Yamaha 40hp JetDrive (Help a newbie?)

[LundMiniJet]

If anyone jet-knowledgeable out there feels like giving a few minutes and a few pieces of advice, it would sure be appreciated by me and my motor. If this is the wrong forum for this kind of request, anyone let me know. Thanks!

Total jet newbie here. Got a new-to-me Lund 16ft with a 40hp Yamaha JetDrive (1999). Got a crash-course from the local marina guy about basic maintenance, i.e. greasing lower unit, listening for clumps of grass when running the boat, setting the motor correctly on the transom, etc. It didn't seem too complicated, even to a NON-mechanical, NON-technical guy like me.

Then I talked to a different guy who started talking about filing cups, pulling lower units yearly, SHARPENING SHOES??? Now I'm damn near afraid to run this thing.

Any opinions/advice/your policies on jet maintenance, any at all, would be hugely appreciated. A few problems, a few questions:

P) I notice in cold weather that the area around the lower unit, maybe 10-16 inches above the waterline, gets very warm and steams a bit, even after short runs. Not too hot to touch unless its been a long run and you press your hand onto it hard. Is this a sign of something bad going on in the lower unit?? If so, what to do??

P) When I suck up a stick or some seaweed, I shut the motor off and shake it a bit. If that doesn't do it I get my hand under there and pull it out. Someone told me you can get stuff un-stuck without turning the motor off. Anyone know how to do this? Any other tricks you like to use??

Q) Is regular greasing sufficient per-use maintenance?

Q) The previous owner seemed to take good care of this motor. Can't be too careful, though: What are some things I can check myself (keep in mind, I'm no grease monkey) to ensure that the pump (and motor, for that matter) are in good and safe running shape? The motor runs well, a little finicky of a starter but always stays running.

Q) Should I even bother to think about filing and sharpening??

Q) Any other basics I should know about??

If you've read this far, I thank you. If you are willing to impart a little knowledge, thanks again. It would truly be a good deed done. I'm a young guy just out of college, new to this kind of boating, and it so often seems that those who know about this stuff don't care to explain it to a newbie. I understand that, but its not like we learn this stuff in high school and my family is not real boat-savvy. Where to learn?

ANY advice, answers, comments, etc. that you can give me would make my day and help my motor stay happy. If this forum isn't the appropriate place for this, feel free to email me.

nickelll@plu.edu

Thanks very much!!

-Laurent Nickel

 

[rodbolt]

Re: Yamaha 40hp JetDrive (Help a newbie?)

best advice I can give is purchase the shop service manual covering not only the jet unit(usually made by American jet) and the manual for the powerhead.
there are no shoes on or in that motor.
what the so called tech was refering to is the impeller blade face, also called the leading edge.
its not hard to inspect nor is impeller to wear liner clearence measurements and adjustments.
yearly cooling water pump replacements and periodic maint before it breaks will help keep your rig runing a long time.

 

[cdrandy]

Re: Yamaha 40hp JetDrive (Help a newbie?)

The two biggest things to jet unit efficiency is the clearance between the impeller and the sleeve, basically you want a CH, as close as you can get them. You do this by moving the washers on the shaft (I think there are about 8) from the bottom one at a time to the top of the impeller, that moves the tapered impeller down into the sleeve.
#2; The impeller leading edges, (the bottom where the nut is) are filed kind of like a chisel point. If you do a google search there are some good articles on what it is supposed to look like. The sharper and smoother, less turbulence, more efficiency, longer life.

 

[Lone Duck]

Re: Yamaha 40hp JetDrive (Help a newbie?)

The boys are right. Google (enhancing outboard jet performance) And (scott and jens getting to know your outboard jet) Also you will find out that even a jet pump has a rubber impeller cooling system the same as a prop boat. Some times you can clear your pump from sticks etc. by idling down and reving again. Grass leaves and snow on the water are the worst. Jets do not go faster. They go shallower. And are safer for folks and marine life in the water. Have fun.

 

[Delakid]

Re: Yamaha 40hp JetDrive (Help a newbie?)

Lund,

I can help you having runs jets for years.

1) All jet pumps that I have seen or run are made by Outboard Jets from San Leandro Ca. **** Stallman is the owner and is usually available to answer any questions that you may have.

2) Unabstructed water flow (without bubbles or air pockets) is key to getting good jet performance. If your Lund has a keel that goes all the way to the stern......have 10 or 12 inched of it removed. You will see a noticeable increase
in performance.

3) Yes you should lube your pump bearing after every trip with the special grease Lubriplate 630-AA grease.

Only use this with a jiffy lube gun as normal lube guns and grease will blow out the bearing seal. Outboard Jets sells the grease and special gun.

4) If you run the engine at full throttle it will be difficult to clog the intake unless you go through a large patch of leaves in the fall.

But hould you get clogged if you tilt the engine out of the water then there is no suction..........and usually whatever is in the intake will fall out. The engine should not be held out of the water but for a few seconds as this can /will burn your water pump impellor. Rodbolt was ready to jump on this one .....did I cover myself good enough Rod ?

5) Yes you should sharpen your jet impeller. nicks can and will cause cavitation burns on the impeller and can ruin it. The outboard jet website has a diagram of the propoer sharpening. Get 2 or 3 good hand files from coarse to smooth and hand file the impeller once it gets nicked up.

6) Impeller spacing....already properlly coverd by CDRandy

7) Make sure the grill bars are straight and not bent.

8) Keep your load as light as possible. Battieries should be as far forward as possible. If you can drift it.....you can run it.

9) Get into trouble, real shallow water.........run it faster. Hit bottom .....ride it out. Most guys when they are new and hit, first thing they do is shut it down. This causes more damage. As the boat will sit down in the water and hit harder. The faster you ride the higher. Usually if it is a gravel or sand bar you push enough water over it to get you through it.

10) Your going to hit. Normally it sounds worse that it really is. Ride it out, don't stop until you reach deeper water.

I hope this is helpful,


Don /Kid