Leaking oil from exaust?

S

SevenFiftyNL

New member
Location
Amsterdam area, the Netherlands
Hello,

This is my first post on here so correct me if I do anything wrong...

I went to the Laverda meeting in Breganze 3 weeks ago (I was probably the youngest rider around) and my exaust started leaking oil right where it leaves the engine.
I went to visit Ricardo Oro (probably many about who know him) and he said that I should try replacing the rings at the beginning of the pipes. So I did. No result.
I didnt take my bike but went by car, which was stupid, so he couldn't take a look.

Does anyone know what this could be? It's getting quite irritating as it keeps throwing it out all over my sidepanel, exaust and.. my pants.

Things that might the relevant to know:
It's a 1972 750SF1. It's bleeding from one cilinder. Sparkplug was powdery black. Oil level remains the same over the weeks (so it's not that much..)

Hope to hear from you!

Drive safe.
 
i had the same problem and new exhaust copper crush gaskets/seals didn't help - that is until someone suggested adding a bit of "the right stuff' gasket sealer around each  new gaskets - problem solved and no more oil leaking from my exhaust (the exhaust flanges  need to be tightened up  too after running the bike up to temp)

hope this helps
 
Hello
For some reason header pipes that are not sealing correctly in the head will cause oil to be pulled into the exhaust chamber and into the exhaust and sometimes past the header pipes onto the engine when they are sealing very badly

Regards
Tetley
 
At one point early in my ownership I found the thickening ring around the outside on the end of my header had come away from the pipe.Its not supposed to be separate from the pipe Not sure if your bikes headers has these but worth a look.
 
mik667 said:
i had the same problem and new exhaust copper crush gaskets/seals didn't help - that is until someone suggested adding a bit of "the right stuff' gasket sealer around each  new gaskets - problem solved and no more oil leaking from my exhaust (the exhaust flanges  need to be tightened up  too after running the bike up to temp)
Click to expand...

The 'right stuff' for me is 5926 Loctite blue silicone gasket goo.
Just smear it around the copper ring fairly generously and then assemble. Re-tighten after first run.

meZG3hZguZ8i2zRtwxYpVmQ.jpg


Works every time - a top tip which came from the top man Keith Nairn.
 
oil coming out the exhaust port means you have a leaking valve guide/bent valve or head gasket that is allowing oil into the combustion chamber.  All the sealing goop and new exhaust rings does is hide the problem.
You need to find out where it is coming from and fix that first, then the new sealing rings and sealing goop.

I'm sure more technically competent people will provide some guidance on what/how to check.
 
Hi DaveH,

it seems, for some complicated gas dynamics reason (which non of us truly understand), a leak at the exhaust rose joint does indeed cause artifically low pressure around the exhaust valve guide and oil is drawn down. It's pretty well observed, over many bikes and years. To get a good seal there is the right place to start before diggting further.
 
I bow to the superior knowledge of the forum.
Interesting.  Do triples do the same thing ?

My 248,000mile purchased new SF2 has only ever leaked oil intothe exhaust when the valves and guides were due for replacement - now on its 2nd set.
I have never had oil leak from the exhaust ports, evidence of guide wear being a slightly oily exhaust and plugs, both times around the 100,000 miles mark.   
 
Wow, thanks for the great responses! It's truly amazing that Laverda is still so much alive.

In response OT:
First of all I made a mistake; I changed the crush gaskets and completely tightened the exhaust rose and never tightened it again, so I think I need to get new ones and repeat the process.
But the last conversation got me confused; do I need to try new rings first? Or first look further inside the engine for a bigger problem? And if so, what to look for?
 
Paul H said:
it seems, for some complicated gas dynamics reason (which non of us truly understand), a leak at the exhaust rose joint does indeed cause artifically low pressure around the exhaust valve guide and oil is drawn down. It's pretty well observed, over many bikes and years. To get a good seal there is the right place to start before diggting further.
Click to expand...

