Barn of Parts Frozen Roll Over Valve Solution

[hibshman25]

My findings this week indicate that some rollover valves are opening later than others. With my bypass installed, a valve that opens later allows crankcase pressure to build just enough to force oil vapor into combustion chamber which will create some smoke haze. To remedy this I need to hold back a bit more pressure in the tank. so that it forces the rollover valve open sooner.

On next batch of caps I get made I'm going to be changing the hole diameter in the plugs. I have carb jets installed in a cap and am drilling out to different diameters to test. Need to find the right balance to ensure it can bleed off enough pressure at idle during warm up but transition to rollover sooner. I will be finalizing this next week.

At this point I am confident it's ok to install the kits as I now understand what was happening. For kits already shipped, even if not smoking I'm going to be sending out a restrictor to insert inside the line to regulate the bleed off on my bypass line. I'd rather be conservative and have rollover valve taking over sooner.

 

[DennyTuna]

Never in doubt that you wouldn't figure this out, I installed mine anyway.

 

[Phatboyc]

also just put fitting in tank to atmosphere, should work for now

Looking good but did you start your engine to test? My guess is you have constant vapor going to your foot/boot now instead of you bulkhead fitting. Even if hose is just 1/4 is probably the path to least resistance with the ROV spring in place.

Also I think if you do roll your sled over its a good idea to have the end of the blue tube below the oil tank so it doesn't constantly drain the oil when upside down.

 

[Phatboyc]

Again, it's not the roll over valve freezing causing the problem.

Yes its the condensation and sludge but the problem/solutions remains the same?

I read through the original 43 page thread Mike started. No solution is bullet proof. So why not continuing to find a different mouse trap.

 

[HABS 1]

Looking good but did you start your engine to test? My guess is you have constant vapor going to your foot/boot now instead of you bulkhead fitting. Even if hose is just 1/4 is probably the path to least resistance with the ROV spring in place.

Also I think if you do roll your sled over its a good idea to have the end of the blue tube below the oil tank so it doesn't constantly drain the oil when upside down.

never started no, ill see , i might put to valve cover with other fitting and restrictor, see how it goes! just knowing it wont blow tank seal is good for me

 

[DennyTuna]

I have started mine a few times as well as my buddy's 18 Tcat and we have not seen any plume of white smoke.

 

[NYTurbo]

Yes its the condensation and sludge but the problem/solutions remains the same?

I read through the original 43 page thread Mike started. No solution is bullet proof. So why not continuing to find a different mouse trap.

The problem is not the roll over valve freezing , it's moisture build up in hose leading to the roll over valve that freezes over night, then you fire it up in the morning and the hose is frozen . Best solution for a trail sled is a simple chunk of hose looped up and down and out which is being used by a lot of 998 owners with zero issues. Also with this set up on a cold morning all you have to do is start the sled , have a look at where it exits and you'll see the hose venting . Also keeps all the sludge and residue out of your intake.

 

[1nc 2000]

Just like NYturbo said and many others have done.
With the breather hose routed like this it has it benefits. Lay the sled on the right side, no oil runs out as the hose curves inward toward the steering stem.
Left side no oil comes out due to location of fitting on top of tank.
Up side down very little comes out due to the hose going below the bottom of the tank.
Don't forget to cut the breather hose at an angle also.
Not my design but copied from others on this site.
Also no more oil in the intake, cooler and sensor hoses.

 

[DMCTurbo]

Still running my 17 stock. Never had an issue in 8500 miles.

 

[Janne339]

 

[hibshman25]

Did some more testing and I think I've got this pretty much wrapped up. I found some Mikuni jets that are a snug fit inside the bypass hose and tried some different sizes. I've got it sized so that the bypass can bleed off enough pressure at idle so there is no pressure build up if the rollover valve is frozen shut. At 2300 RPM that tank will build 1psi of pressure which then forces the rollover valve to take over if functioning. While simulating a stuck valve At 3500 rpm there 5psi of pressure in tank, and at 4500 rpm 8psi.

On my current test sled here in shop, with no restrictor the tank only builds enough pressure to open rollover valve at around 8400 rpm so all the tank pressure is going to the the valve cover. For whatever reason the 2 year test sled had no issue with this. Part of me suspects that some engines, especially lower mileage engines have more blow by so there is is more pressure to begin with in the crankcase. As mentioned before a variance in the spring tensioner on the valve spring could likely play a factor too.

The restrictor will ensure that minimal pressure is going to the valve cover, but still vent enough to prevent pressure build up at idle during the cold morning start ups when valve could be froze. I would bet most let the sled sit and idle for several minutes until up to operating temp which would be sufficient for heated valves to thaw and most likely even non heated valves. Even if you move sled around when not fully warmed up the bypass will minimize the extreme pressure build up.

I've compiled a list of customers who already have the kit and hope to start shipping the jets out next week.

 

[Phatboyc]

What you have done will work just fine and will minimize oil loss during a rollover as the hose is only 1/4 diameter.

Since I already bought the BOP bypass, I'm now thinking of using just using the end that screws to the oil tank and vent it to atmosphere. Similar to drilling small holes in the ROV. Should work?

Warning. Do not do like I did and vent the BOP bypass to vent to atmosphere. I was loosing 1 liter of oil in 200km! This is Habs1 pictured but I was setup the same.

Travis knows about this from me a month ago but he is probably very busy so I though I would update this thread. His updated tube with jets inserts would of probably been fine.

 

[Confused]

View attachment 165746


Warning. Do not do like I did and vent the BOP bypass to vent to atmosphere. I was loosing 1 liter of oil in 200km! This is Habs1 pictured but I was setup the same.

Travis knows about this from me a month ago but he is probably very busy so I though I would update this thread. His updated tube with jets inserts would of probably been fine.

So venting to the valve cover is still the recommended method? I questioned this some when I installed mine. Correct me if I'm wrong, but I thought part of the dry sump system was the scavenge pump creating a minor vacuum in the crank case which would assist piston travel?

 

[Phatboyc]

So venting to the valve cover is still the recommended method?

I can only assist in answering your first question. Travis's fix has always been to vent to vavle cover. I was just experimenting with his blessing. But it turns out my idea was not a good one.

 

[Turboflash]

So venting to the valve cover is still the recommended method? I questioned this some when I installed mine. Correct me if I'm wrong, but I thought part of the dry sump system was the scavenge pump creating a minor vacuum in the crank case which would assist piston travel?

Ring seal is not perfect. There will always be a small amount of blow-by, even in the best engines. (This is what a cylinder leak-down test shows - how well the rings are sealed). Also, as the engine oil is heated, it expands and generates some oil mist/fumes/vapor. There is a small amount of pressure in crankcase/engine. That's the reason for the vent line that goes from valve cover to airbox.