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Question: Did MV provide a drilled weep hole passageway in the cylinder head, to drain any oil leaking from the cam box into the recess for spark plugs?

Elaboration: At 7,5000 miles, I removed valve cover to check valve lash. Upon reassembly, I replaced the valve cover gasket (#24 below) and used silicone sealant in half moon recesses per MV workshop manual. I DID NOT replace seals #25 or #25, nor did I replace o-rings #5 #16.

Upon putting engine back into service, I now have a slight weep of oil below exhaust port #1. There is zero indication of oil running down the outside of the cylinder head. Talcum powder and several other methods of oil detection have been used. However, the joint between the head and the cylinder block are wet below exhaust port #1.

It appears to me, that MV has a drilling approximately 2.0mm in diameter, below each exhaust port. I noticed this drilling to be wet with engine oil. I can insert a plastic tube as found on a can of WD-40 or Contact Cleaner into this hole to a depth of approximately 50mm.

I have since ordered the above referenced parts and in advance of pulling the valve cover, and making the inspection myself, I have the following question.

Might someone with personal experience with this engine know the answer? Does this drilling lead to the chamber around the spark plugs?

Ciao,
Dick
 

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Hi Dick,

What a good question ! I have now retrieved a cam cap bolt from the waste trap in the sink as a consequence of trying to answer it lol.

The answer is yes. There are four passage ways as you describe and they each lead to a spark plug well to drain off oil / water

I tested by pouring some baby oil down the spark plug wells in my ( off the bike ) 1000R cylinder head and sure enough it pees out of the little orifice under the exhaust port.

My hands are now lovely and soft ha ha

Logical to assume it is same basic system for your bike.

joe
 

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Yes, the 1090 is the same. While you have the rocker cover off, make sure to check the cam chain tensioner. They have a propensity to jam and will not move in or out.
There is a gradual increase in engine noise as the chain stretches and starts to slap around.
 

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Common to almost all bikes, at least every one I have worked on......yes, there is a passage drilled to allow fluids to escape from the spark plug well. You likely dislodged the seal on the valve cover for that particular plug.
 

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what part number that i have to check or replace #25 or #24???

its leak from 4 hole cylinder i think maybe because i change the spark with ngk cr9eix ??? or maybe I did not tighten too strong ????
#4 cylinder would be #25.....but kind of unusual to dislodge or damage that seal just changing a spark plug. Did you remove the cylinder head cover?

Confirm the oil is coming from the drain hole before going further. Could be from the head cover perimeter seal # 24 (much more common). Since the bike leans to the left on the side stand, oil pools in the left front corner and will leak from the cover seal in that area....especially once the head cover is removed and seal not replaced.
 

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what part number that i have to check or replace #25 or #24???

its leak from 4 hole cylinder i think maybe because i change the spark with ngk cr9eix ??? or maybe I did not tighten too strong ????
No mate, spark plug torque has nothing to do with your oil leak, either you messed up a seal, or you had an existing leak which just popped up while you changed the spark plug, you will probably want to replace all those seals (24&25), but it depends your skill's mate.

That's a nice design/
As usual, your technical feedback is amazing...........:jerkoff:
 

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Question: Did MV provide a drilled weep hole passageway in the cylinder head, to drain any oil leaking from the cam box into the recess for spark plugs?

Elaboration: At 7,5000 miles, I removed valve cover to check valve lash. Upon reassembly, I replaced the valve cover gasket (#24 below) and used silicone sealant in half moon recesses per MV workshop manual. I DID NOT replace seals #25 or #25, nor did I replace o-rings #5 #16.

Upon putting engine back into service, I now have a slight weep of oil below exhaust port #1. There is zero indication of oil running down the outside of the cylinder head. Talcum powder and several other methods of oil detection have been used. However, the joint between the head and the cylinder block are wet below exhaust port #1.

It appears to me, that MV has a drilling approximately 2.0mm in diameter, below each exhaust port. I noticed this drilling to be wet with engine oil. I can insert a plastic tube as found on a can of WD-40 or Contact Cleaner into this hole to a depth of approximately 50mm.

I have since ordered the above referenced parts and in advance of pulling the valve cover, and making the inspection myself, I have the following question.

Might someone with personal experience with this engine know the answer? Does this drilling lead to the chamber around the spark plugs?

Ciao,
Dick

If i'm not mistaken one would have to remove the cam caps to get to 5 & 16, so if you only removed the valve cover then you shouldn't have to worry about those. Usually the valve cover gasket and spark plug o rings don't need replacing so soon. Have torn into countless motors over the years and the only leaks i've ever come across were because while trying to jimmy the valve cover back into place with motor still in the frame i inadvertently bumped something somewhere that didn't get a good seal. Its only happened twice so its not all that common. I suspect you could remove the valve cover, check the rubber gaskets for cuts or pinches, and if all checked out ok then reassemble more carefully. If i had to venture a guess i'd say the spark plug gasket didn't get a perfect seal thus allowing oil to seep into the spark plug chamber. If you already have new parts then good to use them. Although, it may not be necessary.
 

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sealing?

I do not replace the seals unless they're cut.....

the manual says to use sealant around the half moons on the valve cover gasket only

I use it all the way around top and bottom....and on the cover bolts, the F4 cover and the oil pan gasket too

I'd rather seal it once and not have it leak.....given what a pain it is to pull the valve cover or pan
 

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The last time I pulled the cam cover I replaced all the seals (they weren't that expensive) and put a light smear of silicon on all surfaces, I don't like using silicon but seems its a must if you don't want to take the whole lot apart again, and yes check the tensioner if you haven't do so, they fail. On the + side once the clearances have bedded in they don't seem to change.
 

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Valve cover plug seals

Here are the spark plug seal at the underside of a 312R Valve cover.

These are recessed into the cover and the whole thing presses down on the cam caps.


The holes in the four and eight oclock position are the inlets for the secondary air system. There must be a reed valve in there as you can only blow not suck .." Pardon the expression best beloved !"

joe
 

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