oil seeping from under cylinder - new trouble ... look inside the port

[arek]

Hi. I took off the heads put them back on both sides without removing the cylinders. I was told that the gasket under the cylinder should be ok. But now I see small oil seepage under the cylinders from the gaskets, in the very center on the outside of both cylinders - above it sits the head bolt next to the spark plug. So, what can I do now? Is the only option to remove everything again? I torqued all head-bolts to recommended 40 Nm. Could I tighten the bolt that is above the leak, without any damage? If I do remove the heads again, can I just clean the gasket and the block and put it back together? Thanks for any suggestions. Arek

[gstallons]

My 87 LeMans was doing the same thing.Joe Eish told me it was (and was) the o-rings under the rocker arm stands. I don't know if these are still this way or not.

[Guest ratchethack]

Wot Gene said is still true with the V11. There are oil seal o-rings that go around 4 of the studs of each head that should be replaced whenever the heads come off. If you're ordering these, it's also a good idea to replace the o-rings that go under the oil gallery plugs over the inboard studs (one each cylinder).

 

Do not under any circumstances over-torque one -- or any -- of the head stud(s)!

[arek]

Thanks for the input! I did replace all o-rings - bought everything from Greg at Moto International - with new ones, so I did not want to think this was the issue. I though about it though. So, do you think I should now replace the cylinder gasket or at least clean it from the oil, or leave it as is and try to replace the o-rings? Of course leaving it as is will be an easier job. Thanks again. Arek

[Guest ratchethack]

Arek, I'd defer base gasket replacement if there's no other reason to have the cylinders off. If you were going in to do a ring job it'd be a no-brainer to put new ones in, and this is just me (many seem to consider this an act of barbarism ), but to ensure no seepage, I'd put an ultra-thin rub-in of silicone gasket sealant on 'em (just enough to soak it into the gaskets and make 'em shiny), have both case and cylinder surfaces surgically clean before installing, and quickly set the cylinders down before the silicone takes a "set".

 

But then, if it's just a little seep, I'd be more inclined to just wipe it off occasionally and take a long ride instead.

 

But o' course, that's just me.

[Greg Field]

Arek:

 

If the leak is coming from the area around the short studs, changing the o-rings inside would be unlikely to fix it, as the o-rings for the short studs are underneath the cylinder.

 

Is the oil showing itself only near the base gasket surface or also at the cylinder head, around the stud near the spark plug?

[arek]

Greg, I can see the oil coming only from between the block and cylinder (not head), seeping through the base gasket I guess, and it is shows only in the very center - bottom short stud on both cylinders. It is slowly seeping onto the block. There are no leaks from the head gasket, or anywhere else. Thanks.

[Greg Field]

Well, I am sorry that my advice failed you. I so rarely see base gasket leaks that I try to save people time and money by not automatically replacing them. If you want one, I'll send a free base gasket.

[arek]

Greg, oh no no ... it was not you who suggested that the base gasket would be OK. Sorry for the confusion. I will need replacements for both sides, but I will give you a call at MI, as I need some other parts as well. Thanks. Arek

[arek]

Where to start ... I finally had the time to replace the cylinder gaskets, and I went at it this weekend. So, I take off the heads, and what do I see ... a bucket of oil inside the combustion chambers – unburnt oil at that. It was obvious even before I opened it up, as the spark plugs were soaked in oil. So I am thinking, without lots of knowledge and mechanical experience that the o-rings are to blame, or maybe I have done something wrong the first time. So, I go ahead, replace the base gasket, new o-rings, replace the head gasket, new o-rings, tighten everything to spec ... blah blah. So, I fire it up and all sounds good, but out of caution I remove the plugs ... guess what - soaked in fresh oil

 

Can someone please tell me, how in the world is the oil getting inside the chamber? Is it possible it is going through the valve guides? What are the possible ways for oil to leak into the combustion chamber? When I took off the cylinders, I oriented the rings spacing properly for reinstallation, and they looked good. I think I can eliminate oil going through the rings. All of the o-rings are new. Can we eliminate this? I do not know enough about the heads to know what other way it can seep in there.

 

To give some background on the heads - I removed the heads to begin with, to clean the valves and clean the chamber. I sent the heads to a shop up in LA, and they tell me that the valve seats are worn - 6k miles on bike - but guides are ok. So, I let them replace it, and $500 later I get them back nice and clan with new valves. Looked good uninstalled. Is it possible I am doing nothing wrong, and the problem with the heads after the work at the shop?

 

I appreciate any help and ideas.

