Oil Disappearing

Hello,

I would like your advice and opinions on my '73 850 Commando and the cause of disappearing oil. I estimate I have added in the ballpark of 1 1/2 quarts of oil over 1000 miles of riding. When I top off or change the oil, I typically fill the tank so that the dipstick reads just above the "L" or maybe a quarter or a third between the "L" and the "H" (always biased towards "L"). I am leaking a bit of oil, from where I have not unequivocally identified. But when I park on my cardboard mat, I reckon I am loosing quarter size drops over a day or so, not cups or pints or quarts...I do not notice excessive smoke from the exhaust, not on starting the engine nor riding the bike, although it is hard to say when I am the one riding it. Riding companions have not remarked upon smoky exhaust.

Upon examining the spark plugs, I found that the right plug was fouled; it was black and there was visible oil. The color of the left plug resembled toasted marshmallows, which I think is good. After cleaning up both plugs, I swapped the plug wires and plugs together. After riding a bit, the right plug (originally toasted marshmallow) was now black and oily.

I previously checked compression and it was around 140 psi on both cylinders if I remember correctly. I did this on a cold engine; not sure if that is the right procedure. Fuel consumption has been in the mid forties (U.S. gallons, not imperial). One last bit of information that may be pertinent: on the right side, the bolt next to the spark plug on the cylinder head appears to have oil weeping around it. I noticed this while cleaning the engine and was not able to scrub it away with Dawn and a rag. I am not sure if this has been there since I acquired the bike.

I am sorry if this is too long, but I figure the more detail the better. Is this serious? Valve guides, rings, head gasket? Does the asymmetry of the plugs tip you in one direction? I would not mind a little burning of oil, but the volume seems excessive. Should I start adding it to the tank as for a two stroke?

Thank you in advance.

Well I'd say you had better plan to pull the head and investigate . New teflon seals as a minimum .

The oil around the cylinder head bolt could be coming from the rocker spindle gasket above.(photo helpful)
You mentioned ...(have not unequivocally identified)...Where does the oil thats leaking from the bike congregate...eg: rear wheel...air filter box ?

You only have to use /burn a small amount of a drop of oil on every stroke to have oil consumption.

Just to be clear are you saying the right plug was fouled, then you swapped plugs was it the original left plug in the right cylinder that was oiled or the original right plug that got oiled in the left position.

Sounds like a head off and new inlet valve seals.

After cleaning both plugs, I swapped the originally on the left, clean-looking plug with its lead, to the right side, where it was subsequently fouled. The originally on the right plug which was oily and black, looked clean after running it on the left. I.e., I do not think the plugs or wires have a say in the matter; the right cylinder is the misbehaving one.

KiwiShane, the oil on the cylinder head has never seemed fresh, but an old remaining stain. Perhaps the head gets so hot it dries it so fast that I would never know, but the profile of the oily spot seems unchanging. It does not appear to be leaking down from the gaskets around the spindles if I follow the discoloration, although I do see similar discoloration around both inlet rocker spindle gaskets. I will see about a picture. As for where the oil is going or coming from underneath, I have seen it around the sump plug and dripping towards the front of the bike and also onto the center stand, but I think this may just be gravity. After cleaning up the bike, I thought it would be much easier to identify where it is leaking from, but this hasn't proved to be the case.

As for pulling the head, could someone elaborate on what he or she would do in this position? Is there a bit of "while you have it off you might as well..." Not looking to spend unnecessary money, but if I do it I would like to be thorough as I plan on riding this bike indefinitely.

Thanks

In that case you will need a few specialty wrenches/ sockets to do the job . Whitworth ones .
Last time I pulled a head it was stripped down and sent to Gord Bush , A competent machinist in Etobicoke ( Toronto ) . It was cleaned , new valves ( Black Diamond type ) , cut and ground in ( didn't ask ) new guides after he inspected and new teflon intake seals from Kibblewhite .
You will be fitting a new head gasket too .
This forum has Threads on how to do it if you search and take notes , you can do the pull and refit yourself using bungy cords for weight support but it's more fun to ask for help from a bud . Good luck .

