wacky oil pressure gauge

My dashboard oil pressure gauge continually moves up to the max when driving and jumps up and down while idling. In fact, it moves rapidly enough to make
a knocking noise inside the gauge when it hits the bottom and top end. What engine conditions should I look for as a cause or is that a sign of a wacky gauge? Could this be related to my electrical short problem in the turn signals?
Also, what range of oil pressure is normal? Should there be a significant difference in pressure for idling vs. driving?
Thanks for all the ongoing help! Tim
--
Bluff City, TN



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wrote:

your sender is bad, replace it.

7psi idle, 10psi per 1k rpm is the service minimum.
Should there be a significant

there can be... on a new motor with tight clearances, it is completely possible to be up against the oil pumps pressure relieve valve at all times, leaving a constant oil pressure... as the motor wears, the oil pressure will slowly go down below the relief pressure of the valve and you'll see the fluctuation.
if you've got more than 7psi at idle and more than 10psi at 1krpm, 20@2k, 30@3k, etc your motor is just fine.
oh and one more thing... the factory electrical gauge is notoriously inaccurate.. I've got a mechanical OP gauge in my truck and the factory gauge can be reading +/- 5psi (or more) from the mechanical gauge.
hth, Bret

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Thanks, Bret- that is very helpful!
Tim
etc your motor is just fine.

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wrote:

I replaced the sender on my 88 Suburban 5.7L for this very reason. I replaced it with a Sorenson brand I bought at Advance Auto. The new sender moved the gauge in a step-wise fashion. Instead of moving smoothly up and down, it goes up and down in ~7psi increments. After 1 month, the new sender is again bouncing around like the old sender. :-/
-RC
R.Clarke spam snipped-for-privacy@BlocKmindspring.com RTP, NC, USA
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It was a defective sensor when you got it!
It's actually a transducer.
Was it lifetime guaranteed?
The Advanced Auto Parts in my area, don't offer a lifetime warranty anymore. I think they're on the way to where Parts America went. (Buh Bye!)
Refinish King

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Is there any particular reason these units fail or is it just a coincidence that RC's 2nd sender failed? Should I be looking for an internal problem such as a plugged oil passage way? BTW, I noticed Advance has a 1 yr. warranty on the Sorenson sender.
Tim

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wrote:

it just one of "those things".... electrical transducers have a limited life... esp ones sourced from a DIY oriented parts store.. I've found NAPA Echlin electrical parts to be far superior to the crap that autozone and advanced sell. I just plumbed in a mechanical gauge on an A pillar pod in my '88 k2500 and have ignored the factory gauge since.
-Bret
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That's good info to have (re: NAPA vs Autozone/Advance). What type of pillar did you get for your gauge? Is it custom or a universal model?
Tim

coincidence
problem
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wrote:

I used an Autometer Gauge Cage 2 gauge mount that I bought from Summit. I've been considering changing it out with a full A pillar triple mount for my 88 k2500 but I haven't decided on what the 3rd gauge should be... thinking a vacuum one would be cool.
-Bret

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It's called the law of averages!
Sorenson was an A brand ignition company since the 30's, till the late 90's, when Standard Ignition bought it. For an outlet for it's second quality parts.
So if you're selling seconds, a few are bound to come back, and bite you in the ass!
Refinish King

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On Sun, 18 Jul 2004 23:49:12 -0400, "Refinish King"

It has some sort of guarantee but I don't plan on using it. I've got better things to do than replace junk with junk.
I could've ordered an AC Delco from gmpartsdirect if I'd been patient. I went to Advance because they carried AC Delco. At least until recently. I guess I was the only buying it from them.
Now I need to change the sender _and_ fish all the TFE tape shreds out of the fitting. Who was it told us not to use that stuff? :-)
-RC
R.Clarke spam snipped-for-privacy@BlocKmindspring.com RTP, NC, USA
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So what should you use instead of tape?
Tim

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PTFE Pipe Dope:
Put the PTFE tape a few threads back and don't worry about it!
Refinish King

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Tim Urbin wrote:

There isn't anything wrong with using the tape. It's just a matter of knowing how to apply it properly.
Ian
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