Author Topic: Another pressure question  (Read 305 times)

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Offline FTBY55

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Another pressure question
« on: November 08, 2018, 07:35:14 PM »
Today after stopping for morning coffee, started '96 Fatboy and as I accelerated the oil light came on very dim and than went out. It did this everytime I accelerated and shifted. Oil level okay, running 10/60 and oil temp was only about 175. This afternoon after stopping to pickup parts it started to do the same thing, then pressure gauge falling to zero but no light showing unless accelerating. Once moving I have about 20 psig at 3000 rpm when cold I had 30. Can my oil pump be going. Typical riding is at about 3500 to 4000 rpm.

Offline koko3052

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Re: Another pressure question
« Reply #1 on: November 08, 2018, 10:11:52 PM »
Some history...mileage....?

Offline Wicked

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Re: Another pressure question
« Reply #2 on: November 09, 2018, 07:22:08 AM »
...and mount a temporary guage on it to measure exactly. A symptom of a failing pump though, because of probably another reason...

Offline PoorUB

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Re: Another pressure question
« Reply #3 on: November 09, 2018, 12:08:26 PM »
Check it with a known good mechanical gauge.

There was a guy on Twin Cam a while back that used a bad test gauge. Tore down the cam chest, put it back together,  retested, same problem.  New test gauge solved the problem! :banghead:
I am an adult?? When did that happen, and how do I make it stop?!

Offline turboprop

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Re: Another pressure question
« Reply #4 on: November 09, 2018, 01:20:47 PM »
Today after stopping for morning coffee, started '96 Fatboy and as I accelerated the oil light came on very dim and than went out. It did this everytime I accelerated and shifted. Oil level okay, running 10/60 and oil temp was only about 175. This afternoon after stopping to pickup parts it started to do the same thing, then pressure gauge falling to zero but no light showing unless accelerating. Once moving I have about 20 psig at 3000 rpm when cold I had 30. Can my oil pump be going. Typical riding is at about 3500 to 4000 rpm.

I experienced the same thing some years ago. The Evo engine was in fantastic condition, oil level was almost perfect, but the oil light came on while cruising on the highway at a steady state. I immediately pulled over, did all the usual checks, etc. Had been a long week at Daytona, and I was in the last half hour of of a twelve hour ride home. After confirming oil level, flow out of the feed line, etc, I decided to just ride through it, assumed it was an electrical issue. Light stayed on the whole way home. Several days later I got to troubleshooting the oil light circuit. Everything was normal. Put a gauge on it, again everything normal. Some local clowns thought there was air in the system and the pump needed to be 'burped'. That didn't work. Went as far as to remove the oil pump to inspect everything. Still, the oil light was on. It eventually cleared itself up. I hope you have better luck at pinpointing the cause of your oil pressure phenomenon.
No time for the ambulance chasers or online experts.

Offline choseneasy

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Re: Another pressure question
« Reply #5 on: November 09, 2018, 03:08:32 PM »
Those lights can do odd things.
  Remember the lifters will lose oil first, if the top end starts clattering AND flickering light, shut it down.

Offline FTBY55

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Re: Another pressure question
« Reply #6 on: November 10, 2018, 09:05:03 PM »
Some history...mileage....?

31,000 miles on her. Have been running the LiquiMoly 10/60 and a K&P Oil filter. Thought perhaps the less restrictive Screen filter created less back pressure , especially when the oil heated up and thinned a bit.
The oil pressure gauge is just a few months old and has been consistent. It was the first time I had seen the light come on other then when ignition switch is turned on, It came on dimly while accelerating. Have ordered a new switch and will replace and change oil now that the summer heat in AZ is over. Back to 20/50. The manual oil gauge is installed above the lifter oil screen, idling at about 1050 rpm. just a slight tweek of he throttle will bring it up to 10 psi on the gauge.

Offline wfolarry

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Re: Another pressure question
« Reply #7 on: November 11, 2018, 10:06:52 AM »
Do you have a rubber boot covering the sending unit? I have seen them trap water giving the light a mind of it's own.

Offline capn

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Re: Another pressure question
« Reply #8 on: November 11, 2018, 01:07:18 PM »
Take the check ball and spring out the oil pump start it up quick.If its pumping it will make a mess. If not check for good oil feed to pump .

Online 1FSTRK

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Re: Another pressure question
« Reply #9 on: November 11, 2018, 04:38:30 PM »
Some history...mileage....?

31,000 miles on her. Have been running the LiquiMoly 10/60 and a K&P Oil filter. Thought perhaps the less restrictive Screen filter created less back pressure , especially when the oil heated up and thinned a bit.
The oil pressure gauge is just a few months old and has been consistent. It was the first time I had seen the light come on other then when ignition switch is turned on, It came on dimly while accelerating. Have ordered a new switch and will replace and change oil now that the summer heat in AZ is over. Back to 20/50. The manual oil gauge is installed above the lifter oil screen, idling at about 1050 rpm. just a slight tweek of he throttle will bring it up to 10 psi on the gauge.

I would pull the bypass spring and plunger out of the oil pump and make sure it is clean and closes smooth and tight.
"Never hang on to a mistake just because you spent time or money making it."

Offline FTBY55

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Re: Another pressure question
« Reply #10 on: November 11, 2018, 09:09:24 PM »
Started the bike with the fill cap out and I could see oil circulating and some fine bubbles. Started at 30 with choke on today and idled at 25 while cold. Shutdown and gauge fell to a bit over zero. Will do the suggested checks after the next ride when changing oil. Thanks all.