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Old 09-03-2011, 12:26   #1
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Jittery Oil Gauge

Hi,

This is likely a basic question, but here it goes.

Our oil gauge has been steady as a rock right at 80. We changed the oil and all was fine, but after about 30 hours the gauge has started to jitter, hovering around the same 80, but jittering. When we lower the rpms it steadies.

No other problems are apparent: purrfect sound, oil levels are normal, temperature is ideal, etc.

In the past the gauge jitterred when running the engine at lower rpms, but now it's jittering at our normal running rpms of 1800.

We're just checking to see if there's a reason for concern. Is this something we need to look into?

Thank you,

Linda and Ricardo
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Old 09-03-2011, 12:55   #2
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Re: Jittery Oil Gauge

The first thing that comes to mind is the relief valve. The second is the pump is pulsating for some reason. Third might be the sending unit.
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Old 09-03-2011, 13:41   #3
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Re: Jittery Oil Gauge

The first thing that always comes to mind for me is wiring (the sending unit or the wiring to it). I had a similar thing last year, in the end after a lot of panic all it was was flayed wire at the sending unit.
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Old 09-03-2011, 14:29   #4
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Re: Jittery Oil Gauge

FWIW, If itís a rapid pulsating needle my first look would be at the sender itself. Normally easy enough to check with a simple cheep multi meter. Ya know, the ones they sell for 9.99 at Wally World. Disconnect the engine wiring to the sender and sub in the meter from the terminal to engine ground. On a lower ohms scale watch the needle on the meter after starting the engine. The sender is nothing more than a variable resister and vibrations from a running engine can affect its constant value. Kind of like a dirty volume control on an old radio. If your subbed in meter is not steady replace the sender. Be sure that you disconnect the original wire and isolate it as you donít want to induce voltage to a meter measuring ohms.

A quick jitter of the gauge does not normally indicate internal engine problems and is mostly electrical as Don said
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Old 09-03-2011, 15:36   #5
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Re: Jittery Oil Gauge

You say you just changed the oil. How about the filter? Most oil filters have a by pass valve in them. If you installed an after-market filter, the bypass valve could be chattering. I would replace that with an OEM to see if that does the trick.

If not, then I'd suspect a loose wire on the motor or any where else that vibration can affect the wiring at high RPM's.
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Old 09-03-2011, 16:17   #6
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Re: Jittery Oil Gauge

My first question is 80 what? That seems really high compared to other engines I've used. 80 psi is really high.
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Old 09-03-2011, 16:27   #7
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Re: Jittery Oil Gauge

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Originally Posted by Kettlewell View Post
My first question is 80 what? That seems really high compared to other engines I've used. 80 psi is really high.
Kinda goes back to the sender, ya think?
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Old 09-03-2011, 16:28   #8
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Re: Jittery Oil Gauge

I'd have the same question. At idle it should be 30 to 40 and build to maybe the highest at 60 from my experience.
kind regards,
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Old 09-03-2011, 16:36   #9
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Re: Jittery Oil Gauge

That is extremely high unless motor is cold ie: freezing! on my trucks in the winter we would register about 70 psi to 90 psi in 0 degree weather if you brought the rpms up a bit say 800 to 1000. after the engine warms up it should idle at no more than 40 psi, usually 10-30 depending on mfg. our Volvo-Penta (Perkins) idles at about 20 then goes to 40-50 maybe 60 depending on rpms. note the other thing that can cause that situation is air. if after your oil change you got air into the orfice that is at the bottom of the sender, that will cause a pulse in the reading , because the engine oil pressure has to compress the air in the sender to make it show a reading, and because air compresses it will a bouncing needle. this was quite common on senders with hard oil lines to the senders and to a lesser extent on the wired ones. only my two cents worth!
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Old 09-03-2011, 16:54   #10
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Re: Jittery Oil Gauge

If possible, you could tee in a mechanical gauge and then you'd know what the oil pressure really is.......LL
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Old 09-03-2011, 17:22   #11
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Re: Jittery Oil Gauge

Quote:
Originally Posted by Kettlewell View Post
My first question is 80 what? That seems really high compared to other engines I've used. 80 psi is really high.
This would depend on what motor. My old Pathfinder, 100 psi was normal at start up. Now, my Yanmar it's 80 psi at start up.
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Old 15-03-2011, 13:39   #12
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Re: Jittery Oil Gauge

Thank you all for your insights. Now we have a road map -- or chart -- to follow!

And yes, Mr. Perkins runs at 80 psi.

Regards,

Linda and Ricardo
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