Sand in motor (12 WR450)

TWHeat:

 

Altho I'm very sad to have learned of this design "feature" on your shoulders, I'm delighted you've told us (me) about it.

 

Thanks very much for the education.

Ok I'm back at it. Got the cases split yesterday. Oil pump has scoring on it. That will need to be replaced. Crank seems to be fine. Measured it for wear and tolerance and its well within for everything. Not sure I want to dole out the money for a new crank. One main bearing is toast, has sand in it and you can hear it when you spin the bearing. I'll be replacing both of them. Theres a few more bearings in that lower end in the cases that spin and sound fine but seeing the main bearing with sand in it makes me wonder if I should just replace them all.

 

I also called Yamaha to file a design flaw complaint after a recommendation of my dealer. Yamaha's response: "That's the risk you take riding in the sand." I knew that one was coming but I have ridden the sand for decades with zero issues what so ever.

 

Anyways, thats where I'm at. Ill update as I go a long.

The person I spoke to had no understanding of what the issue was. He had a schmatic on his computer as did I and I pointed out the parts and he still didn't seem to get it or know what to say. In the end I wasn't looking for anything other than them to take a complaint and thats what they did (they say). For now I will rebuild the motor, add a crankcase breather filter and move on.

It's been a big problem on YZ's for years.  I just bought an '09 and it stalled twice on first ride going through high water.  Came home and changed the oil.  Found a tiny amount of silt.  Next thing I did was reroute the breather line into the air box and put a filter on the end.  This thread should be a sticky somewhere on this WR forum.  That's how I found the issue on the YZ forum.

Ok I'm back at it. Got the cases split yesterday. Oil pump has scoring on it. That will need to be replaced. Crank seems to be fine. Measured it for wear and tolerance and its well within for everything. Not sure I want to dole out the money for a new crank. One main bearing is toast, has sand in it and you can hear it when you spin the bearing. I'll be replacing both of them. Theres a few more bearings in that lower end in the cases that spin and sound fine but seeing the main bearing with sand in it makes me wonder if I should just replace them all.

 

Yes you should.   You'll also have to pressure flush all the oil galleries in the engine or you'll have the same problem when you start it up again.

 

I'm unclear on something.   You found sand in the hose going to the starter breather port.   Did it come in through the air box ?  Did sand get into the air box ?

Yes, found sand in the breather hose going to the starter one way. It is plugged into the airbox. Before I left for the trip I put an oiled airfilter outerware over the airfilter as an extra layer of protection. When I got home I went to remove it and there was sand all over it and a little bit in the bottom, so yes thats how it entered. The thing that gets me is really anything can get into the airbox and pass down that tube. Just seems like a weird design. I'm pretty sure my old Yamaha YFZ450 ATV had the breathers on the clean side of the filter.

Don't know about YFZ's but Suzuki DRZ400's vent to the clean side of the air filter

My Raptor 700 vents to the dirty side.

Edited by vlxjim

I question if the sand could have entered the motor through this route. First of all this tube blows not sucks. Also if you follow the routing of the tube it be very hard for that much sand to make it that far.

I question if the sand could have entered the motor through this route. First of all this tube blows not sucks. Also if you follow the routing of the tube it be very hard for that much sand to make it that far.

 

Unfortunately you are incorrect

This tube suck and blows 449cm of air every time the piston rises and falls

Its job is to vent this air movement to reduce pumping losses which reduce the hp of the engine

Without it, the crankcase would be pressurised every time the piston went down, and a vacuum created every time the piston rose which would try to suck air past the rings.

 

On multi cylinder engines, they open up the passage way between the cylinders so they cancel each other out - as one oiston rises, the other is falling so the air is merely pushed around.

This is not possible on a single cylinder engine

It is entire possibly for sand to be sucked into the engine via this hose

I have been educated. Thanks

Unfortunately you are incorrect

This tube suck and blows 449cm of air every time the piston rises and falls

Its job is to vent this air movement to reduce pumping losses which reduce the hp of the engine

Without it, the crankcase would be pressurised every time the piston went down, and a vacuum created every time the piston rose which would try to suck air past the rings.

On multi cylinder engines, they open up the passage way between the cylinders so they cancel each other out - as one oiston rises, the other is falling so the air is merely pushed around.

