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BMAN BMAN is offline
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Join Date: Sep 2000
Location: Maryland
Posts: 861
Originally Posted by Sniff View Post
First off, sorry for the novel, but this job is more involved than it might first appear. History -- My oil pressure gauge was reading 0, however the oil light would turn off right after start up. I was confident my engine was getting oil and that my problem was either the sender, the gauge, or the wiring between the two.

To check to see if the gauge is good, disconnect the wire from the sender. Turn your key to the accessory position and your oil pressure gauge should peg at 5. Now ground the wire (I had to use a long wire extension to ground it on the door jamb). Your gauge should go to 0. If this happens, your gauge should be OK as well as the wiring.

To check to see if the sender is bad without removing it (a total pain in the butt), you need to test resistance. Use a multi-meter and set it to OHMs. Disconnect the wire from the sender and attach the red lead to the sender's prong. Then attach the black lead to a grounding point. Start your car (if you know for sure you have oil pressure) and measure the resistance. If the sender is good, you should get fluctuating readings with changes in RPM. If the sender is bad, it should read infinity.

Reference the following diagram for the rest of my thread:

Now there are all sorts of techniques to replace the sender, however I RECOMMEND NOT USING A CROWS FOOT WRENCH . . . PERIOD! If your sender is like mine (and several other Pelicans out there), it is really attached to the sending unit mounting block tight! The sending unit mounting block (#46) is attached to the aluminum engine case with a hollow oil line through bolt" (#48), and may not be able to withstand the level of torque placed on it when the crows foot technique is used. If the through bolt snaps off, your next thread is going to be "how do I remove a broken bolt from my engine case??" People who have successfully used the crows foot technique have gotten lucky IMHO.

Since my sender was definitely bad, I knew it needed to be replaced. I read several previous threads on the subject and felt I had a pretty good handle on how to do it. Also, someone had asked if you needed to drain the oil to replace the sender. You do not.

I contemplated removing the A/C bracket, but didn't want to mess with removing the muffler. So I disconnected the A/C belt and moved the compressor all the way to the right. That gave me enough access to loosen the oil line nut (#32) with a 14mm wrench (with another wrench on as an extension to give me some more leverage). This nut connects the oil line to the though bolt, and was on there pretty tight so don't give up. Also, it will be very difficult to back the metal oil line out unless you disconnect the line from the side of the engine. Just trace the oil line back and you will see where it connects to the engine on the right side just below your oil filter. This is an easy connection to get off (17mm).

With the oil line disconnected, I was able to rotate the sender mounting block down a bit which gave me better access to the oil line through bolt (#48). You will need a 17mm wrench to loosen this. This is very tedious (1/8 turns and a lot of wrench flipping, but stay with it). With the through bolt loosened, I was able to remove the sender and sending block as a single assembly. I took the assembly over to my vice and was able to remove the sender from the block. I AM SO GLAD I DIDN'T USE A CROWS FOOT. I'm 200 lbs and really had to lean into it to snap it free. Once you have the through bolt in your hand, you will see how flimsy it is and why you don't want to put a whole bunch of torque on it.

Now with the sender off, just put the new one back on the block. You should replace the copper washer (#44) which did not come with my new sender so I had to make a quick trip to Auto Zone. Amazingly they had the same exact one I needed. Also, I would recommend you replace the two aluminum washers (#47) on either side of the sender block. Cheap insurance against future leaks.

From there it's just the reverse to put everything back together. BE VERY CAREFUL NOT TO CROSSTHREAD THE THROUGH BOLT INTO YOUR ENGINE CASE!! This is easy to do if you are not careful. Also, one of the toughest things was getting the oil line nut (#32) to thread back onto the through bolt. Again, make sure you don't cross thread.

Once it was all back together everything worked perfectly. I let the car idle for a couple minutes to check for leaks. None. Then I drove it for a few miles and pulled over checking for leaks. None. This project took me a total of 6 hours on a Saturday morning. It will test your patience, but it is worth it to get accurate oil pressure readings. You can save money by purchasing a URO parts sender, but I decided to go with a genuine Porsche part (~$80). The washers are minimal so don't scrimp on those. Definitely replace them.

I hope this sheds some light on a process that worked for me. Again, this is what worked for me and my '89 so I am sure others will have opinions.
So now you got me all paranoid about using the crows foot wrench. I looked into it this evening trying to figure out how to remove it like you did. If I remove the a/c unit it seems the bracket is still going to be in the way of the sensor and oil line. Not much room to work.
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Old 06-07-2012, 07:04 PM
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