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Discussion Starter #1
91 164L auto

I just had to post this...

I just tried the fix from a previous post to fix the oil pressure sender. It really works nice and all for the cost of an aviation drill bit, less than $4. Drilled a small hole in the top of the sender opposite the groove, heard a little pressure come out, started the car and now my oil pressure guage works.

Here is the post "Bad oil pressure sender?".

Thanks - Terry
 

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Isn't life sweet when you can save yourself about $40 or so? My cars have had the same senders with the fix for about 10 years now. I wish other fixes were as effective and inexpensive, sigh.
 

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AlfaBB search is being inscrutable as usual. Can you paste link in? Seemed not to work last time.
 

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Discussion Starter #4
Hope this is what you are looking for. Otherwise, do an advanced search for "Bad oil pressure sender?" (without the quotes) and search for posts by Del. That should bring it up. If not let me know. I've attached a picture from the post.

http://www.alfabb.com/bb/forums/164...ender.html?highlight=Bad+oil+pressure+sender?

The hole should be drilled where the white dot is. There should be a groove in the sender on the side opposite that dot (for reference). I purchased a long aviation drill bit from the local hardware store so the sender did not need to be removed to be fixed.

Terry
 

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How does this work? Doesn't it leak oil?
 

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Discussion Starter #6
No. Mine as well as others that have done this fix have reported no oil leak. Use a very small drill bit. I was concerned about the same thing before trying it. I figured that worst case I could plug the hole with JB Weld or similar product, but no leak.

Terry
 

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Del's description from when he discovered how to do this was that the void region behind the diaphragm sender is air-filled and sealed off from the main oil supply by an O-ring. The O-ring leaks over the years and lets teaspoon amounts of oil into the intended to be gas-filled region. When it fills with oil, the diaphragm can no longer move and the sender stops responding. Punching a hole in the can allows the diaphragm to move against air pressure instead of pressing against a closed, oil-filled region (no compliance). The calibration probably (my comment, my supposition) changes, but the gauge resumes responding to oil pressure changes. And yes, over years, it will probably leak another teaspoon of oil. IF the O-ring breaks down significantly, then you will have a problem with oil dribbling out onto your engine. Just keep an eye on it. Or watch the calendar and 5-10 yrs after poking the relief hole, just replace the sender with a new one.

Michael
 

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I know the calibration of the sender must change just a little, probably slightly higher, but I've not worried enough about it to bother doing a comparison with a brand new sender. It would be interesting to know, though.

In ten years of continuous use of the same modified senders, they still don't leak more than being damp. I've idled the cars for some time to see if any more came out, but nothing happens, even when revving the engine. I even went so far as to install a little brass fitting in that hole and attaching a hose to a small container to see if continued road use would make some oil leak, but I never got any oil to flow into the tube, let alone the container. Of course, that doesn't mean that a leak couldn't develop, but that would be obvious, like having a typical Alfa seal leak, something we all learn to live with, lol.

Granted, this sender fix is only a very minor victory over the gods in charge of Italian car related failures, but it's nice to have one once in a while.
 

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While I realize Del takes my comments as intended, I want any other readers to know that I appreciate Del's contribution -- it has saved me from replacing a couple of senders, and they cost around $50 now. (Plus, I like knowing how things work.) I was trying to inform failed sender owners of the (miniscule) downside prospects of poking a hole in the sender can. I think the downside is really miniscule.

And from just my estimate as to relative sizes of the "swept volume" of the diaphragm and the reservoir trapped behind it in the can, I suspect the change in calibration can't be anywhere near 10%, and is probably a good deal less than 5%.. But ... I haven't made the measurement, so I don't know.

Michael
 
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