ByronPA

Jet Outboard Problem / Question

12 posts in this topic

I am looking at a used boat/jet combo, a 16 tin boat with a 2001 50hp factory yamaha jet outboard on it.. The rig has low hours, overall in very good condition and the seller is a good friend.. The price is right and he's willing to pay for / make repairs before the sale as needed..

 

The engine is throwing oil into the boot/foot..  where the water shoots out the outlet nozzle to provide propulsion, the inside of the nozzle is coated with thick oil sludge. If that makes sense....I'm presuming this is from a blown seal somewhere but without tearing it apart really don't know. Being a jet probably doesn't have any bearing on the problem, other that it's not the lower unit...

 

Any ideas, suggestions of things to look at before taking it to a pro? The seller wants to fire it up and see it "it works itself out".. Any danger in firing it up?

 

 

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15 mins ago, ByronPA said:

2 stroke

OK. My guess (since I'm not 100% on how the foot is designed) is that it's the excess un-burned 2 stroke oil coming out the exhaust of the motor and mixing with the jet pump exhaust causing it. Just like when you see a 2 stroke prop OB with black oily substance running out of the prop hub.

Upping the oil ratio, running at lower RPM's can increase this discharge.

Lots of times people think it's their lower unit leaking oil, but it's not.

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8 mins ago, MdCrappie said:

OK. My guess (since I'm not 100% on how the foot is designed) is that it's the excess un-burned 2 stroke oil coming out the exhaust of the motor and mixing with the jet pump exhaust causing it. Just like when you see a 2 stroke prop OB with black oily substance running out of the prop hub.

Upping the oil ratio, running at lower RPM's can increase this discharge.

Lots of times people think it's their lower unit leaking oil, but it's not.

Hmm, that sorta makes sense, hadn't considered that as a possibility... It's certainly a possibility that I like.  

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This issue does not lie with the jet unit. Converting a prop outboard to jet involves removing the prop lower unit and replacing it with a volute, impeller and foot. A jet does not have a gear case oil reservoir like a prop lower unit. There is a grease nipple and the unit has to be greased after each use but in now way shape or form would this cause 2 cycle oil to discharge into the exhaust.

 

The outboard issue should be relatively easy to diagnose and fix. Taking a step back, I'd like to know more about the hull itself.  Slapping a jet unit on an outboard does not give you a true river jet boat. The hull should be jon-style or modfied V at most. The hull should be welded, not riveted and be at least .100 thick. Does the hull have a tunnel and raised transom? A center console rig is infinitely preferable to a side console as you can stand up and see what's ahead of you. With a side console, you're sitting down and can't see very well. Things can go very wrong, very fast in a river. The Susquehanna has these things called ledges which will tear a hull apart. I sold my Rockproof because work was getting in the way, however, that thing was built with a .192 hull, hull-length C channel and .5" UHMW on the hull and sides. Even driving that thing, rivers scared the **** out of me. I'm back to a lake boat.

 

Snyder builds a great boat as well but there are issues with Tom that I won't go into. A terrifying incident was relayed to me by someone who knew the boat owner. They were driving a Snyder on a river and crossed under an abandoned railroad bridge. A piece of train track had fallen into the river and was sticking up up at an angle below the surface. They hit the piece of track which punctured the hull and stopped the boat cold. Both the operator and passenger were thrown out and both injured severely.

 

I drover a Ranger 354 for years and the biggest issues on lakes were knucklehead jet skiers, trolling motor batteries croaking or an outboard not starting. River jetting is an entirely different proposition where real trouble can show up real fast. I'm not recommending against it as it's friggin awesome to be able to get to places where prop boats can't, however, safety is #1. I hired a noted river guide to take me out the first time and show me the ropes of river jetting. He pointed out what a boat-wrecking rock looks live (a V pointing upstream) and that a V pointing downstream is safe to go though. Never drive downstream of the launch ramp as if your outboard fails, you are forked. Driving upstream from the ramp, your tolling motor and the current will get you back. Learn your river one bit at a time. Take a trip where you leave the rods at home and just memorize the water. Take one stretch at a time, learning where shoals, boulders, ledges and holes are. Do that stretch again. Go upstream and learn another stretch. Lather rinse repeat. A dangerous thing is to launch for the first time and rocket up to places unknown. I hit countless times coming downstream buy only once going upstream. Ah, river jetting.....

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11 hours ago, HardyG said:

1 - The hull should be welded, not riveted and be at least .100 thick.

2 - Does the hull have a tunnel and raised transom?

3 - A center console rig is infinitely preferable to a side console as you can stand up and see what's ahead of you. With a side console, you're sitting down and can't see very well.

4 - I sold my Rockproof because work was getting in the way, however, that thing was built with a .192 hull, hull-length C channel and .5" UHMW on the hull and sides. Even driving that thing, rivers scared the **** out of me. I'm back to a lake boat.

 

5 - Snyder builds a great boat as well but there are issues with Tom that I won't go into. A terrifying incident was relayed to me by someone who knew the boat owner. They were driving a Snyder on a river and crossed under an abandoned railroad bridge. A piece of train track had fallen into the river and was sticking up up at an angle below the surface. They hit the piece of track which punctured the hull and stopped the boat cold. Both the operator and passenger were thrown out and both injured severely.

