Over pressurized crankcase Cal III

[Vecchio Lupo]

Gentlemen,
I have been a Guzzi guy for 40 years but this is a problem Ive never had. Perhaps you can help. I dragged home a running (poorly) 1990 Cal 3. It had a huffing left side head gasket and a slipping clutch with oil drip. I replaced rear main seal and clutch stuff, then 2 new head gaskets. Oil tight, runs and shifts great. Decided to ride to Jacksonville from Charleston.

Running on I 95 south at about 80 mph, I stopped for gas at the 175-200 miles mark….i noticed oil from breather tube and what a mess. I checked oil, low-ish but not bad. I slowed to 60 and completed my run. Engine making a wheezing ( not a knock) noise and most oil gone. Trailer back to Charleston and tucked away.

Now, after filling the oil and leaving sit…floor is dry so no leaks. Bike would start but wheezed and bumped in uneven sounding roughness. I’m thinking clogged pvc/ breather valve, or worse a broken piston ring allowing severe over pressure. Or maybe a compromised head gasket but that wouldn’t pressurize the case?

Does the collective have ideas differently from stated?

I’ve started to tear down the left side just now and will break down the rest tomorrow. Just looking for ideas…thank you

[acogoff]

    I wonder previous owner messed with the breather system, the older ones had a check valve or ball in the system.
   Maybe it was lost.

[pehayes]

If the cylinders/pistons/rings/valves were all in theoretically perfect condition there would never be any pressure build up in the crankcase.  Yes, during each cycle of the crank there are periods of slightly increased internal pressure and slightly decreased internal pressure.  Pistons are rising and falling at differing times and rates.  The net effect is a zero sum equilibrium after the cycle is complete.  If  you have an excessive buildup of pressure then you know where it is coming from.  Sorry.  Time for serious wrenching.

Patrick Hayes
Fremont CA

[John A]

What may be happening is the ball check valve in the large hose on the top of the bellhousing is sticking closed. I was cooking down the road on a Cal2, my wife following on an Ambassador as we went home from an Oklahoma rally, ‘84. It suddenly dumped almost a quart of oil out the breather drain onto my wife. I luckily had rerouted the drain from the air box to overboard so it didn’t fill the air box. Then it took some looking to find the problem because it would do it randomly , just puke out almost a quart. What was happening is if the ball check closes off at roadspeed, the oil is forced backward up the oil drain tube in the crankcase until the end of the drain tube is out of the oil. It should be submerged . There was a change to that ball check valve so that it couldn’t completely close. If you look at the ball seat, the updated valve has a square outlet and the old ones had a round outlet the ball could seat in. You can use a file to modify it. I’d look for a problem with that valve .

[guzzisteve]

    I wonder previous owner messed with the breather system, the older ones had a check valve or ball in the system.
   Maybe it was lost.

THIS, before pulling motor all apart I'd pull airbox & look in the larger pipe going in bell housing, metal steelie stuck

John beat me to it

[Vecchio Lupo]

Thank you all, this just confirms my original thought….check valve first…piston rings second.   Years ago I had an Eldo that broke a ring but it sentvsporized oil out the exhaust.     

I feel better about the direction I’m headed. Thank you.

[Frenchfrog]

It's also quite possible that the condensing box/frame is chock a block with mayo which stops the whole from working properly.I'm pretty certain that your bike uses the frame for condensing/separating the fumes from the engine breathers.

[Vecchio Lupo]

Good suggestion, thanks.

[bigbikerrick]

Vecchio Lupo, does your bike have a sump spacer on it?
Rick.

[Frenchfrog]

By that point they were standard with spacers from the factory.....

[bigbikerrick]

My 76 Convert puked oil a couple of times out of the breather, I was able to resolve it by adding a sump spacer,and installing the breather cannister meant for a loop frame bike, with the newer style ball valve  on top of the crankcase.  The stock airbox/breather setup, was hard to service,and a poor design IMHO.
Rick.

[Vecchio Lupo]

Well, my frame box seems to flow fine, none of the hoses are blocked, the ball valve looks ok and I can blow through one way but not the other, so that seems right. I took some photos just now and I saw where my distributor has shifted a bit. I can’t imagine that affects crankcase pressure. What do you boys think? ?

[Vecchio Lupo]

My 76 Convert puked oil a couple of times out of the breather, I was able to resolve it by adding a sump spacer,and installing the breather cannister meant for a loop frame bike, with the newer style ball valve  on top of the crankcase.  The stock airbox/breather setup, was hard to service,and a poor design IMHO.
Rick.

Shout out to BigBikeRick for all his great advice and help with my Convert Police bike. She turned out great. Im disappointed that the Meltdown European Motorcycle Show in N C is canceled this year. I figured I had a good shot at best Italian. 

[pehayes]

I took some photos just now and I saw where my distributor has shifted a bit. I can’t imagine that affects crankcase pressure. What do you boys think?

Please explain that "...shifted a bit."

