Sporti Pod Filters & Crancase Backpressure Anybody had Problems? (Continued)

[Old Jock]

So I'm pretty near to ironing out most of the problems with the Magni Sfida 1100 and there have been quite a few

The last one is persistent leakage from the sump and extender gaskets. I've cleaned the faces meticulously, I've installed new gaskets, I even applied Hylomar to the extender to crankcase face gaskets (including the Roper Plate in there too). The leakage persists and also appears to have moved in part to the extender to sump gasket (no Hylomar on it).

I only get the leaks when the bike has been out on a run, getting the engine hot in the shed does not result in a leak, but then it's only idling most of the time. Out on a run, different story, it always leaks, it's not super bad but it's not exactly insignificant either.

The bike came with air pods so the top pipe on the frame to atmosphere runs overboard and not to the airbox. The airbox space is now used by the battery.

I replaced the frame to atmosphere hose with 8mm fuel hose and I'm wondering if that's the problem. Getting to the point that I'm pretty sure the crankcase is getting pressurized and forcing the oil past the gaskets.

The current plan is to resize the hose I can go up easily to -8, 7/16th inner diameter and that would increase hose area by 90%. Just wondered if anybody else had experienced anything similar.

If the weather is decent tomorrow I'll take it for a short ride with the hose off and see what happens and report back

John

[Chuck in Indiana]

John.. last year the Kid and I spent a week in the Carolinas. It was the first time he had run his Spot hard with a lot of acceleration and deceleration. He had problems with it sucking the valve cover "in" and causing a leak. I can't tell from the picture what kind of breather he is using.. and he (as I do)  doesn't carry a phone all the time. I'll ask what he is using for a breather the next time I talk to him.
2017-06-04_01-30-18 by Charles Stottlemyer, on Flickr

[Old Jock]

Many Thanks Chuck

Hoping to take it out shortly, the weather here is a bit suspect

I'll post up if a temporary removal of the hose has worked or not

As I then progress and if I get a "fix" then I'll let you know

Appreciated

John

[John A]

If it's pulling the gasket in, that's got to be a good breather. I always thought I  have too much positive case pressure and have toyed with the idea of a small vacuum pump. Another idea is to try to draw a vacuum off the exhaust with a siphon type tube in the pipe. I lost my breather return from the frame when I dual plugged the heads.

[Old Jock]

Well just been out for a short ride and the dammed thing is still leaking.

I undid the hose from the banjo fitting at the head of the bike, leaving just the banjo bolt & banjo, which then was venting to atmosphere

I dislike banjo bolts in this application, they create a lot of pressure loss.

So now I'm thinking about this route

M16 to -8 adapter

https://www.ebay.co.uk/itm/AN-8-AN8-AN-08-to-M16x1-5-Metric-Adapter-Black/150840139125

&

90 degree -8 fitting

https://www.ebay.co.uk/itm/AN-8-AN8-90-Degree-Teflon-Stealth-Black-Hose-Fitting/150567959780

I'll need to go and check if I have the available height, I think the Magni tank might give me more room than standard, the 90 deg fitting would then go to a Teflon -8 hose overboard & should significantly reduce the pressure drop, compared with what I had

Like JohnA positive pressure is (I think) my problem so I am trying hard to reduce this. I was also contemplating a pump or Venturi of some sort

VERY interested in "The Kid's" arrangement Chuck

Next I'll remove the banjo and bolt and just run with the M16 hole in the frame, if it still leaks then that is not the problem............ .although I'm wondering if the previous positive pressure has damaged the gasket(s). In which case even if I fixed it, it would continue to leak.

I have new gaskets waiting to go in & I'll Hylomar them all too, can't do any harm if I don't apply it with a butter knife, wont do that though until I get the new breather arrangement in place first

[swooshdave]

You don't need a pump, but rather a reed valve to let the pressure out but no suck anything back in.

[John A]

You don't need a pump, but rather a reed valve to let the pressure out but no suck anything back in.

that's what pcv valves are supposed to do but they are usually disappointing in this particular application.

[swooshdave]

that's what pcv valves are supposed to do but they are usually disappointing in this particular application.

PCV valves aren’t always strong enough. In the wrong application they can just flap around uselessly.


