Engine oil pump problem - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 07-04-2010, 01:24 PM
Soy Soy is offline
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2002 Chevy TrailBlazer LT
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Engine oil pump problem

Hi, My chevy trailblazer 2002 4.2l, after running about 30 minitues, when idle condition oil pump comes to zero. On acceleration it goes back to normal position. I changed oil 5W 30, fiilter. What could be the reason? Please help..
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  #2  
Old 07-04-2010, 01:32 PM
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the roadie the roadie is offline
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Most likely a bad oil pressure switch. In the I6 engine, the dashboard gauge is a lie. The computer creates a number of what it thinks the oil pressure should be, based on temperature and RPM. And then it displays that lie on the instrument panel.

But all it really knows is from a switch that goes on and off at 12 PSI. Switches fail more often than oil pumps.

Pull the switch and get a true oil pressure meter installed into that hole, and make sure the pump is OK. If it is, then just replace the switch. If you don't have the tools to do this, then you really need a mechanic to test the oil pressure. In case the oil pump *is* at fault, you want to know now, before it has a chance to fail on the road and damage the rest of the engine.
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  #3  
Old 07-04-2010, 03:32 PM
Wex Wex is offline
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This is a scan of a page out of the 02-07 Haynes trailblazer repair manual. Every time I see these oil pressure threads, I am amazed at the low pressures they can operate.

6 psi? Is that real or a typo?
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  #4  
Old 07-10-2010, 12:19 AM
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02trailelecprob 02trailelecprob is offline
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sweet i need to repair my truck as well i will pick a switch up this weekend
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  #5  
Old 07-15-2010, 04:14 PM
brians02tblazer brians02tblazer is offline
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oil pressure

having similar problem but only when towing trailer have replaced sender no help.am towing the trailer this weekend with trans cooler newly installed. have learned that oil sender is metric 16x1.5 thread and Pace Performance sells an adapter to 1/8 thread #ATM2268 did not order yet but that seems to be the only way to adapt to an extra gauge. What do you then do with sender wires??does computer need a reading to allow normal ops??
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Old 09-01-2010, 04:40 AM
jakelock jakelock is offline
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I'm glad I found this site! Great wealth of knowledge, I've recently been experiencing this same problem with my 02 Trailblazer. I was prepared to pull the oil pump and replace it until I read this thread. I'll try the sensor, TB clean and spark plugs and hope that clears it up! Thanks again all.
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  #7  
Old 09-01-2010, 09:58 AM
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Super 88 Super 88 is offline
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Quote:
Originally Posted by Wex View Post
This is a scan of a page out of the 02-07 Haynes trailblazer repair manual. Every time I see these oil pressure threads, I am amazed at the low pressures they can operate.

6 psi? Is that real or a typo?
I saw that too in my manual. Note that isn't even at idle that is at 1000 RPM! Weird. I'm not real familiar with modern GM V8's but I'd agree that seems awfully low. Maybe it should have been 16?
Perhaps someone with a GM service manual can comment.
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  #8  
Old 10-27-2010, 02:08 AM
jakelock jakelock is offline
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Sensor seems to have done the trick! Thanks!
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  #9  
Old 04-24-2013, 09:54 PM
odieoner odieoner is offline
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oil pressure

Im new to this forum thing so can somebody please help? When my thermast reaches halfway my oil pressure dips down to 0 then goes back up to the halfway mark. An it does this back an forth until I turn the car off.
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  #10  
Old 10-08-2013, 07:07 PM
lockhartboy407 lockhartboy407 is offline
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my trail blazer is doing the same boucing from almost 0 to 40 back and forth with no noise and when i idle my engine it stays norm but im planing on changing the oil pump just to be safe....... and i already changed the oil pressure switch and no difference but any body got any suggestions before i tare into this
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