Post installation of Comnoz Sump Breather (71 norton)

OK I thought I would start up a thread dedicated to this since he is kind enough to send a breather to me for the try and buy situation. My situation here is that my bike seems to run great for about 50 miles then the sump fills and subsequently pressure forces oil past the crankcase oil seal into the primary. This in turn causes the primary to fill to the chain height and then oil is shot out the primary resulting in the rear half of the bike getting soaked. This is not a good thing when you are 50mi away!

So I had a earlier thread askjing about breathers and such and Comnoz introduces this Sump Breather and the product looks really promising. I am very excited to try it. If this is the fix then I will be happy for a hwile until I break something else!

I decided on making this thread ahead of getting the breather to report some numbers to the group about how the bike has ended up after the trip where the last time the primary filled etc...

The bike has been sitting a few days but here is the findings I have on fluid levels.




Primary: I opened this up and drained it then measured this. Originally I had ATF in there and when I drained it there seemed to be no trace of red in the fluid. I suspect that has been forced out the last so odd miles... 300cc of oil was left in the primary. I am thinking though there is bad news o nthe primary getting filled that maybe the silver lining is the primary isnt filling while the bike is sitting. I believe I only have one thing to look for, pressure while bike is hot pushing the oil into primary.



Sump: 700cc!! of oil in the sump. I believe that constitutes wet sumping? :?

Oil dipstick level: I started out with the dipstick at the halfway mark between L-H and as I check it now its way below the L mark. When I stopped the bike at the end of the ride a few days ago it was right above the L mark.






I am using Rotella 15w-40 oil in the bike now. I saw 50 weight in the autozone and am thinking of trying that later on....

Test ride: Once I get the sump breather I will get it installed and top off the oil to an acceptable level then prepare for a ride. I have a 34mi each way ride to work so I will give that a shot the day after I install the breather. After that I will report my findings. I am definitely hopeful the breather irons out my issues.

Cheers, and once again thanks for sending gthe breather Com, I really appreciate the help you and all the others in this board give to us. It seems in the Commando world theres a couple types... The guys that know and the guys that want to know. All so far have been great people! (I think I will be a "want to know" for years to come!)

Re: Pre installation of Comnoz Sump Breather (71 norton)

Sounds like you have scavenge pump issues.

Better have a close look at that pump, and the scavenge return pipe back to the tank, it may be restricted...

Re: Pre installation of Comnoz Sump Breather (71 norton)

If you want to use SAE50 get the VR-1 Valvoline racing oil. I doubt if it will help the sumping, but it sure comes out of the return nice.

Dave
69S

Re: Pre installation of Comnoz Sump Breather (71 norton)

grandpaul said:

Sounds like you have scavenge pump issues.

Better have a close look at that pump, and the scavenge return pipe back to the tank, it may be restricted...

Click to expand...

Even if it only happens after 50miles? I would think that if the pump or line was messed that the issue would be immediate?

Re: Pre installation of Comnoz Sump Breather (71 norton)

All I can add to this is that I installed one of Jim's breathers in my 71. I have none of the symptoms that your bike has, but it does make a difference, especially if it sits for a few days and lots of oil ends up in the sump. It ends up back in the tank sooner than the oil pump alone will return it. I'm far from a Commando expert, but it sounds to me like you have something else going on as sugested in the other responces to you post. Either way you I don't think you'll be sorry installing Jim's breather.
HTH
MIkeG

Re: Pre installation of Comnoz Sump Breather (71 norton)

Just to be clear here, crank beather modifications and wet sumping are NOT related. Two separate issue, two different solutions.

Re: Pre installation of Comnoz Sump Breather (71 norton)

pvisseriii said:

Just to be clear here, crank beather modifications and wet sumping are NOT related. Two separate issue, two different solutions.

Click to expand...

I am afraid the sumping is happening during ridng, thats where I am getting confused. It seems to run great for afternoon jaunts but when I want to ride more than 50 miles the oil sneaks its way into the primary via the crank seal.

I can pull the hoses or pop the oil top and see normal oil flow and such from the stock timed breather as well as the oil return. I am definitely stumped on this one and any helpful info to get it fixed is appreciated!

The bike did sit about a week before I drained the sump today actually. I reported a few days but after thought it has been a week. I am suspect that the sumping happende after the 50 miles while riding though since the oil found its way to the primary.

Re: Pre installation of Comnoz Sump Breather (71 norton)

Well I guess you could confirm this by going for a ride and when you are done shut it right down and drain the sump. Normal is around 150cc to 200cc (5 to 7 oz.)/

A breather valve may help with some leaking after the fact but it will not help with wet sumping.

Re: Pre installation of Comnoz Sump Breather (71 norton)

pvisseriii said:

Well I guess you could confirm this by going for a ride and when you are done shut it right down and drain the sump. Normal is around 150cc to 200cc (5 to 7 oz.)/

A breather valve may help with some leaking after the fact but it will not help with wet sumping.

Click to expand...

I think my next test will be after I place that breather on. I have about 4 rides that resulted in oil in the primary so far. I have definitely proven the oil migrates after 50 miles. Just dont understand how it works fine up till then....

Re: Pre installation of Comnoz Sump Breather (71 norton)

iceteanolemon said:

pvisseriii said:

Well I guess you could confirm this by going for a ride and when you are done shut it right down and drain the sump. Normal is around 150cc to 200cc (5 to 7 oz.)/

A breather valve may help with some leaking after the fact but it will not help with wet sumping.

Click to expand...

I think my next test will be after I place that breather on. I have about 4 rides that resulted in oil in the primary so far. I have definitely proven the oil migrates after 50 miles. Just dont understand how it works fine up till then....

Click to expand...

