LT1 oil pressure problem
12-28-2012, 11:16 PM
#1
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LT1 oil pressure problem Hey guys i have a 94 T/A LT1. I was driving down the road today and my oil pressure gauge goes dead so i stopped, idle got sluggish and started fluttering really bad. Could this be a bad pump or sending unit? Much help appreciated.
12-28-2012, 11:39 PM
#6
My '95 did the same thing. One caution. The LT1 is notorious for doing this not just because of a bad pump, but also because of restrictions to flow. You don't mention the mileage on your engine, but if it is (like most of that age) getting up there, consider the possibility that your oil passages are partially or completely blocked.
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12-31-2012, 08:32 AM
#9
I have a post on here somwhere that I posted pics of my drive gear. Everyone complains that a HV pump will kill it. So I opted for one from Cam motion (they ground my cam). They run LT1's with alot of HP & oil pressure than most of us will see. Granted it is pricey and they get you on shipping. I think it was about $86 total. $17 just for shipping...I was pissed!!!
But it is a well made piece.
But it is a well made piece.
12-31-2012, 10:17 AM
#11
The LT1 is NOT known for oiling issues or for oil passages clogging. Some guys have had the pickup fall off which causes drops in pressure under high rpm or high G-forces.
Some people do see oilpump drive wear with aftermarket cams, most of us don't even see that.
The fact that you are concerned the oilpupm or sender are "worn" and that would cause the problems says you likely need to enlist more experienced help in resolving this. The oilpump is the best lubed part in the engine, they basically don't wear out unless they suck up debris, the sender has nothing to do with how the engine would run. I believe some years do have a low oil pressure fuel pump cutoff wired in with the sender but if the pressure is that low then there is likely already internal engine damage causing the pressure to be low. and that would shut off the fuel pump.
If I were you I would drain the oil and open the filter, if you find glitter don't run the engine anymore just pull it and fix it or replace it.
If no glitter you could consider refilling with oil and fresh filter hooking up a mechanical oil pressure gauge to verify the lack of pressure being careful to shut it down fast if pressure doesn't build quickly or there are odd noises. With the compromised idle though I will guess it was knocking or something causing the pcm to pull maximum knock retard and the engine is damaged.
Just incase it wasn't clear, low oil pressure is usually caused by something like worn bearings causing a lack of restriction to the oil flow. The oilpump does NOT produce pressure, it moves a certain volume of oil per revolution, what produces the pressure is that volume of oil trying to find a way out through the bearings and lifters and such. Oil pressure drops when something breaks or wears letting the oil leak out more easily.
Some people do see oilpump drive wear with aftermarket cams, most of us don't even see that.
The fact that you are concerned the oilpupm or sender are "worn" and that would cause the problems says you likely need to enlist more experienced help in resolving this. The oilpump is the best lubed part in the engine, they basically don't wear out unless they suck up debris, the sender has nothing to do with how the engine would run. I believe some years do have a low oil pressure fuel pump cutoff wired in with the sender but if the pressure is that low then there is likely already internal engine damage causing the pressure to be low. and that would shut off the fuel pump.
If I were you I would drain the oil and open the filter, if you find glitter don't run the engine anymore just pull it and fix it or replace it.
If no glitter you could consider refilling with oil and fresh filter hooking up a mechanical oil pressure gauge to verify the lack of pressure being careful to shut it down fast if pressure doesn't build quickly or there are odd noises. With the compromised idle though I will guess it was knocking or something causing the pcm to pull maximum knock retard and the engine is damaged.
Just incase it wasn't clear, low oil pressure is usually caused by something like worn bearings causing a lack of restriction to the oil flow. The oilpump does NOT produce pressure, it moves a certain volume of oil per revolution, what produces the pressure is that volume of oil trying to find a way out through the bearings and lifters and such. Oil pressure drops when something breaks or wears letting the oil leak out more easily.
12-31-2012, 09:20 PM
#14
I have a post on here somwhere that I posted pics of my drive gear. Everyone complains that a HV pump will kill it. So I opted for one from Cam motion (they ground my cam). They run LT1's with alot of HP & oil pressure than most of us will see. Granted it is pricey and they get you on shipping. I think it was about $86 total. $17 just for shipping...I was pissed!!!
But it is a well made piece.
But it is a well made piece.
01-01-2013, 08:40 AM
#15
Amazing how many folks like to cause problems with bad ideas and then "fix" everything BUT the bad idea that is causing the problems.
If someone wants to run a HV pump they just need to accept it will make the oilpump drive a wear item.
That said a HV pump has few legitimate useful application in s a gen 1 or gen 2 SBC the oiling is pretty good. I would probably only look at one if making BIG enough power that I know the block will be wiggling around and wanting loose bearings to give it room to do so without wiping bearings.