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[SED]

Here's a strange leak that might help you find yours.

The Monza developed a similar oil leak after I put a sump extender on it.  It seemed to be leaking at the upper gasket, but only after running for a while (maybe 20 miles or more).  Eventually I found oil was migrating up out of one of the sump bolt holes to the top of the block flange, then crawling down and accumulating where the gasket lies.  Because the leak was at the front left it appeared that the gasket failed on the left side.

The sump bolts that came with the extender were just a few millimeters short - they did not extend through the flange like the original bolts did.  Replacing the LF bolt with a longer bolt and some sealer solved the leak.  The short bolt seems to have revealed a casting porosity that was allowing oil from the crankcase (under pressure when running) to enter the threads and puddle up on the short bolt.  The longer bolt blocked the leak.

Let us know what you find.  And post some pictures of your finished project!   

[Old Jock]

Swooshhdave

Are you referring to a check/ball/one way valve? I don't think they won't work on a beam frame bike.

The crank pressure escapes up a pipe to the bottom of the frame at the head of the bike & into the frame. On the top of the frame and a little further forward is an M16 threaded hole to which a banjo attaches to a tube, that tube runs to the airbox on standard bike, on mine it just vents overboard.

At the back of the frame on the sides 2 flexi hoses run down to the sump. What happens (or is meant to happen) is the mist from the crankcase coalesces in the cold frame, the air is vented overboard via the top tube, the oil runs down the frame and back to the sump via the 2 flexi hoses.

If you put a check valve in the breather like the Tontis, then when the valve closed under negative pressure the oil in the crankcase would try to breath via the oil drain lines (I think). I'm not sure of the consequences, but I think Guzzi omitted the valve for reasons other than cost.

As I used to be a Turbine guy in a previous life a PCV (pressure control valve) has a completely different connotation.

SED thanks for that it could be very useful and to an extent applicable as installing the Roper Plate will have reduced the bolts effective lengths into the crankcase, so it's worth considering for sure, that one would have take me forever to figure out.

Next move is either run with the banjo bolt removed to absolutely confirm that it's not a breather problem, if it still leaks, which I'm convinced it will. Then a thorough clean of the whole area. Possibly talcum powder or dye pen developer around the suspect areas. Run the bike to 3k in the shed for 10 minutes and see if I can see any telltale signs of where this is coming from

I'm now starting to wonder if it's coming from the front and the wind is pushing the oil around the sump making it appear to be the base gaskets when it's not.

Of course I'll report back

Many thanks to all

[Old Jock]

I see that PCV in this terminology means Positive Crankcase Ventilation

I think if a check valve was introduced what might happen is when the valve closed, the oil level in the sump would rise as it would be pushed by the pressure in the 2 rear lines or if the lines were near empty introduce air into the sump oil. No ideas of the amounts, probably small, but it might cause either aeration of the oil or foaming as the oil level is pushed up then down by the pressure differences

As I said in the previous post there is probably a reason other than cost that Guzzi eliminated the check valve in the beam frame models

Going to put in the original banjo bolt, check the alternator for oil (seal passing) then clean the bike and run it in the shed at around 2-2.5k to see if I can get the leak to start and positively identify the source

I'm at my wits end with this dammed machine

[SED]

I'm now starting to wonder if it's coming from the front and the wind is pushing the oil around the sump making it appear to be the base gaskets when it's not.

This was what was happening with the Monza.  Initially the leak looked like it was at the left rear of the gasket, but in reality it was above the gasket at the left front - oil blowing back and accumulating in the groove.

Apologies if you know this already - check valves that SwooshDave refers to are put in the breather line - usually on the engine or close to it.  They create a oneway flow of air out of the crankcase (same as PCV valves do) by closing on the up-stroke and preventing additional air entering when crankcase pressure drops.  The vent path to the breather and valve is above the oil level so cannot introduce air into the oil.  If the breather is too low (or crankcase pressure too high), a lot of oil vapor can be pushed out the breather.  The Ariel breather is a 1/4" ball bearing checkball.  Later a reed valve was added to the upper part of the crankcase (dry sump).

BTW, blowby will be high until the rings seat.

[Old Jock]

Hi SED

Thanks for the confirmation that its happened to others

I do know about the check valves, Guzzi installed them on all the Tonti bikes and I have one.

