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#560787 - 02/15/05 05:31 PM Fluttering Mechanical Oil Pressure Gauge
TallPaul Offline


Registered: 10/22/03
Posts: 13092
Loc: By Detroit
My motorhome (1990 460 V8, 77,000 miles, good UOA on 4400 mile Maxlife 10w30) has a mechanical oil pressure gauge I installed. In about 10,000 miles it works fine. Sunday we took it on a 200 mile trip. For some of the time on the first half of the trip the oil pressure gauge would flutter, but the needle remained centered on the normal pressure. At 2000 rpm in OD it fluttered over about a 5 psi range. So I downshifted thinking to knock out the flutter and it started sweeping a 12 psi range at 2700 rpm. The gauge would stabilize and then go back to fluttering. Hadn't driven the motorhome in 7 weeks (nor started it). After a 2 hour stop at the destination I headed home and there was no more flutter. What could have caused it? [I dont know]

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#560788 - 02/15/05 05:52 PM Re: Fluttering Mechanical Oil Pressure Gauge
Smoky14 Offline


Registered: 04/23/03
Posts: 1181
Loc: Nowhere NM
Sticking relief valve. Most factory gages are dampened and you don't see the movement. It is normal for this to happen occasionally as a small piece of dirt will make the valve flutter.
I'd not worry on an un-dampened instrument unless it really gets wild for a prolonged time.

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#560789 - 02/15/05 06:27 PM Re: Fluttering Mechanical Oil Pressure Gauge
Eddie Online   happy


Registered: 12/07/03
Posts: 8325
Loc: Florida, Cape Coral
To TallPaul: I had the same thing happen and found my cause. I had not fully primed air from the line. Disconect the line at the back of the gage and run engine for several minutes to purge all air. This can take many minutes as the oil temp in the line is cold. Ed

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#560790 - 02/16/05 08:35 AM Re: Fluttering Mechanical Oil Pressure Gauge
JHZR2 Offline



Registered: 12/14/02
Posts: 38486
Loc: New Jersey
I dont know how he factory gauge is set up in my 98 chevy s10, but I know that when at operating temperature (the oil is up to temp), when idling, the gauge shakes very slightly. It is noticable though. I figured it was because of how the oil pump 'strokes' or moves to run the oil through the engine. Its rock solid though when running.

JMH

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#560791 - 02/15/05 10:02 PM Re: Fluttering Mechanical Oil Pressure Gauge
ZR2RANDO Offline


Registered: 06/10/02
Posts: 885
Loc: North Carolina
JHZR2-
We have a 95 S10 Blazer that was doing the same thing, when I used 10w30 oil and it was fully warmed up (hot days only..), the gauge would flicker at idle down around 10-15 psi. These days I am swapping out 1 qt of 20w50 for 1 qt of 10w30 in that vehicle (and my 99 ZR2 truck as well) and that gauge no longer flickers...I think the oil was just pretty thin and the gauge was barely being activated (being tickled instead of pushed so-to-speak). Swapping that qt of 20w50 is just adding a little pressure enough to smooth out the gauge anyway..It is always smooth at higher pressures (then and now as well)
Rando

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#560792 - 02/16/05 09:13 AM Re: Fluttering Mechanical Oil Pressure Gauge
TallPaul Offline


Registered: 10/22/03
Posts: 13092
Loc: By Detroit
Thanks all. Nice I didn't hear, "the main bearings are shot," or something like that.

If it keeps coming back I may consider purging the line to the gauge, but would point it out the window in case it comes out faster than I thought. [Big Grin]

Definitely don't want to go thicker on the oil. The 10w30 (on the lighter end of 30 at 10.5 cSt) is getting nearly 60 psi hot and spec is 40 to 65.

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#560793 - 02/16/05 09:18 AM Re: Fluttering Mechanical Oil Pressure Gauge
XS650 Offline


Registered: 12/21/03
Posts: 12385
Loc: Northern CA
If it's got one of those super small diameter lines, the oil won't come out very fast. You can catch it with a rag while you tighten the fitting back up. If its a standard sized line, get a container.

If the gauge is fluttering, it sounds like you don't have a super small line.

