Author Topic: No oil pressure on first start attempt. (Read 3025 times)

beemerbum · « **on:** February 27, 2018, 02:54:21 PM »

I have attached a photo of the upper case of my motor. It has since been assembled. I took apart the oil pump, inspected it and installed a new gasket was well as O rings. I primed the pump and on the bench it seems to function as it should. The pressure and scavenge sides seem to pump as they should. Two quarts of oil in the tank. The motor spins pretty fast with the plugs out. With the plug on the right engine side removed, I wait for oil to show up and it never does. This motor per serial # is a K4. I don't know the source of the oil pump. Is it possible that the gear on the pump is not meshing with the gear on the back of the clutch hub? Was there ever a change in how the oil pump is driven? I attach photo of my motor upper case. Any thing wrong here?

DaveBarbier · « **Reply #1 on:** February 27, 2018, 03:17:11 PM »

When I rebuilt my 550 and 650 both timed I didn’t get oil pressure with only the starter spinning the motor. I used assembly lube and poured oil in the rocker cover and fired it up. The oil light shut off after about 3 seconds and I opened a tappet cover on either end of the motor and saw oil splashing around.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #2 on:** February 27, 2018, 07:24:36 PM »

Pretty normal. You need to get the rest of the oil fill into the sump. After I fill my tank I pour the rest down the rocker cover hole to drain downward. If it doesn't pressure with the electric start which I first try I then fire her up and the pressure comes up quick. Install a pressure gauge in that right side plug hole and you'll know for sure.

beemerbum · « **Reply #3 on:** February 28, 2018, 03:29:03 PM »

I've got two quarts in the tank. I understand the rest should go into the cover. All in one tappet hole or divided between the four? Is the oil pump the same part throughout the life of the SOHC or was there ever a change?

evinrude7 · « **Reply #4 on:** February 28, 2018, 03:55:51 PM »

beemer did you kick the motor a bunch of times to circulate the oil? i haven't rebuilt a motor before and it seems the recommended method for the last quart is down the tappet covers but as with an oil change i'll kick the motor over a bunch to help get the oil moving. not recommending you don't pour down the tappet covers just in addition to.

Stev-o · « **Reply #5 on:** February 28, 2018, 04:02:42 PM »

Quote from: evinrude7 on February 28, 2018, 03:55:51 PM

beemer did you kick the motor a bunch of times to circulate the oil?

This was my method after the Big Bang rebuild. Kicked it 50 times followed by a 5 sec blast with the starter, did it three times.
Then when I finally started it, light came off within 10 sec...

beemerbum · « **Reply #6 on:** February 28, 2018, 05:07:30 PM »

I would like to but the kick starter won't move. My concern is that since the pump is driven by the kickstarter gear, I've got a major problem on which I seek enlightenment.

evinrude7 · « **Reply #7 on:** February 28, 2018, 05:54:11 PM »

Quote from: beemerbum on February 28, 2018, 05:07:30 PM

I would like to but the kick starter won't move. My concern is that since the pump is driven by the kickstarter gear, I've got a major problem on which I seek enlightenment.

beemer, maybe this is helpful. http://forums.sohc4.net/index.php/topic,151764.msg1735805.html#msg1735805

Remcod · « **Reply #8 on:** March 01, 2018, 01:52:13 AM »

Kickstarter and oil pressure can be 2 different things.

From somewhere else on this forum and worked for me, to get oil pressure:
- pour a few pints of oil down the rocker cover (if you did not do it already)
- put some oil in the oil tank
- put the bike on the side stand
- remove the oil gallery plug near the ignition points cover and poor in oil until it takes no more
- close the oil gallery plug
- put the bike on the center stand and run the starter engine
- oil pressure should be there in seconds

This because you have air in the oil pump. Priming the pump before assembly is also often done, but this works also

But you might want to remove the cover of the Kickstarter first to check assembly

Good luck

Henning · « **Reply #9 on:** March 01, 2018, 05:17:23 AM »

All of the above, but keep it on the side stand when you crank the engine, that's what made the difference for me.

ekpent · « **Reply #10 on:** March 01, 2018, 05:25:03 AM »

Quote from: beemerbum on February 28, 2018, 05:07:30 PM

I would like to but the kick starter won't move. My concern is that since the pump is driven by the kickstarter gear, I've got a major problem on which I seek enlightenment.