I must admit Paul, I had to google it as I was mystified as well.
This is from a guy called Ray who seems to know something - So! Apparently, Exhaust doesn't need a stem seal, Inlet does:

http://www.mg-cars.net/mgb-technical-bbs/valve-stem-oil-seals-2007101415220030339.htm

Ray:
'Do not use an oil seal on the exhaust valve guide in a mistaken attempt to reduce oil consumption. High gas pressures within the exhaust port momentarily restrict oil from going down the valve stem to both that induced by mechanical transference resulting from valve stem movement and that by capillary action. As the pulse of hot exhaust gases passes out of the port it leaves a partial vacuum in its wake, ambient pressure within the rocker arm cover then forces oil down the valve stem in order to both lubricate the bore of the valve guide and provide a heat-conducting medium. Thus, the absence of a valve stem seal on the exhaust valve guide will have no practical effect upon oil consumption. The film of oil on the valve stem is an essential part of the cooling of the exhaust valve as it fills the gap between the stem and the bore of the valve guide, acting as a medium for conducting heat out of the valve. Because bronze valve guides have closer operating clearances, valve stem seals are not only unnecessary on the exhaust valve guides, but are actually undesirable as they reduce lubrication of the valve stem, accelerating wear of not only the valve stem and its guide, but also of the seating surfaces as a consequence of attendant misalignment.

However, the opposite is the case where the intake valve is concerned. The low atmospheric pressures in the intake ports draw oil down the stem of the intake valve quite readily, leading to high oil consumption and carbon buildup on the head of the valve and inside the combustion chambers. Additionally, the oil being mixed with the incoming fuel-air mixture consequently interferes with combustion efficiency and actually lowers its octane rating, making preignition a very real risk. Always install the highest quality valve stem seals on intake valve guides'.
 
Don't really see a leaky header joint causing excessive oil to be drawn down the guides.  Should actually be less, vacuum in the pipe will be lower because of the leak.  A leaking joint will only bring the problem into the open...

Simply a worn guide and valve stem imho, more rarely, a loose guide in the head.

Please pass on my regards to Gijs,

piet
 
My one-time SF3 did just that, oil staining out of the exhaust ports/pipe joint. New gaskets cured it immediately.
 
SimonR501 said:
I must admit Paul, I had to google it as I was mystified as well.
This is from a guy called Ray who seems to know something - So! Apparently, Exhaust doesn't need a stem seal, Inlet does:
Click to expand...

Ray may know something or he may not, but fact remains that 1000's of different car and motorcycle models on our roads have valve guide seals on the exhaust guides, including our very own Laverda 500's which came out standard with seals on both Inlet and Exhaust guides and still using cast iron guides



 
no - get new crush gaskets, and add a bit of gasket sealer around each before putting them in (i wipe the exhaust port down with a rag in gas to get some of the crap out before putting the new gaskets in). tighten the exhaust clamps  down let it sit for a day (for gasket sealer to polymerize), start the bike and bring up to temp then shut it off and re-tighten - should be leak proof

i had the same problem on my sf2 with all new exhaust guides etc - new gaskets and sealer stopped the leak some 5000 miles ago with no occurrence

hope this helps


SevenFiftyNL said:
Wow, thanks for the great responses! It's truly amazing that Laverda is still so much alive.

In response OT:
First of all I made a mistake; I changed the crush gaskets and completely tightened the exhaust rose and never tightened it again, so I think I need to get new ones and repeat the process.
But the last conversation got me confused; do I need to try new rings first? Or first look further inside the engine for a bigger problem? And if so, what to look for?
Click to expand...
 
You can peer into the exhaust tract and see the trail from the guide...in my case clearly shot even after remediation. Keith Nairn fits seals to the exhaust valves too,Simon, so yours maybe have em?
I think the advice now is to line the guides rather than replace? K liners? Obviously only by a specialist engineer....
 
nick7 said:
I think the advice now is to line the guides rather than replace? K liners? Obviously only by a specialist engineer....
Click to expand...

Laverda valve guides are way too short to run a K-Liner, they reduce the amount of bearing surface too much
not a fan of them at all



 
Gijs said it's difficult to see wether the oil comes out of the exhaust rose. It could well be comming from the side and leak to the rose and by wind get blown all over the place.

I feel rather stupid not thinking about that, good thing I am not a mechanic.
So, tomorrow I'll bring her in. Keep you posted!
 
I think you're all wrong - it's because you're not using the correct type of crush washer  :D :D

http://www.laverdaforum.com/forum/index.php/topic,91147.0.html
 
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