Topic: Oil Gauge problem in recently completed restoration :( . . . . sigh

[BillEBobb]

• Rebuilt 302 engine has @ 1,000 miles
> Oil Pressure gauge needle doesn't rise above the "L"!
>>• Grounded oil pressure "L" wire with jumper to ground
>>>• Then turned ignition switch to "On" position >> gauge needle moved all the way to the "H" side of gauge.
>>>>• Replaced Oil Pressure Switch (ie, sending unit) with new part.>>No good, still exactly the same readings! 

My thought is that it's the IVR (instrument voltage regulator). I come to this conclusion because the engine temp needle also reads on the "C" when the engine is at operating temp.

Two mechanic friends disagree with me because when the oil switch was grounded that this sent the signal through that IVR, hence it must be okay.

In '69 there is an adjustment screw on the back of the IVR and I feel that in a case like this that that's when that adjuster is put to use.

Thoughts, opinions, feedback??

Thanx, Bill
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[cobrajetchris]

I would have to agree with your mechanic that it's not IVR because if it was the problem the gas and temp gauge would also read low. When you ground the sending unit does the gauge move smoothly over to high or does it stop and start as it moves? If it does not move smoothly over to high I would suspect the gauge is faulty. If the gauge is working OK than I would install a pressure gauge in place of the sending unit to get an actual reading to see what your oil pressure really is.

[midlife]

I agree with Chris.  Is it possible that the oil pressure switch is for an idiot light version?

Yes, it is possible to increase the voltage on the IVR's.  On the back is typically a small screw or potentiometer, often embedded in epoxy.  Break the epoxy and turn the screw in or out.  I set my gauges such that when I know I have a 1/4 gas tank, the gauge reads exactly 1/4 full.

[7Lscjracer]

Since your temp gauge is not working either, I'm wondering if you need a new engine gauge feed harness.
Can't go wrong with this brand:
http://www.championmustang.com/6970-mustang-engine-gauge-feed-harness-302-351w-wo-acbrfont-colordc143cballoy-metals-brand-concours-versionbfont-p-10132.html
Bought 66 version recently and solved my gauge trouble.

[BillEBobb]

I would have to agree with your mechanic that it's not IVR because if it was the problem the gas and temp gauge would also read low. When you ground the sending unit does the gauge move smoothly over to high or does it stop and start as it moves? If it does not move smoothly over to high I would suspect the gauge is faulty. If the gauge is working OK than I would install a pressure gauge in place of the sending unit to get an actual reading to see what your oil pressure really is.
Yes, I agree that the other gauges would be affected in addition -- they are.  The temp gauge shows engine temp (at operating temp range) to be "ON" the lowest bar of the temp range.

Gas gauge is "squirly." It reads "F" for seemingly TOO long a period then drops like a stone.

I agree with Chris.  Is it possible that the oil pressure switch is for an idiot light version?

Yes, it is possible to increase the voltage on the IVR's.  On the back is typically a small screw or potentiometer, often embedded in epoxy.  Break the epoxy and turn the screw in or out.  I set my gauges such that when I know I have a 1/4 gas tank, the gauge reads exactly 1/4 full.

No, the oil pressure switch is not for an idiot light version.

Since your temp gauge is not working either, I'm wondering if you need a new engine gauge feed harness.
Can't go wrong with this brand:
http://www.championmustang.com/6970-mustang-engine-gauge-feed-harness-302-351w-wo-acbrfont-colordc143cballoy-metals-brand-concours-versionbfont-p-10132.html
Bought 66 version recently and solved my gauge trouble.

I replaced the old harness with a new one when I restored the car.

[7Lscjracer]

Is the flimsy printed circuit sheet on the back of the cluster in good shape?
Especially where the harness plugs in?

[BillEBobb]

Is the flimsy printed circuit sheet on the back of the cluster in good shape?
Especially where the harness plugs in?

Perfect condition!

[Brian Conway]

     May not be of any help but I suggest you read the post.  A fella on the CJ Registry site had a similar problem a short while back.  His topic ' Low Oil Pressure '  was discussed and he removed the oil pan to discover a layer of thick assembly lube which could have been clogging the oil pump pick up.  While there he cleaned that all out and replaced the oil pump.  Said that solved his problem.   Brian

[BillEBobb]

     May not be of any help but I suggest you read the post.  A fella on the CJ Registry site had a similar problem a short while back.  His topic ' Low Oil Pressure '  was discussed and he removed the oil pan to discover a layer of thick assembly lube which could have been clogging the oil pump pick up.  While there he cleaned that all out and replaced the oil pump.  Said that solved his problem.   Brian

Thanks Brian.  Although I searched for the topic you mentioned it did not come up. The machine shop that rebuilt the engine for me did not paint it the "correct" blue so I went back in and re-sprayed it as well as taking off the oil pan to re-paint.  I made an observation of the pump/screen at that time and everything was brand new looking.