If someone wants to run a HV pump they just need to accept it will make the oilpump drive a wear item.
That said a HV pump has few legitimate useful application in s a gen 1 or gen 2 SBC the oiling is pretty good. I would probably only look at one if making BIG enough power that I know the block will be wiggling around and wanting loose bearings to give it room to do so without wiping bearings.
01-01-2013, 01:26 PM
#17
Amazing how many folks like to cause problems with bad ideas and then "fix" everything BUT the bad idea that is causing the problems.
If someone wants to run a HV pump they just need to accept it will make the oilpump drive a wear item.
That said a HV pump has few legitimate useful application in s a gen 1 or gen 2 SBC the oiling is pretty good. I would probably only look at one if making BIG enough power that I know the block will be wiggling around and wanting loose bearings to give it room to do so without wiping bearings.
If someone wants to run a HV pump they just need to accept it will make the oilpump drive a wear item.
That said a HV pump has few legitimate useful application in s a gen 1 or gen 2 SBC the oiling is pretty good. I would probably only look at one if making BIG enough power that I know the block will be wiggling around and wanting loose bearings to give it room to do so without wiping bearings.
01-01-2013, 10:18 PM
#18
I think you understood me. Even if you had asked for the HV pump, you would have LEARNED from it when it broke stuff the first time. Too many folks blindly defend their mistakes and even work harder at them rather than learn from them and move forward.
01-01-2013, 11:59 PM
#19
I was one of the first to tell everyone not to run one that is true. I lost my first Cam shaft from one back in 99. It was kind of cool to have a picture of the tack and 7,000 and the Oil Pressure pegged LOL!
Like you I do honestly try to provide help and facts based on my past experience. I have made mistakes and I have always shared them when I under stood them
Like you I do honestly try to provide help and facts based on my past experience. I have made mistakes and I have always shared them when I under stood them
01-02-2013, 07:18 AM
#20
The HV pump is a solution to a problem that doesn't exist and causes a LOT more problems.
Once someone understands the way the system works they realize that at high rpm the HV pump is just recirculating more through the bypass not actually pushing more through the bearings. They will raise pressure and therefore flow at low rpm but beyond that they go into bypass sooner so when the engine is actually working hard they don't move any more oil across the bearings, the do heat it up by recirculating it through the bypass. They do have increased potential for cavitation, they do offer raised oil temps, they do offer a much greater chance of oilpump drive wear as has been documented here.
IMO the SV oilpump drive wear a FEW folks have seen is a result of QC errors or ju7st plain wrong gears used on cams. I have seen original oilpump drive last 60K miles and still going after a cam was put in at 160K miles. Granted it was a $400 cam with the Lunati Everwear gear.
Before that I put like 30K miles or something on a ZZ4 cam in my car when it was my only car, when I did heads and cam I simply reused the original drive. I have NEVER bought a new oilpump drive or replacement gear, never even had one exhibit wear. Only "failure" I have seen in person was a friend over torqued one and cracked the plastic at the mount.
There are enough actual issues to address when modding a car without inventing false ones to try and fix.
On a motor I start modding I put a $1 "white" spring and $7 Melling oilpump driveshaft. I have never seen an oiling failure without those things but for $8(price probably went up) it doesn't hurt. The only time the high pressure spring places extra load on the drive is at short intervals of high rpm so the risk of damage by that extra load is slim. The HV pump is always increased load and we see many clear examples of it being a problem.
Once someone understands the way the system works they realize that at high rpm the HV pump is just recirculating more through the bypass not actually pushing more through the bearings. They will raise pressure and therefore flow at low rpm but beyond that they go into bypass sooner so when the engine is actually working hard they don't move any more oil across the bearings, the do heat it up by recirculating it through the bypass. They do have increased potential for cavitation, they do offer raised oil temps, they do offer a much greater chance of oilpump drive wear as has been documented here.
IMO the SV oilpump drive wear a FEW folks have seen is a result of QC errors or ju7st plain wrong gears used on cams. I have seen original oilpump drive last 60K miles and still going after a cam was put in at 160K miles. Granted it was a $400 cam with the Lunati Everwear gear.
Before that I put like 30K miles or something on a ZZ4 cam in my car when it was my only car, when I did heads and cam I simply reused the original drive. I have NEVER bought a new oilpump drive or replacement gear, never even had one exhibit wear. Only "failure" I have seen in person was a friend over torqued one and cracked the plastic at the mount.
There are enough actual issues to address when modding a car without inventing false ones to try and fix.
On a motor I start modding I put a $1 "white" spring and $7 Melling oilpump driveshaft. I have never seen an oiling failure without those things but for $8(price probably went up) it doesn't hurt. The only time the high pressure spring places extra load on the drive is at short intervals of high rpm so the risk of damage by that extra load is slim. The HV pump is always increased load and we see many clear examples of it being a problem.