Oil Pressure Gage Fluctuation

[wilke3169]

Are there known values for the oil pressure sending unit? My gage fluctuates. At times it will sit on 3 bars as the rpms increase and then jump to the "normal" level. Other times while cruising around 3000 rpms it will drift up to 4 or 4.5 bars. The erractic behavior of the gage makes me think it is the sending unit or the gage. All of this behavior is when the engine is warmed and running very normally. Of course the oil is clean and properly filled.
Any thoughts or experience would be appreciated.

Thanks,
Kevin

[livi]

I wouldn´t rule out the possibility that such behavior is normal. In fact, sounds pretty much like my gauge. I think its rather sensitive to car movement, accel, retard etc because of the design with the dry sump and big oil volume.

But then again, I am a newbie..

[87coupe]

Sounds pretty normal to me.

[syncroid]

Two things come to mind; 1. Replacment of the oil pressure sender. (they go bad frequently) 2. Sometimes in hot weather the plastic gauge face itself will expand inward and touch the needle thus holding it back. My two cents would be on the sender. If you try replacing the sender yourself, be carefull! You can break the engine case if it doesn't come loose with little effort.

[syncroid]

A little more information would be helpfull. Mileage?

[wilke3169]

The car has 170,000 the engine has approximately 2000 since complete rebuild. I do believe it is in the gage or sender but I am not sure it is normal. Is there a normal resistance level at a given pressure or level?

[syncroid]

There should be a normal resistance value, yes.
Cheap insurance; replace the sender. Part # is 911 606 111 01 with a price of $107.30 (if you buy it at the dealer)
Unless your motor was rebuilt by a "non-professional" you should be okay. A pressure sender is not normally replaced on a rebuild unless necessary.
My .02

[87coupe]

My manual says it is normal for anything over 3.5 bar at 5000 rpm, it even goes so far to say that with the oil at operating temp it is normal for the red warning light to llight up.

However, I am not a professional mechanic, where as syncroid is. I would listen to him, always better to error on the side of caution.

[Early_S_Man]

The early 10 bar/150 psi senders measure 15 - 20 Ohms at rest with engine off.

I've never measured a late sender ... maybe someone with an engine out for a rebuild could measure one???

[lateapex911]

The comment about the light coming on, and the manual mentioning it....does that refer to idle??

Sorry to hijack, but am I the only one that freaks when the needle goes to zero druck at idle??