Oil tank venting/vented dipstick experiences

[BTraci]

Wanted to pass-on my recent experiences with venting my oil tank (using an A1 Cycles/M3 vented dipstick, but applies to any of the various solutions for this).  Since going from a 95 to 117 in 2011, I've had chronic problems with excessive oil from the head breathers that I've struggled to address.  After long runs @ high rpm, I'd often lose 200ml of oil out the breathers in less than 50 miles of running.  I went to external breathers and eventually a catch can so I wouldn't soak the rear tire, and the catch can needed daily draining.  After high-rpm runs, the motor struggled to idle and would often stall if not kept at an elevated rpm.  I tore the top end down to ensure ring seal was good, and could never find a fix for this, just band-aids to contain the mess.  Having seen the videos by T-man and Mike Beland explaining how large motors create pressue in the motor, on a lark I ordered the vented dipstick (easiest and cheapest of the manufactured solutions, or can be home-fabbed, but each has their pros and cons).  Since installation, oil flow from the head breathers to the catch can even after extended high rpm running is minimal, the motor has no problems idling and no more symptoms of sumping, and has finally addressed 99% of the challenges I've had with this motor for almost a decade. 

I wanted to pass this on for others struggling with oil control with a bored/stroked motor--I was very skeptical that such a simple change would be so effective, but I've been pleasantly shocked with how effective this has been at fixing a systemic enduring problem.   Best bang-for-the-buck mod I've done to this bike.

[chaos901]

One question please, and I do believe you know the correct answer. 

When you put oil in your engine you do not fill it all the way to the full line do you? 

[BTraci]

Always 1 - 1.5 quarts low

[Admiral Akbar]

What year and model?

Does the breather have a 1 way valve in it?

[BTraci]

03 Road King.  No one-way valve, just a K&N-type filter on the end. 

[Admiral Akbar]

03 Road King.  No one-way valve, just a K&N-type filter on the end.

Thanks.

[jmorton10]

What would be the pros/cons of drilling & tapping a hole in the filler neck, screwing in a hose nipple & using $.20 worth of hose & a $5 K&N filter (or whatever they cost now?)

~John

[kd]

John, IIRC Ray did that and included some pics in a thread.  It may have been someone else but I'm quite sure I saw it here.

[kouack]

Or drill and tap about a 1 inch lower the filler neck, run a hose to the back like the kit zippers is selling!

[road-dawgs1]

 I vented my 19. Since it's a twin cooled, it doesn't have the oil return line as the oil cooled models do. That said, I took the dummy plug where the oil return line would go and bought pn# 62700146 which is the fitting for the oil return and ran a hose up under the right side cover and to a filter. It fits nicely next to the ABS module. I suppose I could have simply drilled the dummy plug, installed a barb fitting and ran a hose from that as well, but the H-D fitting was only $7.

[No Cents]

 I did vent mine
[attach=0,msg1346014]
it's routed up the frame and along the rear fender strut with a 1-way check valve in the middle...then more hose from the valve that connects to a small filter on the end of the hose that I mounted as low as I could in the rear.   

[kd]

Ray, is that just 3/8 hose?  What is that 90 degree fitting assembly from and where did you get it?  I don't really feel I have an issue even running hard over distance but I may get bored one day and if I had the fittings .... well you know.   

[No Cents]

  yes...it is 3/8" hose. I bought the an fittings and the one way check valve all off E-Bay.
They are:
1) 1/8" NPT to 4 an straight pipe thread fitting. $4.75   
2) a 4an 90* swivel to 3/8" hose end fitting. $7.99
3) a one way barbed ended check valve. $5.08
4) 5 foot of 3/8" hose.
5) I already had the filter...but they can be had for around $5.00

[road-dawgs1]

Is a check valve necessary? I didn't use on in my setup.

[No Cents]

  I put the one way check valve in so no built up moisture could flow back to the oil tank. In theory it lets the vent hose only vent one way toward the filter on the end. I don't know if it was necessary...but I figured it couldn't hurt.     I've been known to sometimes take things to the extremes.

[PoorUB]

I would use a check valve. You want air leaving the crankcase and oil tank, not coming back in. In theory the crankcase should run at a slight vacuum.

[No Cents]

  a look at the one way valve and where I mounted the filter. You can't see them unless the bag is off.

[attach=0]

[Don D]

Is any pressure going to come out the head breathers after this mod?

[jmorton10]

I was wondering that too ??

~John

[No Cents]

Is any pressure going to come out the head breathers after this mod?

  according to my catch can...it says yes.

[Don D]

What if you could do away with the head breathers and catch can? Just for the sake of discussion

[Hossamania]

Then it would puke out by the back wheel like the early Evos?

[PoorUB]

You probably could block the head breathers as long as you make up the difference elsewhere.

[No Cents]

   I just like the idea of both the head breathers and the oil pan/crankcase having the ability to exhale.    I don't want any addition pressure being built up. If I can relieve it in a safe way...I will.

[hogpipes1]

Two lungs on exhale are better than one.

[cheech]

You probably could block the head breathers as long as you make up the difference elsewhere.

IMHO The oil sump breather mod is making up for what the heads can't keep up with after engine mods.
I have a Bigdog with a S&S 107. They utilize the head breathers and the case vent like earlier Evo's, both going to the air cleaner backing plate.

