Zero Oil Pressure
08-03-2011, 11:27 PM
#1
Le Mans Master
Thread Starter
Zero Oil Pressure
I posted this almost a year ago regarding low/no oil pressure after an oil change: http://forums.corvetteforum.com/c6-t...-pressure.html
At the time I attributed it to the filter because after changing it, the symptoms disappeared. Well I changed my oil last weekend and noticed slightly lower than normal hot idle oil pressure. As low as 23#. Not really cause for concern, especially in >100 degree weather and ~230 oil temps but I was keeping a close eye on it.
Monday evening I was coming home from the store and it was low again. But while pulling into my subdivision I noticed ZERO oil pressure!
No DIC warnings, oddly enough, but the needle was dead. I limped it the ~1/4 mile to the house. No knocking or anything. First thing I did was to change the filter again but no change. Then I pulled the manifold and tested the oil pressure sender and harness by blowing into it with the air compressor. It registered on the dash. So after a little research I'm leaning towards the pressure relief valve on the oil pump. Similar symptoms here: http://forums.corvetteforum.com/c5-t...-pressure.html
I have a Melling pump on the way and hope to tear it down this weekend. If that fixes it, it may have not been related to the filter at all last year. This problem doesn't seem too rare and affects LS1's, 6's, and 2's. If someone didn't catch it early enough could easily blow a motor.
But who knows. It could be bearings wearing too. But there has been no knocking or any abnormal sounds since it started.
At the time I attributed it to the filter because after changing it, the symptoms disappeared. Well I changed my oil last weekend and noticed slightly lower than normal hot idle oil pressure. As low as 23#. Not really cause for concern, especially in >100 degree weather and ~230 oil temps but I was keeping a close eye on it.
Monday evening I was coming home from the store and it was low again. But while pulling into my subdivision I noticed ZERO oil pressure!
No DIC warnings, oddly enough, but the needle was dead. I limped it the ~1/4 mile to the house. No knocking or anything. First thing I did was to change the filter again but no change. Then I pulled the manifold and tested the oil pressure sender and harness by blowing into it with the air compressor. It registered on the dash. So after a little research I'm leaning towards the pressure relief valve on the oil pump. Similar symptoms here: http://forums.corvetteforum.com/c5-t...-pressure.htmlI have a Melling pump on the way and hope to tear it down this weekend. If that fixes it, it may have not been related to the filter at all last year. This problem doesn't seem too rare and affects LS1's, 6's, and 2's. If someone didn't catch it early enough could easily blow a motor.
But who knows. It could be bearings wearing too. But there has been no knocking or any abnormal sounds since it started.
08-04-2011, 12:07 AM
#2
Le Mans Master
I posted this almost a year ago regarding low/no oil pressure after an oil change: http://forums.corvetteforum.com/c6-t...-pressure.html
At the time I attributed it to the filter because after changing it, the symptoms disappeared. Well I changed my oil last weekend and noticed slightly lower than normal hot idle oil pressure. As low as 23#. Not really cause for concern, especially in >100 degree weather and ~230 oil temps but I was keeping a close eye on it.
Monday evening I was coming home from the store and it was low again. But while pulling into my subdivision I noticed ZERO oil pressure! No DIC warnings, oddly enough, but the needle was dead. I limped it the ~1/4 mile to the house. No knocking or anything. First thing I did was to change the filter again but no change. Then I pulled the manifold and tested the oil pressure sender and harness by blowing into it with the air compressor. It registered on the dash. So after a little research I'm leaning towards the pressure relief valve on the oil pump. Similar symptoms here: http://forums.corvetteforum.com/c5-t...-pressure.html
I have a Melling pump on the way and hope to tear it down this weekend. If that fixes it, it may have not been related to the filter at all last year. This problem doesn't seem too rare and affects LS1's, 6's, and 2's. If someone didn't catch it early enough could easily blow a motor.
But who knows. It could be bearings wearing too. But there has been no knocking or any abnormal sounds since it started.
At the time I attributed it to the filter because after changing it, the symptoms disappeared. Well I changed my oil last weekend and noticed slightly lower than normal hot idle oil pressure. As low as 23#. Not really cause for concern, especially in >100 degree weather and ~230 oil temps but I was keeping a close eye on it.
Monday evening I was coming home from the store and it was low again. But while pulling into my subdivision I noticed ZERO oil pressure!
