Caring for an Aging Italian

[Jeff Higgins]

Well, I spent my day today offering what little help I can to an aging Italian friend. I know they are considered an "at risk" population, and I was taking my chances, but something had to be done. She's been rather incontinent for some time now, often embarrassingly so. It was getting harder and harder to bring her out in public.

I'm hoping for a full recovery. I'll continue the operation tomorrow, with hopes of wrapping it up later in the week. Wish us luck.

[flatbutt]

Whence does the offending leak flow?

[Jeff Higgins]

Between the cylinder head and cylinder on the vertical. There is an oil passage through the cylinder up to the head on the right rear to supply oil to the rocker boxes. There is a nipple on the top of the case that goes into the base of the cylinder, then another similar nipple at the top of the cylinder into the head. Those never leak, however.

The problem lies in how oil is returned to the crankcase. The cylinder has what would be a water jacket if it were water cooled, except it is filled with oil returning from the rocker boxes back to the crankcase. The passages from the head to the cylinder are sealed with o-rings. This is where they leak.

The photo below is from the first time I went in to fix this, over ten years ago. The piece of brass tubing is sticking up out of one of the return passages, with a black o-ring around it. This was a "fix" recommended on a Ducati forum at the time (didn't work). The other return passage is at the upper center of the photo, behind the head stud. You can see it's slightly counterbored in an effort to retain the o-ring. The nipple has the green o-ring around it.



This is one of those annoying "known problems" on these things. I've replaced these o-rings several times now, and the bike only has 85,000 miles on it. I'm trying to come up with something clever this time...

[flatbutt]

The last time I went into the top end of the "L" is the last time I ever will. Good on you bro.

[Jeff Higgins]

Interesting you would say that - did something give you trouble on yours? I tell you, after a lifetime of working on all kinds of Harleys, this thing is a breath of fresh air. I find it very easy to work on. It took me two hours to separate the frame from the motor. It will take maybe an hour to R&R the head to replace the o-rings and implement whatever clever solution I come up with (suggestions are welcome). Then another couple hours to put the frame back on. Oh, and I am drinking Italian coffee while I'm doing this, so that should help.

[flatbutt]

Originally Posted by Jeff Higgins

Interesting you would say that - did something give you trouble on yours? I tell you, after a lifetime of working on all kinds of Harleys, this thing is a breath of fresh air. I find it very easy to work on. It took me two hours to separate the frame from the motor. It will take maybe an hour to R&R the head to replace the o-rings and implement whatever clever solution I come up with (suggestions are welcome). Then another couple hours to put the frame back on. Oh, and I am drinking Italian coffee while I'm doing this, so that should help.

Well simply stated there was a lot of "take this off so you can get to that" and bear in mind I only have the use of two fingers on my right hand. Heck it's takes me 45 minutes to change the oil.

The Beemer was a lot of work but it was pretty much tractor assembly. The Duc is more involved. At least the valves are low maintenance now.

[Jeff Higgins]

True, there is a lot of that. I can see it from here, but... Valve adjustment on these things is a lot like that. Lots of stuff to get out of the way first...

[dafischer]

Just don't start on the Italian vino.

[javadog]

Time to consider a different material for the o-rings. You don't say why they are failing, is it a loss of elasticity? Maybe temperature related?

I'd get an engineer on the phone and see what suggestions they could offer. I'd probably start with Parker Hannifin.

Here's one of their catalogs:

https://www.parker.com/Literature/O-Ring%20Division%20Literature/ORD%205700.pdf

[Zeke]

There are 2 deck heights there, one at the top of the cylinder and one where the O rings sit. Have you compared the difference to that of the head? Does the head need a thinner gasket to the top of the cylinder to compress the O ring? Or is it the opposite and the O ring is being squished too much?

Just throwing out some questions.

And what's up with all the scratches on the cylinder top?

[Jeff Higgins]

Originally Posted by javadog

Time to consider a different material for the o-rings. You don't say why they are failing, is it a loss of elasticity? Maybe temperature related?

I'd get an engineer on the phone and see what suggestions they could offer. I'd probably start with Parker Hannifin.

Here's one of their catalogs:

https://www.parker.com/Literature/O-Ring%20Division%20Literature/ORD%205700.pdf

Thanks, I'll take a look through their catalog. I've now tried at least two different o-ring materials, the standard issue Ducati replacement black rubber and the same diameter and thickness in green viton.

I do believe it is temperature related. The horizontal cylinder uses the same arrangement, but, curiously, only has one return passage. It's at the bottom, on the exhaust rocker box side, so the intake rocker box probably drains well enough down to it that they didn't feel the need for its own return. The horizontal runs cooler, kind of "leading with its head" so to speak. The o-rings that fail come out solid, lacking elasticity, so they have pretty obviously been cooked.

Originally Posted by Zeke

There are 2 deck heights there, one at the top of the cylinder and one where the O rings sit. Have you compared the difference to that of the head? Does the head need a thinner gasket to the top of the cylinder to compress the O ring? Or is it the opposite and the O ring is being squished too much?

Just throwing out some questions.

And what's up with all the scratches on the cylinder top?

