Where's my oil pressure??

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The normal And common PSI for Cdo's is 50-100 on cold starts and very low to no show on hi way. Some report up to 50 PSI at head on highway but then low to nil nearing top speed. There is at least 3-4x's more oil flow through rod ends than head and most of rod end flow and PSI is generated by the crank spin sling and oil wedge. Norton may have been cheap short cutting but not stupid to state in so many words of Service Notes, if the oil is seen returning to tank and tends to get warm as expected then oil supply is just fine - short of land speed event down hill with tail wind over crank whiplash rpm's.

Also to get the metal-metal sacrificial protection of the zinc-phos content needed in flat tappet push rod engines, oil must get near boiling water temps to from the zinc-phos 'nano' pads that get wiped off at start up so must reform before shut down. Another reason I best not idle slow long or not let warm up pretty good on each start up before shut down. Try not to lug engine, hard as that is for me to avoid enjoying the Harley like short shifing and chug a lugging down rural lanes.
 
JimC said:
Not so sure what you mean by "blow toward the engine". Before you start replacing crankcase seals, I suggest you read some of the posts concerning PCV valves. If you prefer a Commando that keeps its oil on the inside rather than the outside, a PCV valve is a must.

"blow toward the engine" = lip debouches in the inboard direction = moves to your left as you're sitting on the bike

Since the one installed now has not blown, I'll leave it alone. My experience with the previous one, the blown one, was that I finagled the garter back into its groove - not easily done with the seal still installed - and reinstalled the timing cover. When oil pressure did not reappear, I pulled the cover and observed it blown again (note, it showed signs of having been damaged at a previous timing cover installation step). That's when I went to the present seal. And I have a spare.

I've read all the threads on PCV valves, etc. (as well as every other subject of interest). When I first got this bike, it leaked like crazy through the points cover. But a new camshaft seal fixed that and now the only leak is a very minor drip from the primary cover, which hasn't been off yet. I did put an inline PCV valve on the breather hose from the oil tank, just in case it might have some beneficial effect. If I can't stop the primary cover leak with basic measures, I'll have to face the breather issue again, but right now I'm not ready to drill the crankcase. If I thought I could do it without getting chips in the interior, I'd be all over it.
 
JimC said:
The crank seal is of course weak in containing pressure from the crankcase side, but even though mine is the one with the timed aperture breather, the crank seal did blow toward the engine.

kartiste

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Joined: Mon Oct 12, 2009 8:16 pm

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Not so sure what you mean by "blow toward the engine". Before you start replacing crankcase seals, I suggest you read some of the posts concerning PCV valves. If you prefer a Commando that keeps its oil on the inside rather than the outside, a PCV valve is a must.
I think he means the seal in timing case at the crank.
 
kartiste said:
Since the one installed now has not blown, I'll leave it alone. My experience with the previous one, the blown one, was that I finagled the garter back into its groove - not easily done with the seal still installed - and reinstalled the timing cover.

Is it possible the seal is in backwards? You shouldn't see the spring side with the seal installed?
 
bpatton said:
Is it possible the seal is in backwards? You shouldn't see the spring side with the seal installed?

The current seal is installed correctly, with garter on the (invisible) back side. The previous, blown out, seal was installed correctly, likewise with the garter unseeable. That's why it was heroically difficult to get back into position, back then, when I was trying to solve the OP problem before I overhauled the pump. To clarify, my present situation has nothing to do with this seal or with crankcase ventilation - but I'm glad as heck that all you guys take an interest in the intimate details of a piece of machinery that was obsolete when it was new, back when I was new. Who would have thought that 40 years on it would be possible to tap such knowledge and know-how? Incidentally, I've decided to lap the pump body some more, being as how the bike is already up on the work table with the cover off, and all. After that, if it still goes to zero pressure when warm, I'll resign myself to a "philosophical" attitude.
 
