Loss of Oil pressure when braking - Chevelle Tech
Troubleshooting Diagnosing problems done here.

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  • 3 Post By lucifershammer
  • 4 Post By lucifershammer
  • 1 Post By Dave Ray
 
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post #1 of 11 (permalink) Old Jun 20th, 19, 10:49 PM Thread Starter
 
Join Date: Jun 2019
Location: Victoria BC Canada
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Loss of Oil pressure when braking

Hi all,
I have a (scratch my head scenario) which I'm hoping someone can help me with.
I have a 69 Chevelle with a 350 cid engine that is rather fresh.
The oil pressure is perfect when idling, driving and in park, but when I am driving down the road and have to come to an aggressive slow down/stop, the oil pressure drops rapidly and even hits zero on the brand new mechanical gauge and the red oil light on the dash comes on.
I have recently replaced the sending unit and the synthetic oil I use is not low.
My engine never used to do this and I haven't changed anything recently.
I'm almost thinking that the oil is rushing to the front of the pan when braking, and starving the pump, but why now all of a sudden?
It's not so bad when I go uphill and brake fast.
Can someone please help?
Cheers,
Ragtop Malibu
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post #2 of 11 (permalink) Old Jun 20th, 19, 10:57 PM
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Steve
 
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Re: Loss of Oil pressure when braking

First thing I would check is if the oil pump pickup fell off.

1972 Chevelle, 454, 2004r, 4.10
1981 Camaro Z28, 355, TH350, 3.73
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post #3 of 11 (permalink) Old Jun 20th, 19, 11:02 PM Thread Starter
 
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Re: Loss of Oil pressure when braking

Thanks Lucifershammer,
I never thought of that, good point, I will.
Unfortunately I have to lift the engine in order to clear the cross member, but oh well, worth the effort if it fixes my problem,
cheers
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post #4 of 11 (permalink) Old Jun 20th, 19, 11:05 PM
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Steve
 
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Re: Loss of Oil pressure when braking

You could give it a colonoscopy first. Use a borescope up the oil drain plug hole and see what you can see.

Quote:
Originally Posted by Brad McDonnell View Post
Thanks Lucifershammer,
I never thought of that, good point, I will.
Unfortunately I have to lift the engine in order to clear the cross member, but oh well, worth the effort if it fixes my problem,
cheers

1972 Chevelle, 454, 2004r, 4.10
1981 Camaro Z28, 355, TH350, 3.73
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post #5 of 11 (permalink) Old Jun 21st, 19, 1:10 AM
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Re: Loss of Oil pressure when braking

https://smile.amazon.com/SHEKAR-Mega...ateway&sr=8-22

You might be able to see it with a flashlight through the oil drain plug. Or fish a wire in there and feel around for loose pieces. I'm almost certain the pickup tube has come loose and is lying in the bottom of the pan.

Maybe you're out of oil? Any chance you have the wrong dipstick tube. You should know by how much oil you put in it at the last oil change. Sorry, have to ask the stoopid questions.
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post #6 of 11 (permalink) Old Jun 21st, 19, 9:34 AM
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Re: Loss of Oil pressure when braking

I bought one years ago on Amazon for less than $10 - https://www.google.com/search?client...nspection+Wire

Original post and link - https://www.chevelles.com/forums/69-...borescope.html


and use the free Webeecam software for use on my Android phone


Forgot to add that the phone needed a usb adapter but plugs directly in to the laptop.

Last edited by Mike; Jun 21st, 19 at 10:04 AM.
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post #7 of 11 (permalink) Old Jun 21st, 19, 1:01 PM
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Re: Loss of Oil pressure when braking

Also, for our engines, there are after-market pickup support brackets. They bolt to the oil pump end cap, and straddle the pickup, not allowing it to fall out. Not expensive compared to an engine, and Summit, Jeg's have them. Of course, these clamp on brackets will not stop a very loose pickup from rotating downward to the pan floor. Chevrolet should have done this from the very start. I build my own,and weld them to the pickup.
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post #8 of 11 (permalink) Old Jun 21st, 19, 10:24 PM Thread Starter
 
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Re: Loss of Oil pressure when braking

Thanks Dave,
any chance you could provide me with the part number on Summit?
I've been looking but can't determine which one.
Thanks in advance,
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post #9 of 11 (permalink) Old Jun 22nd, 19, 9:38 AM
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Re: Loss of Oil pressure when braking

For a stock type pump/pickup combo ,this should work - https://www.summitracing.com/parts/pio-839061/overview/
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post #10 of 11 (permalink) Old Jun 23rd, 19, 6:06 PM Thread Starter
 
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Re: Loss of Oil pressure when braking

Thanks Mike, really appreciate your help,
Brad.
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post #11 of 11 (permalink) Old Jun 23rd, 19, 9:24 PM
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Re: Loss of Oil pressure when braking

Quote:
Originally Posted by lucifershammer View Post
First thing I would check is if the oil pump pickup fell off.
Yep. happened to me on a 1971 Nova I had. Happened while drag racing it. Cross the finish line and hard on the brakes to make the turn off road. Pulled the oil pan and the pick up tube was laying in the bottom of the pan.
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