No DIC warnings, oddly enough, but the needle was dead. I limped it the ~1/4 mile to the house. No knocking or anything. First thing I did was to change the filter again but no change. Then I pulled the manifold and tested the oil pressure sender and harness by blowing into it with the air compressor. It registered on the dash. So after a little research I'm leaning towards the pressure relief valve on the oil pump. Similar symptoms here: http://forums.corvetteforum.com/c5-t...-pressure.htmlI have a Melling pump on the way and hope to tear it down this weekend. If that fixes it, it may have not been related to the filter at all last year. This problem doesn't seem too rare and affects LS1's, 6's, and 2's. If someone didn't catch it early enough could easily blow a motor.
But who knows. It could be bearings wearing too. But there has been no knocking or any abnormal sounds since it started.
08-04-2011, 08:28 AM
#4
Safety Car
Check out post #5 in this thread:
http://forums.corvetteforum.com/c6-t...g-back-up.html
Our '08 has been seeing as low as 9 PSI at Hot (210+ degree oil temp.)Idle...
Although it does immediately go up to 30+ when you start to accelerate.
I called and talked to a Service Advisor at a local dealership, and although he had not seen PIP4158C, he said get the car in here and we'll put a mechanical gauge on it. If the confirms the DIC reading, which I expect it will, they will replace the pump or sending unit under the 5/100 warranty.
roscoe
http://forums.corvetteforum.com/c6-t...g-back-up.html
Our '08 has been seeing as low as 9 PSI at Hot (210+ degree oil temp.)Idle...
Although it does immediately go up to 30+ when you start to accelerate.I called and talked to a Service Advisor at a local dealership, and although he had not seen PIP4158C, he said get the car in here and we'll put a mechanical gauge on it. If the confirms the DIC reading, which I expect it will, they will replace the pump or sending unit under the 5/100 warranty.
roscoe
08-04-2011, 08:43 AM
#5
Melting Slicks
I had a Zero oil pressure problem, it does not sound like yours but I will throw it out anyways. Mine was electrical, the OPS is 3 wire, ground, 5 volt & reference. The 5 volt was shorted in the harness to the reference wire so the gauge showed zero oil pressure. It is easily checked by measuring the voltage on the reference wire @ the OPS connector, Key on, should be zero volts.
The other thing that comes to mind is the infamous O'ring, not sure if that applies to LS2's or not.
The other thing that comes to mind is the infamous O'ring, not sure if that applies to LS2's or not.
08-04-2011, 09:20 AM
#6
Le Mans Master
Thread Starter
Definitely not electrical. As I said I yanked the intake, unscrewed the sensor and blew into it with the air compressor and it registered on the DIC and gauge. Then I tried cranking the engine and no oil came out of the hole where the sensor goes.
I saw that thread. Although my model year does not fit, the problem goes back to C5 days.
I wasn't aware of the Katech pump so I got the Melling which has the spring in it to raise the pressure and is said to flow ~18% more than stock.
I saw that thread. Although my model year does not fit, the problem goes back to C5 days.
I wasn't aware of the Katech pump so I got the Melling which has the spring in it to raise the pressure and is said to flow ~18% more than stock.
08-08-2011, 01:43 AM
#7
Le Mans Master
Thread Starter
I haven't started it back up yet but I think I can safely say it was a stuck relief valve on the oil pump.
You can see the burr it got caught on. I couldnt get a good pic of the plunger but it was pretty scored up from going past the burr. I guess it just had enough.
Pic of the inlets of the new Melling and stock pump.
I was worried that the Melling may eventually suffer the same fate but it's a different casting method that seems to result in a smoother finish. I'm sure it's still machined in much the same way so it's not impossible for it to happen to the Melling but I thought it best to not crack it open and mess with it. Without a long reach tip for the Dremel it would be hard to deburr it anyway.
I think my problem last year that seemed to get fixed with a new filter was a pre-cursor to this. The filter was likely fine and not the culpret.
So thats good. Now I get to put it all back together.
I had forgotten what a pain it was to get at the oil pump. Basically everything you need to remove to do a cam swap. Alternator and power steering come out to get the lines off the rack, blower comes off to get at the water pump, radiator comes out so the pulley puller will fit......
You can see the burr it got caught on. I couldnt get a good pic of the plunger but it was pretty scored up from going past the burr. I guess it just had enough.
Pic of the inlets of the new Melling and stock pump.
I was worried that the Melling may eventually suffer the same fate but it's a different casting method that seems to result in a smoother finish. I'm sure it's still machined in much the same way so it's not impossible for it to happen to the Melling but I thought it best to not crack it open and mess with it. Without a long reach tip for the Dremel it would be hard to deburr it anyway.
I think my problem last year that seemed to get fixed with a new filter was a pre-cursor to this. The filter was likely fine and not the culpret.
So thats good. Now I get to put it all back together.
