Airhead oil priming "problem" HA!

Discussion in 'Airheads' started by rgears, Dec 5, 2011.

  1. rgears

    rgears Adventurer

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    Howdy All!
    Yep, same bike, similar problem! I wasn't sure if I should start a new thread, but I figure this is more of an oil pump scenario more than anything else.
    First off, thank you all again for all the help and info I have gotten in this ever-deepening endeavour to get my bike back to the road.

    I've been going through the engine for my '76 R90/6. So far, new crankshaft, conrods, big end shells, main bearings (WAY easier to replace than I thought it would be), oil presure relief spring/piston, full gaskets and seals, and I'm sure plenty more than I care to price up. In other words, new guts all around and everything is spec'd nicely with all the new tools I got to buy. The problem now is I simply CANNOT get the oil pump to prime. I am wondering if there are any other tricks or methods anyone knows of, or I have overlooked something horribly wrong and it is just bleeding back into the case.
    And for FYI, story so far is here.

    Just a run down, I worried the pump spurs were worn, though the gap checked out, so I went ahead and replaced the outter rotor (not the inner too, I couldn't afford the $65 at the time). I read on another post about priming was to pack the pump with vaseline and prime by pushing the bike in 2nd gear a bit or just rotating the tire. Did that, nothing. Tried priming by grounding the plugs and turning over with the starter, nothing. I was finally able to get oil into the galleys enough to get the presure sensor to flicker after filling the filter by hand then priming, but then it dropped off again. Which is only more baffeling.

    So far I have tracked it all back to the pump, as with the oil pan dropped, I plugged the sump hole and could feel no pressure when using the starter and I tried removing the oil filter to see if any oil would come through the canister fill galley. Still nada.

    Unless I can find something else to try, I guess I just need to have a real mechanic look at the thing. And just as an extra, I did pull the jugs enough to squirt some oil over the crank and conrod bearings to make sure there was some lubrication on there. I really don't want to replace them again.

    So yeah, anyone have any ideas or something that I am just completely overlooking? After two weeks of troubleshooting, I think I have a bald spot from head scratching over this one.
    #1
  2. DoktorT

    DoktorT BigBrowedNeandereer

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    Just 2 things to verify. Pickup mount leaking. If not that, oring seal for the oil pump cover.
    #2
  3. supershaft

    supershaft because I can

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    It takes a LOT of fast turning to get them to prime. I always do it before I put the cam chain on. It is still very often a PITA.
    #3
  4. bmwrench

    bmwrench Long timer

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    Before I start a rebuilt motor, I pump oil into the motor via the hole for the oil pressure switch. An oil pressure gauge will show good pressure very quickly after start up.

    Have you checked the woodruff key on the inner rotor?

    Another possibilty-fairly small-is that the front cam bushing is badly worn.

    Any chance the top front cylinder stud has been Heli-Coiled? Have a look at Bill Harris's thread: "Cylinder Stud Advisory"

    There has to be an answer.
    #4
  5. supershaft

    supershaft because I can

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    How do you pump the oil in BW? That probably is the answer here if the engine is assembled. It is hard enough to get the pump to take turning just the cam on its own before you hook it up to the crank. I could see it being impossible with an assembled engine. I wouldn't want to turn an assembled engine over that much to find out! I set up my rebuilds to start up instantly with the oil pump pre-primed to the rod journals before I even put the rods on.

    Of course, there might be a problem but I do know from lots of experience that the pump is a PITA to prime with everything set up perfectly.

    I thought I would point out that I prime the pump before I put the rods on AND hook the cam up to the crank. Much easier to spin the pump thusly and it still takes some spinning!

    Degree of difficulty priming? It all depends on how clean the engine is. A super clean engine takes some serious spinning in order to prime the pump.
    #5
  6. wmax351

    wmax351 Been here awhile

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    I had someone do the bottom end. I assume he put some vaseline or assembly lube in there.

    For the rest, I put some oil in the filter housing (turned the engine sideways) and made sure everything important had assembly lube on it. Gently cranked it over with the kickstarter, with no spark plugs. It was primed in ~5 kicks.
    #6
  7. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Feh. This should not be happening.

    To recap this sad tale:

    May 2011: r90/6 heart attack (engine seized)
    http://www.advrider.com/forums/showthread.php?t=691189
    Lost oil pressure, engine seized.

    Sept 2011: r90/6 Oil pressure sensor, I got nuthin...
    http://advrider.com/forums/showthread.php?t=723774
    Rebuilt engine (bottom end), lost oil pressure. Back into engine to check.

