Can anyone verify my diagnosis?

jmitchell38925

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Apr 13, 2005

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Mar 7, 2008

#1

• Mar 7, 2008

• #1

I recently rebuilt my 1986 302. At some point during the rebuild, the oil pickup tube was bent slightly, not thinking much about it I bolted it on and it seemed to fit ok, creating a good seal to the pump.
Since the rebuild, I've been having problems with oil pressure. Most notably, when the front of the car is pointed uphill. (When pointed downhill, the pressure seems to run fine).
Thinking it may have been a bad pump, I changed it out. It did nothing to fix my problems.
My current best guess is that there is a crack somewhere in my pickup tube, near the front of the engine, perhaps even at the point where the tube connects to the flange that bolts to my pump.
I was wondering if anyone had had symptoms similar to what I'm experiencing, (differences in oil pressure related to the pitch of the car), and what they found to be the problem.

 

Fast63

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Sep 20, 2007

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Mar 7, 2008

#2

• Mar 7, 2008

• #2

angle of the car should have zero effect on your oil pressure. Does the pressure bounce around, or is it constant, just lower? If there is a crack or it is not sealing somewhere, you would be sucking air which is really bad. If you thought you had a problem with the pick up tube, and even went in and replaced the pump, why did you not replace the pick up tube?

 

jmitchell38925

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Apr 13, 2005

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Mar 7, 2008

#3

• Mar 7, 2008

• #3

At the time I changed the pump, it did not occur to me that the tube could have been damaged.
Pitch does most definitely affect the pressure in my case as I have tested it thoroughly. What I'm thinking is that there may be a crack at the front of the tube, so when the nose is downhill, the level of the oil covers the crack, effectively sealing it and allowing normal draw for the pump. When facing uphill however, it would pull that end of the tube out of the oil so that it was drawing air.
I just needed to know if it sounded like a crack in the pickup tube could cause this, before I went through the trouble of removing the oil pan again.

 

Fast63

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Sep 20, 2007

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Mar 7, 2008

#4

• Mar 7, 2008

• #4

well, it's really hard to say whether it is a problem with your pickup or not. Maybe something else is wrong, like the guage freaks out when tilted a certain way. Unlikely, but some weird stuff happens sometimes.

I have another question though, are you only using the stock oil pressure gauge? Because the one in my 85 (same as your 86) runs all over the place all the time because it's a crap gauge, or the instrument cluster regulator piece is crap.

 

M

mercurycapri

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May 30, 2006

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washington

Mar 7, 2008

#5

• Mar 7, 2008

• #5

Fast63 said:

well, it's really hard to say whether it is a problem with your pickup or not. Maybe something else is wrong, like the guage freaks out when tilted a certain way. Unlikely, but some weird stuff happens sometimes.

I have another question though, are you only using the stock oil pressure gauge? Because the one in my 85 (same as your 86) runs all over the place all the time because it's a crap gauge, or the instrument cluster regulator piece is crap.

Click to expand...

My pressure gauge does the same thing I just ignore it and keep driving and never had any problems.

 

jmitchell38925

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Apr 13, 2005

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Mar 7, 2008

#6

• Mar 7, 2008

• #6

Yes, it is stock, but I do have another indicator of low oil pressure when facing downhill. I get a ticking that sounds like a lifter, when the pressure drops. Being hydraulic lifters, it seems that low oil pressure is the culprit. Would that assumption be wrong?
Also, when the oil pressure reads low, I get light smoke.

 

talladam

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Apr 3, 2007

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Monroeville OH

Mar 7, 2008

#7

• Mar 7, 2008

• #7

grab a mechanical gauge, hook it up and then check it out.

 

Fast63

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Sep 20, 2007

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Mar 8, 2008

#8

• Mar 8, 2008

• #8

jmitchell38925 said:

Yes, it is stock, but I do have another indicator of low oil pressure when facing downhill. I get a ticking that sounds like a lifter, when the pressure drops. Being hydraulic lifters, it seems that low oil pressure is the culprit. Would that assumption be wrong?
Also, when the oil pressure reads low, I get light smoke.

Click to expand...

Well, first of all, you shouldn't be getting the problem facing DOWNHILL if it is what you're thinking, you should be getting it UPHILL because all the oil will go to the rear of the pan and away from the pump and where the pickup bolts up to it. Are you sure you really have a problem with the setup? Get an aftermarket gauge to verify because I don't see how what you're describing could be happening.

 

jmitchell38925

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Apr 13, 2005

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Mar 8, 2008

#9

• Mar 8, 2008

• #9

"Since the rebuild, I've been having problems with oil pressure. Most notably, when the front of the car is pointed uphill. (When pointed downhill, the pressure seems to run fine)."

sry, in a later post I did say downhill, but yes, the problem is facing uphill. I have also verified the change in pressure using a manual gauge.

 

Fast63

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Mar 8, 2008

#10

• Mar 8, 2008

• #10

In that case, I wouldn't run the engine anymore and I would inspect the pump and the pick-up tube. Let us know what you find, that is definitely a strange symptom.

 

jmitchell38925

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Apr 13, 2005

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Mar 9, 2008

#11

• Mar 9, 2008

• #11

ok, should have access to a cherry picker sometime in the next couple of weeks, any suggestion as to how I could test the pick-up tube? Under negative pressure, I'm assuming it would pull air even through a crack that was invisible to the naked eye.