Jumping oil pressure gauge

[coxfmly]

Hi,
For the last few weeks my oil pressure gauge has been jumping all over the place when I first fire it up. This usually last for 5-10 minutes then rides steady at 45 lbs. Normally it runs at a solid 65 when cold and then drops to 45 when warm. Could this be symptomatic of a larger problem? OPS, PMD and lift pump have been replaced within the last 5K.

thanks

[DmaxMaverick]

More likely the OPS, gage, or wiring in between (check IPC ground). If it were the IP or PMD, the engine would run like you are seeing on the gage. Lift pump problems can indirectly cause issues with oil pressure, but that would be the last indicator (you'd know it already). Narrow your problem down to the affected components. The OPS is a likely candidate, in any case. If it is causing the gage to be flaky, lift pump operation is next (if it isn't already).

[john8662]

I've quit using aftermarket replacement electrial parts for some specific things on the 6.5. The OPS is one of them. I always throw on a new AC Delco D1808A.

I got 3 bad Borg Warner OPS's in a row, so I fired them for good on those.

[Robyn]

Yup Yup

The OPS is the most likely culprit.

These have, depending on the year, a potentiometer inside that feed a variable signal to the oil pressure gauge, plus an on off switch that feeds power to the lift pump after oil pressure rises.

If the potentiometer gets flakey, and the after market ones due as John mentioned, its a crap shoot as to what will happen.

I would bet a sizable sum that a new Delco OPS will solve the issue.

I have seen these do all manner of wierd crap and the jumpy thing is common.

At least its an easy part to change.

Missy

[JohnC]

Slap a mechanical gauge on there and see what's really happening.

[Kennedy]

I'd be suspicious of the dash gauge, but the OPS is simpler and cheaper. Like John W said this is definitely a situation where OE is best. There was a "miracle OPS" released aftermarket some time back. Now it's just a faded memory. Same goes for lift pumps and many other parts...