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xlr8r

Priming the oil pump?

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Hey,

I'm rebuilding my 650L engine and was wondering if there is a specific way (if it is even necesary) to prime the oil pump. I oiled the hell out of everything on assembly but it still scares me to pull the trigger. Thanks!

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I have a XR600, but the engine is basically the same. I never figured out how to prime mine, but here is what I did. I laid the bike on the left side and filled the oil fliter as much as I could. I closed the filter up and tipped the bike back up. Then I put the rest of the quart in the front left side valve adjuster opening. That way I was sure that there was oil in the head. I put another quart in the frame tube. I loosened the top oil tube bolt about 2 turns. Then I started it. It still took almost 90 seconds for oil to come out of the loose top oil tube. 2 turns loose was too loose and a lot of oil came out. I'd say no more than 1/2 turn after the bolt is no longer tight. The total time from filling the oil filter to running was less than 5 minutes. I didn't want to give the oil time to drain out of the filter.

Let's just say that was a long 90 seconds. :lol:

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The pump can be primed by removing the oil feed hose that comes out of the frame rail where it connects to the crankcase. Use a squirt oil can and a piece of rubber tubing if necessary for a seal and squirt oil into the feed hole, this will fill the oil pump cavity. Replace the hose and as cleonard says, loosen the banjo bolt on the oil line fitting that goes from the crankcase to the head. Start the engine and as soon as you see oil coming out, tighten the bolt.

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Great! I'll do all those things... twice. I'm not going to try this but is it posible for the pump to prime itself? Is the procedure you guys described just insurance?

Thanks!

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It just helps reduce the time that there is no oil pressure. I suppose that you could truly prime the pump by operating it before putting the engine completely together. With the right side cover off, put a quart in the frame reservoir. With the drive gear off turn the oil pump until it starts pumping oil. Put the gear back on and install the side cover. Then put the rest of the oil in there and start it. I think it has a good chance of being very messy with oil all over.

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It is definitely possible to cavitate the pump and starve the engine for oil. It is possible that the pump will eventually prime itself, but it is also possible it will not.

I once was servicing my NX650 (650L motor) and drained the oil, then decided to do a valve adjustment while I let the oil to continue to drip out. While turning the motor over by hand to do the valves, I pumped the remaining oil out of the pump. After finishing the service I opened the oil line at the head and started the bike, but was not getting any oil to the head. I tried several different things, but finally got oil pressure after pouring oil down the feed line (filling the filter area) and down to the pump.

When I rebuilt my 600 I primed the new oil pump when I put it in, but while checking piston to valve clearance I turned the motor over several times and pumped the oil out. When I finished the motor and started it, I again had the oil line at the head loose and was not getting oil pressure. I tried back-feeding the oil, but it still would not take. I pulled the side cover off, pulled the gearbox feed line off and then turned the pump by hand. After gurgling out some air, the pump finally started pushing oil. I wrapped it back up and it was fine. Would it have eventually started pumping? Maybe, but I was not interested in taking the chance with a brand new motor :lol:

oilpump_bleed.jpg

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Thanks for all the input guys. Can anyone tell me why there is no mention of this procedure in the service manual? Seems kind of important.

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PLEASE, don't do this until you hear it from somebody smarter than me :confused: ... I don't now if this is a good idea or not, but on MY OWN bike, I would yank the spark plug, and spin the engine with the starter, to pick up it's prime ... would this work?, or is it risky ? ... :lol:

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Thanks for all the input guys. Can anyone tell me why there is no mention of this procedure in the service manual? Seems kind of important.

Not really sure why. Maybe it really is unlikely that the pump will not start working before engine damage? Being a mechanic though, I have little faith that things will "just work". Sometimes I think ignorance really is bliss :lol:

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PLEASE, don't do this until you hear it from somebody smarter than me :confused: ... I don't now if this is a good idea or not, but on MY OWN bike, I would yank the spark plug, and spin the engine with the starter, to pick up it's prime ... would this work?, or is it risky ? ... :lol:

This is good, since it is an easy way to build or verify oil pressure without any real risk. I assume you open the oil line (or something similar) to verify the oil is flowing? Even starting it is probably fine as long as you are checking and shut it off if oil pressure does not show up quickly (10 seconds?)

