Do oil pressure gauges go out on 1968 corvettes very often(no oil pressure)
03-26-2012, 09:28 AM
#1
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Do oil pressure gauges go out on 1968 corvettes very often(no oil pressure)
Ok Just got my 68 corvette running yesterday.The previous owner let it sit 12 years. It sounds amazing and runs great but it has no oil pressure reading. I replaced the line from the engine to the gauge and still nothing. I know its getting oil though because I can see it coming out all over the rocker arms and if you look at the new oil pressure line I see oil then an air pocket then oil then an air pocket,etc. Do I need to bleed that line or do you think the gauge is bad or could it be something more serious. I bought a new set of gauges for my 69 Nova so I was going to try hooking a new one to it to see if I get oil pressure on the new gauge. Is there a better way to check it rather then look at the rocker arms. I dont want to sieze it up it only has 64,000 miles on it. Thankyou....Dave
03-26-2012, 09:47 AM
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Thanks Mike I'll try disassembling the gauge befor I try the new gauge.When I put in the new line I used a new fitting so nothing is clogged.I did notice the little donut that crimps around the line at the gauge end crimped alittle more then the other end but I could still see a hole through it. I figure if there is a hole it should still put pressure to the gauge.Thanks.....Dave
03-26-2012, 10:42 AM
#6
Race Director
The early mechanical gauges are very simple and rarely fail. What happens (like previously posted) is that dirt gets into the gauge and makes it stick. Take it apart and clean it out real good with WD40 and it will most likely work fine.
03-26-2012, 12:24 PM
#9
03-26-2012, 09:47 PM
#10
Le Mans Master
Willcox Repair and Installation Help - Corvette Oil Gauge Repair - Cleaning 63-73
http://willcoxcorvette.com/instructi...repair_new.pdf
This is the one thing I've found more often than not to cause problems with the direct pressure gauges in old cars and the best method (from above) to address it...
To clean the inside of the tube you can take the red spray extension and some aerosol brake dry. Insert it in to the spray nozzle on the can and then insert it in to the opening where the oil pressure line nut screws in. Be sure to be outside and have the back of the gauge pointing down toward the ground. When you hit the nozzle button it will inject the brake dry (cleaner) in to the tube. When it runs out it will look almost black! Do this several times and the solution will start to run clean. When the inside of the tube is clean the solution will run out clear.
Good luck... GUSTO
http://willcoxcorvette.com/instructi...repair_new.pdf
This is the one thing I've found more often than not to cause problems with the direct pressure gauges in old cars and the best method (from above) to address it...
To clean the inside of the tube you can take the red spray extension and some aerosol brake dry. Insert it in to the spray nozzle on the can and then insert it in to the opening where the oil pressure line nut screws in. Be sure to be outside and have the back of the gauge pointing down toward the ground. When you hit the nozzle button it will inject the brake dry (cleaner) in to the tube. When it runs out it will look almost black! Do this several times and the solution will start to run clean. When the inside of the tube is clean the solution will run out clear.
Good luck... GUSTO
03-27-2012, 12:07 AM
#11
Team Owner
The mechanical oil psi gauge is a Bourdon tube type mechanism. As oil pressure increases, the metal tube inside the gauge wants to 'straighten out' more. That movement is translated to needle movement.
So, either the Bourdon tube is plugged up so that it never 'sees' the oil pressure...or, the gear mechanism which translates movement to the needle is gummed/locked up.
Either situation can be repaired fairly simply. The first thing to try is to shoot some volatile cleaner into the gage pressure fitting and see if that causes it to free-up. Once removed from the car, you can use air pressure (from compressor or pressure bottle) to test the movement of the mechanism. A Bourdon tube movement doesn't care what the pressurized medium is. Keep exercising the gauge with solvent/PB Blaster, whatever, and air pressure until it loosens up or you decide that is NOT the problem.
Then, you can dig into the mechanism to see if it is corroded/frozen or mechanically bound up.
So, either the Bourdon tube is plugged up so that it never 'sees' the oil pressure...or, the gear mechanism which translates movement to the needle is gummed/locked up.
Either situation can be repaired fairly simply. The first thing to try is to shoot some volatile cleaner into the gage pressure fitting and see if that causes it to free-up. Once removed from the car, you can use air pressure (from compressor or pressure bottle) to test the movement of the mechanism. A Bourdon tube movement doesn't care what the pressurized medium is. Keep exercising the gauge with solvent/PB Blaster, whatever, and air pressure until it loosens up or you decide that is NOT the problem.
Then, you can dig into the mechanism to see if it is corroded/frozen or mechanically bound up.
03-27-2012, 09:42 AM
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Well guys I pulled the gauge out last night and it was definatly stuck. I shot WD40 into the hole and on the gears and gently worked it for 5-10 minutes until it was all freed up moves very nice now. I then shot it with WD40 again and let it soak on my workbench last night. I'll flush it out real good after work today give it a couple drops of oil and reinstall it and see what I got. Hopefully it will show a reading,I'm pretty confident it will 
thanks again.....Dave
thanks again.....Dave
03-27-2012, 11:22 AM
#14
Race Director
Cool. But I do not recommend you put any oil on the gears. It will just attract dirt & dust and crud up on you again. A little WD40 and blow it off gently is all you need.
03-29-2012, 08:26 PM
#17
Le Mans Master
Clean it up just a little and thump the tube with your finger. Usually wakes em right up. As long as you use it and there is not too much moisture in the car, it will work forever.
