Can't be lost on a Harley as long as there is road in front of you.

The vent valves are one way rubber diaphragm check valves. Out only. If you look careful at the flow chart you will see this. The old evo's had a cylindrical rotary valve driven off the cam gear for this system. Not sure if it worked but a lot more trouble for Harley to build. We keep complaining enough and sales will probably go to a full PVC system and water cooled? HA.

 

1. I do not believe it is possible for oil to drain back into the engine case while the engine is running...I believe the intake can suck excess oil out of this hole...don't think the oil gravity drains back into the case against the force of the vacuum effect.

2. I believe excess oil that gets foamed up, can escape into the intake thru the case vent lines that are routed into the intake.

I can make this happen on my bike by filling the engine oil to the max level while cold. I can get this to stop on my bike by brining the fill line while hot to the lower line of the fill point.

sorry if I confused this thread. I did have this problem and after talking to folks who also had this problem, did the changes to my oil level. I think I run a half a quart low using the dip stick as an indicator, but I am not worried about that since I have an oil cooler and thing the oil in the oil cooler closes that gap a bit.

 

If a piece of a tensioner broke off and plugged up an oil hole that might cause some oil problems. That was what I was referring to in my post. I agree that one needs to determine whether it is simply blow-by or an actual "gushing."

 

If it is 'blow-by', it is extreme blow-by

 

If it's the size of a return hole, why now, after 11 years?

 

In any event, if you have 40k on a pre 07 bike you better be checking the cam chain tensioners. I'd update it to the SE hydraulic upgrade kit which includes a higher flow oil pump and whilst I was in there I'd drill the rocker supports with a #43 drill bit to make the oil return hole slightly larger. That would also give you a chance to check/change everything else out as you go (breather baffles, oil feed o-rings, etc.)

 

What year is your bike? Does it still have the old crappy plastic breather baffles in it?

 

I've seen twin cams with the old spring load tensioners with a lot less miles than 40k on them with the tensioners completely gone. Down to the spring and the backing that the shoe sets on. Just for peace of mind, why not just open the cam chest and take a look?

 

Hole or plugged = no hole, plugged up with chunk of RTV or cam chain guide (doubt it the later since a chunk that big would never get there--even the small chunks stay in there because Harley designed the cam chest to keep it there) The top area were the valve springs go goes from pressure to slight vacuum depending on were the piston is. if you have ever hooked a vacuum gage up to the intake of a v-twin you will realize what I am talking about. Unlike a car that holds it steady at a constant rpm, V-twins at idle rocks the needle like a yo yo. that is why the vent valve is one way. Its designed as a back up if one hoses broke or someone took it out and just hung it down, with out the baffles it would pull dirt into the engine.

 

at higher rpm those pulses become a constant pull..... having a piece of foreign material in the return hole doesn't make sense as the puking is intermitent......if the hole was plugged it would puke constantly regardless of engine speed .......MAYBE ???????at a certain rpm those little rubber valves reach a harmonic speed and stay open ??????????? but he did say he had new ones installed and it still did it ...?????????