: Oil Pressure Drops to 0 at 60mph



MauiV
05-09-09, 12:49 AM
OK, my V just scared the ever living shit out of me. Cruising at 60mph my dash lit up like a Vegas slot machine and says "Stop engine immediatly" Oil pressure (!) was going nuts and chimes everywhere (Clarkson would have loved it).

I parked the car, popped the hood and smell nothing, look under the car, smell nothing (its dark out). I call the wife to come get me and dial Roadside Assistance to come pick it up when I decide to fire it up again since I cant smell a drop of oil anywhere. Fires right up, all sensors normal and pressure at a nice 40lbs. I drive it the last 3 miles home, pull it into the garage and cant find ANYTHING wrong. Dipstick shows normal level.

I searched but couldnt find anything fitting this. I did see the thread about the bad sending unit causing 129lb readings. Can the bad unit also cause 0 readings?

:banghead:

The Tony Show
05-09-09, 01:05 AM
Yes it could- it's happened to a few people here. Either a bad sensor or a bad connection/ground somewhere.

rand49er
05-09-09, 09:04 AM
Your reaction is probably the same as just about anybody would have had. :eek: I would've filled my pants.

Might be a different failure mode than what the 129 psi thing is. That one might be a bad sensor; your's might be a bad connection ... just guessing here, mind you. Either way, you gotta get back behind the maggie, something I've been putting off. Let us know how that goes.

darkman
05-09-09, 10:56 AM
Your reaction is probably the same as just about anybody would have had. :eek: I would've filled my pants.

On the other hand, there are those that would have thought "time for an LS7" and nailed the throttle.

Rey
05-09-09, 11:02 AM
I wrote the thread on the failed oil pressure sensor. Besides showing 130psi, it also showed zero psi for a while after I changed the oil.

But, it never triggered any check engine lights or low oil pressure signals. These lights and signals may be truly indicate no oil pressure.

MauiV
05-09-09, 01:05 PM
Well I just went to the garage to start it and see what happens, cranks fine, idles fine, oil pressure reads 0 and all the bells and whistles go off again. I let it sit for a couple minutes, check under the car and all around the engine bay. Nothing. I start it back up and pressure immediatly climbs to 81lbs then down to 54 and back up to 77 back down to 54 etc etc etc. When it gets into the mid 7s I tap the thoddle and it starts to go down again. Everything sounds fine, car runs a little rough but that is normal from cold.

The erratic numbers have me wondering if maybe the car has a bad oil pump? It does have 80kish miles so I am at a lose right now

darkman
05-09-09, 01:39 PM
The Service Manual procedure calls for the removal of the oil filter and the installation of oil pressure gauge.

If the oil pressure is within specification with the gauge installed-
1. Plugged, or incorrect oil filter and/or malfunctioning bypass valve.
2. Malfunctioning vehicle oil pressure gauge or sensor.

If the oil pressure is below specification it says to check for:
1. Oil pump worn or dirty. (Clean or replace).
2. Oil pump to engine bolts loose.
3. Oil pump screen loose, plugged or damaged.
4. Oil pump screen oil seal missing or damaged.
5. Malfunctioning oil pressure relief valve.
6. Excessive bearing clearance.
7. Cracked, porous, or restricted oil galleries.
8. Oil gallery plugs missing or incorrectly installed.
9. Broken valve lifters.

Looks to me like the first thing I would do is change the oil filter to elimante that as a variable.

heavymetals
05-09-09, 02:04 PM
I had the same thing happen to me after taking on a Vette.

BAD SENSOR.

With no oil pressure the car will sound like its' falling apart (clanking and knocking).

MauiV
05-09-09, 06:36 PM
Thanks guys, I will try the filter first, if no dice looks like it goes back to the dealer on Tuesday. Hope they dont give me to hard of a time about working around the Maggie.

rdjiv
05-09-09, 08:21 PM
similar thing happened to me and it turned out to be a sticky valve on the oil pump itself (line item 5 in darkman's list). it was under warranty and i got a free coolant flush to go with my new oil pump.

