LOW OIL!!!!

[00-NUKE]

YEP!

If it was that bad the engine would have shut itself off. Do the above and u should b fine.

I'm sorry, but that's not correct. If you represent a Yamaha dealership you are giving out very poor advise. If the oil filter starts leaking while the motor is operating the oil pressure available to the motor will drop. With a lower oil pressure for a given RPM the rod bearings will be the first to fail. The low oil pressure switch will NOT shut the engine down until it is too late in this scenario. I am sorry to be the bearer of bad news but if the oil filter leak was substantial enough while the motor was doing 4000+ rpm, the rod bearings will be damaged. You can replace the filter and top it up with oil but it will probably grenade ( it will start knocking and if you continue to run it most likely the center rod will put a hole through the crankcase) within the next 100 miles.

You were dead on. The center connecting rod went right through the bottom the next run. BUMMER! Looks like she'll be getting a new motor.

 

[yamahabandit]

00- Nuke, Ultimate bummer! This is what we should do to the people that designed a snowmobile with oil filter in the most vunerable area. .

 

[09nytro]

That sucks

 

[DV8]

I take it you didnt test the oil pressure for before running it again.
Hopefully you can get it up and going again.

 

[kimoajaj]

Gees this sucks!!

Sorry to hear this... what are you going to do?

 

[kimoajaj]

Hey is it possible to remove the oil pan without removing the engine from the frame?

If so replacing a rod bearing should be easy. But I figure the engine has to come out.. .

 

[Mountaintech]

Re: YEP!

If it was that bad the engine would have shut itself off. Do the above and u should b fine.

I'm sorry, but that's not correct. If you represent a Yamaha dealership you are giving out very poor advise. If the oil filter starts leaking while the motor is operating the oil pressure available to the motor will drop. With a lower oil pressure for a given RPM the rod bearings will be the first to fail. The low oil pressure switch will NOT shut the engine down until it is too late in this scenario. I am sorry to be the bearer of bad news but if the oil filter leak was substantial enough while the motor was doing 4000+ rpm, the rod bearings will be damaged. You can replace the filter and top it up with oil but it will probably grenade ( it will start knocking and if you continue to run it most likely the center rod will put a hole through the crankcase) within the next 100 miles.

You were dead on. The center connecting rod went right through the bottom the next run. BUMMER! Looks like she'll be getting a new motor.

Nuke, sorry to hear the bad news, but it's what I feared. Even a small leak will substantially drop the pressure available. A good example is a pressure washer. Using a larger orifice size in the gun tip will drop the output pressure by hundreds of PSI. A motor that spins at 6,7,8000 rpm needs that oil pressure desperately. A rule of thumb in the old school automotive world used to be 10 PSI per 1000 RPM. If the pressure is inadequate the rod bearings will be the first to fail because of the loading patterns they endure. It's just too bad it's happened again. When I first got my Nytro and crawled underneath it, I realized that there was a real need for proper protection that went beyond the usual plastic skid plates that stacked on top of existing panels.

 

[Mountaintech]

Nuke, how long was your oil filter? Was it 2" or 2 3/4"? Any pics of damage to the filter?

 

[00-NUKE]

Filter

I don't know the length on it. It was aftermarket. Longer that the stock one anyway. I'm going to go get some pics of it tomorrow. I'll try to get them posted.

 

[00-NUKE]

Re: YEP!

If it was that bad the engine would have shut itself off. Do the above and u should b fine.

I'm sorry, but that's not correct. If you represent a Yamaha dealership you are giving out very poor advise. If the oil filter starts leaking while the motor is operating the oil pressure available to the motor will drop. With a lower oil pressure for a given RPM the rod bearings will be the first to fail. The low oil pressure switch will NOT shut the engine down until it is too late in this scenario. I am sorry to be the bearer of bad news but if the oil filter leak was substantial enough while the motor was doing 4000+ rpm, the rod bearings will be damaged. You can replace the filter and top it up with oil but it will probably grenade ( it will start knocking and if you continue to run it most likely the center rod will put a hole through the crankcase) within the next 100 miles.

You were dead on. The center connecting rod went right through the bottom the next run. BUMMER! Looks like she'll be getting a new motor.

