Has anyone cracked the neck that the drain plug screws into under the oil tank?

chrisp · 04-05-2002, 09:18 AM

Mine is leaking and I am not sure it someday it will break, spin off, and leave multiple quarts of oil on the floor or if it's just some little niggling problem that's common nd can be sealed off.

Looks like maybe after 19 years of torque-ing that bolt maybe be cracking where the neck meets the tank.

Early_S_Man · 04-05-2002, 12:50 PM

I'm not sure just what 'may be cracking' is ... either you see a crack developing, or you don't!

Unless you don't value your engine very much, I suggest you remove the oil tank, clean thoroughly with Varsol or similar solvent, and repair the drain by grinding away the existing 'neck' and put a weldnut or conventional low-profile nut in the place of the neck.

After cleaning with solvent ... partly fill with water and soap/detergent, and slosh around thoroughly before starting any welding or brazing. MIG or Oxy-Acetylene should work just fine to make the repair ... assuming you don't have a corrosion problem that has weakened the tank.

chrisp · 04-05-2002, 01:14 PM

Thanks. It will drip about a quarter size spot on the grarage floor. I believe it only drips when the oil is very warm. Basically the area around the neck is wet and when returning from a drive it drips maybe 3-4 drips before it stops. The 3-4 drips take about 30 min to form.

Considering the other leaks that come from these motors I have classified this as a low priority problem that I do want to fix but haven't put it to the top of my list...just yet. But if I should then I will.

I hear you about the flushing before welding. Definitely the right way to do it. I can weld it at work. My other thought was some JB Weld after cleaning the area very well. I would use the 5 minute kind. Porsches love JB don't they? I think that's what Ferdinand must have dreamed about at night...how to use more JB Weld in his production process.

pwd72s · 04-05-2002, 01:19 PM

silly question 101. Are you sure the neck is cracked? Do you use a fresh crush washer with each oil change? They can create a drip as decribed if you don't...

chrisp · 04-05-2002, 01:30 PM

Good question. I need to look at that. It may be that when the car is still it drips but when it's rolling the wind blows it onto the neck and make it look like it's cracked or something like that. I guess we have gone full circle from my original question because I haven't heard any responses saying "yes, I have cracked mine before" which leads me to believe that it's not a common problem. I will investigate further and repair accordingly.

Doug Zielke · 04-05-2002, 03:40 PM

Last year at JW's swap meet I saw a oil tank for sale. It was pretty rough (no paint), but notable in that you could see the drain plug boss was *brazed* on. I don't know if all 911 oil tanks are constructed this way, but someone will.

Oldporsche · 05:53 PM

I am not a Porsche expert, however on this board, once in a while I play one.

I believe that the oil tank is copper plated. I think that this is to prevent rust from forming. I also believe that the copper is inadequately is thin and rust and crosion form anyway.

I could believe that the neck you are referring to is probably braised on or maybe even silver soldered. This crack you are referring to maybe repaired by a radiator shop. I would caution welding on the tank. The tank skin could be too thin to be successfully welded with an oxy-aceytline method that introduces oxygen. Besides you would probably mess up what copper plating you have left. However, it being plated with copper would probably react well to silver soldering, or even plain solder.

I would first check the crush washer and its mating surface. I have bought large soft copper crush washers at Pep boys.

Removing the oil tank and cleaning it up to check for leaks is probably a good idea anyhow.

I myself am looking forward to removing my tank and trying to find out what's the matter with the oil level sender unit.

Good luck,
David Duffield