CTSV_510
05-09-09, 09:29 PM
well if you end up needing an oil pump you might as well have them throw a cam in while they're down there. :lildevil:

rlj5
05-10-09, 09:32 AM
On the other hand, there are those that would have thought "time for an LS7" and nailed the throttle.


:yeah:

Just a sign from the V gods that it's time something bigger & better

C66 Racing
05-10-09, 03:52 PM
Engine is not going to last long if oil pressure really was 0 psi (been there done that with an LS6 on the track). I suspect one of the other causes, most likely the sensor, but who knows, might be a problem with the oil pump such as the relief mentioned above. Good luck with it. Please let us know what it turns out to be.
:cheers:

MauiV
05-12-09, 01:50 PM
Well it took me about 6 attempted starts this morning to get the system to quit showing 0psi. I let it warm up for about 15 mins in the garage and when I got in it showed 129psi. Gave me a pretty good feeling that it is in fact the sensor. The small "no questions asked" dealer I go to since the big shiney intake install is about 25 miles away. About 22 miles into my drive the pressure starts dropping and I get all the alarms again and the 0psi reading. I pull over restart it a coule times and get normalish readings in the 57psi range. My car tends to run about 44. Sure enough when I arrive at the dealer a couple mins later everything is showing normal. I try about a dozen restarts and all idle at about 30psi. I talke dto the service mgr and the tech that normally deals with my car and they agreed that it is almost certainy the sensor so they ordered one and hopefully it will arrive tomorrow.

HUGE relief.

rand49er
05-12-09, 02:28 PM
VERY interested ...

Keep us posted on the results. :yup:

CTSV_Rob
05-12-09, 03:24 PM
on the other hand, there are those that would have thought "time for an ls7" and nailed the throttle.
+1...

MauiV
05-19-09, 05:22 AM
Car has been acting totally normal for a solid week now. Weirdest thing, seems to have just "fixed" itself, well at least till the next time it does it. I still plan to have the sensor changed though.

lollygagger8
05-19-09, 10:15 AM
It's be nice to know the exact location of the sensor you replace.

Also, would it help to undo the battery and let it sit overnight to reset everything ?

Scatillac
05-19-09, 11:30 AM
The oil pressure/temp sensor location is at the rear of the intake manifold on the valley cover on the driver's side. The main engine grounds are behind the cylinder heads and in the harness under the dash (you'll need a Helm manual to trace them through).

To confirm the oil pressure (or lack thereof) you can remove the small adapter plate just above the oil filter and replace it with one of the available GM plates with a boss for a fitting. The Corvette plate is threaded metric and the truck plate has the boss but it is neither drilled or tapped. I prefer the truck plate as it can be drilled and tapped to 1/8" NPT, which makes it easier to adapt a manual guage fitting (no metric/sae adapter needed).

As a safety measure, I use this on startup of a new build to confirm/compare to the electronic readings. It's easily removed (not too messy) and can be reinstalled, if necessary, without any problems.

CTSV_510
05-19-09, 11:40 AM
I still plan to have the sensor changed though.

Do they know yet that they'll in all likely hood have to remove that weird shiny intake manifold attached to the front drive belt to replace that little sensor? ;)

MauiV
05-19-09, 12:24 PM
Heavy says it can be done by removing the wiper shroud :cool:

Oh yeah, it my normal service dealer ends up on the GM chopping block Im going to try to talk my way into a new diff too before they fold up shop.

heavymetals
05-19-09, 03:09 PM
It is part ref #4

CTSV_510
05-19-09, 10:22 PM
hmm...

http://forums.corvetteforum.com/c5-forced-induction-nitrous/2329307-introducing-plug-n-play-oil-pressure-relocation-kit.html

MauiV
05-19-09, 10:25 PM
Good find, VERY tempting

CTSV_510
05-19-09, 10:30 PM
Yeah I guess you could just leave the faulty sensor in it's place, install the new one and use the wire harness extension. You wouldn't get the dealer to pay for it though. But you wouldn't have to worry about a PITA replacement if and when the new one fails.