Snortin Vache said:

After cleaning both plugs, I swapped the originally on the left, clean-looking plug with its lead, to the right side, where it was subsequently fouled. The originally on the right plug which was oily and black, looked clean after running it on the left. I.e., I do not think the plugs or wires have a say in the matter; the right cylinder is the misbehaving one.

KiwiShane, the oil on the cylinder head has never seemed fresh, but an old remaining stain. Perhaps the head gets so hot it dries it so fast that I would never know, but the profile of the oily spot seems unchanging. It does not appear to be leaking down from the gaskets around the spindles if I follow the discoloration, although I do see similar discoloration around both inlet rocker spindle gaskets. I will see about a picture. As for where the oil is going or coming from underneath, I have seen it around the sump plug and dripping towards the front of the bike and also onto the center stand, but I think this may just be gravity. After cleaning up the bike, I thought it would be much easier to identify where it is leaking from, but this hasn't proved to be the case.

As for pulling the head, could someone elaborate on what he or she would do in this position? Is there a bit of "while you have it off you might as well..." Not looking to spend unnecessary money, but if I do it I would like to be thorough as I plan on riding this bike indefinitely.

Thanks

Click to expand...

Management is a lonely place ....in regards to your decision to pull the head... as Kommando explained... new valve guide seals would be a must do for me regardless if everything else checks out ok.
Re anneal /replace the copper sump plug and magnetic plug washers ...evaluation of the head once removed/valve guides inlet track and chamber /gasket surface should be a telling...
Reducing crankcase pressure is also another way to reduce possible leaks

Oil leaking through valve guides can mask worn rings but inasmuch as the other cylinder is running clean I doubt the rings are excessively worn. However, when you pull the head the additional cost to do rings too is the cost of the rings and a base gasket. There's the extra time to clean the ring lands but I wouldn't think it would be more than an hour to R&R the barrel and do the rings. Then you'd have a fresh top end and no worries on that account.

Firstly, when do you check oil level, immediately after a ride or just prior to next ride, days/weeks later? If you have good level right after a ride, but low level sometime later, you have a wetsump situation and adding oil when appearing low will result in risk of over fill once oil pump returns oil to tank after some minutes running.

How is oil level in primary? You could have engine oil getting into primary via loose inner primary case mounting bolts or the crank seal. If too excessive, it will eventually come out the felt seal ring and soak the rear wheel.

When idling, watch the tail pipes and give throttle a few blips. In right lighting conditions, against dark background, you should see puffs of bluish smoke when blipping, especially when ending the blip, if the valve seals are leaking. My 850 mk2 did that on one side, oily plug. I followed the in-situ seal replacement procedure described in another thread here:
Post in thread 'Replacing Valve Stem Seals (in situ) Pitfalls?' https://www.accessnorton.com/Norton...stem-seals-in-situ-pitfalls.35061/post-576640

My original seals just crumbled away when removing. Also check the tiny oil drain hole at the floor of intake rocker box, right side, towards rear, halfway under the spring seat. Hard to see. Pour in a bit of oil and time how long it takes to drain down. The passage can get a blockage, leading to oil build up in rocker, more drawn into valve guides and burnt. I ran a long thin wire down that drain to timing chest, then sprayed some WD40 down. Drainage time went down.

Tornado,

The primary is an interesting point. I had the cover off not too long ago and I replaced it along with ~>200 mL of oil. Then I noticed a little dripping at the bottom front of the cover after riding. I thought I needed to replace the felt o-ring item, which I have purchased but not yet replaced. I also do not think I over-torqued the cover, so maybe oil is making its way into the primary case and pushing past the felt. Does the oil in the primary, assuming no contamination from the crankcase, stay clean or does it turn black like used engine oil? Because what I have found leaking out the cover is black. I use the same oil by the way in the primary and the oil tank. None of this explains the fouled plug but I'll take a look here as I already planned to rectify this leak.

Thomasa said:

Oil leaking through valve guides can mask worn rings but inasmuch as the other cylinder is running clean I doubt the rings are excessively worn. However, when you pull the head the additional cost to do rings too is the cost of the rings and a base gasket. There's the extra time to clean the ring lands but I wouldn't think it would be more than an hour to R&R the barrel and do the rings. Then you'd have a fresh top end and no worries on that account.

