15 replies to this topic

[sdkirby]

Well, I backed the trailer into a local lake and fired up the engines. At idle, the port side motor had a dribble of water coming out the little squirt hole and the starboard engine didn't at all. I pulled the exit hose off each head and they both had water sputtering out so I think the starboard squirt hole is clogged or something.

First thing I noticed was my reverse didn't work worth @#$%! I pushed the boat off the trailer and began to taxi out of the no wake zone. Steering this thing was very hard at low speed. When I got far enough out I gave 1/2 throttle and the engines hit the rev limiter and boat would barely accelerate. I was scared to let the engines bounce off the limiter like that but I finally just let it rip and once the boat was at about 15mph, it accelerated much more and I beleive I was going about 40mph before i shut down. I am not sure because the gauges fuse blew again.

Also, I noticed the exhaust smoked quite a bit.

Is any of this normal???

[sdkirby]

Here are some pics I took. Anything look like it may be causing my lack of power problem?

Port Side:

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•  DSC00356.JPG   91.07KB   73 downloads

[sdkirby]

Starboard side:

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•  DSC00355.JPG   89.17KB   48 downloads

[sdkirby]

Port Impeller:

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•  DSC00358.JPG   128.31KB   55 downloads

[sdkirby]

Starboard Impeller:

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•  DSC00357.JPG   123.85KB   38 downloads

[sdkirby]

Port Impeller:

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•  DSC00360.JPG   95.68KB   57 downloads

[sdkirby]

Starboard Impeller:

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•  DSC00361.JPG   119.28KB   38 downloads

[tiggerman]

Well, I took backed the trailer into a local lake and fired up the engines. At idle, the port side motor had a dribble of water coming out the little squirt hole and the starboard engine didn't at all. I pulled the exit hose off each head and they both had water sputtering out so I think the starboard squirt hole is clogged or something.

First thing I noticed was my reverse didn't work worth @#$%! I pushed the boat off the trailer and began to taxi out of the no wake zone. Steering this thing was very hard at low speed. When I got far enough out I gave 1/2 throttle and the engines hit the rev limiter and boat would barely accelerate. I was scared to let the engines bounce off the limiter like that but I finally just let it rip and once the boat was at about 15mph, it accelerated much more and I beleive I was going about 40mph before i shut down. I am not sure because the gauges fuse blew again.

Also, I noticed the exhaust smoked quite a bit.

Is any of this normal???

Yer squirt hole probably is clogged. Did the boat smoke bad when you first started it and clear up, or did it smoke bad the entire time?
From the looks of the pics, your wear rings are shot. Also, looks like alot of nasty silicone that the pump was "sealed" to the hull with. All that junk needs to be cleaned off and fresh Ultra Black RTV silicone needs to be used. Also, look down through the pump intake. The lower piece is the ride plate. See the seam between it and the hull? Seal it up too.
The impellers look like they have alot of nicks in the leading edges. You may try to file them lightly to try to smooth that out- short of buying a new pair of impellers. Do the spin freely in the pump housing? Does the impeller rock back and forth in the pump housing? Im getting at the shape of the pump bearings.

You have now experienced what is known as cavitation. Thats where the pumps aren't grabbing enough water because the flow is "aerated" by whatever- in this case probably the wear rings and that bang up seal job around the pumps. The engine runs away but the boat goes no where fast.

[sdkirby]

Thanks for the info.

It smoked a lot when I first fired them up. Then after they warmed up it wasn't so bad. So are the engines supposed to bounce off the limiter like that at low speed or is that just due to the cavitation? Will it hurt anything?

If I pull the heads to check the squirt hole, must I replace the gasket or is it reusebale?

