LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Drop in oil pressure upon braking

Old 08-05-2009, 09:46 AM
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Default Drop in oil pressure upon braking

Pretty self explanatory, but when I get on the brakes hard, my oil pressure goes down to zero, then the check guages come on, then when im done braking and the nose of the car comes up, it goes back up to normal. Any ideas? We tack welded the pickup tube by the way.
Old 08-05-2009, 09:51 AM
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i know you welded the pickup tube, but thats exactly what it sounds like. or your severly low on oil.
Old 08-05-2009, 09:53 AM
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Originally Posted by bww3588
i know you welded the pickup tube, but thats exactly what it sounds like. or your severly low on oil.
Just changed the oil yesterday with 5 quarts of syn 5w 30..
Old 08-05-2009, 10:30 AM
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The welds must have broken, because thats what caused my car to do exactly what your describing. The pickup was just sitting in my pan.
Old 08-05-2009, 10:36 AM
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Originally Posted by bufmatmuslepants
The welds must have broken, because thats what caused my car to do exactly what your describing. The pickup was just sitting in my pan.
Does that mean Im really losing oil pressure or is it just showing it on the guage? It did the same thing for you, with braking and all?
Old 08-05-2009, 10:55 AM
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My pickup on my last motor fell off into the pan and my gauge did the same thing. I just tried to keep it full, something I didnt try was putting more oil in the pan...like another quart.

When I took the motor apart, the only damage was a pitted cam, everything else looked fine.
Old 08-05-2009, 11:11 AM
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Originally Posted by Stroked96Bowtie
My pickup on my last motor fell off into the pan and my gauge did the same thing. I just tried to keep it full, something I didnt try was putting more oil in the pan...like another quart.

When I took the motor apart, the only damage was a pitted cam, everything else looked fine.
I am worried about damage to the motor. Did you run the car like that with the pickup in the pan for a while? Its only dropped down to zero a couple of times, for a second or two each time. Do you think I have to worry about damage to parts?
Old 08-05-2009, 11:44 AM
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Originally Posted by My2kz28
I am worried about damage to the motor. Did you run the car like that with the pickup in the pan for a while? Its only dropped down to zero a couple of times, for a second or two each time. Do you think I have to worry about damage to parts?
To be honest..I ran it for about a year that way. Id use 20-50w wieght oil, little thicker oil might help, what I always ran in that motor. Maybe try putting another half quart in it on top of the 5 just to see if it helps. Seemed to always act right as long as it was full on oil.

Dont think you have to worry about any serious damage, or at least I had very minimum amount. I ran that setup at the track and on nitrous too..no severe issues.
Old 08-05-2009, 12:17 PM
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From what ive been told by a very knowledgable person is that if the oil pressure did drop to 0, that the hydraulic lifters would make a ton of noise. There is no loud clicking from anywhere, so is there a possibility that the problem is the guage? I will hook up a oil pressure guage to the block and see what it says.
Old 08-05-2009, 12:27 PM
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Originally Posted by My2kz28
From what ive been told by a very knowledgable person is that if the oil pressure did drop to 0, that the hydraulic lifters would make a ton of noise. There is no loud clicking from anywhere, so is there a possibility that the problem is the guage? I will hook up a oil pressure guage to the block and see what it says.
Good thinking...could possibly be the gauge.
Old 08-05-2009, 12:28 PM
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Did your engine make a ton of noise when the OP was low?
Old 08-05-2009, 12:28 PM
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If it was the guage your oil pressure would read funny all the time. Bein that this is occuring when you are on the brakes, most likely the pick up fell into the bottom of the pan. Whoever told you if the oil pressure did drop to 0 the lifters would make a ton of noise is right. most likely your pressure is droping off severely, but not all the way to 0. The oil pressure guages from the factory are not the most accurate, kind of like the rpm/tack. If the engine is not makin a **** ton of noise, you still are getting oil to all the parts in the engine. Maybe try sticking a heavy magnet on the pan and move it around to see if the pickup is actually in the bottom of the pan now?
Old 08-05-2009, 12:32 PM
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Originally Posted by kinglt-1
If it was the guage your oil pressure would read funny all the time. Bein that this is occuring when you are on the brakes, most likely the pick up fell into the bottom of the pan. Whoever told you if the oil pressure did drop to 0 the lifters would make a ton of noise is right. most likely your pressure is droping off severely, but not all the way to 0. The oil pressure guages from the factory are not the most accurate, kind of like the rpm/tack. If the engine is not makin a **** ton of noise, you still are getting oil to all the parts in the engine. Maybe try sticking a heavy magnet on the pan and move it around to see if the pickup is actually in the bottom of the pan now?
Good call..when i drive around town normal the OP stays pretty steady, increases/decreases with rpm as it should, but i did get on the gas hard in 3rd and saw the needle bounce around a tad. It happens everytime i brake hard, so im thinking the pickup tube might have come loose. From what i understand there is a port behind the oil filter where a mechanical guage can be installed. Is it pretty easy to find and screw in?
Old 08-05-2009, 01:00 PM
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http://shbox.com/1/aux_oil_port.jpg

Get the mechanical gauge on there. If it is loosing pressure, fix it! Any time spent at low oil pressure is asking for it...
Old 08-05-2009, 01:03 PM
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Originally Posted by My2kz28
Good call..when i drive around town normal the OP stays pretty steady, increases/decreases with rpm as it should, but i did get on the gas hard in 3rd and saw the needle bounce around a tad. It happens everytime i brake hard, so im thinking the pickup tube might have come loose. From what i understand there is a port behind the oil filter where a mechanical guage can be installed. Is it pretty easy to find and screw in?
If you are 96 just install it in the stock location thats what i did. right behind the intake manifold. Pretty easy to install I used a autometer gauge.
Old 08-05-2009, 01:06 PM
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Originally Posted by derekderek
If you are 96 just install it in the stock location thats what i did. right behind the intake manifold. Pretty easy to install I used a autometer gauge.
He's asking where to temporarily hook up the mechanical gauge.
Old 08-05-2009, 02:13 PM
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Originally Posted by ss.slp.ls1
http://shbox.com/1/aux_oil_port.jpg

Get the mechanical gauge on there. If it is loosing pressure, fix it! Any time spent at low oil pressure is asking for it...
Thanks for the link! I am not driving the car until i get the mechanical guage on there. It can be driven, just got to brake real slow to keep the nose dive from happening.
Old 08-05-2009, 09:32 PM
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Originally Posted by My2kz28
Does that mean Im really losing oil pressure or is it just showing it on the guage? It did the same thing for you, with braking and all?
Yea dude, your guage is right at no oil pressure. Thats why Im on my second engine right now. I made it 2 years and 30k of all highway driving, blipping the throttle at every stop sign to bring the oil pressure back up. Ended up with a "knock knock knock knock knock knock". Fix it sooner than later.
Old 08-05-2009, 09:42 PM
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My pickup tube fell off my old car and did the same thing. We installed a new pump and welded the pickup on, it held for about 6 months and fell off again.
Old 08-06-2009, 01:01 AM
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My car will have the stock gauge drop real low and on a rare occation the check gauges light will come on but i also have a mech gauge installed and that has never dropped below 20psi even when my idle was set at like 500 and you would let off the gas and the rpm would drop real low. I would say mine is more from a low low drop in RPM as opposed to the slowing down though....

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