Oil pump resurfacing re wet sumping

I thought I'd post this FWIW...

I resurfaced my oil pump IAW the Commando service manual at the same time that I installed new rings/valves in my 850. After some initial issues with a vacuum leak which I sorted out, the bike was running for a while but has NOT been run in three days. The pistons were not left at compression and I put a cup under the crankcase drain screw which I removed after the initial running of the engine. Other than what came out of the sump right after running, NO oil has drained from the tank/crankcase over the last three days. The level in the oil tank - right at the "add" mark - has stayed exactly there. Not saying it won't wet sump over a longer period but previously it would drain some oil overnight, whether left on compression or not. So obviously a good bit of wetsumping can be eliminated by surfacing the pump per the shop manual.

Whether wet sumping actually hurts anything at all is a different issue and one that I have insufficient knowledge to address.

Here's hoping, Mike.

That's another job on my list. Which has stopped growing, for the most part, but hasn't shrunk in a while. You are giving me some inspiration, thankfully.

Our own Norbsa had (has) a nice pictorial of this job online. I used to have it bookmarked, but given I seem to go through a hard drive a month lately, I've lost it. Anybody got a link?

Rings, oil pump, automatic cam chain tensioner, something else I'm forgetting. I gotta get going.

Frickin' "new" Eldo has kept me as busy as I want to be, but I'm getting philosophical about it - only the world's worst shifting gearbox is left now, and I'm inclined to just learn to live with it (necessity, meet virtue). That leaves me some bandwidth to turn back to the Norton. I think....

Hey Mike, did you replace any studs or other hardware while you were in the top end? What did you use at cylinder base (gasket/no gasket/sealant?)? How about head gasket - flame ring/copper/any sealant?

Thanks - BrianK

Brian, I used the eyeleted gasket from Old Britts -" 065051 Gasket, Cylinder Head, 850, Eyletted") with no sealant anywhere. Everything looks great but so far the bike has only been running in the garage so there hasn't been any load on the engine though I've revved it up to 5k+ quite a bit. I used Permatex super Grey at the cyl to crankcase joint - there was no base gasket there before so I didn't put in a new one. The super grey is Permatex's Yamabond. Previously someone had used regular RTV silicone and it was squeezed into the intake rocker box drain hole, obstructing it by about 1/2 its diameter. I was extremely careful with this, insuring the drain hole was kept clear by inserting a pipe cleaner in from the top of the cyl and having it stick out the bottom and then into drain hole in the crankcase as I Iowered the cyl in place. After it was torqued down, I removed the pipe cleaner, inserted a new on soaked in lacquer thinner and rotated it around a bit, repeated that with a new clean pipe cleaner, and then blew compressed air through the passage from the crankcase side.

I was planning to replace the three studs that are screwed into the head but the new ones (Andover Norton parts) wouldn't screw in due to the plating on the studs being too thick so I cleaned up/reused the old ones as well as all other studs/bolts/nuts/washers. I was hoping to take the bike out this weekend for some serious loading but then I got involved in checking the front Isos and found that the internal bushing were in pretty bad shape so it's all apart waiting for new bushings. SO it'll probably be next weekend, assuming the bushings arrive next week sometime. I could put it all back together with the old ones and go out but I have some sort of mental issue with doing so, even though it probably wouldn't take 30 minutes at the most reassemble/remount. We all have our little "quirks."

I'm not so optimistic to believe the oil pump work will completely eliminate wet sumping but it clearly reduced it pretty dramatically.

Thanks Mike - your experience parallels what I'm planning on doing exactly (except for even trying to replace studs prior to their making it absolutely necessary) so gives me additional confidence.

I agree on getting it right the first time rather than assuming you'll go in again. Somehow that second trip in is so much more painful.

Thanks, and best of luck. - BrianK

MexicoMike said:

I thought I'd post this FWIW...

Whether wet sumping actually hurts anything at all is a different issue and one that I have insufficient knowledge to address.

Click to expand...

It can cause a good bit of blow-by into the breather and possibly push some oil past the rings which could foul the plugs.

