Vital Velocity

Driving around today in the vette and the oil pressure became erratic; at idle it dropped to as low as 11psi; as i start driving it gets up to a more normal level (35-50psi). As i come to a stop it drops again down to 11-15psi until the rpms increase.

I know that as long as you have pressure and 10psi per 1000rpms you should be fine; but its a little nerve wrecking to see oil pressure at 10psi....im not getting any sort of low oil pressure warning or anything like that.

Are these known for faulty sensors? The car is an 05 with z51; heads, cam (gx5) ls2

RicK T

Pretty common for the sending units to fail but "usually" when they do the gauge pegs at 80 (the default for failure). For peace of mind might want to get it checked with a mech gauge because at this point you just don't know for sure. There could be something wrong.

Vital Velocity

Yeah i know when i had some c5s i had a lot of pegged gauges so i figured it would be the same thing for this but wasnt sure. Where would i plug in a mech gauge on a c6?

RicK T

Uh....not sure. I think there's a place on the oil filter boss but you should probably wait for someone to confirm or ask the guys in the Tech Forum.

Vital Velocity

Just went up to check it, started it and it say at 0psi for a second, flashed low oil pressure for a second and then kicked up to 38psi?

kliph

It could be the sending unit, but it's a good idea to have it checked.
Also check your oil level.

RicK T

That seems weird. I suggest you do another thread with all your symptoms in the C6 Tech Forum and see what the guys over there have to say tomorrow. Good luck.

Vette5.5

I'd definitely have this checked out, as sometimes a sign of engine bearings going bad. Hopefully not, but better catching this right away, or things could get real ugly.

rayk

I had ford pu with a 351 that the oil pressure sensor went bad on. It had erratic readings and was losing oil as it was leaking through a crack.

Replaced the sensor and everything was fine. Glad I stopped to check the oil level when it happened as I was already down a couple of quarts.

If you have bad bearing, the pressure will be mostly normal when cold and then oil pressure will go low at idle as the oil heats up. I don't know why it would be erratic. Maybe a spun bearing?

Vital Velocity

Yeah just was throws me off is the irregularity of it, like when I went back to start it up it was zero for a second and then 38 psi

roscoe118

We had a very similar issue, perhaps the same but we never saw 0 psi, with our '08 Coupe. Normal pressure when cold, but after is warmed up and the oil temp. reached close to 200 degrees, the pressure at idle would drop as low as 9 psi. It would go right up to normal 38+ as you accelerated. We had the oil pump replaced under the 5/100 warranty. Now we never see below ~27-28 psi when hot.

Seems that it is not uncommon for the pressure relief valve to stick open (mostly when hot) with these pumps. Also, there is a relief valve in the oil filter. You might try starting by replacing that. I did, but no such luck. I know of at least one person that the filter resolved this issue for.

Keep in mind that even 9 psi is above the GM minimum spec. (I believe it is like 6 psi), even though "typical" is always closer to 30. But if you are seeing 0 at any point in time, I'd get is looked at asap...

Vital Velocity

Yeah I'm hoping it's just the oil pressure switch ( was replaced in past 3 weeks) as from what I understand the oil pump is internal

Wayne O

I wouldn't feel comfortable with oil pressure dropping that low at idle. IMO you're in the danger zone. I suggest you have it checked out. Good luck and let us know the outcome.

Vital Velocity

Yeah I know it's within spec but I just won't be able to enjoy the car with oil pressure sitting that low. Anyone have a write up of an oil pump swap?

C7&7

Replacing a oil pump is just about the exact same procedure as changing out a cam. Of course minus taking the valve train apart and pulling the cam. The oil pump is under the timing cover right at the cam. Basically the power steering rack, crank pulley, and timing cover have to come off to get at it. If you ever had any plans on doing a cam now is the time ... The pump comes off for a cam swap. I just had mine replaced during a cam swap.

There is a great DIY thread on a cam swap. I think it is even a stinky in the tech section.

Vital Velocity

It's already got a gx5 cam by LG lol


I'm hoping it's that sending unit since its erratic and that piece was just replaced ( hopefully faulty ready ).

C7&7

Well that stinks. Yeah it seems fishy the sending unit was just replaced and it started acting this way. Or was it replaced because it was acting this way?

Replacing the pump is probably a $500 deal at most including a new pump. Most shops do cam swaps for $600 and you're actually doing about half the work of the cam swap.

What year is the car?

Vital Velocity

Is there a specialty tool for changing the oil sending unit ?

Corby

"Also, there is a relief valve in the oil filter. You might try starting by replacing that. I did, but no such luck. I know of at least one person that the filter resolved this issue for."

I would start with an oil and filter change. Then the oil sending unit. If both fail to resolve the problem, it's off to get it checked. Good luck.

Vital Velocity

I ask about the tool because the person who changed it said he had a specialty tool?