Oil Pressure Sender failure?

[CCM911]

In this case, Search has not been my friend.

My Oil Pressure Gauge pegs at 5 even when fully warm. It also "bounces quickly up and down" every so often.

Do the sending units ever wear out?

Thanks.

[nettles503]

Chances are it's the sending unit has gone bad. Mine was exhibiting the same behavior before I changed it. Here's how to test it: Turn the ignition on, remove the wire from the sending unit and ground it. The gauge should drop from 5 to 0. If so, replace the unit. Here's a good thread that I followed when I did mine.

CAUTION: Don't try to just unbolt the sending unit from the engine. You MUST remove the oil line and hollow bolt first.

Another Oil Pressure Sender Replacement Thread with pics

[CCM911]

Nice thread! I am a bit bummed that I may need to remove the AC Bracket.

I will test tonight to be sure it is the sending unit.

[mnez]

It turned out that mine was the connection to the sender, not the sender itself. The connection had gotten loose over time, with vibrations causing on intermittent open connection (pegged at 5), and bouncing around quickly when the connection was almost working.

Check your connector. If it is not snug, that may be your problem. My solution was to take a small piece of aluminum (ie pop can) and insert it into the connector between the plastic part and the circular metal connector, like a shim. Now it is snug, and the needle is stable.

Worth a try, much simpler that replacing the sender.

Mike

[KNS]

CCM,

I had a very similar contdion with my '84. I really didn't want to remove the AC bracket and muffler. This really is the only way to do it correctly.

Once I got the muffler, cross pipe and AC brackets out of the way (not difficult at all, just takes some time), the sender was a piece of cake. My new oil pressure reading was great.

While I had all that stuff out of the way I also installed the little mounting brackets for the small oil lines leading to the tensioners. The factory started installing these in 87 or 88 because some oil lines were breaking due to vibration, Wayne outlines this in his rebuild book. I did have to replace the right side cam oil line because it is a different shape.
Nice little "to do" while your in there.

[KTL]

Originally Posted by KNS

CCM,

I had a very similar contdion with my '84. I really didn't want to remove the AC bracket and muffler. This really is the only way to do it correctly.

Once I got the muffler, cross pipe and AC brackets out of the way (not difficult at all, just takes some time), the sender was a piece of cake. My new oil pressure reading was great.

While I had all that stuff out of the way I also installed the little mounting brackets for the small oil lines leading to the tensioners. The factory started installing these in 87 or 88 because some oil lines were breaking due to vibration, Wayne outlines this in his rebuild book. I did have to replace the right side cam oil line because it is a different shape.
Nice little "to do" while your in there.

Good tips there by nettles and KNS. Don't fall victim to the desire to remove the sender w/out removing the holding block. Last thing you want to do is break the engine case!

Also, i've seen those tensioner feed lines cracked in person on a number of occasions. His tip to check if your tensioner lines are the updated shape w/the support brackets & clamps is very good advice. This change by Porsche wasn't an overkill alteration by the engineers. It was a fix for lines that leak (heavy leak) due to vibration failure, just like KNS said.

[CCM911]

Thanks, guys! I was going to remove the compressor mount anyway, so I will be doing it the right way.

[porsche930dude]

i sprayed mine out with carb cleaner and it worked again. had gunk in it i suppose

[bryanrex]

I experienced an oil pressure sending unit failure earlier today. The sending unit somehow failed in an intermediate range where it would register 0 bar with the ignition off and between 0.5 to 1.0 bar with the engine running (depending on rpm). Obviously when I ungrounded the feed it registered at 5 bar.

At first I suspected an oil pump failure (very, very bad), but there were no loud noises coming from the engine so I simply removed and cleaned the sending unit with WD-40 and some engine gunk. The sending unit started rattling again when shaken, so I reinstalled it and everything worked perfectly. Apparently with age it can get gummed up (like an old carb float), so cleaning it out and tapping it with a hammer can save you some time and money. If it fails again I'll replace it (and re-post).