Click to expand...

So the idea is that the leaking oil seals up the worn rings? But on a cold engine would I still get 140 psi compression in both cylinders with what you are describing? Good point either way as that is what I was looking for in terms of what I potentially would want to do if I was pulling the head anyway.

I think I will investigate some of Tornado's points as they cannot hurt and are simpler, cheaper fixes than pulling the head. And perhaps the valve stem seals can be replaced anyway without removing the head, we'll see.

Snortin Vache said:

Tornado,

The primary is an interesting point. I had the cover off not too long ago and I replaced it along with ~>200 mL of oil. Then I noticed a little dripping at the bottom front of the cover after riding. I thought I needed to replace the felt o-ring item, which I have purchased but not yet replaced. I also do not think I over-torqued the cover, so maybe oil is making its way into the primary case and pushing past the felt. Does the oil in the primary, assuming no contamination from the crankcase, stay clean or does it turn black like used engine oil? Because what I have found leaking out the cover is black. I use the same oil by the way in the primary and the oil tank. None of this explains the fouled plug but I'll take a look here as I already planned to rectify this leak.

Click to expand...

I use ATF type F in my primary and it tends to stay clean, reddish in colour so easier to identify a leak from engine oil. I have original sintered bronze clutch plates which i think shed less material into oil. If you are running Barnett type plates, with the more aggressive friction material, I'd think the oil would darken more rapidly.
You can check for over fill by way of the level plug at bottom edge of over cover, with bike on level ground, on centerstand, remove the level plug and see if much oil comes out, should only be a dribble and no more if level is correct.

There is no excess oil in the primary, and I added very little before it poured out of the level plug, so I must not have lost much through the o-ring in the cover. Before going for a ride, I looked carefully behind me and blipped the throttle. I do not see any smoke whatsoever, but I am not sure if this changes anything about what others have said. I did not have the chance to remove the tank and rocker cover to see about this drain passageway, but I will do that soon.

Tornado, I read up on replacing the seals in situ, and wonder because you have done it, do you really think the time savings (are there much anyway?) are worth it compared to just removing the head, in which case you glean more than just replacing the valve seals through the rocker cover?

I do not want to do unnecessary surgery, and I definitely do not like the idea of sending the head away to somebody when I could be riding it. Something tells me if I remove the head, I'll see something(s) that will lead me down a path that has my bike parked for a bit.

Torontonian said:

In that case you will need a few specialty wrenches/ sockets to do the job . Whitworth ones .
Last time I pulled a head it was stripped down and sent to Gord Bush , A competent machinist in Etobicoke ( Toronto ) . It was cleaned , new valves ( Black Diamond type ) , cut and ground in ( didn't ask ) new guides after he inspected and new teflon intake seals from Kibblewhite .
You will be fitting a new head gasket too .
This forum has Threads on how to do it if you search and take notes , you can do the pull and refit yourself using bungy cords for weight support but it's more fun to ask for help from a bud . Good luck .

Click to expand...

Ignoring my own labor to remove and refit the head, how much would I be in for for what you described, if you don't mind my asking? I already contacted a nearby guy about getting a set of Whitworths, so I'll probably be doing that anyway.

Snortin Vache said:

There is no excess oil in the primary, and I added very little before it poured out of the level plug, so I must not have lost much through the o-ring in the cover. Before going for a ride, I looked carefully behind me and blipped the throttle. I do not see any smoke whatsoever, but I am not sure if this changes anything about what others have said. I did not have the chance to remove the tank and rocker cover to see about this drain passageway, but I will do that soon.

Tornado, I read up on replacing the seals in situ, and wonder because you have done it, do you really think the time savings (are there much anyway?) are worth it compared to just removing the head, in which case you glean more than just replacing the valve seals through the rocker cover?

I do not want to do unnecessary surgery, and I definitely do not like the idea of sending the head away to somebody when I could be riding it. Something tells me if I remove the head, I'll see something(s) that will lead me down a path that has my bike parked for a bit.

Click to expand...

