LT1/LT4 Tech 1993-1997

Oil pressure / Idle question.

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  #21  
Old 10-18-2013, 04:49 PM
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The motor is not damaging itself. If your pump is working as it should be low oil pressure is a sign of larger then normal clearance in the motor. Low oil pressure is a normal part of an engine wearing out. It can be caused by an event like over heating or over reving but the results are the same. The LT1 is not really known for low oil pressure (unlike the 3.4). If I had to guess on an engine with 29K either your oil pump beginning to fail, the regulator spring broke or your motor has overheated to the point if caused clearances to increase. The later is effectively a worn out motor. A single event like a failed water pump can cause enough overheating to cause internal clearances to be increased. It is very common after a headgasket, water pump even a thermostat failure and repair the customer will come back the next day saying his oil pressure was always 60PSI now it 30PSI.

These are all just opinion:

I do not run my car hard but I like to know that if I want to I can. I would not trust a motor with oil pressure as low as your gage was reading to be pushed hard at high RPM anymore then I would do that to a motor with 150K on the clock, which is why I would be looking for a short block. Of course that is AFTER I verified the oil pressure. I am the same guy that said 90% of the “low oil pressure” complaints end up being gage issues.
 
  #22  
Old 10-18-2013, 06:35 PM
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Appreciate the input, my wife's family owns a body shop, it's there now and they are going to check with a mechanical gauge. It also seems to have a little stutter under steady throttle which they are going to look into. The water pump was replaced in 2010, maybe the previous owner had an issue like you suggest (probably a huge difference between 29k easy miles and 29k hard ones)?

I don't really hot rod around, don't think I've really been over 3k rpm's yet, so if I'm easy on it anyway I imagine if it has low pressure it becomes less of an issue?

My main issue is I have no idea if the engine sounds or feels normal, wife's uncle says it sounds just as a Chevy 350 should....

If there is a shop in the Chicagoland area (preferably south) that I can have check this out I am all ears....I have enough money in so far that a little more isnt going to kill me if I can diagnose an issue and fix it now...I am sure the body shop can do some basic stuff but I mean a shop that deals specifically with cars like this.

Do these tell us anything?
 
Attached Thumbnails Oil pressure / Idle question.-1.jpg   Oil pressure / Idle question.-2.jpg  

Last edited by firstcamaro94; 10-18-2013 at 07:01 PM.
  #23  
Old 10-18-2013, 08:23 PM
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yep, you got a new opti and water pump. wow 200 bucks to change the ignition module, 20 minute job. i dont rod mine either,,, bahaha long as your under 5500 you should be fine,

 

Last edited by craby; 10-18-2013 at 08:26 PM.
  #24  
Old 10-19-2013, 06:46 AM
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I am conservative with this stuff. As a former mechanic I got to see the aftermath and hear the stories an there is almost always a tell, a little hint that that something is going on and then bang failure. I am sure there are a lot of guy out there with low oil pressure that do not have failures. Since I was the one repairing them I only met the guys that had failures.

Just a FYI: On a motor with larger than normal bearing clearances deceleration is the biggest risk. If you are running at a high RPM and you let off the gas quickly with the car in gear two things happen. First, your intake manifold vacuum sky rockets. This means it much harder to the crank to pull the piston down. Then the weight of the car tries to turn the crank so now the whole forward momentum of the car is trying to pull the piston down and there is 25 inchs of vacuum trying to pull it up. This will stress the rod bolts and cause even more clearance and results in a spun bearing.

In short, easy off the throttle or pop it out of gear when you let off after a high RPM run and no down shifting going downhill or pretty much no down shifting on a worn motor. This is even more important for anyone with a stick.
 
  #25  
Old 10-20-2013, 09:38 AM
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Since I don't plan on driving it over the winter I would like to decide ASAP and if it needs work have it done over the winter, where do I take it for a rebuild (if it's needed)?

If the 383 is $10,000 forget that idea, can I get a more standard rebuild with some added power for <$3,000 ? Anyone know reputable shop I can take to (Chicago area)?

I think if I can keep it to a $3k budget to get it fixed and add some power I would probably say heck with it better safe than sorry, is that realistic?
 

Last edited by firstcamaro94; 10-20-2013 at 09:40 AM.
  #26  
Old 10-20-2013, 10:27 AM
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my first lt1 had 20-40 oil pressure for years then it went to 10 at idle at operating temp. i put a new high pressure pump in and pressure went to 25-45. drove it for 50k miles and sold it. was still goin fine. are you sure the gauge cluster is original?
 
  #27  
Old 10-20-2013, 12:40 PM
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Based on carfax report, trust in person I purchased from, and overall interior condition I don't think there have been any shenanigans with the odometer.

The more I read the more I believe that I'm fine, there are literally hundreds of threads on various forums where people ask the same question about the same oil pressure "issue" and I think I am best served to just leave it be even if I confirm gauges are correct. I don't race it, don't run at high rpm's, so I find it very hard to believe that my engine is going to lock up while the oil pressure is within factory spec and perfect according to the owners manual.

I would really like to have a qualified tech look it over and give me their opinion but unless I can find one I don't see the point of messing with it or using thicker oil when everything appears to be operating as it should. I have read dozens of posts by people with the exact same oil pressure as mine....maybe it's not good enough for you guys but it certainly sounds normal.
 

Last edited by firstcamaro94; 10-20-2013 at 12:43 PM.
  #28  
Old 10-20-2013, 05:19 PM
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I asked earlier but didn't see a response. What's the oil pressure when the transmission is in neutral/park?
That's your engine's idle speed, and where you should be concerned with where the oil pressure reading is.
 
  #29  
Old 10-20-2013, 05:29 PM
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Originally Posted by Camaro 69
I asked

earlier but didn't see a response. What's the oil pressure when the transmission is in neutral/park?
That's your engine's idle speed, and where you should be concerned with where the oil pressure reading is.
It does not go up noticeably, MAYBE 1-2 psi.

Why am I reading everywhere that +,- 20 psi @ idle is typical for LT1 if it's abnormal?
 

Last edited by firstcamaro94; 10-20-2013 at 05:47 PM.
  #30  
Old 10-20-2013, 07:08 PM
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Are those who are saying that's normal also have only 29k miles on their engine? At or below 20 is "normal" for an engine that has a bit of miles and wear. There are some exceptions, like with my LT1 with 106k on the clock doesn't go below 30 psi. That's with using 10w40 oil though, which will likely make a positive difference on yours. And I don't run 10w40 in the winter. I'd stop sweating it, and see what you get in the summer with using some higher viscosity oil.
 


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