Good questions, Zeke. I've used clay to measure the gap outside of the CE ring when the head bolts are tightened, both to the flat deck and to the depth of the counterbore. The Ducati supplied o-rings appear appropriate for the gap they fill. In other words, they get compressed a bit without being overly flattened. I'm not sure thicker or thinner o-rings would change anything.

These don't use head gaskets - just like our 911's, they use a CE ring. The scratches visible on the raised CE ring are just machine marks, which are made to appear much more pronounced than they really are due to the lighting. It really is quite smooth. The scratches on the lower deck really don't matter, since there is about a .010" gap to the adjoining surface on the head.

So, thanks for the suggestions and questions, guys. This one is a real "head -scratcher". It is the subject of endless conversation (and frustration) in the Ducati world. Some leak, some don't. No one has really nailed down "why", or any kind of proven fix. I would like to finally do that.

[javadog]

I would talk to an engineer and ask if that application might be suitable for a metal o-ring, or something similar. If you've cooked a Viton o-ring, I don't see any rubber o-ring working long term.

You might also talk to a sealant company and see if a sealant might be a solution, alone or in combination with something like a metal o-ring. 3M, Loctite, etc. all have engineers on staff to look for solutions to particular problems

[Zeke]

Originally Posted by javadog

I would talk to an engineer and ask if that application might be suitable for a metal o-ring, or something similar. If you've cooked a Viton o-ring, I don't see any rubber o-ring working long term.

You might also talk to a sealant company and see if a sealant might be a solution, alone or in combination with something like a metal o-ring. 3M, Loctite, etc. all have engineers on staff to look for solutions to particular problems

Yeah, a copper ring would be an answer. It would need to be a very soft copper but if anyone —Jeff can do it.

Some copper rings I have seen start out looking like a finger ring, flat and round. Then they are rolled over towards the outside and over a piece of gasket material. Sort of like how the copper on some head gaskets is pinched over the gasket.

I bet there's some on a shelf somewhere in this world.

Another idea is to sleeve that passage with a sealing ring in the depression.

[javadog]

There are copper and aluminum crush rings of various profiles along with some made from steel that are more or less hollow.

A sleeve that is a press fit into the crankcase and a tight fit to the cylinder head, installed with some sealant, might be my preferred choice.

[gtc]

If viton is not cutting it, you could try FFKM. Better temp resistance and compression set properties. I bet those heads get pretty toasty.

[flatbutt]

sometimes you guys just impress the ***** outa me.

[javadog]

Originally Posted by gtc

If viton is not cutting it, you could try FFKM. Better temp resistance and compression set properties. I bet those heads get pretty toasty.

There's a version of those that stand up to repeated heat cycles better. Like these:

https://www.mcmaster.com/ffkm

They do better with oil than Viton, too.

One question, were the failed o-rings from a known, reliable supplier, or were they possibly from somewhere unreliable, like China? It might be useful to know if they failed because they were not suited to the operating conditions, or were just ****ty quality... Stuff like this, I want to know where it came from...

[Jeff Higgins]

Well guys, here is the failed o-ring. In the three or four times I've replaced these, I have never seen this failure mode. They talk about it a lot on the Ducati forums, though, as a fairly common occurrence:



What they think is happening is that oil is getting around the outside and applying pressure to the o-ring. Unsupported on the inside, it simply collapses. Some guys have found them all the way down inside the cylinder's "oil jacket", having been forced down through the hole.

Both o-rings are still soft and pliable. The other one was still just fine, and not leaking. It was the forward one that failed. Interestingly, the passage in the head is at a different angle, and does not precisely align with the one in the cylinder at that forward position. That may be how the oil gets to the outside of it and makes it collapse inward. The aft one is straight through and lines up perfectly. The angle of my little brass tube "fix" in the forward passage illustrates the angle between the cylinder and head.

The o-rings that were in there this time came from Ducati of Seattle with a full rebuild gasket kit. Previous o-rings were obtained at auto parts stores, so God only know what formula of "Chinesium" rubber they are made from, even the green "viton" ones. Every one of those dried out and got hard. This last set did not. Fortunately, there were a lot of extra o-rings in the kit, so I had a pair to use this time.

So, in an effort to keep this one from collapsing in, I installed a modified version of my brass tube liners. I made this set so I could install them in the cylinder and have them protrude just high enough to make contact with the head. All I'm after is an inner ledge to keep them from collapsing.

I just don't think o-rings were ever meant to sit unsupported on their inner diameter. I cannot think of another application where I have seen that. So, hopefully this simple fix will do it. This brand of o-ring has already proven itself, staying soft and pliable over about 15,000 miles. Maybe too soft and pliable, resulting in getting pushed into the hole. The ones that dried up and hardened didn't do that, but they leaked because they were dried up and hardened...

[javadog]

If it is just oil draining back down into the crankcase, it's shouldn't have any noticeable pressure.

What does the hole in the head look like and how tight a fit was the brass tube into the head?

I took another look at the pic and it looks like the o-ring around the brass nipple "fix" has too big an OD for the recess in the case. That might be part of the problem. It's hard to tell from the picture but you might check it.

[Zeke]

Chances are the cam covers, etc. are not vented. Some pressure may exist. It probably does or the O ring wouldn't cave in.