While changing the oil and filter this weekend on my 03, I noticed that a threaded plug located near the oil filter housing was dripping a little oil. After cleaning it off I could also see it was not fully seated. I tried to tighten it but it felt like it was bottoming out even though 2-3 threads were still exposed. I unscrewed it, cleaned everything up and tried again but same result.

I've done three or four oil changes on this truck since I bought it in March but I never noticed this plug before. I'm wondering if the previous owner put the wrong size plug in there? It threads in smoothly but definitely bottoms out early.

Here are a couple of pics. Any idea what this port is for and if this is the correct plug? Thanks.

 

I could be left over from when LR used to put oil coolers on DiscoII's

 

I noticed the same one on my 04 yesterday while I was under it admiring all my leaks. Mine was also leaking a tiny bit and wasn't seated flush either, but I'm sure it's all the way in.

 

Yes, that is one of the two connections that pumps oil to the front oil cooler on my 2001. You just have plugs on 03's and 04's because they removed that system.

 

If you need a replacement plug they are 3/4" thread count 16.

 

Excellent. Thanks for the plug detail.

I found this one on the RockAuto site: Dorman Oil Drain Plug which looks like it will fit much better. Cost is $3.60 each.

Thanks.

 

Great spot to put an oil pressure sending unit in the future.

 

And a little searching turned up this thread from 2010 where someone did exactly that. Looks like he used the other unused oil cooler port than the one I found (next to the filter), but it's got the same size plug in it. And from the clean vs dirty threads it also looks like it wasn't fully seated. Go figure.

Oil Pressure Sending Unit Install

 

that one has no pressure it is the return from the cooler and can not be used for a oil pressure switch

 

he good new is you can, if you don't have a oil cooler, buy a used one and still install it to have a cooler running engine.
An yes, you can not install a pressure gauge to that port, because as mentioned it was the return line fitting.