[pete roper]

There definitely SHOUDN'T be great pools of oil in the combustion chgambers. There are only three ways for oil to get in there, either down exceptinally worn guides, from the pushrod holes, (Both of which are highly unlikely as what usually happens if the gaskets fail into the pushrod tubes is all the oil gets pumped out of the sump through the breather system, unless you only travel downhill on a trailing throttle it is unlikely to be that!) The third and most likely way is past the rings. so;

 

Check the ring wear by taking the rings off the piston, setting them squarely in the bore and measuring the end gap.

 

Make sure the rings are free to rotate in their grooves but without excessive up and down play.

 

Are the rings in their correct grooves? Do you have an oil control ring that uses an expander? If so is it installed correctly?

 

The top two rings? What position are they in? The top ring is a 'Plain' ring. It should have some mark on its top surface but this may of worn off. The second ring is an torsional taper-faced semi-scraper. It has a 'Step' on the outer edge of one face. This step should be facing DOWN towards the bottom of the piston. If it has been installed the wrong way up it will be pumping oil UP into the combustion chamber. The oil control ring, if one piece, is ambesidestrous.

 

Check the ring lands for any cracks or unusual wear. Examine the bores closely. If they look extra shiney in patches they have probably glazed. You haven't been using a Friction Modified oil have you, (If the oil number has an FM suffix it is friction modified.) FM oils are instant bore glaze on air cooled engines. If this has happened use a boron ball hone to remove the glaze then go around with some 1200 wet and dry, wash VERY carefully in warm soapy water, dry, stick the ball hone through again and re-wash and dry. Install new rings.

 

My guess is that you'll find the stepped ring installed in the top groove with the step facing up because it was thought to be a 'ridge hunter' ring. These are an antedeluvian device used on crappy old motors with cast iron bores and lousy tollerances. The top ring had a step so that if for some reason the piston rode higher in the bore than it did before the rebuild the "step' avoided the top ring running into a wear ridge in the cylinder. It's the sort of thing that hasn't been used since the days of the Morris Oxford but some nutter might of thought he was doing the right thing!

 

Pete

 

PS, Seat wear at 6,000 miles?????? Never seen it myself and while I might accept one faulty seat installation, all four????? Hmmmm.

[Greg Field]

I have never heard of a Guzzi valve seat needing to be replaced from wear. I have seen a few that were ruined by porting jobs and bad machining, but never one from wear. Certainly not four in one engine. I would strongly suspect their work.

[arek]

Thanks for the replies … I really appreciate it.

I think that the possibility of the oil getting through the piston rings is highly unlikely, as there were no hints of this before I took off the heads. I mean I did not see any symptoms of oil in the combustion chamber when I removed the heads. When I took the heads off initially, the spark plugs were golden brown, dry and no hits of oil anywhere. In fact, the first time I re-installed the heads after receiving them back from the shop, I did not remove the cylinders at all. So there is no way the rings mysteriously began to leak. It has got to be one of the other 2 ways, through the guides or push rod holes. Is there any way to check for either one?

[pete roper]

Thanks for the replies … I really appreciate it.

I think that the possibility of the oil getting through the piston rings is highly unlikely, as there were no hints of this before I took off the heads. I mean I did not see any symptoms of oil in the combustion chamber when I removed the heads. When I took the heads off initially, the spark plugs were golden brown, dry and no hits of oil anywhere. In fact, the first time I re-installed the heads after receiving them back from the shop, I did not remove the cylinders at all. So there is no way the rings mysteriously began to leak. It has got to be one of the other 2 ways, through the guides or push rod holes. Is there any way to check for either one?

 

Do a leak down test . If the gaskest are shot you'll hear bulk noise out of the engine breather. Guides? Remove heads, test for valve leakage, disassemble heads and feel for play betwixt valve stem and guide.

 

If there were no oiling problems prior to the heads being 'Serviced' then it can only be gaskets or something that the shop has done. Like Greg I have never seen a set of heads on ANY big block that needed re-seating after such a short period of use. In fact apart from VERY early loopframes I can think of only about three big bloks I know of that have EVER needed new seats and they were very, very high mileage or the valves had been allowed to burn and then the seats were damaged by flame.

 

Any chance of some pics of the combustion chambers of these 'serviced' heads? The shop did have enough heat equipment to drop the originals out, (Like a kiln maybe?) and a Serdi bench or equivalent to service the new seats? I still lean towards another cause though as this sort of stuff is actually quite hard to screw up so badly that you allow oil into the combustion chambers. There should be NO oil anywhere near the valve seats???

 

Pete

[Garsdad]

While you were taking the heads on and off, did you do anything different with the breather set-up? Have you checked to see if the oil isn't coming in with the air and fuel?