Better fix that problem first before moving on.

johans · « **Reply #11 on:** March 03, 2018, 05:44:16 PM »

Did you prime the pump fully ? on my last rebuild of a 78 k i did not prime the pump fully and it never built up pressure . pulled the pump & primed until there were No bubbles and had fast oil pressure.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #12 on:** March 04, 2018, 11:30:11 AM »

Quote from: beemerbum on February 28, 2018, 05:07:30 PM

I would like to but the kick starter won't move. My concern is that since the pump is driven by the kickstarter gear, I've got a major problem on which I seek enlightenment.

Your clutch pack could be installed wrong causing it to stick. Easy to diagnose by removal.

rumpleblumpkinz · « **Reply #13 on:** March 05, 2018, 08:07:04 AM »

How exactly are you guys adding oil to the top end? Removing a tappet hole cover and dumping it in there?

Remcod · « **Reply #14 on:** March 05, 2018, 10:09:08 AM »

Yes thats it

Ellz10 · « **Reply #15 on:** May 09, 2023, 05:56:59 PM »

Quote from: Stev-o on February 28, 2018, 04:02:42 PM

Quote from: evinrude7 on February 28, 2018, 03:55:51 PM
beemer did you kick the motor a bunch of times to circulate the oil?

This was my method after the Big Bang rebuild. Kicked it 50 times followed by a 5 sec blast with the starter, did it three times.
Then when I finally started it, light came off within 10 sec...

After you did this method, did you have ANY oil pressure showing on the gauge?

HondaMan · « **Reply #16 on:** May 09, 2023, 07:52:11 PM »

Quote from: rumpleblumpkinz on March 05, 2018, 08:07:04 AM

How exactly are you guys adding oil to the top end? Removing a tappet hole cover and dumping it in there?

Yep!

PeWe · « **Reply #17 on:** May 09, 2023, 07:59:58 PM »

Oil priming
As I wrote in another thread based on my oil pump priming experience.

Did you prime pump by submerging it in a box with motor oil, just big and deep enough to cover it completely in oil?

Then rotate the sprocket so you can feel underpressure from any of the 2 holes for stock oil hoses. Continue to rotate until finger reallly will be sucked by the hole.
Rotate in other direction while cover the other hole by your finger. Alternate rotations will help to get air out.

I had to unscrew the plug for oil relief valve to let air out.
When all air is out the finger will be sucked as a vacuum cleaner can.

HondaMan · « **Reply #18 on:** May 09, 2023, 08:08:31 PM »

Quote from: beemerbum on February 28, 2018, 03:29:03 PM

I've got two quarts in the tank. I understand the rest should go into the cover. All in one tappet hole or divided between the four? Is the oil pump the same part throughout the life of the SOHC or was there ever a change?

