I have a 2003 1500HD 4X4. 6.0L engine with approx 100K miles.

A few days ago my oil pressure gauge started reading maxed out. Didn't matter whether the engine was at idle or running down the highway. As soon as I started it, the gauge pegged. Truck seemed to be running fine so I wasn't really worried about it. I was thinking its was just the gauge, or the sending unit.

Today it maxed out when I started it, but when I gave it gas, the pressure gauge would fall to zero. When I let off the gas, it would max out again. It did that for a while, then after the engine got warmed up, it just stayed maxed out. Now I don't know what to think. Engine still seems to be running fine.

Any ideas?? Suggestions?? I'm not sure what to think.

 

I'm leaning towards bad sending unit.

 

And I'm wondering why the sudden change under acceleration? For some reason, when there's a lot of juice provided at the alternator, the gauge reading changes...

How's your negative battery cable? Possibly a bad firewall/engine ground strap?(The one on the engine now will fight you like a dog unless you have access to a lift. Add a negative battery cable between the block and the firewall on the passenger side, and save yourself a lot of grief.) Another possibility is the ground wire at the gauge.

 

Sounds like the pressure sender or the ground as rivereye pointed out.

 

Replace the sending unit and it has worked perfectly ever since.

Thanks for the input.

 

This exact problem just happened to me. The oil pressure guage is just maxed out... How hard is it to replace the oil sending unit? I see that it is behind the intake manifold on charts. Is this a DIY type of job? I mean I have changed the brakes and ebrake on this truck butI am far from being a mechanich. Also, trying to save money during a personal financial crunch. Anyone have any insight as to how difficult this is and or a basic step by step? For instance to I have to remove fuel lines? If so I am thinking its going to a mechanic because I don't have those quick release tools.


thanks in advance.
Jay