454 Chevy/Sudden Oil Pressure Drop

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  #1  
Old 07-29-16, 01:27 PM
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Question 454 Chevy/Sudden Oil Pressure Drop

Traveling on interstate, noticed engine temperature gauge creeping up. Checked oil pressure gauge which was slowly falling/normally the oil pressure has always pegged out @ 60psi while driving. Stopped the vehicle and oil pressure had fallen to 30psi. Waited two hours for engine to cool and restarted. Oil pressure would not go above 30psi even at high RPM, called a tow truck.

I installed new oil filter and new thermostat, but oil pressure still only max of [email protected] RPM. Any suggestion to diagnose problem is appreciated. A friend suggested to drain oil and replace with 5w30 plus one quart of transmission fluid and run engine twenty minutes to "clean" oil pump screen.

Any suggestion on my next step?

Thanks,

rebel
 
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  #2  
Old 07-29-16, 01:35 PM
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You checked the obvious - oil level, correct?
How many miles on the engine? how hot did it get?
 
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Old 07-29-16, 03:13 PM
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Replace oil pump!

The oil pump pressure relief valve is sticking and not closing enough to raise oil pressure.

Check for spun main bearing. A common problem with 454 engine.

Good luck!
RR
 
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Old 07-29-16, 04:00 PM
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I looked at a video to replace the oil pump which might be above my mechanical skill. Do you think the suggestion of light weight oil and transmission fluid has any merit?

Thanks for the input,

rebel
 
  #5  
Old 07-29-16, 04:03 PM
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Oil level ok, 125,000, temp 'bout 200 but not enough to overflow the reservoir.

Thanks for the reply.

rebel
 
  #6  
Old 07-29-16, 04:38 PM
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Not guessing on reply. Many years of shop experience supporting the suggestions.

Sudden oil pressure loss is a problem. Check with manual gauge to verify pressures. (your electric gauge could have malfunctioned) That would be the very first thing I would do before anything else.

If the job is beyond your skill-set, then by all means engage a trusted professional to remove oil pan and check for just what happened.


RR
 
  #7  
Old 07-29-16, 05:59 PM
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could just be a defective sending unit or gauge having it pegged out at 60 psi while driving isn't normal anyway for a warmed up engine you would typically only see pressures that high on a cold engine, you do need to check oil pressure with a manual gauge.
 
  #8  
Old 07-30-16, 04:00 AM
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About a year after I bought my 1976 ford truck the oil pressure dropped real low and I was all set to replace the oil pump when I noticed that the low oil pressure at the gauge was the same with the engine not running. All I needed was a new sending unit That was a dozen or more years ago. As the others said - check with a manual gauge to verify!
 
  #9  
Old 07-30-16, 05:43 PM
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Guys:

Thanks for the suggestions. First heck will be the oil pressure sending unit and a confirmation with a manual gauge. I have owed this truck since new, however, and the oil pressure always pegged out at the 60psi. Since the motor got hot as well in conjunction with the oil pressure drop seems like the rise in temperature points to low oil pressure. So first I will flush the cooling system, check the oil pressure sender, and then do a manual check.

Thanks! You guys are great.

Its all fun.

rebel
 
  #10  
Old 07-30-16, 05:55 PM
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GUYS:

Thanks for the input. I have owned this truck since new and the oil psi always pegged on the 60 psi. Since the engine got hot and the oil pressure dropped I will flush the cooling system, check oil pressure with manual gauge, and check the sending unit.

You guys are great.

Its all fun.

Rebel
 
  #11  
Old 07-30-16, 05:59 PM
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I have owned this truck since new and the oil pressure always pegged on the max 60psi. Since the engine got hot in conjunction with the oil pressure drop I will: flush the cooling system, check oil pressure with manual gauge, and check the sending unit.

You guys are great!

Its all fun.

Rebel
 
  #12  
Old 08-16-16, 01:57 PM
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Right advice!!

Guys:

Thanks for the "fix it" suggestions. Its been awhile 'cause I went sailing.
I hooked up a oil pressure tester, started the 454 and the pressure held steady at over 65PSI. Today I ordered a new oil pressure sender/switch and will install tomorrow. Then a road test to ensure pressure holds steady up to eighty MPH.

Thanks again.

Its all fun.

Rebel
 
  #13  
Old 08-16-16, 01:59 PM
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I would install a T fitting so you can have both gauges.
 
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Old 08-16-16, 02:05 PM
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pugsl

Funny you should mention the T fitting, 'cause I had the same thought. Great minds run together.

Thanks,

rebel
 
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