[Don D]

Consider a gauge and testing. A 100 Kpa gauge could be used to measure crankcase pressure, connected just for testing. There is no windage to speak of at the inlet spout.
Along this path of hot rodding things evolve. Consider that S&S now offers their crate motors with their 3 stage pump and Harley head breathers instead of their rubber flapper. Must have been a reason for that. Just hanging hoses and hardware will work too. 

[turboprop]

1. The oil pump pumps oil and air to the oil tank. In oem form, the ir in the oil tank is rebased via the vent line between the oil tank and engine case.

2. Piston blowby is expelled via the head vents.

3. Blocking off the head vents in conjunction with adding a vent line to the oil tank will not be good, but the engine/oil tank vent line can be removed and the holes in the trans and engine cases blocked off.

4. Paul Morris and I myself have been running this setup on out TC 124" engines for a couple of years. Works great.

5. Those of you with supplemental oil tank vents can do a simple experiment and see for yourself. Simply pinch off the vent line. Watch it idle for a few minutes and then if everything s alright, go for a ride. If something goes wrong simply remove the clamp on the vent line.

[HDDOC]

I vented my 19. Since it's a twin cooled, it doesn't have the oil return line as the oil cooled models do. That said, I took the dummy plug where the oil return line would go and bought pn# 62700146 which is the fitting for the oil return and ran a hose up under the right side cover and to a filter. It fits nicely next to the ABS module. I suppose I could have simply drilled the dummy plug, installed a barb fitting and ran a hose from that as well, but the H-D fitting was only $7.

I like this mod you did, How well does it vent and do you have to run your oil level low to keep the oil from puking out the filter you installed  ?   Thanks Doc

[road-dawgs1]

I vented my 19. Since it's a twin cooled, it doesn't have the oil return line as the oil cooled models do. That said, I took the dummy plug where the oil return line would go and bought pn# 62700146 which is the fitting for the oil return and ran a hose up under the right side cover and to a filter. It fits nicely next to the ABS module. I suppose I could have simply drilled the dummy plug, installed a barb fitting and ran a hose from that as well, but the H-D fitting was only $7.

I like this mod you did, How well does it vent and do you have to run your oil level low to keep the oil from puking out the filter you installed  ?   Thanks Doc

It vents well. When I took the dummy plug off the case I used a flashlight to verify that it indeed shared the same space as where the oil fill spout goes. I could see where the cavities meet. I'm running the usual amount of oil that I was prior to the mod and no issues.

[HDDOC]

Thanks for the reply, Did you try the Dipstick vent before trying the oil line return plug ? Reason I ask is the dipstick vent blows oil all over the place if the oil level is full have to run it at 4 qts or lower

[road-dawgs1]

Thanks for the reply, Did you try the Dipstick vent before trying the oil line return plug ? Reason I ask is the dipstick vent blows oil all over the place if the oil level is full have to run it at 4 qts or lower

I didn't try any other methods, just this one as it was minimal money and does the same thing as the higher priced dipstick doo-dads

[HDDOC]

Thank You Road Dawg 

[HDDOC]

My 2019 Tri glide has the breather vented to the ground external , A friend gave me a A-1 ventilator to try , So I tried it out , It vents great with a pulse like the older engines did, I have noticed that now the head breathers now have a slight vacuum when I put my finger on the vent hose from the head breathers which I though very strange as the head breathers have a one way valve in them. I will say that the stock M-8 breahers never gave a pulse feel to them and vented very little in my opinion . What is everyones thoughts on this    Thanks Doc

[Ottawaair]

Imo, every motor should have crankcase venting. 
Pull out the dipstick and start the motor.  You'll see/feel the pressure coming out.
Having only small breathers on the heads is not enough.  Especially when a modified motor.

Most race bikes, and some cars I've seen,  actually have a "pan pressure " gauge. 

They can see what the motor is doing by knowing the pressure in the oil pan/crankcase.
Example,  cracked piston, broken ring, clogged vent, etc....  the pan pressure is an indication of a problem. 

[Rokinrider]

I installed the A1 vent plug. Playing with my oil level so it doesn't spew and it has not yet, I'm 3 dots down hot on the dipstick. No temp readings to back it but the bike runs a little cooler and seems happier. 17 RG stage 2, RS 468, HD Ventillator AC, Fuel Moto slip ons and Tune using PV-2. Runs great, I was getting oil seeping by my dip stick. No big deal to pull cap and insert dip stick? Just not sure where the final resting place will be for the outlet?

[Jim Bronson]

It has been about 200 mi since installing an A1 vent plug, and I see no oil leakage while running about 3 dots down on the dipstick.

[Bagger]

For those that don't want to piece parts together, Feuling offers these kits, albeit high price

https://www.feulingparts.com/product?category1=OIL+TANK+BREATHERS

[jmorton10]

WOW those prices are ridiculous !!

~John

[wfolarry]

I've been running a quart low since my Shovehead days. Fill up the oil tank & it would blow it right out. Quart low didn't use a drop.
I like the breather combination turboprop suggested. Might do that on my own bike when I replace all the oil lines.

[Rob L]

I just made an oil cap vent for my 124. I had and old broken dipstick I used and I bought a small breather filter from my local auto parts store. I got about $17. into it. I havent had a chance to get a good run with it on but in thinking it'll be fine now