I was doing an oil change today and instead of using common sense I was using my Harbor Freight special torque wrench to tighten the plug. It seemed like it was plenty tight but I kept putting on more pressure waiting for the click. Just when I was letting up it felt like it started to strip a little. So what gives first the plug or the pan? I'm sure it's fine for now, but next time when I take it out I'm not sure what I'll find.

 

typically it is the pan.

The worst is when the threads are so bad that you can not back out the plug.

Salim

 

Never tried it, but if Toyota were smart, they'd use a softer alloy for the plug.

 

Yes, the pans are usually made out of a softer sheet steel or aluminum. On the bright side, you can probably get the pan tapped out to a larger size and just use a bigger plug. Watch those thread shavings, though!

 

It has more to do with how the pan is made ... flat sheet is stamped to form a pan. A soft metal collet (sp?) is stamped in the hole and threaded to accept the plug.

Although a quick method to fix is to load the tap with grease and cut new threads [the grease holds on to the filings] the better way is to remove the pan, cut threads and clean it.

When you get to that point, you will have to analyze the situation. There are quite a few possibilities and options.

Salim

 

A "relatively" inexpensive solution is to have a good machine shop install a HeliCoil. The pan boss is tapped with a special tool and a hardened coil is installed in it. You can probably install a stock plug back in the pan, but you'll have to check around to see what sizes are available.

I've had a number of these installed in moderate to large displacement 2-cycle outboard marine engines that were early users of aluminum heads. Many of these heads required spark plugs to be torqued to 35 ft-lbs, but the head yielded at about 30. In time plug manufacturers came up with softer washers that deformed at as little as 20 ft-lbs and prevented this kind of damage. A lot of us OG's ended up with HeliCoils in all of the plug bosses where they performed flawlessly for years. If it can take the forces present in a combustion chamber, one of these repairs should have no trouble living in your oil pan. .
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http://www.emhart.com/products/helicoil.asp

 

Thanks for the advice. I'm so pissed at myself, I know better! Maybe I'll get lucky and when I take the plug out the threads will hold. It looks like a new pan is $130 OE or $63 from Rock Auto. Got to wonder if the Rock Auto one is OE. I know the pan crosses over to a ton of Toyota vehicles, but how much demand is there for oil pans? A HeliCoil is a great idea. Maybe just fix mine and be done with it. It looks like they just use sealant instead of a gasket. I wonder how hard it is to get it to seal the 1st time?

It's hard to believe that they don't make the plugs softer as a standard practice.

 

carguy- I have never had to use one but I'm pretty sure they have replacement plugs for that very purpose. They are cut just a little bit oversize so that they will fit tight in a stripped hole. I don't believe you have to retap or anything. Most of the parts stores should carry them. I don't believe I would do a helicoil since they make oversize plugs if you have to retap. You stand a chance of a slight seep around the helicoil threads. I have tightened pan plugs all my life just by feel. I have a couple of torque wrenches and do use them a lot but never for tightening a pan plug. (It doesn't have to be tightened that tight)-most are over tightened- hence the reason so many are stripped when they should actually last the life of the engine.
I'm sure there are pans that have stripped but the ones I have seen have only ever been the plug, not the pan. Good luck!