Oil Sending Unit Leak

[Sloan66]

Couple of months ago I had a significant oil leak on my 307 which the board was able to solve. It was the old sending unit, where it had cracked. I have the non guage type dash.

I replaced it and it stopped the leak for a while. now it is back. It appears to be leaking from the threads. I have tightened it (using the correct type socket) and the sending unit is actually touching the back of the manifold to point I cannot tighten it any further.

Are there longer type sending units? Not sure what to do, I'm I right in not using any sealant as that would effect the operation of the sending unit? Or should I apply teflon.

Thanks

[geezer#99]

Put a little teflon on it.

[imjeff]

Some have a nipple and a brass 45 that gets the sending unit away a touch.

[cdowns]

you could move the sender to down by the filter

[davepl]

Unless I'm mistaken this should be a tapered thread and the fact that you can run it in all the way makes the threads on one or the other seem pretty tired.

Teflon tape is a quick cheat, though you don't want any of it to get into your oil passages, so I try to avoid it on oil fittings.

[truckster]

Make sure you use the Teflon tape that's rated for petroleum products. It's usually yellow, and it's thicker. Your local Lowes or Home Depot will have it.

[davepl]

Originally Posted by truckster

Make sure you use the Teflon tape that's rated for petroleum products. It's usually yellow, and it's thicker. Your local Lowes or Home Depot will have it.

Good tip, but I thought the yellow tape was for natural gas... which is I suppose ultimately some kind of petroleum product, but are they the same thing, or is there a different yellow?

[Tx Firefighter]

Reading closely you said the sending unit is screwed down down until its touching the manifold. It sounds like you're screwing it directly into the block. You need the factory elbow that goes between the block and sending unit. It allows the clearance you need to get it sufficiently tight.

[Sloan66]

Does anyone have a photo of the elbow? Firefighter is correct the original sending unit I removed was screwed directly into block at back of manifold. Source for elbow?

[Tx Firefighter]

It's called an "1/8 NPT street elbow".

When you buy one, you want a brass one rather than iron. The brass ones are close clearance and will fit down behind the manifold while an iron one is bulky and will hit the manifold.

You screw this into place and then screw your sending unit into it. The sending unit is now pointed away from the engine.



As an alternative, you can use a nipple and an elbow.





You want to end up with something generally like this...



Your best bet is to use a factory one. You can find them on virtually any small block powered car, truck, or van from the 80s to the 90s. The GM one fits and works excellent.

If you decide to just buy stuff from the plumbing supply section of your hardware store instead, remember you want 1/8 NPT fitting size for everything.

[geezer#99]

Good stuff Tx!!
Fwiw here's a link with some info on teflon tape.
Different grades in the white and yellow.
http://ca.answers.yahoo.com/question...2101532AAivGIh

[Sloan66]

Thank you, very helpful.