There's several things to know about the pump.
1. If you did not change the shaft seal between the 2 rotors, it will be very difficult to get the pump to prime inside the engine, the first time. You can remove the pump thru the oil pan cover and hand-prime it while fully submerged in oil, but be SURE to use 15w40 or 20w50 oil, as 10w40 will leave you spinning your wheels for many hours trying to prime it. And, you shouldn't use that light weight oil in this engine, anyway.
2. If you did change the shaft seal, but didn't hand-prime it in at least 3" deep oil in a (I use Tupperware) container, then you'll need to flood the engine's crankcase with no less than 1 full quart of oil to get the pump's suction side wetted and all the air out. This will then seal the vacuum to the pressure side enough to let it pull up from the oil hose, provided the oil tank has at least 2.5 quarts in it (3 in apre-f0 750, 2.5 in the later ones with the smaller tank). This pump only generates a couple of inches of vacuum head at the inlet hose, so a pressure column of oil is expected to be "sitting" on the pump's inlet port - this is accomplished by having the oil tank sitting above the pump.
3. When the pump was out: did you check/replace the pressure relief valve? The tunnel these plungers live in sometimes get warped, making the piston stick slightly open. If so, it will NOT prime, no matter what you try to do. And that's good, because it will also cause low oil PSI when the engine is running below 2500 RPM, so you'll KNOW something is wrong.

Finally, one more thing: if the tips of the inside rotor of the pressure side of the pump are nicked or chipped, even changing the shaft seal will make no difference - it simply will not suck oil onto the chamber. I was reminded of this last summer while rebuilding a K1 engine that had 2 small chips in each of the 4 lobes if the inner rotor: no matter what, it would generate zero pressure, although it would flow a little bit if the pump were fully submerged up to the top of the rotors. In this case you will need at LEAST new pressure rotors, donor rotors from another pump, or just another pump.

rotortiller · « **Reply #19 on:** May 10, 2023, 03:14:48 AM »

The engine has a dry sump oil system which employs a low pressure check valve to hold the oil in the tank when the engine is not running. The oil pump cavitates due to empty air filled lines and fittings so it will not pump oil, so this is why it sometimes needs to be primed. If you lightly pressurize the oil feed line with oil before attaching to the tank, the valve will open and oil will seep into the critical voids allowing the pump to pump. Think about it, when we have a leaking check valve the sump fills with oil while sitting in the garage emptying the oil tank. There are other ways to skin the kat. You can remove the scavenge oil line and venting cap then pressurize the tank very slightly, just enough to crack open the check valve.

willbird · « **Reply #20 on:** May 10, 2023, 04:25:16 AM »

Holy zombie thread ??

rotortiller · « **Reply #21 on:** May 10, 2023, 11:43:49 AM »

Quote

Read reply #13 RE: Fresh Rebuild.

We all know what it had….it has no tank or oil lines….

Sorry dude, I missed that on this thread.

HondaMan · « **Reply #22 on:** May 10, 2023, 05:01:46 PM »

Well, the Sumpthing was a b#$^&$! to prime on the last one I did...

I ended up taking the pump out and cover off, then wiped grease onto the rotors (thin coat) to get it to make the first pickup. It had perfect rotors, too. If the rotors are nicked up, it's probably not going to prime, IMHO...

Ellz10 · « **Reply #23 on:** May 10, 2023, 07:27:03 PM »

Quote from: HondaMan on May 10, 2023, 05:01:46 PM

Well, the Sumpthing was a b#$^&$! to prime on the last one I did...

I ended up taking the pump out and cover off, then wiped grease onto the rotors (thin coat) to get it to make the first pickup. It had perfect rotors, too. If the rotors are nicked up, it's probably not going to prime, IMHO...

Hey Mark, I'm going to send you an email with a pic of my oil pump rotors and you can tell me if they look great or not.

HondaMan · « **Reply #24 on:** May 11, 2023, 07:29:33 PM »

Quote from: Ellz10 on May 10, 2023, 07:27:03 PM

Quote from: HondaMan on May 10, 2023, 05:01:46 PM
Well, the Sumpthing was a b#$^&$! to prime on the last one I did...

I ended up taking the pump out and cover off, then wiped grease onto the rotors (thin coat) to get it to make the first pickup. It had perfect rotors, too. If the rotors are nicked up, it's probably not going to prime, IMHO...

Hey Mark, I'm going to send you an email with a pic of my oil pump rotors and you can tell me if they look great or not.

Okie-doke!

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Author Topic: No oil pressure on first start attempt. (Read 3025 times)