No oil pressure, 2000 duallie truck?
 

We have a 2000 Chevrolet CK3500 duallie, 454 gas engine. The oil shows as full, but no oil pressure. SOmetimes it shows low, when warmed up, and in gear at idle. Once the revs come up, it picks back up to 40 psi. Now, today, no oil pressure at all, no matter what. In a somewhat related note, the fuel guage is also incorrect, as the gas tank will be full, yet will show as empty (sometimes hit a bump, and go up to 1/3, 3/4 etc). So I know the fuel tank guage is not right.

Is it possible there is a bad sensor for oil pressure? Is this a common problem for anyone on here? Just wondering before I spend a wad of money to have everything looked at (which I may have to anyway, but if I can save a few bucks, I would like to).

Thanks in advance.

Re: No oil pressure, 2000 duallie truck?
 

I have a '98 Chevy dually 454 and the oil pressure guage and gas guage bounce all over the place. One of these days I'll put a mechanical oil pressure guage on it. Yours (and mine) may be a bad ground.

Re: No oil pressure, 2000 duallie truck?
 

Just hook up a mechanical gage and see what kind of pressure you really have. It doesn't have to be permantly mounted, to do the test

Re: No oil pressure, 2000 duallie truck?
 

Mike,
If it had absolutely no oil pressure I would think that the lifters would start rattling pretty quickly. I would suspect the gauge also and the only way to find out for sure is to hook up a mechanical gauge like Dave mentioned.

Re: No oil pressure, 2000 duallie truck?
 

Mike, I have the same 2000 454 Chevy truck. Had the same problem with the fuel gauge. The fuel pump went out, was replaced, and the problem went away. I was told the fuel level sending unit is attached to the pump in the tank. The only way to fix it is to replace the pump.

As for oil pressure, I've never had it show no pressure, but like yours mine shows very low at idle when it is hot. No matter how much oil is in it or how many miles I've driven, if I change the oil it goes away for two months or so. My truck only goes to the races so it sits a lot. I just assumed it didn't like old oil.

Re: No oil pressure, 2000 duallie truck?
 

if you have a real oil pressure issue you would have the light come on in the dash cluster along with the gauge ,, there are two separate circuits for low oil pressure and if I not mistaken the fuel pump circuit has to see oil pressure in order for the pump to run ,gmonde

Re: No oil pressure, 2000 duallie truck?
 

Chevrolet's can handle low oil pressure, especially a small block and I think that the big block also. I have raced a small block with 10 to 15 pounds at idle. So the sometimes low pressure may be normal. I agree with checking with a mechical guage however if you find zero pressure then I would change the oil filter. In my race car with no bypass I have had two oil filters fail and create zero oil pressure. On a street engine I assume that if the filter fails that you would not know it with the bypass. But, maybe the bypass failed.

Re: No oil pressure, 2000 duallie truck?
 

Thanks for the replies guys. Got a lot of good asnwers on Facebook as well. Common thing seems to be sending unit or stepper motors for the guage cluster.

The only thing that lights up is "check guages" on the dash. Will probably look at it, have it checked, etc on Saturday (lot of freezing rain here tomorrow in the forecast).

Re: No oil pressure, 2000 duallie truck?
 

Bad Oil Sender?

Re: No oil pressure, 2000 duallie truck?
 

I have a 2001 Suburban with the 8.1L (496) and had the same thing to happen. No lifter noise or any other symptoms of no oil pressure, so I drove it home and changed out the sending unit, fixed the problem.