    Dec 2011: Airhead oil priming "problem" HA!
    http://www.advrider.com/forums/newreply.php?do=newreply&noquote=1&p=17450345
    This thread. No oil pressure.

    Let me read through these, there are so many twists and turns to the plot.

    In a nutshell: you've rebuilt the bottom end and can't get oil pressure. You've checked and double-checked everything. It's nothing obvious so let's go back to the beginning.

    Start with the oil pickup in the sump: the bolts on the pickup should be tight, no air leaks and the gasket should not be blocking the inlet passage to the pump. There should be a straight shot to the pump. Double check for no blockage.

    The Eaton/trochoid pump has fairly positive displacement: if it's turning, some oil will be moving. Pull the pump cover, check and verify that the woodruff key is in there and that the pump rotor is locked to the camshaft end. Is there evidence of oil in the pump cavity? What happened to the vaseline in the pump cavity? Still there? Pushed out to the oil filter housing?

    From the pump, the oil flow goes to a passage on the lower left side of the engine. There are screws plugs front. back and sides, it it is a fairly straight shot to the oil filter housing. Keep that oil passage in mind, we may check it in a minute.

    That oil passage opens into the outer side of the oil filter, the oil then flows through the filter to the in side of the filter where it thence goes to the engine bearings (or, if so equipped, to the oil cooler and then the bearings). Pull teh oil filter. You should see the vaseline in the housing. If not, plan to look for blockage in that oil passage from the pump. While the pump cover is off and the oil filter is out, you might want to see if you can blow some air from the filter to the pump and vice versa. With the pump cover, sump, etc, on, but the oil filter removed, turn the engine over and see if you can get oil flow to the filter-- even with no pressure, there should be some flow to the filter.

    Got an oil cooler? Check for blockage, both in the cooler and the associated plumbing/adapters/thermostat.

    No oil cooler? The oil goes from the filter to the from cam bearing and then up to the front main bearing carrier. The oil passage in the block mates with an oil passage in the bearing cap and goes to an annulus-- or groove-- in the front main bearing shell, and from that annulus, to other places. The annulus, and the corresponding matching holes, are the key. If a hole does not match up with a passage in the cap, and the passages in the cap do not match up with the oil passage in the block, no oil is going anywhere. Triple check that-- who did the installation of the main bearing shell? Are you sure it's correct? What about the locking in for the bearing shell?

    From the main brng annulus, the oil goes through passages in the brng cap to: Right side-- top cylinder studs to the rocker arms. Top-- oil pressure relief valve. Left side (upper)-- top cylinder studs to the rocker arms. Left side (lower)-- back to the rear main bearing and the oil pressure switch.

    Check out the "Airhead stud advisory" thread-- it has a diagram of the oil sytem.

    http://www.advrider.com/forums/showthread.php?t=745116

    Go back and start checking-- start at the beginning and work towards the end. I'll read back through your posts and see if I can spot a puzzle-piece.
    #7
  8. rgears

    rgears Adventurer

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    Wow, now that's comprehensive Bill. Thanks!
    Just so I go through everyone's notes:
    Yes, the sump screen and pickup at sealed with a new gasket. As is the oil pump o-ring. And all around, no outter leaks.
    The woodruff is locked, I even replaced that for sound mind. The front cam bushing is sound and in spec and the cylinder studs are secure. No Helicoils.
    As for Bill's notes, of the top of my head:
    Vaseline was found in the filter canister. Prior to assembly, all lines were cleared with compressed air after a good acetone then simplegreen flush. No stop ups. I even went so far as to unscrew the galley pulgs and check visually. Blue lockttite and torqued back in place. No oil cooler. As for the rest, I will have to just suck it up and pull the guts out again. At least I have plenty of experience by now.
    The only other thing that comes to mind, even if something like the front main spun/ lock pin did not set correctly, is that I managed to pump some oil into the crankshaft bearings galley where the presure sensor is using the pump. Pulling the sensor, oil dribbled out. Just no real pressure to speak of.

    So what I am seeing and is really odd, is that it seems that the ways are clear and oil IS moving, just not at a functional rate. At least before when there was just not enough presure a likely culprit was the presure relief valve at the timing chain, so that just got replaced.

    I'll pull it open again and start at the pump tonight...
    #8
  9. bmwrench

    bmwrench Long timer

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    With the main bearings BMW has provided for the last several years, only the rocker oilers and locking pin need to be drilled. The others are provided for by the slots in the bearing.

    'shaft, I fill the galleries with oil with an oil-fashioned pump gun via a gauge adapter. The idea here is to fill the oiling system. Even just filling the oil filter cannister should result in getting oil pressure fairly quickly.