This is not possible on a single cylinder engine

It is entire possibly for sand to be sucked into the engine via this hose

Just been thinking and I'm no engineer but if this hose is reasonably long and I'm thinking the constant inhale and exhale from this hose caused by the piston/ motor are happening very fast and short then I also wonder haw sand would make it all the way up the hose to the engine, I would think the engine would have to take a very deep breath in to suck sand the full length of the hose other wise what sand does get sucked in the hose would most likely also get

winblown back out,

Not saying it didn't happen and couldn't happen but was just thinking

^^^^

Kinda what I was thinking. Also thinking that every wr in Michigan would have fallen to the same fate by now. With that said I have taken steps to prevent sand from entering my motor through this tube.

Just pulled mine from the air box. Stuffed some PVC replacement foam in the end and threaded safety wire through it and the hose so there's no possibility of it getting sucked in. Then rerouted up under the seat. Around battery and tied it near the o2 sensor at top of airbox. Question is what will happen to motor if this tube gets kinked or flow has been constricted too much. Blown seal or something? Will bike run bad when plugged before something get ruined?

I was thinking the same thing until yesterday.  Plus I always thought that engines mostly breathed out when they ran.

 

Yesterday I pulled the valve cover off my WR to check the valve clearances.   I found a bunch of dirt particles (loam) scattered around the valve train.   At first I thought maybe I dropped it in when I pulled the cover, but then I realized it was oil soaked dirt.  The valve train was dry by the time I pulled the cover.

 

Then I inspected the underside of the valve cover where the breather attaches.   It had a bunch of oil soaked grit on the side.  I also found that the surface of one of the valve buckets was all marked up.   I can't be sure it was caused by debris that came in from the breather, but I can't rule it out either.

 

I don't know how yet, but I'm going to put a filter on the breather hose of my bike.

 All the EPA restricted japanese enduros (and some mx bikes) have the same issue

 

When you take it off road beyond just a fire road, you have to prep the bike for extreme conditions.  If you think you might encounter more that 10" of water, you had better be prepared.

 

One of those prep items is to re-route all crankcase breathers to end either above the tank, or inside the dirty side of the airbox (and re-route carb'd bike breather hoses, and dielectric grease the electrical connections, and anti-sieze all the bi-metal fastening points)

 

This has been the case since about 1974.........

 

Please, please don't try and make this a 'bad design' issue, when these manufactuers are up against EPA and DOT scrutiny like you have no idea. 

You are not entitled to something you are not even aware of to begin with....that's just dumb. 

They do the best they can without making the bike cost too much. 

 

It's your bike, you need to know exactly what it needs, before being ridden. 

All the EPA restricted japanese enduros (and some mx bikes) have the same issue

When you take it off road beyond just a fire road, you have to prep the bike for extreme conditions. If you think you might encounter more that 10" of water, you had better be prepared.

One of those prep items is to re-route all crankcase breathers to end either above the tank, or inside the dirty side of the airbox (and re-route carb'd bike breather hoses, and dielectric grease the electrical connections, and anti-sieze all the bi-metal fastening points)

This has been the case since about 1974.........

Please, please don't try and make this a 'bad design' issue, when these manufactuers are up against EPA and DOT scrutiny like you have no idea.

You are not entitled to something you are not even aware of to begin with....that's just dumb.

They do the best they can without making the bike cost too much.

It's your bike, you need to know exactly what it needs, before being ridden.

I hear ya krannie. Took your advise. Filtered it and rerouted into top of airbox. grease on all my connections( damn that sub frame is pain to get off). What's my engine gonna do if I kinked the breather hose while rerouting it?

Just been thinking and I'm no engineer but if this hose is reasonably long and I'm thinking the constant inhale and exhale from this hose caused by the piston/ motor are happening very fast and short then I also wonder haw sand would make it all the way up the hose to the engine, I would think the engine would have to take a very deep breath in to suck sand the full length of the hose other wise what sand does get sucked in the hose would most likely also get

winblown back out,

Not saying it didn't happen and couldn't happen but was just thinking

 

The tube isn't long enough to contain 449cm of air, which is what gets sucked in when the piston rises from BDC to TDC, and so some air from the atmosphere will get sucked in as well

There's enough evidence to suggest this can and does happen

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