JET PUMP FAIL ... SOMETHING YOU SHOULD KNOW

[Leojay]

Does your jet pump sound a bit noisy while out of the water? To some extent this is normal, but many times it's not. My latest video provides some insight to a known Yamaha jet pump fail:

 

[FSH 210 Sport]

The greases…this should be an interesting discussion.

The marine grease is put into new bearings, not when doing a service, to provide lubrication until the the low viscosity EPNOC grease gets hot enough to flow from the cone up into the rest of the housing, and provides a bath of grease throughout the entire bearing channel, EPNOC grease is a lithium based grease that holds any water that would get into that area in suspension and still provides lubrication. See post #18 in this thread; https://jetboaters.net/threads/winter-2022-2023-maintenance-repair-improvements.39932/#post-644741

In my opinion you did not put nearly enough grease into the bearing cone, you should pull it off and fill the cone basically to the top. Can you please provide a picture of the part of your service manual that states .7 ounces in the cone? My manual makes no reference to the amount of grease it just says to fill them with grease. When I filled the cones with grease I used a straight seal pick to stir it frequently to remove any air bubbles, when you stir the EPNOC grease you’ll be able to see how it liquifies very easily and how it will flow up into the bearing housing providing lubrication up to the front bearing. Imagine looking at the assembly from the side in a cut away with the cone on the right, the cone is the reservoir of EPNOC grease and due to the height of the grease in the cone when full, is higher than the front bearing, as the grease gets warm and is spun in that channel it flows forward to the front bearing, equalizing. As the shaft and bearings spin in the housing, the EPNOC grease is circulating around everywhere inside providing a bath of lubrication.

Loctite 572 specified in the service manual is a low strength thread locker, but it’s main attribute is that it is a thread sealer to assure that the bolts, which are a dissimilar metal to the aluminum transom plate, do not seize in the holes. In the thread linked above I mention how I run a tap into the bolt holes and a die over the bolts to remove the old 572 prior to re assembly, this assures a nice smooth assembly. The only time I did not use 572 is when I was testing impellers as I was swapping three sets of impellers in a day but I always applied 572 when I knew I was not going to be disassembling the pumps for a while. Permatex makes a similar product which you appeared to use in your video, and is a fine product. Permatex and Loctite are owned by the same entities thes days.

Using the super lube on your rubber is a great idea to avoid pinching the rubber and creating a leak ?.

 

[Leojay]

The greases…this should be an interesting discussion.

The marine grease is put into new bearings, not when doing a service, to provide lubrication until the the low viscosity EPNOC grease gets hot enough to flow from the cone up into the rest of the housing, and provides a bath of grease throughout the entire bearing channel, EPNOC grease is a lithium based grease that holds any water that would get into that area in suspension and still provides lubrication. See post #18 in this thread; https://jetboaters.net/threads/winter-2022-2023-maintenance-repair-improvements.39932/#post-644741

In my opinion you did not put nearly enough grease into the bearing cone, you should pull it off and fill the cone basically to the top. Can you please provide a picture of the part of your service manual that states .7 ounces in the cone? My manual makes no reference to the amount of grease it just says to fill them with grease. When I filled the cones with grease I used a straight seal pick to stir it frequently to remove any air bubbles, when you stir the EPNOC grease you’ll be able to see how it liquifies very easily and how it will flow up into the bearing housing providing lubrication up to the front bearing. Imagine looking at the assembly from the side in a cut away with the cone on the right, the cone is the reservoir of EPNOC grease and due to the height of the grease in the cone when full, is higher than the front bearing, as the grease gets warm and is spun in that channel it flows forward to the front bearing, equalizing. As the shaft and bearings spin in the housing, the EPNOC grease is circulating around everywhere inside providing a bath of lubrication.

