Disturbingly high oil pressure?

[TheJMFC]

Today on the way to work in the '93, I noticed that my oil pressure gauge had pegged itself at 120 psi. I just happened to look down while accelerating from a stop (so maybe it's been this way for a while now, but not too long - I'm a gauge watcher).

The gauge currently shows around 60 psi (one mark past 40) at anything between idle and 2000 RPM. At around 2250, it begins to creep up. At 3000, the gauge is maxed out, just past 120 psi.

My drive to work is only around 7 miles, so the oil may not be completely warmed to it's long-trip constant temp. The coolant temp is there though.

It does this predictably (I've been watching it constantly since). Load makes no difference (Neutral or OD), only RPM. All other gauges look fine, including temps. No strange noises that I can tell (car is a bit noisy though).

So... what does this mean? Do I have some blockage somewhere? Is there a pressure relief that isn't doing it's thing? A brief search didn't turn up much.

Help? Thanks in advance.

[tpulliam79]

look into a oil pressure gauge/ switch these seem to cause the symptoms your having

[TheJMFC]

look into a oil pressure gauge/ switch these seem to cause the symptoms your having

Well that was my first thought - "woah, the gauge flaked out for a minute"

But it's so consistent now, and so obviously coincides with engine RPM's... it can't just be a faulty sensor then, can it?

Unless the sensor is reading slightly increased pressure, and way, way overreacting to it. I don't even know if that's possible.

[tpulliam79]

when mine went it did all kinds of craziness up and down back and forth its about a 30 dollar part and relatively easy to change if you need im sure there is a link here somewhere ..let us know if ya need help on how or anything else.or you can try to get a mechanical oil pressure gauge on there to test it for sure. 9 times out of ten its the sender/switch though

[wjcollier07]

if it pegs at a certain RPM, its definitely the sending unit. its just going out of range is all. my 89 used to do that, it'd give me the pressure at anything below 1100 rpms, and then peg at anything over.

make sure to replace it with only delco

[TheJMFC]

If it makes any difference, it doesn't peg itself all at once. It's variable with RPM's still. It doesn't just suddenly click over to 120.

Hopefully that's all it is, anyway.

Not sure I'd bother replacing it though. As long as it's not going to seize or throw a rod, that's all I need to know. I'm hoping not to keep it too much longer, anyway. I'm not nearly as pleased with this one as I was my old '89.

[Archon]

I'd recommend swapping it out anyway, for a few reasons. To confirm that is indeed the problem, as well as with it in the current condition, if something does go wrong, you won't know. Plus, a prospective buyer may be as much of a gauge watcher as you are, and you could lose a sale.

[Billha]

Yep, I'd bet the oil pressure sensor is defective (I recently posted a topic for a similar problem on my '93 SSEi).
If you replace it, and I recommend that you do, I recommend using only the Delco replacement...I've replaced mine twice so far, both times with parts from a local auto parts store (only because they were less $$$ than the Delco part), and the gage still doesn't read like it should so I'm shopping for the Delco part.

The downside of not replacing it is that if there's an engine oil pressure problem in the future (not likely, but always a possibility) the sensor may not detect it and warn you.

[TheJMFC]

Perhaps I'll price out Delco sensors then. I cringe at putting any more cash into it though, since money spent on this car is money I'm not saving towards it's replacement.

The suggestion that prospective buyers might also be gauge watchers is legit though. Good thinking.

I'm just glad that the consensus is that it's probably not really a mechanical issue. I'll go from there.

Thanks all.

[willwren]

Check Rock Auto before the dealer, then compare to GMPD.

[wjcollier07]

Delco # 25535479



RA: $20.79
GMPD $19.19
CSK/Murray's/Checker/Advance: $33.99 http://www.partsamerica.com/productdeta ... r=25535479

[willwren]

Make sure it's for a gauge-system. Not a dummy light. Dummy light car would be one or two contacts. You need the sensor with your SSE that supports the gauge and one set of contacts.

[TheJMFC]

$20-30 isn't bad at all. Thanks for the lookup WJ.

Thanks for the heads-up on the two types, Bill.

[grey3800]

If its not too late (if you havent bought that new sending unit) have you tried getting ahold of a mechanical pressure gauge? This would help rule out sending unit and guage cluster.

[Billha]

I also began shopping for one recently, and I found that the correct Delco part should be #25627057, which is $41.17 + shipping from GM Parts Direct, or $58.79 + shipping from Rock Auto...that's why I opted to spend roughly half that price and buy another brand from a local parts store instead.
I regret that purchase because the non-oem part that I first installed didn't work correctly, so I returned the first part and bought a different brand and installed it, and although it works much better than the first part did, it doesn't work quite right either.

[TheJMFC]

I haven't bought one yet. I considered putting a mechanical gauge on it, just to be sure. I don't have one, but my brother might. We'll see. I'm not too concerned about the possibility of it being anything more than a sensor going out now, since it's still running fine after a couple of days. It just freaked me out initially.

If the correct part is indeed $41 or more plus shipping, I think it's going to have to suffer not having one. Maybe I'll snag one from a junkyard for $5. If I'm going to put $50 into this car, there are far more pressing issues than a slight gauge malfunction.

[wjcollier07]

Sorry Jon, that's a pissoff. Its listed under AC Delco's part catalog as being correct for both the L27 and L67, but I knew it looked quite short to be a sending unit (when labeled correctly, Sending Unit=Gauge, Switch=Light) but Billha is correct, delco part # 25627057 is correct.

This is what the pin layout should be on the correct sending unit



And the actual sending unit..

[TheJMFC]

Thanks again, other John. No biggie on the mixup. I've known pros to do the same.