low oil pressure - Team Camaro Tech
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post #1 of 12 (permalink) Old Jul 27th, 14, 03:08 PM Thread Starter
lentel
 
Join Date: Jul 2014
Location: burbank
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low oil pressure

I just added new heads, new cam, new cam bearings, new rod bearings, new main bearings and a rehoned crank to my 350 engine . Now there is very low almost zero oil pressure at idle and about 10 or so at higher rmp. I double checked with a manual gague.

what could be the problem there?
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post #2 of 12 (permalink) Old Jul 27th, 14, 03:25 PM
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Scott
 
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Re: low oil pressure

Improper (too loose) bearing clearances with one or more of the bearings allowing the oil to get around the bearing and journal thus lowering pressure to the rest of the engine.

Did you replace the oil pump or install the original oil pump?

A bad pump could also cause incorrect oil pressure.

69 Camaro Z/28 RS, original Azure Turquoise, M21 & 3.73 12-bolt posi. NOM 406ci, AFR 210 heads, Straub hyd. roller cam & Dynatech 1-3/4" > 1-7/8" headers, QuickFuel 750 Annular. Photos at:
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post #3 of 12 (permalink) Old Jul 27th, 14, 03:28 PM
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Rich
 
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Re: low oil pressure

Did you check the clearance between the oil pump pickup and the oil pan when you put the pan on? If it is hitting the pan, you might not be able to pull oil into the pump.

69 Z/28 RS clone. Azure Turquoise. First car--owned for 32 years and counting.
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post #4 of 12 (permalink) Old Jul 27th, 14, 03:52 PM
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Mark
 
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Re: low oil pressure

Wrong lifters will do this too. I spoke with a guy at a Cruise last Thurs that built a Roller 3.8 motor in his 87 T-Type Turbo and the recommended lifters from Comp in the book were the wrong ones for the cam he bought.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #5 of 12 (permalink) Old Jul 27th, 14, 04:13 PM
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B
 
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Re: low oil pressure

And the simplest cause no one has mentioned is too much oil.

That happened on a roadkill the I just watched a few days ago.

Formers: 1969 RS 350, 700HP 1967 Flash-in-a-pan Firebird 400, 2002 Z28 M6 1SC/1SZ
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post #6 of 12 (permalink) Old Jul 27th, 14, 11:14 PM Thread Starter
lentel
 
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Re: low oil pressure

re installed same oil pump and all oil pressure was good previous. The clearance from pan to oil pump pick up is same as it was, with same pan and pump.. Oil shows at correct level on dip stick
I am having a feeling the rod and main bearings the machine shop sold me are incorrect size for the crank they also sold me
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post #7 of 12 (permalink) Old Jul 27th, 14, 11:20 PM Thread Starter
lentel
 
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Re: low oil pressure

I bought a comp cam and lifters in a set, so I am assuming the lifters were correct
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post #8 of 12 (permalink) Old Jul 28th, 14, 05:27 AM
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Scott
 
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Re: low oil pressure

Quote:
Originally Posted by lentel View Post
re installed same oil pump and all oil pressure was good previous. The clearance from pan to oil pump pick up is same as it was, with same pan and pump.. Oil shows at correct level on dip stick
I am having a feeling the rod and main bearings the machine shop sold me are incorrect size for the crank they also sold me
Did you check the connecting rod and crankshaft bearing clearances during reassembly with plastigage?

If not, you'll need to drop the oil pan to do so at this point to eliminate that as a possibility.

69 Camaro Z/28 RS, original Azure Turquoise, M21 & 3.73 12-bolt posi. NOM 406ci, AFR 210 heads, Straub hyd. roller cam & Dynatech 1-3/4" > 1-7/8" headers, QuickFuel 750 Annular. Photos at:
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post #9 of 12 (permalink) Old Jul 28th, 14, 10:37 AM
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Sean
 
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Re: low oil pressure

Quote:
Originally Posted by NH69Z28RS View Post
Did you check the connecting rod and crankshaft bearing clearances during reassembly with plastigage?

If not, you'll need to drop the oil pan to do so at this point to eliminate that as a possibility.
Checking with Plastigage could also be the issue, especially on the rods. I checked my 383 with plastigage and after hearing a few things about it, decided to ease my mind by having the machine shop re-check with inside mics, etc. Good thing, as the plastigage was indicating that I was way tight (especially on the rods) when in actuality I was about .0024 across the board. Had I loosened up the bearings the way the plastigage was indicating, I would have been way loose and probably in a similar oil pressure situation.

1969 Z28 Clone/383 SBC/Holley #4779 750DP w/HP center section/Tremec TKO600/Dutchman 9"/Pypes 3" race pro/Doug's D368/ 17x8, 17x9 VWW/Nitto 555
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post #10 of 12 (permalink) Old Jul 28th, 14, 10:50 AM
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Mark
 
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Re: low oil pressure

Quote:
Originally Posted by lentel View Post
I bought a comp cam and lifters in a set, so I am assuming the lifters were correct
Don't assume as I mentioned above.

Mark 70 Z28 M22 3.73 Z21 Z87 - Lunati 20120121 Roller Cam

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post #11 of 12 (permalink) Old Jul 28th, 14, 08:48 PM
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Scott
 
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Re: low oil pressure

Did you "Hot Tank" the block? Were the galley plugs replaced?

68 302 M20 - 85 IROC Z
The older I get the faster I was.
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post #12 of 12 (permalink) Old Jul 29th, 14, 04:54 AM
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David
 
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Re: low oil pressure

I would start with the oil pump and go from there.
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