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Old 08-25-2011, 08:48 PM   #1
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Oil pressure issues

Hi everyone, I'm new here from the jeep world. I just bought a one owner 85 GT. It has a Jasper 302 engine with right at about 17,000 miles. It is 6 yrs old as well. I was driving to nashville 2 days ago, and when I got off The exit ramp, the rpms went down to about 500 rpms, it was running rough, And the engine was ticking. Sounded like valves or something up top. The oil pressure guage went all The way down to nothing as it started idling.
So I pulled it over immediately. Oil level looked good.

I had it towed to a friends shop that night. I figured it must be either The oil pump or the shaft. So we replaced The oil pump and the shaft from the distributor. Once we finished the job, we fired up the engine and the oil pressure guage went up about half way and it only had a slight ticking from the top of rhe engine. I figured it was good and the ticking will go away. So I drove it about 12 miles, The oil pressure went down to about 1/4 of the way on the guage. I pulled in to the median and it had all of The exact same symptoms as when I got off the exit. (rough idle 500 rpms, ticking worse again, oil pressure guage went down)

I'm baffled at this point. So I let it Cool down a little for about 30 -45 minutes. Fired it up and the oil pressure went back up to about 3/8" on the guage. It idled much better, and the ticking got a little better. So I drove it about 10-15 miles, And The oil pressure never really changed.

It doesn't make sense that the bearings would be bad and cause this since the engine only has 17,000 miles.

Any thoughts or help is appreciated. Also, is there a pressure relief valve somewhere besides The oil pump somewhere that might be messed up to cause this? I've heard some chevy engines have this but not sure about The 302's. Thanks!
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Old 08-25-2011, 09:16 PM   #2
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Re: Oil pressure issues

What does the oil look like, any metal?

It sounds like you spun a cam, main, or rod bearing.
Colder oil is thicker and will result in higher pressures.
Then when it heats up the pressure will drop.

Has the engine ever had forced induction of any type on it?

What is a Jasper 302?
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Old 08-25-2011, 09:32 PM   #3
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No metal in The oil. The pan appears clean. Never had any forced induction at all. Jasper is The company that builds it. They are based out of indiana, And do engines, transmissions, And axles. They generally have a good name. I really hope I didn't spin a bearing. It only has 17,000 miles on The engine. That's why it doesn't make sense that it would happen, but who knows. Oil has always been changed faithfully, but it has sat a lot. 6 years And only 16,500 miles. Less than 3,000 miles per year. :/
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Old 08-25-2011, 11:02 PM   #4
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Re: Oil pressure issues

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Originally Posted by Klinton View Post
No metal in The oil. The pan appears clean. Never had any forced induction at all. Jasper is The company that builds it. They are based out of indiana, And do engines, transmissions, And axles. They generally have a good name. I really hope I didn't spin a bearing. It only has 17,000 miles on The engine. That's why it doesn't make sense that it would happen, but who knows. Oil has always been changed faithfully, but it has sat a lot. 6 years And only 16,500 miles. Less than 3,000 miles per year. :/
During that time sitting the oil has time to drain completely out from under and around the bearings.
If you don't remove the distributor and prime the engine with a drill and primer shaft, then you are starting it up on "dry" bearings.
Unfortunately this can lead to enough bearing damage to cause them to spin.
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Old 08-25-2011, 11:25 PM   #5
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Yeah, that makes sense. The oil pressure never was real high. Always about 1/4 or 3/8 the way up. I really hope Idon't have to tear this engine down...
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Old 08-26-2011, 12:51 AM   #6
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Re: Oil pressure issues

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Yeah, that makes sense. The oil pressure never was real high. Always about 1/4 or 3/8 the way up. I really hope Idon't have to tear this engine down...
Sorry man, but it sure sounds like you will have to.
Best of luck to you though.
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Old 09-11-2011, 02:52 PM   #7
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Ok, so I took the valve covers off yesterday and inspected the rocker arms, and springs and push rods. Everything is CLEAN! so I'm assuming that it is a bearing. So me and a buddy started pulling the engine out to rebuild. Storage I'll know everything is good to go after this... :/
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