriented side by side from the factory. I have even found them that way from good shipyards. I don't remember where it was some 40 years ago that I learned to orient clamps opposite, but it did impress me at that time that I remember it today. Especially below the waterline, and on passenger carrying vessels.

 

[MaxOut]

Good advice Dale!

 

[gray duck]

hard core - what size and brand permatrims did you add to your engines? Are the motors 150's? I'm interested in doing this but have been told by some to not. Others on this forum have tried 4 bladed props - waiting to hear some results.