I'm still learning all the oboselte features and fualts my self but warn ya not to over do the lapping as causes pump heating drag and not much to gain pressure wise from output. Try the pump spun dry then with engine oil dribbled in to see the effect of its sealing and pump efficiency turning by hand. There are 4 leakage seams in pump and the side plates are only one of them, if the major one. I came across a saved post the details the upgrades possible like grooving for oil ring shaft seals. Will send it later today for your review in over kill.

Still think you just have normal variation in PSI reading and watching the spray out spindle rocker feed &/or oil tank return is only way to know if sufficient to ride as long and hard as Commandos can. Next level of exam entails looking at wear surfaces in hand, ugh.
 
hobot said:
I'm still learning all the oboselte features and fualts my self but warn ya not to over do the lapping as causes pump heating drag and not much to gain pressure wise from output. Try the pump spun dry then with engine oil dribbled in to see the effect of its sealing and pump efficiency turning by hand. There are 4 leakage seams in pump and the side plates are only one of them, if the major one. I came across a saved post the details the upgrades possible like grooving for oil ring shaft seals. Will send it later today for your review in over kill.

Still think you just have normal variation in PSI reading and watching the spray out spindle rocker feed &/or oil tank return is only way to know if sufficient to ride as long and hard as Commandos can. Next level of exam entails looking at wear surfaces in hand, ugh.

What's that about examining entrails? (HA!) OK, looking forward to more overkill. Incidentally, I'm assuming the scavenge side efficiency isn't playing a part here, but I suppose I need to confirm that by observing tank return. Also, I guess I could control end play - if not internal clearance - by shimming under the pinion, no? Then if I had shim stock of the correct thicknesses, die cut to the OD of the gears...

"Carry on, and dread nought" - Winston Churchill
 
Lets hope the Oil pickup gallery doesn't have any foreign bodies floating around inside. Mine had a full length sliver of 5/16 nut caught inside from
the "Compound Fracture"...Please be 100% sure that your oil is returning all the time... SORRY... Just had a thought... Perhaps one of the other guys
can tell us if you can get to the small, screw in, plug at the end of that gallery and remove it and try a small magnet up the hole?... Worth a thought.
AC.
 
The pump is spinning with the motor running, ie drive gear not just spinning on shaft, or at the pressure end
 
Collect rags, Remove seat, open oil cap, start up and blip up as normal warm up, if normal function, no need to look into tank, oil will show itself all over returning to source in ground and then some.
 
There are four possible wet sump leakage paths in a norton oil pump and
lapping the ends only address one.... shaft o-rings address the second.
3rd= gear to gear wear 4th=gear tip to pump body wear

3 o-rings....
2 on the rotating main shaft,
one between the feed and scavenge side gears
and one between the scavenge gear and the drive gear.
The shaft is ground with grooves to sliding o-ring fit tolerances.

1 on the idler shaft between the feed and scavenge side.
This shaft is stationary and the gears turn, therefore, this
shafts is ground with a groove to stationary o-ring fit tolerances.

These groove tolerances are easy enough to find, sorry I don't
have the numbers readily at hand.
 
hobot said:
There are four possible wet sump leakage paths in a norton oil pump and
lapping the ends only address one.... shaft o-rings address the second.
2 on the rotati
3rd= gear to gear wear 4th=gear tip to pump body wear

OK, the O-rings address wetsumping, but they don't do anything for pump efficiency, because the leakage path along the shafts between feed and scavenge sides is between areas of similar pressure, so there won't be any volume lost there; and while there could be volume lost to the outside along the shaft toward the pinion, whether it is stopped or not, it has already been lost to the output and would otherwise recirculate to the input side. As for the other two - gear-to-gear and tip-to-body wear - these can only be fixed by pump replacement (I can't buy new gears anywhere, can I?). So if I want improvement I'm back to additional attention to the end plate interface, or else a new pump. Or side shims - if I had any shim stock that thin and also correct-size die to cut it with. In other words, if we had some ham, we could make ham & eggs, if we had any eggs.
 
hobot said:
Still think you just have normal variation in PSI reading and watching the spray out spindle rocker feed &/or oil tank return is only way to know if sufficient to ride as long and hard as Commandos can. Next level of exam entails looking at wear surfaces in hand, ugh.

