Water pump failure

[STAIN]

Good research. It seems they have some really valuable experience when it comes to this part of the machine. I am guessing those machines run a bit hotter than ours.

 

[justinator]

It seems with sustained use over 8000 rpms, the thrust of the impeller and extra heat in cooling system cause the impeller to come apart from the shaft. The s x s’s get alot warmer then the sleds so this issue is pretty big for them, more so then the sleds. Im gonna try to find a little more info on the kit from speedsxs before biting the bullet. I wont hesitate to spend the money if its a cure but would hate to spend the money and time if its not much of an improvement over what we have. I cant see how this kit from speedsxs would be failure prone but then again who knows.

 

[twyztid]

I did a little reading last night on the s x s forums and it seems dasa is on their 4th revision of this billet water pump impeller. It seems that once the impeller was strengthened the shaft would break just before the first hole closest to impeller. That is the reason that speedsxs kit includes a gear. The shaft has no holes for the pins, both sides are machined to accept the pin sort of like a key way and the gear is machined to accept this obviously. Its double the money for this kit but includes all orings and seals and bearing. This stuff would run you about another $75-80 through babbits on top of the $250 for the impeller from dasa. Now the question is........Is this 4th revision impeller from dasa cured of its faults or not? Sounds like the speedsxs kit has 2 years of testing into it and no bad reports I could find but also will say the information available on either of these options is limited.

I had read that last night as well about Dasa having multiple revisions so far.

 

[twyztid]

What I am curious about is why you don't hear about more Vector, Nytro, or SR Viper guys. I believe it is the same part number for the impeller/shaft for all of the 998cc &1049cc motors.

 

[justinator]

I had read that last night as well about Dasa having multiple revisions so far.

Ya, seems they had shaft issues and some guys also had trouble with the seal that fits into back of impeller only lasting a few rides. Wish I knew if it was all cured, half the price of the speedsxs kit but that dont matter if you have to walk

 

[justinator]

What I am curious about is why you don't hear about more Vector, Nytro, or SR Viper guys. I believe it is the same part number for the impeller/shaft for all of the 998cc &1049cc motors.

You are correct, same numbers. My best guess would be that at some point the parts began being built with lesser quality materials to save money. There would be no change in part number because its not an update or revision of an existing part. All the same, just made of lower quality materials. Thats about the only thing I can think of.

 

[twyztid]

You are correct, same numbers. My best guess would be that at some point the parts began being built with lesser quality materials to save money. There would be no change in part number because its not an update or revision of an existing part. All the same, just made of lower quality materials. Thats about the only thing I can think of.

I had thought of that but didn't add that to my post. I bet Yamaha at some point started outsourcing some parts production to China. Some other threads have mentioned this as a possibility as well.

 

[fatchance]

I wonder what's really going on there because that is quite a leap from the impeller head spinning on the shaft to the shaft itself breaking. I'm going to sit back on this one until we can do some more research. I have reached out to Dasa, but I have not heard back yet.

 

[twyztid]

I wonder what's really going on there because that is quite a leap from the impeller head spinning on the shaft to the shaft itself breaking. I'm going to sit back on this one until we can do some more research. I have reached out to Dasa, but I have not heard back yet.

The impeller head can't spin on the Dasa one because it is threaded on so the next weakest link is the shaft by the 2 holes drilled through it.

 

[fatchance]

The impeller head can't spin on the Dasa one because it is threaded on so the next weakest link is the shaft by the 2 holes drilled through it.

Correct, but I'm referring to the ease of the stock impeller head to spin on the shaft compared to the shaft breaking on the billet impeller. shear forces here would be much greater to shear a shaft compared to a plastic impeller head just spinning on a shaft which makes me wonder what is actually causing this to happen.

 

[justinator]

Correct, but I'm referring to the ease of the stock impeller head to spin on the shaft compared to the shaft breaking on the billet impeller. shear forces here would be much greater to shear a shaft compared to a plastic impeller head just spinning on a shaft which makes me wonder what is actually causing this to happen.

Hard to say but I wouldnt think to far into it, the shaft may have been over hardened and became brittle or some other defect in the manufacturing making it weaker. The one I saw the picture of broke right on the edge of the hole, its fairly thin walls around those holes. Theres probably a suprising amount of thrust force on that impeller at 8-9000rpms.

 

[GT Mills]

We've been flying Vector and Nytro engines on gyrocopters since 2007 (although I prefer RX1 and Apex motors on my personal gyrocopters since they have the rubber harmonic damper, which is perfect for decoupling prop and gearbox harmonics from crankshaft harmonics). We typically run all of the Yamaha Genesis (YG) motors at 7000 - 8500 RPMs all day long, 7000 is minimum cruise speed in flight.

The guys over at Tango Gyro use the Vector and Nytro (YG3) exclusively, all years, while Mohawk Aero Corp (MAC) uses YG4 and YG2 engines exclusively - RX1, Apex and 2007+ Phazers.

My friends flying Tangos have had a lot of these YG3 water pump failures, and burned up several engines or blown the head gaskets at the very least. Some YG3's have even had the same issue twice on the same engine.

A buddy from my Peachstate Rotorcraft Club in Georgia just bought the impeller+shaft from https://www.dasaracing.com/product-p/xx-wpim.htm
and we're all eager to find out how it works for him on his Nytro YG3.

Do the YG4's have the same problems? I've never had this happen on any of mine...

 

[STAIN]

Interesting. Keep us up to date on this if you would. Good to have some summer testing!!

 

[74Nitro]

I've been wrenching on these sleds for years and years, but have yet to see this impeller failure. It is surely something I will watch for however.

 

[Turboflash]

We've been flying Vector and Nytro engines on gyrocopters since 2007 (although I prefer RX1 and Apex motors on my personal gyrocopters since they have the rubber harmonic damper, which is perfect for decoupling prop and gearbox harmonics from crankshaft harmonics). We typically run all of the Yamaha Genesis (YG) motors at 7000 - 8500 RPMs all day long, 7000 is minimum cruise speed in flight.

The guys over at Tango Gyro use the Vector and Nytro (YG3) exclusively, all years, while Mohawk Aero Corp (MAC) uses YG4 and YG2 engines exclusively - RX1, Apex and 2007+ Phazers.

My friends flying Tangos have had a lot of these YG3 water pump failures, and burned up several engines or blown the head gaskets at the very least. Some YG3's have even had the same issue twice on the same engine.

A buddy from my Peachstate Rotorcraft Club in Georgia just bought the impeller+shaft from https://www.dasaracing.com/product-p/xx-wpim.htm
and we're all eager to find out how it works for him on his Nytro YG3.

Do the YG4's have the same problems? I've never had this happen on any of mine...

In this forum, there have been posts from guys who have had water pump impeller failures on the 998 engine. You could do a search and find those posts and pics.