 

 6 - I hired a noted river guide to take me out the first time and show me the ropes of river jetting. He pointed out what a boat-wrecking rock looks live (a V pointing upstream) and that a V pointing downstream is safe to go though. Never drive downstream of the launch ramp as if your outboard fails, you are forked. Driving upstream from the ramp, your tolling motor and the current will get you back. Learn your river one bit at a time. Take a trip where you leave the rods at home and just memorize the water. Take one stretch at a time, learning where shoals, boulders, ledges and holes are. Do that stretch again. Go upstream and learn another stretch. Lather rinse repeat. A dangerous thing is to launch for the first time and rocket up to places unknown. I hit countless times coming downstream buy only once going upstream. Ah, river jetting.....

Where to start? Well, I'll start by thanking you for your concerns and insight. But, of course, being in the internet and all, I need to discuss. I'm not a mechanic, which is why I was asking for input here. However, I've been fishing/boating the Susqy between Harrisburg and Sunbury for forty five years. This is the 5th jet outboard I've owned and have half a clue on how to run the river. 

Please don't think I'm being a smart ass or argumentative, just throwing out a different opinion. I literally live on the Susqy (well, right beside it) and watch it out my kitchen window. My opinions on boats are based on what I see, or don't see, day in and day out. 

I'm pretty sure that I've watched a video or two you posted? And no doubt your views mirror those of many...

 

1 - Everyone says that, especially folks who build welded boats. But, a couple thoughts to keep in mind, riveted boats are a bit lighter, easier to repair on the water and cheaper. A thinner hull is much lighter, easier to repair and cheaper.... You might notice I have a theme going on here.. Lighter is better. Not only do you need to be able to run skinny, you need to be able to drift skinny. A boat that will run in 2" of water but drafts at 14" is worthless around here. And when you get stuck on a rock, you'll appreciate a boat you can lift off by yourself..

 

2 - No on the tunnel. I remain unconvinced that a tunnel on a jet serves any real purpose. The lowest point on my boot is 1/8 of an inch below the bottom of the hull, and obviously, that is the rear of the boot. Since, on a well thought out jet boat 90% of the hull (maybe 95%) should be out of the water when running, I fail to see the advantages of a tunnel. A tunnel also leads to cavitation, which leads to performance issues. And, it leads to more weight, not just the tunnel but the raised floor that goes with it...

 

3 - Defiantly true, but there are work arounds. The biggest issues with SC is that they place your bodies weight on one side and are generally located to far back.  My current rig has a side console, but it's not that difficult to extend wires/steering cable and move the console forward. Batteries can be relocated from the rear to the front, opposing side, of the console to provide a boat that will fun flat and skinny.. 

 

4/5 - Rockproof builds an awesome boat, and if your're willing to work with Tom, Snyder builds an awesome boat as well. Tom has repaired several hulls for me over the years, a bit of a character but a good guy.  The problem with his boats, and others, they are heavy. Yes, they run skinny, but they only run skinny at full throttle. And they sure don't fish skinny. And when you get hung up on one of those ledges you mentioned, you better hope you have strong friends with you...I see these (and other similar boats) running up and down the river all spring when the water is high, as soon as levels drop, I don't see any.  And the reason I don't see any, is because they don't fish skinny....

 

6 - Good idea..

 

In my my mind, a well thought out, properly set up, lightweight rig is the way to go for fishing. Yes, you need to be good at reading the water and maneuvering your rig. Yes, you're going to damage something eventually. No, ripping a hole in your hull in inches of water will not be the worse thing that ever happens to you.. 

 

Just my thoughts...

Edited by ByronPA

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Great conversation between you two. 

 

I just got a quote on a Crestliner yesterday. 1860 with a tiller jet. I like the idea of the casting deck in front with a pretty open floor. I want as little to go wrong as possible and as much fishing space as I can. 17 or 18 footers seem to be a good compromise on stability and room but also light enough to be handled alone and pushed by a smaller, cheaper, lighter, jet.

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2 hours ago, PhilCVG said:

Great conversation between you two. 

 

I just got a quote on a Crestliner yesterday. 1860 with a tiller jet. I like the idea of the casting deck in front with a pretty open floor. I want as little to go wrong as possible and as much fishing space as I can. 17 or 18 footers seem to be a good compromise on stability and room but also light enough to be handled alone and pushed by a smaller, cheaper, lighter, jet.

What size jet? I'll offer two pieces of advice; get as much weight as possible up front. My last jet was a 28hp tiller on a 15ft flat bottom, and it took some tinkering but that thing ended up being an awesome rig. One problem with a tiller is that you have to sit in the back to operate it, along with the weight of the outboard, gas tank, batteries, etc it ends up being very unbalanced. The more weight that you can put up front the better it'll perform.

And regardless of how the dealer sets it up, don't be afraid to adjust the height/tilt of the outboard. There's a very fine line between too high and too low and it'll probably take several adjustments to get it right....  

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3 hours ago, ByronPA said:

What size jet? I'll offer two pieces of advice; get as much weight as possible up front. My last jet was a 28hp tiller on a 15ft flat bottom, and it took some tinkering but that thing ended up being an awesome rig. One problem with a tiller is that you have to sit in the back to operate it, along with the weight of the outboard, gas tank, batteries, etc it ends up being very unbalanced. The more weight that you can put up front the better it'll perform.

And regardless of how the dealer sets it up, don't be afraid to adjust the height/tilt of the outboard. There's a very fine line between too high and too low and it'll probably take several adjustments to get it right....  

 

I haven't committed to it yet but it was quoted with 40hp jet. 

 

And that makes a lot of sense. 

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