If i were you ...I'd top up your oil tank and take her for a decent long ride
Once she is at running hot temperature and at a good speed preferably down hill ...back the throttle off completely for as long as you can then open the throttle and have a mate or your self observe to see if she burns oil then.
Valve guide seals can successfully done while the head is still in place
A re torque of the head bolts and reset/check/adjust the tappets would also be my recomendation at this stage...Unless I missed something?

1 1/2 quarts (1.5L) of oil consumed over 1000 miles (1600 km) is excessive! Provided compression is good, I suspect worn valve guides, a leak past the inlet valve guide, or a crack in the cylinder head allowing oil to be sucked into the offside inlet duct. Head gasket may also cause pushrod tunnels to leak , but then oil would make itself noticeable at the exterior of the engine, and this would not explain the fooled plug.

- Knut

KiwiShane said:

If i were you ...I'd top up your oil tank and take her for a decent long ride
Once she is at running hot temperature and at a good speed preferably down hill ...back the throttle off completely for as long as you can then open the throttle and have a mate or your self observe to see if she burns oil then.
Valve guide seals can successfully done while the head is still in place
A re torque of the head bolts and reset/check/adjust the tappets would also be my recomendation at this stage...Unless I missed something?

Click to expand...

Perhaps I am ignorant, but I thought you torque the head bolts upon installation, then go for a certain period and retorque. I did not know that it was part of a maintenance regimen. But I'll give it a go. Also, I am going for a 200 or so mile ride tomorrow and will try as you suggested. I'll bring a quart of oil with me of course.

I do not think you are missing anything, but as it is my bike I do have the nagging suspicion that there could be something more wrong. The fact that I do see some oil residue around one or two cylinder head bolts as I mentioned, and that a few of the rocker spindles gaskets also show some old signs of oil seepage (not apparently fresh though) has me concerned. One of the rocker spindle gaskets additionally has a slight tear, even though this particular one has no visible oil whatsoever. Perhaps it is my personality, but until I have seen into every nook and cranny of the thing I will always assume the worst is lurking just out of sight.

Snortin Vache said:

Perhaps I am ignorant, but I thought you torque the head bolts upon installation, then go for a certain period and retorque. I did not know that it was part of a maintenance regimen. But I'll give it a go. Also, I am going for a 200 or so mile ride tomorrow and will try as you suggested. I'll bring a quart of oil with me of course.

I do not think you are missing anything, but as it is my bike I do have the nagging suspicion that there could be something more wrong. The fact that I do see some oil residue around one or two cylinder head bolts as I mentioned, and that a few of the rocker spindles gaskets also show some old signs of oil seepage (not apparently fresh though) has me concerned. One of the rocker spindle gaskets additionally has a slight tear, even though this particular one has no visible oil whatsoever. Perhaps it is my personality, but until I have seen into every nook and cranny of the thing I will always assume the worst is lurking just out of sight.

Click to expand...

Sorry I am unaware of your time of ownership ? or can see whats going on.
But like you I make sure I cover all bases before dismantling anything
I've re torqued/checked some head gaskets 3-4 times (copper/flame ring ?)...to be satisfied over a period of time....and it costs nothing but a wee bit of time....
Maybe I should have asked originally how long have you owned her for.?
I wish you well.. and look forward to what you discover

KiwiShane said:

Sorry I am unaware of your time of ownership ? or can see whats going on.
But like you I make sure I cover all bases before dismantling anything
I've re torqued/checked some head gaskets 3-4 times (copper/flame ring ?)...to be satisfied over a period of time....and it costs nothing but a wee bit of time....
Maybe I should have asked originally how long have you owned her for.?
I wish you well.. and look forward to what you discover

Click to expand...

No worries. I bought the bike last fall, but didn't get much chance to ride it before the snow came. Now I am trying to balance riding it with working on it, which are like two spouses who seem like a good pair but have somewhat incompatible interests...

I really would not mind taking the head off as I have never done that, but I do not like the idea of sending it to someone and waiting weeks when I could just be topping off oil after every ride. I know I could just replace the seals, but something tells me it will be a bit more than that. If I can do most of it in my own time, I am more than willing to do pretty much anything to my bike, but once I remove it I am afraid what I might find.