Loctite 572 specified in the service manual is a low strength thread locker, but it’s main attribute is that it is a thread sealer to assure that the bolts, which are a dissimilar metal to the aluminum transom plate, do not seize in the holes. In the thread linked above I mention how I run a tap into the bolt holes and a die over the bolts to remove the old 572 prior to re assembly, this assures a nice smooth assembly. The only time I did not use 572 is when I was testing impellers as I was swapping three sets of impellers in a day but I always applied 572 when I knew I was not going to be disassembling the pumps for a while. Permatex makes a similar product which you appeared to use in your video, and is a fine product. Permatex and Loctite are owned by the same entities thes days.

Using the super lube on your rubber is a great idea to avoid pinching the rubber and creating a leak ?.

Hello, well first let me thank you. There is so much disinformation on the internet these days, I strive to provide as accurate information as I can in consideration of the fact that I'm not a trained professional. That being said, I appreciate your insight and it really sounds like you have a good understanding of the inner workings here. I appreciate you taking the time to lay it out for me.
Here is the page from the service manual depicting the required amount of EPNOC.
Be well!

 

[Bottom Bracket]

Item 16 driveshaft holder!
Gotta get me one of those.

 

[FSH 210 Sport]

Well I’ll be darned.. checked my shop manual and on the similar drawing in my shop manual it states the same thing about .7 ounces of grease, but there was way more than .7 ounces of grease in my caps when I disassembled them for the first time.



however if I look on the preceding page where it is showing the bearing housing cut away and the required grease amount of .7 ounces which makes sense for this small space.



So I have to reasonably conclude that grease amount for the “cap” is incorrect. Again, imho the cap should basically be full. Consider what your cap looked like when you pulled it off, and what it looked like with only .7 ounces of grease in it. If I were to wager a guess, I’d say a decimal point got put in front of the 7 for the cap and it should be 7 ounces?

In the Periodic maintenance section of my shop manual regarding the impeller ducts …





It doesn’t even say to add grease or what amount should be in the cap, just to inspect for water intrusion and to disassemble if there is water intrusion. Its only in the disassembly and assembly section does it mention a grease amount.

Sort of like the owners manual specifies the amount of grease needed for the intermediate bearing..




But the shop manual does not… weird. I guess Yamaha figures that if you are looking at the shop manual you know how to grease those bearings. And there is a lot of discussion about these bearings as well.


Thanks for making a thoughtful and helpful video again LeoJay!

 

[Leojay]

The greases…this should be an interesting discussion.

The marine grease is put into new bearings, not when doing a service, to provide lubrication until the the low viscosity EPNOC grease gets hot enough to flow from the cone up into the rest of the housing, and provides a bath of grease throughout the entire bearing channel, EPNOC grease is a lithium based grease that holds any water that would get into that area in suspension and still provides lubrication. See post #18 in this thread; https://jetboaters.net/threads/winter-2022-2023-maintenance-repair-improvements.39932/#post-644741

In my opinion you did not put nearly enough grease into the bearing cone, you should pull it off and fill the cone basically to the top. Can you please provide a picture of the part of your service manual that states .7 ounces in the cone? My manual makes no reference to the amount of grease it just says to fill them with grease. When I filled the cones with grease I used a straight seal pick to stir it frequently to remove any air bubbles, when you stir the EPNOC grease you’ll be able to see how it liquifies very easily and how it will flow up into the bearing housing providing lubrication up to the front bearing. Imagine looking at the assembly from the side in a cut away with the cone on the right, the cone is the reservoir of EPNOC grease and due to the height of the grease in the cone when full, is higher than the front bearing, as the grease gets warm and is spun in that channel it flows forward to the front bearing, equalizing. As the shaft and bearings spin in the housing, the EPNOC grease is circulating around everywhere inside providing a bath of lubrication.

