My sons 04 pontiac bonneville oil pressure gauge seems to be reading high. It show 80 pounds while driving down the road and about 50 or 60 at rest. Installed new oil pan gasket and steering rack the first of December and it's been fine ever since. The only other thing that was changed was the oil and filter. Could this be a bad filter ? I have gotten bad oil filters before and they normally starve the engine for oil. Any ideas where to look ?
04 Bonneville oil pressure
- Thread starter hardheaded
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I've noticed some 3800's tend to show higher oil pressure, at least on the dash. The mother in law's LeSabre shows 70+ PSI driving down the highway with 5w30 and over 160K miles.
We don't know the grade of oil in the engine.
You might laugh, but some SWEAR by putting 20W-50 in the engine because they feel there is nothing you can then throw at the engine but that it can't handle.
If going by "Higher HTHS is better," then I wonder if they have a point.
Mobil High Milage10w-30 in the engine. Been using this since he bought the car a couple of years ago with no problems. Maybe a sender problem ?
Nick1994
$100 site donor 2024
Could be a bad sender, but that era GM instrument clusters are pretty whacky.
Do you have a scan tool to check what the computer sees, rather than the gauge? Even the $10 ELM327 scan tools.
Do you have a scan tool to check what the computer sees, rather than the gauge? Even the $10 ELM327 scan tools.
As mentioned, I would try a new sender. Your readings do seem high.I remember my 3800 was around 80 when cold @2000 RPM, 60 PSI when warm @2000 RPM and at warm idle was around 35 PSI. I was using 5w-30 oil in it at all times, which was the recommended weight.. Did it always read high before your last oil change?
The easiest thing to do would be to check the pressure with a mechanical gauge.
Yes i do have a scan tool. I think when he comes by after work i will plug it in and see what the computer says. THANKS.
I remember my 99 LeSabre hardly ever dropped below 60, makes me wonder now if it was accurate. After owning all three series the series ll was the best.
Not the Series 3?
I've had a Series 1..
I want the last year Supercharged Regal I think it was 2004.
Heard that car will do a quarter mile in the 12s with simply smaller pulleys...
Series 1 had no get up and go like the series ll, the series lll my Lucerne is ok it's just the throttle is weird, hard to explain, like it doesn't react right away.
I know exactly what you mean, even our Cruze was like that near the end like.. gas pedal and actual driving were two different things.
I think the Series 1 pulled fine but now that I think about it.. I did have a Series 2 in a Buick and
Oh man.
Not even sure I want a BMW after that, I am pretty sure the Buick was faster.
No way on Earth that car is doing 12's with a smaller pulley.
Remember these are old school twelve valve pushrod engines. Great torque down low and midrange, but no top end. Rated 240hp stock, most are lucky to get in the 14's. You can't just throw a small pulley on there and call it a day (unless it's a minor change), it requires supporting mods to keep detonation / preignition in check, unless you like blowing engines up.
I had an '00 Bonneville with the L67 Series II and with headers, cat-back exhaust, high ratio rocker arms (1.9 to 1), stiffer valve springs, high flow fuel pump, 1.4" pulley (which is about the smallest you can run reliably without serious engine work or S/C upgrade), dyno tuned and I barely broke 240whp. Don't get me wrong, 350lb-ft torque at the wheels makes for a seriously snappy FWD car and great rolling burnouts, but no way you're getting close to 12's even with a W-body, without a ton of work and $.
Back on topic, I'd try the oil pressure sender first, it should be inexpensive and easy to replace. But checking oil pressure manually would eliminate any guessing or throwing parts at it. I don't think you're going to be able to read oil pressure through a cheap OBD2 adapter, mine has never shown that, but perhaps more expensive scanners might.
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Okay, 13s not 12s. I misremembered.
It seems to me like all of that gen 3800's read high oil pressure according to the dash.
I can't recall many FWD GM's with the 3800 that had an actual oil pressure gauge, but the two that spring to mind are the Bonne and the same-era LeSabre's with the up-level gauge cluster that showed oil PSI on a digital display. They always seems to read 60-70 at cruise and 45+ at idle. I don't see 80 PSI indicated as much of a problem, with the margin of error between the sender and the gauge would make it seem feasible.
I can't recall many FWD GM's with the 3800 that had an actual oil pressure gauge, but the two that spring to mind are the Bonne and the same-era LeSabre's with the up-level gauge cluster that showed oil PSI on a digital display. They always seems to read 60-70 at cruise and 45+ at idle. I don't see 80 PSI indicated as much of a problem, with the margin of error between the sender and the gauge would make it seem feasible.
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I don't think you have any issues at all. Here are pictures of my go to work Lesabre beater with 183K on the odometer and 71-72 psi digital oil pressure readout on a cold start in the garage with a coolant temp of 59F. My daughter's Lesabre with 93K on the odometer has 78 psi cold start. Both vehicles are running Amsoil SS 5W30. In line with what 14Accent above says, I get ~42-45 psi hot idling at a stoplight. I also have zero understanding what an oil pan gasket or steering rack have to do with oil pressure? Those 3800s are bulletproof.
I didn't know those cars came with digital readouts, I wish that feature was universal.
First generation Buick engines had horrendous low oil pressure issues, Spur pumps driven off the distributor with a aluminum housing. GM decided to "fix" the issue with a crank driven Gerotor Pump & a high PSI bypass spring.
3800 4th Gen Camaros have a 120 PSI oil pressure gage compared to a 80 PSI gage on the Chevy V8 models.
3800 4th Gen Camaros have a 120 PSI oil pressure gage compared to a 80 PSI gage on the Chevy V8 models.
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