losing oil pressure under load?
losing oil pressure under load? I need some help trying to diagnose an oil pressure issue i'm having on an lq4. i hooked a mechanical test gauge up to the pressure sensor port. when the car is in neutral it has 25psi at hot idle and builds pressure with rpm as it should. so i decided to leave the gauge hooked up and take a short ride. when the car is under load the pressure doesn't build at all and actually drops slightly under throttle. when i push the clutch in it builds pressure quickly (70psi) but as soon as the clutch is released it drops like a rock (under 20psi at times)
. when i stopped the car and left it in neutral it returned to normal and built pressure with rpm again. anybody have any ideas
. when i stopped the car and left it in neutral it returned to normal and built pressure with rpm again. anybody have any ideas 
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Thrust bearing is moving too much under application of the clutch disk. Before you break down the motor, check the crank endplay. Sorry buddy, I went through this exact same thing. Here's my thread with pics of the damaged thrust.
https://ls1tech.com/forums/racers-lo...ew-engine.html
Be looking for .004-.008 as acceptable. Mine was .040. Thats 5 to 10 times too much depending on if you are using the low or high figure. The only thing that was stopping it from going any further is that the crank was rubbing the block itself internally.
https://ls1tech.com/forums/racers-lo...ew-engine.html
Be looking for .004-.008 as acceptable. Mine was .040. Thats 5 to 10 times too much depending on if you are using the low or high figure. The only thing that was stopping it from going any further is that the crank was rubbing the block itself internally.
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Verdad Gallardo Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Absolutely, just takes about 5 minutes. Get the front of the car on ramps. Pull the main and ac belt off the front of the engine. Get a dial indicator with a magnetic base. Put the base on your sway bar and the dial indicator needle on your crank pulley. With a 1 to 1 1/2 pry bar. Pry behind the crank pulley. Gently as it will go past what you are supposed to be reading. Now when mine was .040 and my crank was trash, you could literally push and pull the crank by hand and it would slide forward, thud, slide back, thud, slide forward, thud. You get the idea. When its .004, you need the indicator to measure it, its very precise. At .040, it rediculously loose.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Teching In
Joined: Jul 2009
Posts: 15
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From: Houston
That is what made me think it could be a oil level issue because it almost sounds like the oil is see- sawing around the pickup so to speak. But I could be wrong but for the OP I would hate to see him go through alot of trouble if it were something simple.
oil level is good. i'm gonna try and check end play in the am