Loctite 572 specified in the service manual is a low strength thread locker, but it’s main attribute is that it is a thread sealer to assure that the bolts, which are a dissimilar metal to the aluminum transom plate, do not seize in the holes. In the thread linked above I mention how I run a tap into the bolt holes and a die over the bolts to remove the old 572 prior to re assembly, this assures a nice smooth assembly. The only time I did not use 572 is when I was testing impellers as I was swapping three sets of impellers in a day but I always applied 572 when I knew I was not going to be disassembling the pumps for a while. Permatex makes a similar product which you appeared to use in your video, and is a fine product. Permatex and Loctite are owned by the same entities thes days.

Using the super lube on your rubber is a great idea to avoid pinching the rubber and creating a leak ?.

Thanks, all great points and possibilities. You are making me re-think my work now. Truth be told I added additional grease to the cone off camera, not huge amounts and certainly did not fill it to the brim. I do wish it was bit quieter, it still seems like I can hear the impeller tapping a bit. When I grab the shaft and rotate it while the pump assembly is out of the boat I don't feel any play in the bearing at all. Not sure if it's my imagination at all. When the garden hose is turned on and the water flows, it does quiet down. I wonder how the nylon ring housings would sound. I hear they are quiet.

 

[FSH 210 Sport]

Thanks, all great points and possibilities. You are making me re-think my work now. Truth be told I added additional grease to the cone off camera, not huge amounts and certainly did not fill it to the brim. I do wish it was bit quieter, it still seems like I can hear the impeller tapping a bit. When I grab the shaft and rotate it while the pump assembly is out of the boat I don't feel any play in the bearing at all. Not sure if it's my imagination at all. When the garden hose is turned on and the water flows, it does quiet down. I wonder how the nylon ring housings would sound. I hear they are quiet.

I think that ringing sound we hear on the trailer when we first start the engines and the whole assembly is dry is the impeller blade ringing from the engine and couplers from the power pulses from the engine, when it’s on the hose the water dampens those noises, and when it’s in the water the impeller is loaded from water pressure so it’s even quieter. Mine sounds the same.

Did you use a feeler gauge to check the clearance between the impeller and the new wear ring? When I was testing impellers I had to use a mill file to remove small amounts of material to set the gap at .014” which is the minimum gap as the impellers were scraping on the wear ring.

 

[Leojay]

I used a feeler gauge during my first install two years ago with the OEM housing. I did not check it again with Solas SS. If there is any rubbing I imagine over time it will quiet itself down via wear on the impeller, ring or both. Check here at the 14:00 mark in my video:

 

[Bottom Bracket]

So I must have missed it,
Performance improvements with the fancy impellers?

 

[Leojay]

So I must have missed it,
Performance improvements with the fancy impellers?

I must have missed the fancy impellers part. I still have OEM.

 

[drewkaree]

So I must have missed it,
Performance improvements with the fancy impellers?

The Solas wear ring assembly is what he swapped in, not their impellers

 

[Dave burke]

Great video as always @Leojay. And very helpful info @FSH 210 Sport. I also thought there could have been more grease.

Just so I’m clear, if I’m just doing routine maintenance on the pumps, I need to use just EPNOC grease right?

And my boat is 6 years old with about 150 hours on it and I’ve never checked the grease in the cones. Mainly because I’ve never had an issue with the impellers or wear rings (knock on wood). But I’m thinking I should do this maintenance this fall or next spring. Make sense?

 

[Cobra Jet Steering LLC]

Thanks, all great points and possibilities. You are making me re-think my work now. Truth be told I added additional grease to the cone off camera, not huge amounts and certainly did not fill it to the brim. I do wish it was bit quieter, it still seems like I can hear the impeller tapping a bit. When I grab the shaft and rotate it while the pump assembly is out of the boat I don't feel any play in the bearing at all. Not sure if it's my imagination at all. When the garden hose is turned on and the water flows, it does quiet down. I wonder how the nylon ring housings would sound. I hear they are quiet.

