HarleyTechTalk

So on my 86 Softail I have trans fluid coming out the breather tube. It's been this way since I rebuilt the bike back in 07.
I've tried heavier gear lube, a longer breather tube that reaches up higher instead of one that points down, my thinking here was that it might harder for the fluid to climb up the tube and i put a breather filter on the tube also.
Still got a leak. If i'm on the highway and kicking it up some then it leaks more. At the time i rebuilt the bike i put on a chrome tranny top cover. I think the stock cover had a vent hole in it. Is this true ? The chrome cover has no vent hole that I can see.  Can this be the reason for the leak ? Or what ? :

That rubber tube is the vent. How much lube you running in trans.?
Paul

 

Which breather tube?   Ideally there should be three - Engine case, trans cover, and primary.   Primary vent is u-shaped and sits in the channel between inner primary and trans.  If you have no breather tube in trans cover, the trans should blow off some of it's pressure through the mainshaft. 

RE READING your first post...

The Tranny Needs and Should have a top vent tube like describe by   rageglide
Usually working good, I find that tranny's find their OWN correct level... Yes your bike is Older but I have Found that true for many years.

I will ONLY use Redline Shockproof Heavy in any of my rides over the years.

Using the correct amount the spitting out the overflow Vent tube is still not uncommon.

I would keep an eye on the level and allow it to Seek the level it needs... As long as it shows on the dip-stick and you know Lube is there IT will probably Quit in a short while...  Adding More when needed BUT not wanted (finding it's own level) will not help here. It will Just keep spitting...

Were/Are you using A Light Motor Oil? or a GEAR LUBE in the first place? the final number on the Viscosity of a GEAR Lube should be at least 140... Redline SP shows 250...

Try to out wait and allow it to SEEK the level it WILL run in...

ADDED? Was it OK before that added Chrome cover? IF SO Change back.

Just My Way...

signed....BUBBIE

I've got the fluid up to the full mark on the dip stick. Could it still be too full ?  So a vent hole should not matter. This is what I thought from the beginning. I'm using 140 gear lube and it's coming out the tranny vent tube.
I've thought for some time it's finding it's own correct level. 
 

What does you bike call out for the Amount needed for your year tranny?

Shorting that amount by 6 oz. IF it seeks its level there should not be a problem.

signed....BUBBIE

Quote from: sneakypete on July 24, 2015, 12:23:38 PM
I've got the fluid up to the full mark on the dip stick. Could it still be too full ?  So a vent hole should not matter. This is what I thought from the beginning. I'm using 140 gear lube and it's coming out the tranny vent tube.
I've thought for some time it's finding it's own correct level. 

The bike should be upright when checking dip stick.

My older bike had Problems like yours. Filling to the full line SPIT....After a few rides, it would stop Spitting out through the vent tube and was HAPPY...

Like Max said Checking it properly is important and Then letting it Spit some is OKAY...

signed....BUBBIE

Well I just checked it on the table and the fluid is hardly registering so after yesterdays ride it seems to have blown out more then it should have. Maybe I'll try heavier gear fluid.

Where's the pressure coming from?

My '86 softail took 28oz of trans lube.  Never checked the level.  Never spewed from trans, but did have a leaky inner primary because I was too cheap to replace it or get the inner seal surface re-machined.

Now that I think about it, the primary may have vented via the external mounted bendix...  Trans through the trans top cover.

Add to Max's comment... Sidestand, AND the dip stick NOT screwed in... totally hokey set up, hence why I put in 28oz and forget about it.

Glens, I don't know where the pressure is coming from but something is pushing the fluid out...
I went back on the records I keep and this bike had Valvoline 75/140 in it.

Not being empty....Try a ride with Oil in the lower position to see IF it stopped spitting... It may be right where it needs to be.
You can dip a dowel rod or ? into the tranny to see the level right now...

I doubt a Heavier lube will do any different.

signed....BUBBIE

ALSO; drain it and measure it.... (just to see how much is left there) before you add to it...

MIGHT the old top have had a cover deflector so oil didn't Just blow out the vent tube? can you look at the original or is it gone...

With a screw driver stuck down in the trans it's reading about 1/4 in. The only fluid on the dip stick is barley on the tip of the dip stick. Fluid is present but below the dip stick.

bubbie, the old top might very well have had some kind of inner cover on it. I'd have to go dig it out and have a look.

So I found the old cover and in front of the vent hole theres an aluminum tab that looks like it might very well keep the fluid from getting to the vent tube. maybe thats what the deal is. I don't remember if the new cover had that. even still the tab doesn't block the vent hole, you'd think fluid could still make it's way around it and out. Maybe it's enough ?   

QuoteMy '86 softail took 28oz of trans lube.

That is a lot for an early 5 speed.

On Sneakys 86 if the Primary isn't vented or the vent is blocked or non functional then isn't it going to vent through the mainshaft to the trannie?

So the trans top Does have a vent?  I am totally confused...

If it doesn't have a vent, when was the last time you looked in your primary?  28-32oz of fluid would make one hell of a mess if it's coming out the vent and blowing all over the bike.

add - FSG, Maybe it was 22oz... In my defense it's been about 20yrs since i sold it... :-)

FSG, I don't think the vent is blocked because theres fluid coming out so it seems to open. Other wise the motor, trans and primary are as tight as thermos bottle. no leaks anywhere.


rageglide, The trans is vented. Thats where the fluid is coming out. The question is why ?

Just pulled the derby cover checked the primary fluid level and it's where it should be. So primary fluid ain't going that-a-way. To trans.

Ok... in your original post you said there was no vent in the new cover... hence confusion and several of us asking what vent.

Then as FSG noted, if your primary is rock solid sealed without a vent it Will vent through the mainshaft into trans and may be making the problem worse.

Sneaky, my isn't vented or the vent is blocked or non functional  was in reference to the Primary Vent, not to the Trannie Vent.

Built up pressure in the primary has to go somewhere and if it isn't vented separately to atmosphere then it has nowhere else to go except into the trannie and push trannie fluid out along the way to atmosphere.


Rage   

I apologize  for the misunderstanding, originally I was talking about a small pin hole that I thought was in the stock cover and might have been a vent hole but there is no such thing and so the only vent we're talking about is the vent tube on the trans lid.
After I dug up the stock cover I realized i made a mistake.
At this point I did notice a defector tab on the stock cover that may keep the fluid from coming out. other wise i'm wondering whats pushing the fluid out.

QuoteIt's been this way since I rebuilt the bike back in 07.

With a sealed primary all that is needed is the vent tube on the trannie lid.

Pressure is pushing the oil out, so where is it coming from? 

Is the crank seal leaking pressure into the primary?  What exactly got rebuilt back in 07?

The motor got rebuilt. I took the entire bike down to the ground. The only work i did on the trans was to adjust the shifting paw and put on two chrome covers, side and top.