[tiggerman]

The engines bouncing off the limiter means that the limiter is working. It is doing that simply because of the cavitation. Once you get that driveline all sealed up and the wear rings replaced, you should be in good shape.The sound is awful when the pump is cavitating like that, and allowed to continue, it could damage the impeller. Wear rings are relatively inexpensive, I paid $37.47 each for the last ones I bought. Yours look chewed up- anything that goes through the pump besides water has the potential to damage the wear ring- but thats what it is for.
In one of the photos, it looks like the pump mount is damaged right under the little hole for water flow, but it could just be silicone.
The smoking issue means that more than likely, oil is seeping past a seal or two while the engine is sitting. It could be the rotary valve seal or it could be the crankshaft seals in the carnkcase. My boat does the same thing- it smokes like a house fire when I crank it up, for about as long as it takes to burn the excess oil off. After that, it is good to go for the rest of the day, without smoking.
Pulling the head, hmm.... I don't know. depends on how long the gasket has been on whether I would reuse it or not. It needs to reseal without using any silicone.
Can you take off the hose and check the pee hole? Like, with a coathanger? Thats just the water jacket anyhow, and it shouldn't hurt anything if you can get to it.

[sdkirby]

Ok, I am ordering the wear rings today. So is cavitation harmful or just a PITA? I wanted to take the boat out again and make some carb adjustments before the new wear rings come in.

As for removing the impeller. Does the impeller shaft have right handed threads or left handed? I can't seem to break it loose.

Also, with a flick of the wrist the impeller spins about 2-3 times freely. Is that good enough?

[tiggerman]

Cavitation is harmful to the surface of the impeller. It will erode the surface of the metal and cause stress cracks. I suppose you could do the adjustments now, just to see if there are any flat spots in the throttle response. Just be careful and don't lean the carbs out too much, or you could fry your Rotax......
As for the impeller, you need a special splined tool to insert where the driveshaft goes. The threads are right handed. To be honest, I did not remove my impeller to replace the rings. When I got my new ones, I put them in the freezer. Then, I got 2 pieces of 4X4 on my workbench and turned the pump up so I was looking down into the outlet (the cone side). I took a long screwdriver and put the tip right where the ring meets the pump housing. I held it so I didn't get too big a bite and score the housing. Then I carefully drove the ring out, alternating sides until it popped free. I was careful about avoiding hitting the impeller and the pump vanes with the screwdriver.
After I cleaned the pump up some and looked at it good, the new rings were good and frozen. I let the pump stay wet with soapy water, and turned it the other way. I had my wife hand me the ring straight out of the freezer, and dropped it in the pump. It more or less fell all the way in and bottomed out in the hole. I made sure right quick that it was all the way in, and it was. Once it had thawed out, it fit tight like it should. Not exactly done the way the book recommends, but it worked.
On your boat, you could do it the same way, or get the tool and remove the impeller. It sounds like yours has led a rough life, and it might not hurt to take a look at the pump seals and bearing while you're there. I would at least change the pump oil while you had the pump off. It should be black, with no sign of water. If it is milky or you see water in it, you need to replace the seal.
Sounds like it spins well enough. As long as it spins with out noise. BTW, where are you located? I don't recall you telling us....

[sdkirby]

I am in Arlington, Texas. About 15 miles southwest of Dallas.

I went ahead and just picked up a couple of wear rings from the local dealer yesterday and put them in. My impellers must be hooked up differently than yours because all we had to do is chuck the impeller and use a cresent wrench on the flats of the impeller shaft to break it loose. Then it just screwed out. After struggling with getting the old rings out and putting the new ones in, we put new pump oil in and reinstalled the carriers on the boat with a nice new coat of black RTV.

Unfortunately, weather wasn't good today so maybe tomorrow I will get to test drive it.

[tiggerman]

It's a shame weather wasn't good... wasn't good here either. I'm pretty sure the pumps are designed the same. I put locktite on mine the last time I had them out, and I just couldn't break them loose.
Hope weather turns nice tomorrow, and you can take it out and see what I was talking about. That thing ought to hook up out of the hole and GOOOOO......

[sdkirby]

Weather still too bad to take the boat out for a test run. Looks like it will have to be next weekend. I will start a new thread and let yall know how it goes.

[tiggerman]

Rained here all weekend too... Oh well, It will give me time to decide how I want to run the wiring for my new depth finder......and recover a couple more seats!!! I removed the seat backs today. I just thought the bottoms were hard to get to! I wish I had a picture of me all curled up on top of the engines reaching WAYYYYYY up under the armrests.....