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Replaced the stock oil pressure gauge a couple years ago. Current (stock) gauge reads about 20-25 psi lower than another gauge we hooked up. The stock gauge reads about zero at idle and then climbs upon acceleration.
I am thinking my gauge could be okay, but perhaps the manner in which I plumbed it could be the issue.
I read in some post (which I can't seem to find right now) about how a smaller insert needs to be installed. Does anyone have any info on this? I have attached a pic of the 90 elbow I used. Is this correct? Finally, I bought a copper plumbing kit ($10) for Accel gauges. Will I be able to plumb this up w/o any small inserts?
Thanks in advance for the help,
AL
Your 90 degree elbow looks identical to the elbow on my '71. One other thing to check is to see if the tube that connects to the back of the oil pressure guage is kinked. That would cause a low reading on your gauge. I also see that there is air in your oil tube. Perhaps you can disconnect the tube from your gauge, put the end of the tube into an empty bottled water bottle (or something similar) and crank your engine to bleed the air out of your tube. This will also show you if the tube is clogged or severly kinked.
You didn't specify if the gauge you installed was new or used. If used, read on: My gauge was completely inoperable when I bought my car. After following the repair procedure from Willcox Corvette, it works properly and the oil pressure matches the reading from an external oil pressure guage that was attached directly to the oil gauge line fitting on the engine. See link http://willcoxcorvette.com/repairand...lp.php?hID=101
Thanks for the reply and the Willcox link. Those guys are so helpful.
When I look at the elbow, I see a narrow passage - is that was is meant by the "insert"?
No kinks in the line, but plenty of air for sure. I will attempt to get all of the air out before reinstalling.
Thanks for the reply and the Willcox link. Those guys are so helpful.
When I look at the elbow, I see a narrow passage - is that was is meant by the "insert"?
No kinks in the line, but plenty of air for sure. I will attempt to get all of the air out before reinstalling.
I had the same problem with my 69. I disconnected the line from the gauge and used a shot of compressed air on the line then reassembled. That did the trick.
I had the same problem with my 69. I disconnected the line from the gauge and used a shot of compressed air on the line then reassembled. That did the trick.
Did you "bleed" the air out of the line when re-assembling?
I have the same issue with my 69. Pressure is fine when cold but after warm at idle it drops very low. I really don't buy it being that low as there is no noise from the lifters and the pressure comes up when you accelerate. I just have not had time to investigate it further. I was thinking of getting an external gauge to attach directly to the sending unit as a first check. Mine has small 1/8" black plastic tubing and I see not kinks but didn't think of blowing it out with air. I did not purge the line when I had it out restoring the interior, but really don't think it should need to be purged since it is just reading pressure and moving a cylinder or anything. I look forward to see what you find, I was about ready to pull the pan to see if the strainer is partially plugged and possibly put in a new pump just for safety.
Did you "bleed" the air out of the line when re-assembling?
No. Just cleared the line. I bought a new gauge and line but figured I would try blowing out the line first. It worked. I now have 30 psi at idle and it was zero before. That was over a year ago and no problems since. I think since there is no real flow through the line, just pressure, they tend to get clogged after all those years.
No. Just cleared the line. I bought a new gauge and line but figured I would try blowing out the line first. It worked. I now have 30 psi at idle and it was zero before. That was over a year ago and no problems since. I think since there is no real flow through the line, just pressure, they tend to get clogged after all those years.
Just wanted to confirm, I didn't think the oil pressure line would need to be purged.
No need to bleed air out of the oil pressure line. Pressure is pressure, whether it's oil or air. Won't make any difference.
If you have no kinks or blockages in the line, your plumbing work is fine. Elbows or bends in the line won't cause your problem. I suspect that it's just a problem with the gauge. Bourdon tube gauges have very little to go wrong...only the gear mechanism which transfers movement from the [Bourdon] tube to the gauge dial could be in question. So, I suspect that there is some binding in that gear set. The only way to really know is to plumb another (hopefully, more accurate) gauge into the line so that you can compare readings. If you do have a mechanical gauge problem, that is obviously a manufacturing issue and the seller should offer you a replacement...regardless of how long you've had the gauge.
12-29-2014, 03:12 PM
low oil pressure on gauge only
