328 Oil Pressure ?

I have never had a problem with my oil pressure (or the gauge itself, for that matter) but tonight an issue came up. I drove my car to work this morning and everything seemed fine. As I was driving home tonight I noticed that the needle on my oil pressure gauge was reading 0. It did not make a difference whether I was idling or running at full acceleration. The needle didn't budge. At first I panicked and then I checked the oil level. There is plenty of oil in the engine and the car sounds and drives normally. Also, there are no warning lights on and everything else appears to be fine. Could this be the gauge itself malfunctioning or could the sender be the culprit?

 

20/80 with synthetic

 

Yes

Unplug the wire from the sender and touch it to the engine block or cylinder head (ground) with the key "on":

gauge needle moves to full right position (high pressure indicated) = sender probably bad

gauge needle stays at full left position (zero pressure indicated) = gauge probably bad

See Bob's (RJay) excellent thread on this subject:

http://www.ferrarichat.com/forum/showthread.php?t=103015

(..."a thimble full of corrosion fell out"... - classic...)

 

It's been awhile since I read the manual on this subject but I believe it states it should be reading 67 when warmed up, I'm not sure at what RPM and what oil temp. Mine seems to be right around that when at 3000-5000 RPM consistently. At idle, more like 35-40 which I would expect given the reduced RPM's.

Jeff

 

Steve,

Thank you! I will give that a try. I'm hoping it's just the gauge because that looks like an easier fix. I'm not very good with electrical devices and the thread on repairing the sender, although very well thought out and detailed, was over my head.

p.s. Is there a difference between the Euro oil pressure gauge and the US version? I got a very generous offer from a fellow F-chatter regarding one if it turns out to be the gauge itself that malfunctioned.

 

Euro cars are usually in "Bar", USA cars are in "psi". I'm betting it is simply the sender. Although the clock and tach are known to fail pretty regularly.

 

Just for discussion, here is a picture of the gauge together with the sending unit, euro spec.
Ciao
Eugenio
p.s. picture was taken upside down, then rotated.
Image Unavailable, Please Login

 

One last thing before I do this. I don't need to remove the oil filter, do I?

 

No, not yet

 

Advice from Superformance UK to me was don't believe the meter, and unless your low pressure light comes on you don't have a problem

 

Okay, here are my latest notes. I fired the car up this morning and let her get warm. This time I paid extra attention to the guage. As I revved the engine I noticed that the needle did move slightly each time. Would this suggest more of a problem with the sender as opposed to the gauge itself?

Also, I located the sender so that I could disconnect the wire and test it against a ground. Well, as you can see from this pic, the access to the sender (in my engine bay at least) is horrible. I had no real way of getting to it, let alone detaching a wire from it. What can/should I do?
Image Unavailable, Please Login

 

bump

 

You've just got to get in there somehow Gus -- even if it means taking some bits off.

 

I think if you remove the oil filter, you'll have easy access. Just make sure the car has not been run for a few hours, so oil dripping from the filter will be minimal.
(Or just wait until your next oil change to do it.)

 

As briefly suggested above, I had my mechanic check oil pressure with a manual gauge elsewhere in the system to get an additional reading. This might be one way to go to get some more data before you start investigating the sender and whatnot.

OK, I just busted out the wiring diagram and traced it for you. The "low pressure" red warning indicator is driven by a different switch / mechanism than the actual oil pressure sender. So it is not just a "red light comes on when gauge value is low" light. Nice design. So that's a comfortable failsafe (it that light ever comes on in normal driving, stop the car.) Also confirm the "test phase" of the light in that it comes on briefly when ignition is in the "run" position and just after starting until pressure comes up.

I've only seen this light come in in my old 308, when tracking it going around long, tight corners.


--Mike

 

Okay. Thanks again guys. I am going to give this another stab.