Hi Danno,
I'm not sure if wet sumping itself does any harm BUT, it does show that your pump has wear & tear in it & may be lowering your oil pressure & causing engine wear.
My pump has never been removed since new in 1972 & has got 46000 miles on the clock but it does wet sump.
I have been told how to do it & its one of my jobs to do before the weather gets warm again.
Resurfacing the pump sides properly can only make it work as intended & improve engine longevity.
Your name reminds me of Steve McGarret in Hawai 50 who always said to his sidekick Bookem Danno.
Cheers Don

Don Tovey said:

Hi Danno,
I'm not sure if wet sumping itself does any harm BUT, it does show that your pump has wear & tear in it & may be lowering your oil pressure & causing engine wear.
My pump has never been removed since new in 1972 & has got 46000 miles on the clock but it does wet sump.
I have been told how to do it & its one of my jobs to do before the weather gets warm again.
Resurfacing the pump sides properly can only make it work as intended & improve engine longevity.
Your name reminds me of Steve McGarret in Hawai 50 who always said to his sidekick Bookem Danno.
Cheers Don

Click to expand...

Guys on my work crew started saying that years ago when I would fill out job reports and timesheets.

My 850 wet sumped from the day I rode it off the dealer's lot. The factory rider's manual says it will. Expecting that to go away with oil pump resurfacing is a mistake. I replaced the pump with a new one ($$$) last year and it still wet sumps, just as it did when new.

IMO as long as the return side is bringing oil back to the tank faster than it pumps it in, the pump is working as designed.

"Expecting that to go away with oil pump resurfacing is a mistake. "

Well, I cant speak from long term experience, and you may be totally right and it won't last, but prior to resurfacing the pump my 850 would "leak" oil every day from the tank to the sump when it wasnt running. In a couple of days it would go from oil about 1/4" above the "add level" on the stick (where I kept it) to no oil on the dipstick at all. I never actually measured the specific amount that was draining per day by putting a cup under the open drain.

But since resurfacing, the oil on the stick has stayed exactly where it was after running (at the add mark) for 4 days now. Again, as you noted, it may begin leaking as the pump wears but it certainly made a huge difference initially.

My '73 850 wet sumps and it only has 18000 miles on it, I know this is genuine as i've owned it since it was about 18 months old! Due to the low mileage I have always been reluctant to pull it apart so I fitted a tap in the feed line some time ago which has an interlock switch attached to cut the ignition when turned off. I have been thinking recently, I don't seem to remember the problem in the early years, could it be that the oil seal in the timing cover has deteriorated over time?
Dave.

maylar said:

My 850 wet sumped from the day I rode it off the dealer's lot. The factory rider's manual says it will. Expecting that to go away with oil pump resurfacing is a mistake. I replaced the pump with a new one ($$$) last year and it still wet sumps, just as it did when new.

IMO as long as the return side is bringing oil back to the tank faster than it pumps it in, the pump is working as designed.

Click to expand...

Your assumption that the oil pump was set at a tight enough clearance from the factory is erroneous. Until you have ensured that the oil pump is at the proper clearance you cannot make that statement.

Maybe that applies to mine then too swooshdave, perhaps the factory clearance was too slack?
Dave

The oem oil pump, as installed, is rather rough-finished. On mine there were fairly prominent factory machining marks on both sides of the body of the pump. These machining marks would catch a fingernail. I can't imagine that the pump was "oil tight" at the covers. There was no noticeable internal wear on the top or bottom cover so seepage past the pump was, IMO, less due to any wear than due to initial machining tolerances. It took me about a half hour on the glass plate/320 wet or dry lubricated with WD40 to get the pump top/bottom surface to fit the gears as per the Norton shop manual and remove all traces of the factory machining.

So it seems entirely possible to me that new Nortons may have wet sumped simply due to the tolerances of the factory machining. And I wouldn't be surprised if, due to the machining tolerances that seem to have been acceptable, some pumps wet sumped considerably and others did not. I have no idea if the pumps were actually made by Norton or not...not that it matters.

The gears in my pump were below the mating surface of the pump body. I should have measured them but didn't. The Norton service manual calls for having a slight stiffness in the movement of the gears with the pump dry - caused by virtually no clearance between covers and gears. Before resurfacing, my pump spun freely and the gears would rattle in the pump.

daveparry said:

My '73 850 wet sumps and it only has 18000 miles on it, I know this is genuine as i've owned it since it was about 18 months old! Due to the low mileage I have always been reluctant to pull it apart so I fitted a tap in the feed line some time ago which has an interlock switch attached to cut the ignition when turned off. I have been thinking recently, I don't seem to remember the problem in the early years, could it be that the oil seal in the timing cover has deteriorated over time?
Dave.