I was trying (and obviously failing) to explain that a PCV won't work, well unless you installed 3, because as well as the main breather line there are 2 oil return lines also going to the sump at atmospheric pressure

Put a PCV on the breather and you might get oil aeration or foaming in the sump from these oil return lines, I think there is a good reason that Guzzi did not fit check valves to these bikes

John

[John A]

I tried three valves and it only worked at less than 4K rpms for me.

[bigbikerrick]

There is a guy named Rex Bunn that has done alot of research on motorcycle crankcase breathing, and came up with a system of valves to improve the breathing on older bikes. I installed one on my eldorado, and it has been working great for years. It may be of interest to you. Here is a link to info on Greg Benders site.
Rick
http://www.thisoldtractor.com/moto_guzzi_loopframe_breather_box_-_rex_bunn_breather_alternative.html

[bigbikerrick]

This link has some good info on motorcycle crankcase breathing, from Rex Bunn. I found it helpful, when I was sorting the breather issues with my eldorado.
Rick.

https://bunnbreather.wordpress.com/tag/bunn-breather-kit/

[swooshdave]

The one thing I'm not sure about in the Bunn system is needing an "inlet" valve. There's enough blow-by that you don't need additional "holes" in the crankcase. If you bring in fresh air then you really aren't bringing the crankcase to neutral pressure. You're just making an air pump, and the engine isn't designed to pump air.

BMW used a reed valve on the /5 and some of the later bikes. Not sure if they still do. Ducati still uses them.

If I were to put one on a Guzzi I'd block off the breathers to the heads. The heads breathe into the crankcase through the push rod tunnels.

[Old Jock]

Interesting bigbikerrick and good point swooshdave

I've sent a feeler out to Rex about the Bunn system, but I'm more on a course to just "fix the bloody leak" and if I find it, I'd quite happily leave the breather system alone.

I still don't know if it's a red herring, but it is a possibility, although the more I'm checking the existing system the less I can find that could be wrong with it.

That said at low rpms anyway there is a pretty shocking amount of air getting shifted.

I have no clue if it gets worse or better as revs increase, gut says worse but I have yet to hold the bike at say 3ks and see what the breather is doing. 

[swooshdave]

Put a PCV on the breather and you might get oil aeration or foaming in the sump from these oil return lines, I think there is a good reason that Guzzi did not fit check valves to these bikes

John

I haven't actually thought about the implication of a reed valve on a wet sump engine. I don't think it would cause any issues.

As for why Guzzi didn't spend a lot of time on the engine's breathing, they don't have the resources. Breathers usually help bikes that have a few miles on them when the blow-by increases. In Guzzi-speak this is known as "out of warranty"...   

[RinkRat II]

The crank pressure escapes up a pipe to the bottom of the frame at the head of the bike & into the frame. On the top of the frame and a little further forward is an M16 threaded hole to which a banjo attaches to a tube, that tube runs to the airbox on standard bike, on mine it just vents overboard.

If we think about that tube, it is in the airbox to see lower air pressure and help with the flow of air from the frame. I would find a way to re-attach it to the pods or some type of manifold to allow it to do it's job. 
 
 By the way, the only reason a pcv has a check in it it to prevent an explosion in the crankcase should a backfire occur.
 My $.02

        Paul B

[Old Jock]

If we think about that tube, it is in the airbox to see lower air pressure and help with the flow of air from the frame. I would find a way to re-attach it to the pods or some type of manifold to allow it to do it's job. 
 

        Paul B

Hi Paul

Yeah I figured that it is into the airbox to get some suction, also there to catch any oil mist that does escape where it's not meant to and burn it. I do not buy this as the problem, there are hundreds of Daytonas and Sports out there running pods and I've never heard of anybody reporting case pressurization as a problem.

Look at Chuckee's "kid's" machine, its breathing so well its pulling in the gaskets & what is the filtration it has?
 

[jacksonracingcomau]

Jock
Hope this helps
BB engine does not know if it has loop frame, old tonti,frame beather or spine frame, principle is exactly same,
Oil return on yours, to sump plug is the best.
As long as not blocked and you can feel pressure at vent it is breathing

My experience
1/ PCV in tube is beneficial, without , system is sucking and blowing but loads do run this way without obvious issue, without breather box a filter on vent is wise.
2/ If breather system blocked or insufficient, first symptom is always seals failing, not gaskets, far easier for oil to get past rubber.