I personally have excellent results with the nylon liners and have had for many years doing some pretty wild things like hooking a rope to a beached boat and using the p w c pump to wash out the sand under it to free it. Plus I run in less than a foot of water most of the time when playing along the mangrove trees, remember the dissimilar metals corrode and the liner gets high spots under it from the corrosion I actually did a post about a poor mans fix for that years ago, I like that the pumps are basically silent with the liners and I stick with the stock impellers also, Remember this if your impeller housing is stainless steel and your pump housing is aluminum you still have dissimilar metal corrosion . Back 40 years ago I was working in a repair shop for boats in my spare time, in Bay Pines called Rudi's Marine. I volunteered there so I could learn boat and engine repair from a German Engineer who owned the place. One thing I taught him was how bees Wax was excellent for marine use , when the O M C sea drive units had several long stainless steel bolts that went through the lower unit the dissimilar metal corrosion would make it damn near impossible to remove those bolts so I put the wax on them once we did get them out and after doing a good cleaning job to solve the problem in the future . In any event if you have aluminum and stainless making contact you have to understand that dissimilar metal corrosion will still occur. Also if your engine is slow to crank after sitting out of use for a while spray some WD-40 in the pump around the impeller and see if it cranks over faster and if so you know your liner is swelling from the corrosion. I have seen more than one jet boat get sold cheap with what they were told was a bad locked up engine when in fact it was just a locked up impeller preventing the engine from starting. I also have reviewed the parts diagrams and it looks like Yamaha is now using the plastic liners in the newer boats, good move .

 

[FSH 210 Sport]

Great video as always @Leojay. And very helpful info @FSH 210 Sport. I also thought there could have been more grease.

Just so I’m clear, if I’m just doing routine maintenance on the pumps, I need to use just EPNOC grease right?

And my boat is 6 years old with about 150 hours on it and I’ve never checked the grease in the cones. Mainly because I’ve never had an issue with the impellers or wear rings (knock on wood). But I’m thinking I should do this maintenance this fall or next spring. Make sense?

Yes just epnoc grease.

I was over too on the maintenance check at years and 200 hours. it’s supposed to be 100 hours or annually. I’ll be checking mine again over the winter.

 

[Cambo]

I wonder how the nylon ring housings would sound. I hear they are quiet.

They are very quiet no noise at idle or when revved up.

 

[tdonoughue]

I think that ringing sound we hear on the trailer when we first start the engines and the whole assembly is dry is the impeller blade ringing from the engine and couplers from the power pulses from the engine, when it’s on the hose the water dampens those noises, and when it’s in the water the impeller is loaded from water pressure so it’s even quieter. Mine sounds the same.

Given the report of the nylon rings quieting things... do you think it is valid that the ringing is not so much the impeller blade ringing as the same power pulses flexing the blade just enough to slightly contact the rings? Then all the dampening you hypothesize would still reduce the ring, of course--just from a different mechanism.

Just mentally playing here... interested in your thoughts.

 

[Cobra Jet Steering LLC]

The cause is the edges of the impeller striking the stainless pump liner, either by high spots from dissimilar metal corrosion under the liner or from play in the bearings of the pump . you can see the contact areas as they darken from the heat caused by the contact. I did a post years ago . https://jetboaters.net/threads/low-budget-fix-for-yamaha-pump-liner-swelling-issue.12121/

 

[FSH 210 Sport]

Given the report of the nylon rings quieting things... do you think it is valid that the ringing is not so much the impeller blade ringing as the same power pulses flexing the blade just enough to slightly contact the rings? Then all the dampening you hypothesize would still reduce the ring, of course--just from a different mechanism.

Just mentally playing here... interested in your thoughts.

I do not think the power pulses flex the blades enough to contact the wear ring, if that was true then when under full load they would really scrape.

I think the nylon ring absorbs a substantial portion of the high frequency sounds that come from the impeller blade. The blade probably is getting its ringing from the power pulses, that ringing is probably coming from the slop in the spline drive slapping back and forth with the pulses in the intermediate bearing area. The reason you don’t hear any of that when in the water is due to the fact the impeller is loaded, and of course the water dampening it.