    If it was me, I'd pull the oil filter and crank the motor with spark plugs out to see whether oill was getting that far.
    #9
  10. rgears

    rgears Adventurer

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    Yeah, before I gut the thing, I am going to try to fill the system from the sensor hole like BW says. I will go from there.
    #10
  11. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    It's been years since I've held a main bearing cap and more years since I've had to set a bearing insert in one, but I seem to dimly recall a gotcha on the exact orientation of the insert vs the cap and I'll betcha that this is the key here. Oil wouldn't get past the front main cap, no pressure to the switch and no oil to the rear main. This may be a moot point since you've not gotten oil pressure, but pull the valve covers and see if oil made it up that far.
    #11
  12. bgoodsoil

    bgoodsoil Dare to be Stupid

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    Can you pump oil using a drill? a 6mm allens tip will fit in a battery drill. Couldn't we turn the engine using the rotor bolt? With plugs out of course. I can spin my engine with 1 finger using a normal allens. I wouldn't think it would put too much force on that rotor bolt to slowly work it up to speed.
    #12
  13. PaulRS

    PaulRS Dutch fool

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    Question on the mains, did you replace the bearing-rings only, or the front with the flange?

    The front flange, holding the bearing, was altered somewhere in time, NOT lining up the oil passage.

    Paul.
    #13
  14. rgears

    rgears Adventurer

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    Alright. Just pulled things apart enough to do a bit of checking.
    Pump is clear, air through the ways, those are clear and air up through the filter fill into the front cam sounds clear.

    So I repacked the pump with Vaseline, turned it on its side and filled the filter canister and pumped oil up into the sensor galley. Test prime, nothing to speak of. Oil light flickered, but that may have just been wishful staring.

    Before I tear deeper, I had a thought I'd like to run by everyone: back when I was actually riding this thing, I recall the sensor light would not actually turn off until after it had actually started. Thinking back to a few posts that mentioned needing higher RPMs to actually get pressure, should I try putting it back together enough to wheel it outside and try a quick test fire to blip the throttle enough to grap idleing RPMs?

    At least I know tht the mains have oil on them after seeing the back of the crank.
    I think a quick test to pressurize might be worth a try.
    #14
  15. wirewrkr

    wirewrkr the thread-killer

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    At this point, the FIRST thing I would be doing is substituting the sensor for a mechanical gauge and leave it in place until you get it sorted.
    #15
  16. rgears

    rgears Adventurer

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    Oh yeah, way ahead of you there Wire. Gauge was already in place of sensor.
    So tried my experiment, yeah, nada. Or at least noting on the gauge. I'll check the oil canister before I start the tear down for Vaseline globs.

    So as soon I get time this week, I will start pulling it all apart again and track problems...
    #16
  17. bereahorn

    bereahorn Long timer

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    :lurk
    #17
  18. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    You mean like an auto-parts store oiler, little thumb-action pump, flexible spout, holds maybe a pint or so? I need an oil can for the shop, and I might as well get something that'll do the pre-oil duty, too.

    [​IMG]
    #18
  19. bmwrench

    bmwrench Long timer

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    That's it. Mine's a bit lower-tech than yours.
    #19
  20. rgears

    rgears Adventurer

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    PRESSURE! We have pressure! So I pulled the engine, stripped the timing cover, chain and pistons to try shaft's idea of spinning up the camshaft via socket and drill. After a few seconds at my best guess of 900 rpms, the gauge suddenly registered a good 40 - 50 psi. I let it sit for a few, tried again, wouldn't get pressure. Sit again, try again, immediate pressure. So at this point, my best guess is that overall, this thing is just being a general PITA the get going. But once primed properly, we're good to go.
    However, just to make sure, I did pull the crank to check the forward bearing carrier. Everything is aligned and flowing properly.
    So a this point, I ordered a few replacement bolts and such from Maxbmw just to make sure we're good on stretched flywheel bolts and piston clips, but I think I can just about call this sorted.
    While I did not quite register oil at the rocker oil ports, I can only say that I did not quite reach pressure with my drill, but plenty coming through the mains and into the conrods.

    While I am still going to take this slow and I am working on a temporary mount for my pressure gauge, I think the problem was a case of PITA priming. Maybe it was slightly too cold, maybe there was an air bubble that just wouldn't let go. I just don't know. Very strange, but I will keep a close eye on it. Hell, at least now I know how to test the pump and system before putting the whole thing back together!

    I hope this is the last bit to get me on the road for at least a few weeks before the ice hits, but thanks again for everyone's input on this. I greatly appreciate it.
    #20