My suggestion
Pressurise hot crankcase ( no more than 15psi but 5 should show) with sump in water, look for bubbles, fix

[John A]

A reason not to return oil mist to an airbox is theoretically it can cause detonation. Don't know if that's a problem for us but it's why I dump that overboard . That's a good idea to pressureise the crankcase but 5 psi is a lot so start off at zero and gradually increase while spraying soapy water on a warm, not hot engine to minimize localized thermal shock. I've found some cam plugs are free to rotate when the block is heated but were tight when cold.

[RinkRat II]

  Hi Jock,
   

I do not buy this as the problem,

   Me either, all I'm saying is that it was designed to help  airflow by allowing the throttle bodies regulate  the return airflow depending on throttle blade position and of course  emissions. 

       Paul B

[Old Jock]

Thanks jacksonracing that is an idea if all else fails and everybody else for all the suggestions.

Although it seemed a smoking gun I'm getting less convinced that the breather is the problem though.

I checked the original banjo against the alloy one I installed and the new one actually has bigger holes than the Guzzi part.

At idle it blows quite strongly through the banjo.

I cleaned all the mess around the sump and timing case yesterday, so today or tomorrow I'm going to start it, warm it up and then hold it a 3ks for about 5-10 minutes in the shed (ear defenders required) & keeping an eye on oil temp. Then just go around looking for a tell tale weep or drip. Without airflow to spread the oil along all these fins I hope I'll get a more accurate picture on where the hell it's coming from. Knowing my luck it will stay oil tight the problem child that it is.

I ordered up the wider -8 hose and fitting, it won't do any harm and just may do some good.

More later, I really do appreciate all the help here. I've never come across this sort of problem before with Guzzis, they usually are oil tight and other bikes where I've had leaks have been a lot easier to find.

John

[John A]

I personally wouldn't run it like that but if you do have fans and keep the head temps down. don't cook the new rings!

[swooshdave]

From a theoretical view you want the air to go in the carbs (or intake) and out the exhaust. And you want no pressure (neutral) inside the crankcase.

But because the rings don’t seal perfectly you get blow by and pressure inside the crankcase. And the pistons keep pumping the pressure until it comes out, typically as oil leaks.

To get the crankcase to neutral you want to let the pressure out without letting more in, which is why you don’t want an inlet. It just counteracts what you are trying to get to which is neutral pressure inside the crankcase.

Feeding the pressure back through the intake was just an emissions effort to recycle the blow by and now vent it to the atmosphere. Since we don’t really care about the environment (if we did we’d scrap these old bikes and ride electric ones) then routing the blow by back to the intake is just a matter of convenience.

You can bet race bikes don’t shove that crap back into the intake.

Four cylinder engines don’t push the crankcase pressure around as much because of the alternating pistons which is why they can get away with lazy PCV valves. Singles and twins are more violent so reed valves have an advantage and can take the stronger power pulses.

If your only goal is to eliminate oil leaks then maybe a PCV will work, they are certainly cheaper but if you want to reduce the pumping losses then a red valve is the way to go.


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[Chuck in Indiana]

John, the kids says he's using the standard frame breather and just vented overboard. Have you done a leak down test?

[Old Jock]

Not yet Chuck

I have been thinking the same myself and wondering if I'm getting blow by.

I don't have a tester or access to shop air. 

I may be able to rig up something using my mityvac, but I'll need sparkplug to barb hose fittings

Going to start the bike soon to see if I can idntiify any leaks

John 

[Old Jock]

Just ran it

It appears that the leaks are coming from the seals, still hard to be sure, nothing around the sides but it looks like the front might be coming from the alternator seal and the rear, although looking like the top spacer gasket is actually where the crankcase mates to the bellhousing, so that would probably mean it's coming from the rear crank seal

I've got a mate not far away who knows some guys who have a garage, so I'll get a compression and leak down test done on both cylinders and see what that comes up

When I put my hand to the crankcase breather it seemed to be blowing quite a bit too it wasn't huge but it was definitely noticeable that air was getting pumped out of there