'97 K3500 7.4L Votec. Oil Pressure Gauge Is Twitchy!

[wirlybird]

Hi,
The oil pressure gauge on my 454 Vortec is twitchy/jumpy at times while driving.
It shows great oil pressure but can jump around at times up at the 60 mark.
It is not doing it all of the time and can be influenced by engine speed. So, say it is reading 60-70 and I let off the gas just slightly it might jump to 50 then back to 65 and could continue like this for a few seconds.
Step back on the gas and it easily jumps to 60-70 and then is stable.
When the needle jumps around it is a very quick movement, kind of like a momentary power interruption and not the normal slower movement you get if you let off the gas or step on it.
My guess is a flakey sending unit but wanted to check here before replacing!

Thanks for your thoughts on this.

 

[reservoir dog]

I just did the same thing , erratic oil pressure needle. Replaced the sending unit and it still does it. I assume the gauge in the cluster is the culprit. Doesn't do it all the time , holds good steady pressure then jumps around again .

 

[454cid]

Mine would move around with steady rpm, and it was the sending unit. Check how many pins it has before purchase.... there are 1 wire and 3 wire. I assumed mine was a 3, but it was a 1 wire. You'll have to do the work by feel, as it's just about impossible to see back there.

 

[wirlybird]

I just did the same thing , erratic oil pressure needle. Replaced the sending unit and it still does it. I assume the gauge in the cluster is the culprit. Doesn't do it all the time , holds good steady pressure then jumps around again .

Sounds the same as mine.

 

[El Tigre]

Mine does it too. Probably easier to live with ,than to actually fix.

 

[wirlybird]

Mine does it too. Probably easier to live with ,than to actually fix.

Yup, especially since it seems I'm not the only one!
I may try to figure out the sender type and see what the cost is. May be good to replace since it is simply an old vehicle!

 

[El Tigre]

Except everyone who did that said it didn't solve problem.

 

[Schurkey]

I'd be suspecting the wire harness that plugs into the sending unit/sensor.

Broken wire inside the insulation making intermittent contact as the engine moves around on the rubber mounts. Or broken insulation so that the conductor intermittently grounds on nearby metal.

The older trucks have a long, sad history of junk oil pressure sending units. But that part number isn't used on the newer trucks like yours. (Bigass fist-sized sensor, generally with green paint on the end with the electrical connector. Mounted near the oil filter, not beside the distributor.)