If I have spray out the rocker feed I must have return to the tank and can probably assume sufficient flow to the rods - but if I would have spray out the rocker feed I would probably also have some pressure showing on the gauge, which I didn't. [the bike is still hors de combat at this point, so I can't go out and check yet]

If I have oil return to the tank, and no spray out the rocker feed, I may or may not have sufficient flow to the rods - the rod bearings may be worn out and the pump can't keep up with losses there. That condition would not affect return to the tank.

But if no rocker spray or if worn rod bearings, more pump volume will help, even if the gauge behavior is in the "normal" range of variation for a Cdo.

It's the weekend, and my taxes are done. More pump body lapping.
 
OK, so here's how it went: I pulled the pump back off and measured .005" total difference between the pump body width and the width across the gears, about evenly split between the scavenge and supply sides. I decided not to do anything about the scavenge side [I guess by default that makes me a supply-sider...]. I set to work on the pump body with 400 paper, but sure enough, and against the admonition of the manual, I got impatient with the rate of removal and switched to some medium emory cloth and took too much off, to the extent that the pump would bind up completely with that last twist of the body screws. But to fix my screwup, rather than lap the gears, I just "broke it in" by working the pump by hand, keeping some tension on the screws and using some old clutch oil left over from kart racing days to keep the brass (bronze?) from galling. Pretty soon I had the right degree of dry tightness/lube freeness, and in it went (after cleaning, etc.). I put three shims under the pressure relief spring, making a total of four (turns out there was one in the cup already). After setting the slack in the timing chain - and grumbling that my reference marks on the Boyer were now worthless and I would have to retime the engine - I put on the timing cover.

Then I got a big surprise. I have one of those inline anti-wetsumping valves, which looks like the upper one in the picture here <http://www.clubmanracing.com/images/N201Wjpg.jpg>. I disconnected the downstream hose to fill the pump inlet, and when I put the hose back on the spigot and went to snug the hose clamp, the worm gear slipped a cog, preventing it from tightening. Criminy! If this clamp failed when I was out before, the pump could have sucked air, leading to the loss of oil pressure! More grumbling, since that would mean I had wasted my time reworking the pump. Oh well...

After replacing the hose clamp, I pulled the plugs and kicked the engine over until both legs were aching, hoping to see some pressure on the gauge. But nothing.

On to the moment of truth: fuel on, choke on, tickle, two kicks, contact, kick (I won't say how many - timing was approximate), start. After a few seconds and one goose of the throttle and no pressure, I shut it down. Very dark mood ensues...

As noted previously, I had checked the wetsump valve when I went through the system before, but just to absolutely eliminate the possibility that was the fault, I replaced it with a WOG ball valve from the hardware store. This time when I started the engine, the pressure zoomed to 75-80 max, and about 45 at idle. Hallelujah! So now that I'm in business, I shut it down and take two shims out of the relief valve and restart. This time, 55-60 psi, so I add back one shim and get 65-70 psi max (data point: one shim = 10 psi). I set the timing with a light. By this time the day has cooled and it's nearly dark, so I decide to wait until the next day to make my confirmation ride.

Yesterday afternoon, with it cloudy and in the high sixties, I took it out. Just an easy ride around the neighborhood, keeping it between 2500 and 3500 mostly. As the engine warmed, the max OP gradually declined, but nothing alarming. Then after I had gone 2 or 3 miles and maybe 10 minutes, the needle started dropping precipitously - oh $hit. I turned around to head home, wondering how far I'd get before having to kill it. Only this time, the needle didn't go all the way to zero, instead stopping around 10 psi or so, eventually settling at 8, which it wouldn't exceed even during a WOT burst or two. Having previously reasoned that the engine may or may not live with no pressure showing, but can live with some pressure showing, I rode on home. At idle in the driveway, it fell to zero psi.

So, back to the original question: where was my oil pressure the other day? Could be any of five possibilities: a) pump sucked air, destroying prime; b) wetsump valve constricted supply, starving the pump; c) lossy pump couldn't keep up with clearances in the rod bearings, which I have now partially fixed with a partial refurb of the pump; d) 20w-50 VR-1 is too thin for warm weather; e) it's a Norton.