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My bud had his engine professionally rebuilt & when he started, no oil pumped. He had to go thru a lot to get it primed. Definetly prime & confirm!

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While the Honda manual doesn't advise priming, it does tell you to use Moly paste on the cam and rocker arms. This is just for the delay in building pressure. I guess they think that actually priming the pump is too advanced for Honda shops.

With oil in the frame tank there should be enough pressure in the feed to gently force oil into the pump. It can take 60 to 90 seconds. It's not as big of a deal as you might think. I've done the loosen the oil pipe bolt thing when changing the oil and sometimes it takes as long as 20 seconds for the oil to start flowing. And yes the clearances on my oil pump were fine when I looked at it.

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on my ds 650 it says in the manual that if the oil lite does'nt go off after 10 sec,you must crack the bleader valve behind the filter,I have owned my ds since 2000 and this has only happened to me one time,and I change my oil after every 3 rides.

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I have torn into my 91 600r engine twice, and both times have had a hard time building pressure back up.

One thing I noticed is to make sure that when you tighten the flex portion of the feed line (one of the two that comes right our of the case) to the metal tube that runs down the frame that you keep the flex portion as straight as possible when tightening. The first time I could not build pressure for a long time, and this was the problem, it was kinked just a little, didn't look kinked, but twisted just enough to disrupt flow.

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OK. I'll come clean. I started this thread dishonestly by saying I hadn't started the bike after the rebuild. The reason for this is I am embarassed to spill my guts to a bunch of bad-ass-dirtbikers. F**k it though, if it saves somebody else from making the same HUGE mistake I did...

I DID start my bike after the full engine rebuild (my first time, to be fair), didn't do the oil-preasure-rain-dance (BECAUSE IT SAYS ABSOLUTELY NOTHING ABOUT IT IN THE SERVICE MANUAL!!) and seized a brand-new piston in a freshly bored cylinder! Locked the rear wheel at about 45 mph and nearly lost my lunch.

When I first started the bike I let it idle for five minutes. I did this three times. Engine sounded great! Figured I could putt around the block during my lunch break. Didn't get very far at all.

I did prime the pump during assembly (to make sure it worked) but let it sit for a couple of days then did all of the valve clearance ajusting prior to filling it with oil. Stupid.

So there you go, fire away guys! But maybe someone else out there can learn from my $400+ mistake.

Don't worry though, another piston is already on its way!!

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Ouch, sorry to hear that. With it not being an obvious thing to check (at least the 1st time :confused:), I am sure lots of people have done this. I am also sure many others avoided it by pure luck.

It sucks to be the example, but your honesty is definitely appreciated. It is good to know for sure that the pump will not always be able to get things flowing on its own.

Well, the engine build is always easier the second time :lol:

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Take your oil pump apart and check the clearances. If they are out of line, the pump doesn't work like it should. You wouldn't want it to happen again.

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...your honesty is definitely appreciated.

'kin-a. What a total craphassle- personally I *never* would have expected to have to prime the oil pump. What do they do at the factory I wonder?

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'kin-a. What a total craphassle- personally I *never* would have expected to have to prime the oil pump. What do they do at the factory I wonder?

They prime it- once in awhile they don't, and that guy gets a new engine.

Dave

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They prime it- once in awhile they don't, and that guy gets a new engine.

Dave

I don't think that this is true. I bet that most shops don't do it at all. I have had several RFVC engines apart and I didn't know about priming the pump and they ran for years. The shop manual tells you to put moly paste on the cam and rocker arms, just for the lack of oil at the first start.

I think one important thing is the condition of the pump. If it is tight without gouges from trying to pump metal bits, it will self prime. A lobe pump is positive displacement. The air gets pumped out and the vacuum draws in the oil. If it is loose, it can't "pump" the air out and the oil doesn't flow. The air just leaks around the extra clearance and stays in the pump.

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