If that is the case then you need to pull your oilpump off and look for obstructions. Yes, I guess the breather will help. Other than the crank seal, oil will pass from the lower inner primary bolt hole. It is at the 4:00 position am.

Here is another thought. If your are wet sumping when running and you relieve some leaking to the primary with the use of a breather valve, then where is this oil going to go. You better think this through. With reduced crank pressure you may wetsump even more, IF you are wetsumping when running. Scavenge!

Re: Pre installation of Comnoz Sump Breather (71 norton)

Funny this thread should come up now.
I just modified a BSA single engine that I'm building so that the crankcase breathes into the primary.
essentially, I am purposely causing the same problem that you are attempting to fix. (oil on the primary)

It's a crazy world!

FWIW:
I think everyone already has your problem figured out - wet sumping.
You probably blew out your crank seal and the crankcase pressure pushing the excess oil into the primary case.

Re: Pre installation of Comnoz Sump Breather (71 norton)

pvisseriii said:

iceteanolemon said:

pvisseriii said:

Well I guess you could confirm this by going for a ride and when you are done shut it right down and drain the sump. Normal is around 150cc to 200cc (5 to 7 oz.)/

A breather valve may help with some leaking after the fact but it will not help with wet sumping.

Click to expand...

I think my next test will be after I place that breather on. I have about 4 rides that resulted in oil in the primary so far. I have definitely proven the oil migrates after 50 miles. Just dont understand how it works fine up till then....

Click to expand...

If that is the case then you need to pull your oilpump off and look for obstructions. Yes, I guess the breather will help. Other than the crank seal, oil will pass from the lower inner primary bolt hole. It is at the 4:00 position am.

Here is another thought. If your are wet sumping when running and you relieve some leaking to the primary with the use of a breather valve, then where is this oil going to go. You better think this through. With reduced crank pressure you may wetsump even more, IF you are wetsumping when running. Scavenge!

Click to expand...

Wouldnt an obstruciton be evident in the first 50 miles? I can fire her up rihgt now and see oil circulating by way of the return feed to the tank. I may just not be understanding so forgive me if I seem redundant. When you say "scavenge" you are referencing the oil pump and its ability to pull oil from the sump right?

Is there a known symptom out there with oil pump fialure where it only happens after so many miles or only when hot? Maybe when hot the oil is thinner and the oil pump is wearing out? ugh i dont know....

Re: Pre installation of Comnoz Sump Breather (71 norton)

pvisseriii said:

Here is another thought. If your are wet sumping when running and you relieve some leaking to the primary with the use of a breather valve, then where is this oil going to go. You better think this through. With reduced crank pressure you may wetsump even more, IF you are wetsumping when running. Scavenge!

Click to expand...

good point!

Re: Pre installation of Comnoz Sump Breather (71 norton)

this may be an obviously dumb question, but is it possible your crank seal is simply old, torn, blown?

Have you installed a new seal lately? How old is your present seal?

And I would take off the breather line all the way to the tank and blow it out with compressed air, maybe you have oil sludge blockage in there, how about just replacing that breather hose with a new line just to make sure its wide open

last, I would install a one way valve in the breather line, either the Dorman or the Mike's SX to reduce crankcase pressure

Re: Pre installation of Comnoz Sump Breather (71 norton)

Just out of curiosity, do you have a Mike's breather valve at the end of your timed breather hose?

Re: Pre installation of Comnoz Sump Breather (71 norton)

iceteanolemon said:

When you say "scavenge" you are referencing the oil pump and its ability to pull oil from the sump right?

Click to expand...

Yes. This is the truer definition of wetsumping. The other of course is the tank draining through the oil pump via gravity.

Maybe when hot the oil is thinner and the oil pump is wearing out? ugh i dont know....

Click to expand...

Maybe. Check flow in the tank when cold AND hot.

Re: Pre installation of Comnoz Sump Breather (71 norton)

If the engine was truly wet sumping while running the result would be a lot more severe than simply pushing oil into the primary. Once the oil in the engine case gets deep enough to touch the crank the engine will blow oil everywhere, smoke out the exhaust and overheat severely. I have seen engines that were run in the wet sump condition that heated the oil enough to melt the solder that attached the screen to the banjo bolt in the oil tank. The screens then fall to the bottom of the tank. The 72 combat engines would do that if run in the 6000+ rpm range for several miles.

My bet is the reed breather will solve the problem although eventually it will probably benefit from a ring job. I do know that the engines with the cam breather will pressurize the cases enough to push oil by the crank seal long before blowby is bad enough to affect performance very much. Jim

Re: Pre installation of Comnoz Sump Breather (71 norton)

OK I will do this for sure! I will try and post up the details on this thread too for reference.


Thanks!

Re: Pre installation of Comnoz Sump Breather (71 norton)

My vote is for:

New crank seal
Double check primary mounting bolts (three around the crankshaft seal) and make sure there is no leaking there.
New breather
50w Oil

And you also remember to plug up the timed breather?

Re: Pre installation of Comnoz Sump Breather (71 norton)

swooshdave said:

My vote is for:

New crank seal
Double check primary mounting bolts (three around the crankshaft seal) and make sure there is no leaking there.
New breather
50w Oil

And you also remember to plug up the timed breather?

Click to expand...

New crank seal *Check, I bought and installed this already.
Double check primary mounting bolts (three around the crankshaft seal) and make sure there is no leaking there. *Totally good, studs installed with red loctite and a small bit of permatex under the nuts.
New breather *In the mail from from Comnoz...
50w Oil *Will migrate to 50w upon breather installation...

And you also remember to plug up the timed breather? *Not installed yet but I will be looking for a nice stainless bolt to place there when I do


Im on the fence about either topping off the oil level and testing the ride to work again then inspecting oil flow when hot or waiting and installing the breather first. I am a glutton for punishment so I may test first to get info.