I had forgotten what a pain it was to get at the oil pump. Basically everything you need to remove to do a cam swap. Alternator and power steering come out to get the lines off the rack, blower comes off to get at the water pump, radiator comes out so the pulley puller will fit......
08-08-2011, 02:12 AM
#9
Le Mans Master
Thread Starter
True. I'm just saying it's the same design so it's possible it could happen with an aftermarket pump too. I'm not worried though.
So for others who found this trying to solve a zero oil pressure problem, I suggest rapping on the front cover or balancer with a rubber mallot. That will likely un-stick the valve at least temporarily.
So for others who found this trying to solve a zero oil pressure problem, I suggest rapping on the front cover or balancer with a rubber mallot. That will likely un-stick the valve at least temporarily.
08-08-2011, 08:52 AM
#10
Melting Slicks
I'm sure GM will make good 
Good find though, it would have sucked not find anything.
The job is a PIA for sure, my new cam will probably arrive this week......I'm not looking forward to that
Good find though, it would have sucked not find anything.The job is a PIA for sure, my new cam will probably arrive this week......I'm not looking forward to that
08-08-2011, 11:55 AM
#11
Racer
Funny you posted this now. I am seeming to have the same issue, and will be tackling this soon. Oil pressure at idle is around 16-18psi, and only rises to around 38psi when in the throttle. Not what you would call severely low oil pressure, but it never used to be this low. Looks like I am in for some fun.
08-08-2011, 10:31 PM
#12
^Did you change oils? Remember different weights and brands can severely be effected by the hotter temps we have been experiencing. With 225+ oil temps, 35-38 psi while cruising seems absolutely normal.
08-09-2011, 08:56 AM
#13
Safety Car
Funny you posted this now. I am seeming to have the same issue, and will be tackling this soon. Oil pressure at idle is around 16-18psi, and only rises to around 38psi when in the throttle. Not what you would call severely low oil pressure, but it never used to be this low. Looks like I am in for some fun.
Is yours still within the 5/100 warranty. Mine is, and is being done under this covereage.
I've also read where the bypass valve in the filter has on occasion stuck and exhibited these exact same symptoms. Unfortunately, changing mine did not help. Did you recently change your oil? If so, you might try a new filter. Cheap, and easy to do...
Good luck.
08-09-2011, 10:23 PM
#14
Tech Contributor
Bill that stinks. But hopefully you caught it before any damage done.
Do you have any tricks on how to get that power steering pump bracket off? Two of those bolts (the lower ones) are a real bear to get to, and that power steering reservoir is a bear to get out of it's bracket.
Thought I'd ask while this headache is on your mind.
Hats off for tackling this yourself!
Do you have any tricks on how to get that power steering pump bracket off? Two of those bolts (the lower ones) are a real bear to get to, and that power steering reservoir is a bear to get out of it's bracket.
Thought I'd ask while this headache is on your mind.
Hats off for tackling this yourself!
08-10-2011, 01:28 PM
#15
Le Mans Master
Thread Starter
The bracket isn't too hard. Remove alternator, remove reservoir (I don't rememver how I removed the reservoir the first time but I have since notched the bracket so it's lots easier to remove) remove the two exposed bracket bolts and then use an open end to get the other two loose as far as they will go. Pull the bracket and pump out and do another round of ~1/8 turns on the two bolts. Pull it out again and one last round should do it. The PITA for me is the connections to the rack.
This is a really good writeup: http://forums.corvetteforum.com/c6-t...s-of-pics.html
This is a really good writeup: http://forums.corvetteforum.com/c6-t...s-of-pics.html
08-10-2011, 01:40 PM
#16
Tech Contributor
The bracket isn't too hard. Remove alternator, remove reservoir (I don't rememver how I removed the reservoir the first time but I have since notched the bracket so it's lots easier to remove) remove the two exposed bracket bolts and then use an open end to get the other two loose as far as they will go. Pull the bracket and pump out and do another round of ~1/8 turns on the two bolts. Pull it out again and one last round should do it. The PITA for me is the connections to the rack.
This is a really good writeup: http://forums.corvetteforum.com/c6-t...s-of-pics.html
This is a really good writeup: http://forums.corvetteforum.com/c6-t...s-of-pics.html
Those 1/8 turns take forever!
08-10-2011, 03:57 PM
#17
Le Mans Master
The hard lines wraping around the stearing box is a PIA. Has anyone designed fittings/lines that are simple to route and can be remove easily with the pump and res intact BEFORE you pull the stearing rack? It sure would make sense.
08-15-2011, 07:04 PM
#20
Safety Car
