Inline Breather Valves Revisited

I have a Dorman 80190 one way valve located in my 73's breather line located just to the right of the inner primary cover.
The smaller line coming out of the breather then takes a left and goes up to the oil tank.

A few questions?
Am I correct in assuming that any oil that makes it to the breather either just sits there and collects in the line, or does it actually get pushed through the valve and all the way up to and into the oil tank?

My guess is that oil just sits in the line, either in front of or on the aft side of the valve, because that's where I find oil when I take the breather lines off periodically to check it out.

Does it matter either way?

Also, I did purchase and try the XS650 all metal valve. From the very scientific mouth blowing tests of that and the plastic Dorman valve, the Dorman takes less air pressure to make the valve open up. I concluded the less pressure the better, especially if it is a good thing to get any oil through the valve and get pushed up to and into the tank.

Wrong conclusion? Is one valve for our purposes better than the other?

Appreciate any thoughts.

I have mine up near the top behind the stock air cleaner where the hoses change diameter. It has no trouble blowing all the oil in the sump out of the breather line when I start it after sitting a few weeks. I see a heavy flow at first and then nothing. ('72 Combat)

High Desert,

IIRC, we've gone over this once before. The Dorman you refer to is a vacuum check valve designed to be used in a vacuum brake booster. My experience has been they give up the ghost rather quickly when used as a PCV valve on the Norton. The XS 650 PCV valve may indeed have more forward resistance than the Dorman, but it, the XS valve, works as intended for a very long time. Probably longer than the engine it's venting. I, personally, think the Dorman provides little more than a placebo effect, whereas the XS 650 valve will stop oil leaking from the crankcase, provided the crankcase is properly assembled. Mainly the crankshaft seal is a leaker. Keeping the crankcase from being pressurized will stop that leak and many others, such as the tach drive. I run a belt drive dry, so I know when I'm getting oil in the primary. With the Dorman I had an oily primary. Doing nothing else other than installing a XS 650 PCV valve, my primary runs bone dry. Also the oil leak on the third fin of the head was eliminated. Since you have both, why not try a comparison test? You run that Dorman for a couple of hundred miles and I doubt it will function any more.

Jim, I did do a search and reading of the discussion regarding inline valves but must have missed the part where oil collecting on either side of the valve and not getting to the oil tank was addressed.

With either the Dorman or the XS650, I find oil in the breather line both before and after the valve. Do you take your breather lines off and empty them of collected oil?

I will take your advice on the Dorman valve being wearing out much quicker. Mine has been in for some six months and 2000 miles now, and the motor is leak free. Removing the valve and blowing air through shows that it is still working in both directions properly, so it does not appear to be worn out.
But your comment about the SX650 valve being metal and therefore much more long lasting is a good one. I will put that valve back in place of the Dorman.

Any comments on my above oil in the lines observations that I seem to have missed being discussed previously?

Thank you

It is difficult to blow oil past this valve so to keep crank pressure down using this particular unit, you should have it near the oil tank. It works best for me to have the right angle at the corner of the oil tank for a neater install.
I have had mine for 2 season and it continues to function.
That being said, I installed a MKIII timing cover and upon removing the timing chain inspection cover while running, I was quite surprised as to the amout of pressure still presant.
For the rest of the season, I will not run an inline valve. I will be doing a case mod, amongst other things, this winter. In the mean time I am trying a breather at the timing cover along with the stock unit. Not done yet.

Interesting that your chosen location for the inline valve is the furthest away from the timing cover, in fact right up by the oil tank.

Just from memory, but I thought the general consensus was the opposite, that the closer to the timing cover the more effective at reducing crankcase pressure.

Without any kind of inline valve, any oil coming through the breather seemed to just collect in the line at its low point, and any emulsified oil was pushed up and into the oil tank.

However, with an inline valve or either design, it would seem much more difficult for any oil to get pushed through the valve and then up and into the oil tank.

Right or wrong?

So, choosing to have a valve in place, one should periodically take the breather lines and valve off in order to drain them of any collected, pooled, oil. Make sense or not?

The correct answer is... drill a drain hole in the valve.



xs650-breather-exposed-t7345.html

Jim, I did do a search and reading of the discussion regarding inline valves but must have missed the part where oil collecting on either side of the valve and not getting to the oil tank was addressed.

Click to expand...

My apologies, High Desert. I thought you were referring to the effectiveness of the XS 650 PCV valve versus the Dorman brake booster check valve.

I have to quit reading this forum until after my upcoming trip every time I read something
i get paranoid.

Hi britbike220, yes I agree! And don't read anything by Mr Hobot, he keeps talking about rod bolts breaking !

Hi Desert, Swoosh Daves, comment re a drain hole it the best idea, that way any oil pushed up the hose can dribble back to the sump.
I used a Ducati one way reed valve which has a small drain hole between the reeds. It's easy to blow the reeds open, but doesn't taste nice.



graeme

GRM 450 said:

Hi britbike220, yes I agree! And don't read anything by Mr Hobot, he keeps talking about rod bolts breaking !

Hi Desert, Swoosh Daves, comment re a drain hole it the best idea, that way any oil pushed up the hose can dribble back to the sump.
I used a Ducati one way reed valve which has a small drain hole between the reeds. It's easy to blow the reeds open, but doesn't taste nice.

graeme

Click to expand...

I was thinking about either the BMW or Ducati valve. Can you show more on how you mounted it?

Dave and Graeme, I like what you guys have done by drilling the holes. Makes sense to allow oil to flow back down.

Great ideas, thanks!

Dave, I made an adaptor so is fits in line. They normally screw to the crank case on a Ducati. The hole is already there from Ducati.