Nuke, sorry to hear the bad news, but it's what I feared. Even a small leak will substantially drop the pressure available. A good example is a pressure washer. Using a larger orifice size in the gun tip will drop the output pressure by hundreds of PSI. A motor that spins at 6,7,8000 rpm needs that oil pressure desperately. A rule of thumb in the old school automotive world used to be 10 PSI per 1000 RPM. If the pressure is inadequate the rod bearings will be the first to fail because of the loading patterns they endure. It's just too bad it's happened again. When I first got my Nytro and crawled underneath it, I realized that there was a real need for proper protection that went beyond the usual plastic skid plates that stacked on top of existing panels.

Why would you suspect the rod bearings to go first? I only ask because Progressive had the shop tear down my motor to prove oil starvation and found the top end clean. The technician at Heinens motorsports is saying that the heat load is in the top and that there would have been cyinder scoring if there was a lack of oil. So now Progressive does not want to cover it by saying that there is not sufficient evidence that this is due to oil starvation. Can you provide me with anything that would help this my case?

 

[jamesc]

rod bearings will not survive without a constant supply of oil. the oil provides a hydrodynamic wedge of lubrication between the crankshaft journal and the bearing. as soon as this wedge of oil is gone the bearing is running directly against the journal and bearing failure is imminent. doesn't matter if it's a snowmobile engine or tugboat engine the results are the same. the bearing will fail before the piston scores because of surface loading and bearing speed it's nothing unusual to burn a bearing without scoring pistons and/or bore. the "heat load" is in the cylinder head and top of the piston, the piston heat is transferred to the rings/cylinder wall where it's removed from both the head and cylinder by the cooling system. some piston heat is transfered to the oil, diesel and turbocharged engines will often have nozzles that direct oil spray to the underside of the piston. heat generated by the rod bearings is mostly removed by the oil which in your case wasn't present. the "technician" needs more education about engines and RCFA

 

[canoehead]

Roest is bang on. The after market filters are too long to run with the stock belly pan unless you remove some of the material on the cross-over webs or change to a good after market belly/skid pan. I believe you can even delete installing the stock plastic pan when using one of these which can also allow you to run the longer jobber filters. Other than that stick to stock Yammie filters they're the only ones with enough clearance to give me piece of mind.

 

[Mtnviper]

rod bearings will not survive without a constant supply of oil. the oil provides a hydrodynamic wedge of lubrication between the crankshaft journal and the bearing. as soon as this wedge of oil is gone the bearing is running directly against the journal and bearing failure is imminent. doesn't matter if it's a snowmobile engine or tugboat engine the results are the same. the bearing will fail before the piston scores because of surface loading and bearing speed it's nothing unusual to burn a bearing without scoring pistons and/or bore. the "heat load" is in the cylinder head and top of the piston, the piston heat is transferred to the rings/cylinder wall where it's removed from both the head and cylinder by the cooling system. some piston heat is transfered to the oil, diesel and turbocharged engines will often have nozzles that direct oil spray to the underside of the piston. heat generated by the rod bearings is mostly removed by the oil which in your case wasn't present. the "technician" needs more education about engines and RCFA

X2

99% of the time rod bearings are the first to go when there is an oil starvation issue. Once in awhile a main bearing will let go first, however it is extremely rare and in most cases it was because the rod bearing clearances were already loose, ie a worn out engine.
The top end can live much longer relatively speaking then the main line without oil.

Also if your going to re-use the head, I highly recommend replacing any valves in the cylinders that had a rod/bearning failure. What can happen is when the rod bearing lets go, the piston can travel further up in the bore and stay there for a longer period of time. Allowing the piston to contact the valves and bend them. It only take a very slight bend in the stem for the valve to "hang" in guide. Once the bent valve starts to stick open, the piston starts smacking it. From there it gets worse until the head of the valve breaks off and it's game over for the engine.

 

[09nytro]

Look at the head very close it may have damage , piston will cause a lot of damage to it seen it

 

[cawcislo]

Hey is it possible to remove the oil pan without removing the engine from the frame?

If so replacing a rod bearing should be easy. But I figure the engine has to come out.. .

Even if you pull the pan off you don't get to the rod. It's not like the engine in a car. The crankshaft is sandwiched in between the top and bottom half of the block(case). You basically have to pull the motor, and take it completely apart to get to the rods. Fun stuff.