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05-19-2014, 04:07 PM
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#1 |
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Registered User
Join Date: Feb 2009
Location: lucas, texas
Posts: 7
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402 Oil Pumps
Is there something I need to know about 402 oil pumps. We bought a 72 GMC with a 402 for my brother in law and drove it from Dallas to Niagara Falls. Everytime we made a right turn, the oil pressure went to zero for a few seconds.
I have a 72 Cheyenne Super with a 402, and I have recently developed the same problem. What's up, and is the problem characteristic of the 402? |
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05-19-2014, 04:35 PM
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#2 |
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Registered User
Join Date: Jan 2011
Location: Chattanooga, TN
Posts: 2,171
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Re: 402 Oil Pumps
Sounds like an issue with the pickup tube and/or low oil level. Should not be anything unique to 402 that is not seen on 366, 396, 427, 454, 502.....Big Blocks.
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'83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project |
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05-19-2014, 07:47 PM
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#3 |
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: 402 Oil Pumps
Welcome to the 67-72 Chevy Truck Board from West Michigan!
As mentioned there is not a flaw in the 402 that would cause this problem. In addition to the pickup screen possibly falling off, the oil pump hold down bolt could come loose. I would plan on pulling the pan to see what is going on. The pick up screen should be welded on or you can use one of the new style clamps to insure that the screen does not come off if that turns out to be the issue. Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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05-19-2014, 07:58 PM
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#4 |
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Registered User
Join Date: Oct 2008
Location: Marianna Arkansas
Posts: 7,280
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Re: 402 Oil Pumps
A lot of people tack weld the pick up tubes in place on the oil pumps to stop that very thing from happening. It is not a 402 thing it is a Small block, Big block 90 degree V-6 Chevy thing.
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05-22-2014, 01:59 PM
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#5 |
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Registered User
Join Date: Feb 2009
Location: lucas, texas
Posts: 7
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Re: 402 Oil Pumps
Thank you guys.
I heard that 402's had something going on pertaining to this problem. It's so weird that none of my many previous non-402 Chevy engines have ever had a problem, but the only 2 402's I've had have had the exact same issue. I'm going to take the pan off this weekend and get it taken care of. Thanks again. |
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05-22-2014, 05:02 PM
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#6 |
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Registered User
Join Date: Sep 2011
Location: Ark City, Kansas
Posts: 3,420
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Re: 402 Oil Pumps
It's just a coincidence that the two engines are doing the same thing...
The screen/tube has gotten loose or been replaced and not re-installed properly. All the unbelieveable vibrations and gyrations going on in the oil pan, anything is possible IF, and screen assy was NOT welded to the pump upon installation. The screen head should be 3/8" off the bottom of the pan, period!!! welded to the pump!!! Don't use loctite or JB weld, weld it... |
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