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#560794 - 02/16/05 04:55 PM Re: Fluttering Mechanical Oil Pressure Gauge
TallPaul Offline


Registered: 10/22/03
Posts: 13092
Loc: By Detroit
quote:
Originally posted by XS650:
If the gauge is fluttering, it sounds like you don't have a super small line.

Only flutter on that one trip in 10,000 miles. Always had air in the line and I had called Autometer (brand in other vehicle) once and they said the air in the line would not affect the reading, but I did not have nor mention flutter at the time. The flutter is in a cheap gauge ($5 on sale [Embarrassed] ). The line is that thin whiteish plastic, maybee 2 mm outside diameter.

Glad to hear it doesn't come out fast as many on the Ford truck site told horror stories that I would get a facefull of searing hot oil someday when the line bursts. I even encased the line in a larger plastic tube for the motorhome so the family would not get squirted in that small chance event. Oh well, no harm. I won't worry about the flutter for now. Next time I have the MH out (could be a couple months) will see. If still flutters, then will purge line (and maybe put the Sun brand OP gauge I got at at garage sale for $2).

Am I cheap? [I dont know] I could afford an Autometer but for some reason keep picking up these cheap gauges. Even the Autogauge (by Autometer) in the pickup truck is a $5 garage sale get. [Big Grin] [Razz]

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#560795 - 02/16/05 09:51 PM Re: Fluttering Mechanical Oil Pressure Gauge
Drew99GT Offline


Registered: 10/11/02
Posts: 21577
Loc: Colorado Springs
Hey Paul, do you have a "mechanics" oil pressure gaugae that you can screw into the oil pressure sending port? That'll give you a truely accurate reading and tell you if it's your mechanical gauge or somethin else [I dont know]

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#560796 - 02/17/05 12:33 AM Re: Fluttering Mechanical Oil Pressure Gauge
TallPaul Offline


Registered: 10/22/03
Posts: 13092
Loc: By Detroit
quote:
Originally posted by Drew99GT:
Hey Paul, do you have a "mechanics" oil pressure gaugae that you can screw into the oil pressure sending port? That'll give you a truely accurate reading and tell you if it's your mechanical gauge or somethin else [I dont know]

I should buy one of those mechanics gauges. Would be a handy thing to have around. Who knows, my cheap gauges could be off by 5 or 10 psi for all I know. Yeah, and the flutter too, could be a loose needle vibrating with the road vibrations.

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#560797 - 02/17/05 03:42 AM Re: Fluttering Mechanical Oil Pressure Gauge
Gary Allan Offline


Registered: 09/28/02
Posts: 39806
Loc: Pottstown, PA
quote:
Yeah, and the flutter too, could be a loose needle vibrating with the road vibrations.
I don't know if this is a side effect ..but what if some vibration is causing the line to "bounce around" and you're seeing the shockwaves?? Mechanical harmonics can cause some odd effects. For all you know you had a stone in a tire that dislodged itself before you started your return trip. [I dont know] If I'm correct ..with a motor home of that vintage ..I doubt that your "rattle free" at this stage of the things life. [Smile]

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#560798 - 02/17/05 07:13 AM Re: Fluttering Mechanical Oil Pressure Gauge
kcryan Offline


Registered: 12/17/04
Posts: 536
Loc: Rochester NY
anyone got a writeup on installing one of theses gauges?

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#560799 - 02/17/05 01:53 PM Re: Fluttering Mechanical Oil Pressure Gauge
mechtech Offline


Registered: 08/11/04
Posts: 2387
Loc: Chicago area
You want air in the line to dampen the readings.

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#560800 - 02/17/05 06:12 PM Re: Fluttering Mechanical Oil Pressure Gauge
427Z06 Offline


Registered: 12/06/03
Posts: 7409
Loc: Austin, TX
quote:
Originally posted by TallPaul:
The line is that thin whiteish plastic, maybee 2 mm outside diameter.

Shouldn't squirt out more than a few cc/sec even if the engine is fully warmed. 30 cc's is a shot glass.

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#560801 - 02/18/05 05:06 AM Re: Fluttering Mechanical Oil Pressure Gauge
mechtech Offline


Registered: 08/11/04
Posts: 2387
Loc: Chicago area
427 - 30cc in a shot, unless you are friends with the bartender.

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