Full Size K5 (1969-1991) GMT415 (1992-1994) Tech Discuss any and all full size K5 general tech topics here.

350 low oil pressure

Old 09-27-2015, 10:49 PM
Beginning Member
Thread Starter
Join Date: Sep 2015
Posts: 11
burnhedge is on a distinguished road
Default 350 low oil pressure

1973 Blazer stock 350. My oil pressure is dropping to 3-5 psi at idle after pushing the motor hard. Runs about 40 at cold start and stays about 20 even after engine is warm. Only drops to the danger level after a couple miles of wheeling hard. The truck is strictly off road so I don't really know what the pressure is like during highway driving. Also the top end starts chattering when pressure drops.
I don't really know the history of the engine so I assume it's reaching the end of it's life. I'm just curious if their's any simple things I should be checking before ordering a crate motor.
I've heard a bad distributor can cause a loss in oil pressure but the symptoms I've read about don't seem like mine.
Old 10-02-2015, 06:49 PM
damadtech's Avatar
Beginning Member
Join Date: Dec 2012
Posts: 14
damadtech is on a distinguished road

With that age and not knowing how well it was treated early in life, it can be the oil pump pickup screen blocked up to a worn out pump. The chatter is lack of oil to the lifters which could be from either of the a fore mentioned issues or even oil passages, lifters etc. just full of hardened oil residue from lack of oil changes or cheap oil/filters before you got it. Have you ever taken the valve covers or intake off before and seen inside of it?
Old 10-29-2015, 05:45 PM
Junior Member
Join Date: Jan 2012
Location: Oregon
Posts: 317
70-K5 is on a distinguished road

What I think you're doing is you're pumping all the oil up to the heads and it isnt' draining back to the pan. Your pressure is fine so it isn't the bearings or tollerances, it is lack of oil for the pump to suck up. Maybe look into your fill level or get a deeper pan.
Related Topics
Thread Starter
Last Post
Full Size K5 (1969-1991) GMT415 (1992-1994) Tech
02-02-2013 10:23 AM
Engine & Transmission
09-30-2010 06:58 AM
Engine & Transmission
10-08-2009 08:36 PM
Engine & Transmission
11-09-2008 05:16 PM
Engine & Transmission
03-28-2008 02:30 PM

Thread Tools
Search this Thread
Quick Reply: 350 low oil pressure

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.