A distributor clamp is supposed to be adjustable.  You may have to rotate the distributor one way or the other every time you tamper with or replace the ignition points. 

Have you checked the static and dynamic timing recently?

If your ignition timing is way off you could be igniting the mixture long before the piston reaches TDC.  If so, I would suspect that combustion chamber pressure is going to be higher than normal  and could blow into the crank chamber.

Patrick Hayes
Fremont CA

[Vecchio Lupo]

Well I noticed the retaining clamp was loose on one side (the slotted side) and was off the bolt. The other side was tight but the distributor could have moved. Previous owner installed DYNA electronic ignition, so points gone. I will check that next..   thanks for the help

[bigbikerrick]

Your Convert  police is super cool!
Rick

[John A]

That check ball looks like the ball could close it off. However the hole doesn’t look all that round. I would make the hole slightly square with a file.

[Wayne Orwig]

Have you done a leak down test on the cylinders?

[acogoff]

     From a distance, your ball/valve looks very worn. May try and source another just for grins.

[Vecchio Lupo]

I have sourced a new ball valve, and while I was tearing down the left side, which for some reason felt/sounded like the problem side I found this wear…….the left side had a blown head gasket when I acquired her, and the PO said it still ran well enough but was leaking oil…..I just changed it.

Anyway, this is the wear I found. I am hoping to hone the lip of the cylinder and smooth the piston rim with very fine sandpaper.

If you know from experience that I’m wasting time, tell me and I’ll start looking for a Cyl piston replacement

For some reason photos are not uploading…I will continue to try.

[Vecchio Lupo]

Well….I was able to hone the cylinder pretty darn good, the piston responded to 3 sessions of progressive yet gentle hand sanding. What do you think?  Try it?

[Vecchio Lupo]

Fellas, nothing is as easy as it seems.    Thought I found an issue on the left cylinder, cleaned it up and reassembled. Tore down the right side and found an issue. The top compression ring looks collapsed and flush with piston all around, the cylinder at first looked terrible but after closer examination, I’m pretty sure that will hone out. The piston will probably not respond to light sanding and polishing…..might need a new or good used “A” piston, what do you boys think? By the way, in piston photo #3 you can see the middle piston ring is broken in several places. I think that explains severe over pressuring of the crankcase don’t you?

[Frenchfrog]

You've found the cause.

[MattP]

have a pair of very nice 1100 pistons and cilinders will bolt right on $250. shipped i can trim base on my lathe. some one dentenated  those old ones.  matt

[Vecchio Lupo]

That sounds pretty damn good to me. I’m in Charleston 29420 message me with how you want your money. Thanks

[Old Jock]

I feel a little guilty for not posting earlier when you were searching for the cause.

Many early posts pointed the breather system and as I'm not familiar with how the Tontis breathe decided I'd nothing to contribute.

However I had a similar problem with a Sporti and was going to suggest the first thing to do was a compression and leak down test if possible, as also suggested by Wayne.

In my case after a rebuild I was getting leaks at the sump spacer after a rebuild. After many gaskets, seals, etc: a compression test showed lower than optimal compression and a difference between the cylinders greater than 10%.

Checking the bores, both were out of spec in size, one side by a staggering amount and the really bad one had ovality too.

The mileage was around 12k, pretty sure it had been that way leaving the factory, but ran Ok.

The teardown and rebuild disturbed the fragile piston ring/cylinder relationship and exacerbated the issue.

I got the cylinders relined and the bike has been fine since, glad I did ,though not at the time. Prior to the fix it was a grenade with a very loose pin

Glad you got to the bottom of it and appear to well on the way to getting it resolved

[MattP]

look some one detenated that thing so. what , well  looks like 2mm longer stroke on 1100  so half 1mill  .03937 thowsands id run them or i could take.020 off want the used rings  how cheep are you ha . any way just looked at them. you will be . you know they put shims under clinders to avoid ping, dettenation let me know what you think  you can allways trim them down you will have a little softer  engine with more heat to
 talarece with plenty power maybe loose a few hp at 7500rpm. kind of bizzy with garadge  build mite make a wood box don,t need busted  finns ect.      mattp or    spiker51@yahoo.com matthew phillippi 500 third st excelsior mn   55331.            at library down street   but can get email on dinglebeary                                                                                                                                       

[Vecchio Lupo]

Matt P,
   
     I have no idea about how much to trim. I guess just the half Mil, ( I won't hold you responsible , we are in uncharted water) I'll spring for new rings. of course I'll turn engine by hand and use putty to see if Ive got any clearance issues. At any rate....I'll email you my address and you let me know how to pay you. Im in Guantanamo until the summer so the parts will sit in Charleston until I get home and resume work.

Thanks.

[MattP]

Joe machined off .020 look nice. Going to try to send  to your home monday . When you get home check them out then just send check. Oh you might clean them up debur base.
 

[Vecchio Lupo]

Guzzisti Unite!!!!

Thats what is so cool about the Guzzi Community. Our dealer network is almost non existent, so we rely on each other. Hell yeah Brother.