From here, I'm going to leave the ball valve in - with an "interlock" link between the handle and the kickstart lever - and see if I really have a wet sump problem: leave valve open at shutdown, set engine to TDC, observe oil tank level prior to next startup. If no problem, replace valve with straight hose. If problem, contemplate my choices for a permanent fix - as well as whether I'm ready for a rebuild yet.

Further discussion welcomed. For instance, am I using the right oil?

"Carry on, and dread nought" - Winston Churchill
 
Correction: it was .010" total diference, not .005"

"Carry on, and dread nought" - Winston Churchill
 
I would guess at option C.
But there is another thing you might check. With the motor hot and showing no oil pressure you might want to cap the oil supply line to the head and run it long enough to determine if your oil pressure goes way up. A loose rocker arm or pivot pin loose in the head or turned the wrong way can loose enough oil to kill the pressure. Jim
 
comnoz said:
I would guess at option C.
But there is another thing you might check. With the motor hot and showing no oil pressure you might want to cap the oil supply line to the head and run it long enough to determine if your oil pressure goes way up. A loose rocker arm or pivot pin loose in the head or turned the wrong way can loose enough oil to kill the pressure. Jim

Hmm....trying to think of a good way to do this.

Would there be any odd noise if this condition existed? Haven't noticed anything so far...
 
You have the upper image inline valve from clubman? Mine from CNW looks identical to the bottom one.

Now you have me scared. I did run a simple lever WOG valve for many years, and just trusted myself to remember to turn it on, but I bought the inline one from Matt at CNW about a year ago, no issues with it at all so far.

Makes me wonder about your valve, look all silver, since you are not going to reuse it, can you cut it open and see how it is built, any evidence the spring or ball may have suddenly failed and not opened somehow?

I really like the concept of these anti sumping valves in that you just forget about them! Still ........
 
kartiste said:
comnoz said:
I would guess at option C.
But there is another thing you might check. With the motor hot and showing no oil pressure you might want to cap the oil supply line to the head and run it long enough to determine if your oil pressure goes way up. A loose rocker arm or pivot pin loose in the head or turned the wrong way can loose enough oil to kill the pressure. Jim

Hmm....trying to think of a good way to do this.

Would there be any odd noise if this condition existed? Haven't noticed anything so far...

Take the lower banjo bolt out and install a spacer in place of the banjo or use a short bolt if you have a 5/16-22 bolt laying around.
With a Norton you will not hear a rod bearing that is loose until the piston begins to hit the head or the rod exits the front of the cases. Jim
 
Oil sound fine but you might want to try a straight 50w.

How is the flow at the return to the tank. Loosen the banjo upper left head and see if it runs well (messy, but do it). Do these things warm when the pressure drops. Report back.

I swapped out my early 72 crankcase to the later reinforced model. This set was not new and when inspecting all the oil tunnels I pulled a good teaspoon of oil ring, compression ring and pinton bits out of the oil ways. The old cases also had ring bits in its ways.

God forbid you have this issue not knowing the history of your motor and it is truly not my intention to scare you. If need be, get a magnet into your sump plug some how and blow out the oil tunnels. Get a couple gallons of cheap/good oil to sacrifice to this procedure. You may be able pick this stuff out on the magnet. Look for grub screws. You may also have one on the bottom of the crankcase. Some do, mine did. These are your access point to tunnels along with behind the pump. Look down in there with a flashlight and a visor magnifier.

The place this stuff is most dangerous are the oil tunnels so I would not be TOO worried about trying to dislodge this stuff thinking it can find its way to bad places. If it's in the oil tunnels, Its already in the bad places. Novice re builders will miss this critical step and BLAMMO, the fresh build is toast.

Please realize I am speculating somewhat and that you maybe be able to retrieve bits to verify that this condition even exists. If you get some bits to the magnet and the pressure does not return keep trying until you come to the decision that a teardown may be luming.

Good luck, keep us posted.
 
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