Oil Level Sending Unit: How to Service / Repair / Maintain

[rxtrom]

Draco thanks for the thread and thanks to the others for some additional input.

I "rebuilt" OLSU today since I thought it wasn't reading correctly but after testing that it and the gauge worked properly I reinstalled the OLSU and think it may just be that I do not have enough oil in the tank..

I want to know if there is a way to test the gauge and measure oil while the car is cold for time's sake. I don't want to run the car for 30 minutes and then let it cool for 90 minutes before I can work on it again if needed.

Below are pics with the dip stick removed to ensure its not inhibiting the OLSU arm. BTW the dip stick was only showing a very small amount of oil on the tip. Almost no oil on stick.

Car off. Pic orientation is bad sorry.



Car on (not running)

[DRACO A5OG]

Really there is no way to check when cold.

Do not worry, the crank only holds about 4 quarts in any case, the rest is in the tank and lines.

Rule of thumb, oil and filter change, fill to 9.5 quarts, get her to operating temps and add as needed. I always end up with 10 quarts. level on dip stick at middle of the hash marks.

Next day, when cold, if the tip of the dip stick is wet, Good, that means you did not over fill. If after you initially filled, you started her and circulated the oil you should see the gauge need start to drop to red. That is normal. If not, you have over filled and will be sucked through the intake, not good.

Hope this helps?

[911T70]

I removed my oil level sender last winter to test it because my gauge was always in the red when my dipstick indicated the oil level was where I like to keep it - near the bottom of the hash marks. It was fine so I added a variable resistor between the gauge and the wire from the OLSU, behind the gauge, and adjusted it so that the gauge reads at the half-way level. This way, I can see if the level drops without having to check the dipstick.

[CobraR1339]

Originally Posted by DRACO A5OG

Here are the results:


Gauge Oil Level at 3 o'clock, Oil temp at 190 Degrees ( verified by infrared thermometer )

Dip Stick at middle mark ( fresh oil change, it is the yellowish part to the middle, sorry for bad pic )

No worries JB, here is my Volt Meter , two would have been too much ( inside joke )



OSLU not leaking after an hours drive:

Thanks much for the link. The PIC i need is a better version of the last one. Or of a tank without the sender installed yet.

BTW really good info. in the post.

Lastly Pacific Cooler will open the tank for me so I can do the modification and then they will put it back together. I too was concerned with the baffle/screen. However if I don't try I can't succeed or fail. Will post the mod when complete or a sad story about why you don't want to try this.

[7783911]

To insert the new unit...can someone explain the best method and also how do you determine the orientation of the unit so the float is in a vertical alignment...does the mounting plate only fit one way?

Thanks

[DRACO A5OG]

Take clear note on how it is removed and re-insert it reverse. See my video in this thread. The plate as well. I did not notice if the studs are assymetrical but I replaced it the way I found it.

[Discseven]

Fine documenting Brother Jim. Am diving into my OLSU---thanks!

.

[Industrialando]

Resurrecting this excellent thread, midway through my teardown I noticed the spring in the OLSU was broken beyond repair. Does anyone know of a vender that sells just the spring? If I'm out of luck and need a new OLSU does anyone have positive feedback on the URO unit?

[Industrialando]

Originally Posted by Industrialando

Resurrecting this excellent thread, midway through my teardown I noticed the spring in the OLSU was broken beyond repair. Does anyone know of a vender that sells just the spring? If I'm out of luck and need a new OLSU does anyone have positive feedback on the URO unit?

Any feedback on my question above? Hoping to avoid throwing an entire sending unit in the trash over a spring. Thanks

[Pedro '84 Coupe]

Originally Posted by Industrialando

Any feedback on my question above? Hoping to avoid throwing an entire sending unit in the trash over a spring. Thanks

Not sure about the spring. If it were me, I'd post a WTB ad in the classifieds for a good, used working unit before taking a chance on the URO part.

[Industrialando]

Originally Posted by Pedro '84 Coupe

Not sure about the spring. If it were me, I'd post a WTB ad in the classifieds for a good, used working unit before taking a chance on the URO part.

Good call, worth a shot. Thanks

[toddu]

I have something odd going on and not sure what it means. With the OLSU out of the car, but connected to the leads, the gauge works as I move the float up and down. As soon as I touch the OLSU to something on the car (e.g. - the studs on the oil tank), the gauge needle goes to red and doesn't move with the float. Gauge does peg when the negative is removed.

No idea where to start troubleshooting.

Thanks!

[toddu]

I was able to figure it out. Turns out the wires are reversed. Was throwing me off because it still moved the needle correctly as I moved the float. Guess the resistance is still the same no matter how the wires are connected, but ground obviously was wrong.

Todd

[Kraftwerk]

Timely post. The sender unit was the first thing i addressed when I bought my car 20 years ago, I remember disconnecting the two wire connectors on the sender / tank they were covered w/ grease and grime I sanded both contacts and it all worked fine for 20 years. Yesterday I noticed the sender is not working again ! ...20 years later. I will now read all 5 pages of the post, see what I can do about it. Hopefully it is as easy as the first time.
These are good cars which last a long time if you look after them.


Industrialando: A spring is a spring. I would think Mc Master-Carr or some reasonably well supplied parts company will have a spring which matches the sender spring.. I am, sure this is the type of thing A.G. Porsche bought in bulk from a spring manufacturer.

[aus911]

Hi All,

I used this post to help repair my sender.
What I found was the contact on the wiper arm was open cct. I manages to rotate it slightly and peen the back side slightly, and bingo, now all good.

Thanks all for the support on pelican.

And Draco A5OG I hope you don't mind I have attached your pic to show the contact and arm. It was the silver contact at the bottom of the pic that needed attention.
I hope this helps.

Cheers

[kgieg]

I know this is an old post but my gauge was pegged and it turned out to be the wires from sender to the right rear tail light area were bad. 50 year old stiff crusty wires replaced both and the gauge works now.

[Jonnybee]

Love this PP forum, I found this old thread and it' s so incredibly helpful as the bouncing oil gauge has been concerning me, now I know how to fix it, i'm new to the Porsche fraternity with an '86 Carrera backdate, lots to learn but looking forward to it.