Click to expand...

Is that how the anti-wet sumping valve mod works?

swooshdave said:

Your assumption that the oil pump was set at a tight enough clearance from the factory is erroneous. Until you have ensured that the oil pump is at the proper clearance you cannot make that statement.

Click to expand...

Point taken. But "tight enough clearance" for what? The factory knew about wet sumping while the Commando was still in production. The rider's manual specifically says to let the engine run for 3 minutes before checking oil level. It was expected to wet sump. In 35 years I've never drained the sump before starting my bike, and never had an issue with it. Nor have any of the other Commando owners I ride with. I'm of the opinion that it's not a big deal.

YMMV.

"In 35 years I've never drained the sump before starting my bike, and never had an issue with it. Nor have any of the other Commando owners I ride with. I'm of the opinion that it's not a big deal."

Although I think the pump is a primary cause of the wetsumping issue, I agree with the above and never saw any problem caused by wetsumping either on my '71 that I owned until 78 or my currently owned '73. I have also never drained a sump before starting the bike. IMO, "correcting" the problem is more a "because I don't like it" rather than any sort of real mechanical issue.

maylar said:

swooshdave said:

Your assumption that the oil pump was set at a tight enough clearance from the factory is erroneous. Until you have ensured that the oil pump is at the proper clearance you cannot make that statement.

Click to expand...

Point taken. But "tight enough clearance" for what? The factory knew about wet sumping while the Commando was still in production. The rider's manual specifically says to let the engine run for 3 minutes before checking oil level. It was expected to wet sump.

YMMV.

Click to expand...

Tight enough so that it wouldn't wet sump. Being a dry sump system, there is always some oil left in the crankcases after the engine stops. What we are talking about is how much. There are guidelines out there (I've heard a couple ounces to a cup) but the factory isn't going to publish a specific amount as if they did they would be liable for repairs if someone measured one ounce more.

Back to how much is too much? If the bike is difficult to kick over because of too much oil? Yes. Is oil getting pushed past the seals? Too much.

Do some bikes not exhibit signs of wetsumping? Sure. But it's enough of a known problem (I've drained my share) to say it does happen.

maylar said:

swooshdave said:

Your assumption that the oil pump was set at a tight enough clearance from the factory is erroneous. Until you have ensured that the oil pump is at the proper clearance you cannot make that statement.

Click to expand...

Point taken. But "tight enough clearance" for what? The factory knew about wet sumping while the Commando was still in production. The rider's manual specifically says to let the engine run for 3 minutes before checking oil level. It was expected to wet sump. In 35 years I've never drained the sump before starting my bike, and never had an issue with it. Nor have any of the other Commando owners I ride with. I'm of the opinion that it's not a big deal.

YMMV.

Click to expand...

It's pretty obvious that the clearances in the oil pump were never 'set' by anybody at the factory. What's the cap plate on the supply side made of? Is that copper? They may have been designed that way to bed in just case the various tolerances stacked up too tight. Just as often, they probably stacked up too loose. The point is that you can knock yourself out getting the gear height just right in the body of the pump but those gears are going to roam and have a field day on that plate. And the oil doesn't just pass around the gears, it goes between the teeth too. I don't see that it matters if you have pressure to spec. If wetsumping is intolerable to you, you could think about getting a check valve, CNW, AMR, whatever. I can't see CNW installing valves that are a dud on their expensive motors.

Somebody pointed out to me that the plate's made of brass not copper. Mea culpa already. I was watching the Daytona 500 and the ATT and screwed up

bpatton said:

Somebody pointed out to me that the plate's made of brass not copper. Mea culpa already. I was watching the Daytona 500 and the ATT and screwed up

Click to expand...

Remember this is considered a service item. It's meant to be trued and cleaned up. And the gears are meant to wear into the brass, this keeps the tolerances tight (until they loosen too much). Not bad for a pump that was probably designed in the 30's.


Stolen from norbsa so I can't take credit for the lack of focus. :mrgreen: