What is this bolt?

96 Tacoma 3.4L V6 5VZ-FE



View from the front of the truck. The bolt is on or right near what I think is the idle pulley, if the diagram is correct.

I found a slow leak of what appears to be engine oil coming from this bolt, if it's a plug? It was only somewhat more than finger tight. I tightened it a bit.

So partly I want to identify it so I can torque it to spec. And if that's not a plug, would something else close by or right above it be leaking?

There's some residual oil from years of leaks I'm gradually degreasing away, but something around there was an active leak. I'll need to degrease and drive it again to check the leak status. The oil will be due for a change in the next few months.

 

Looks like power steering or A/C compressor tensioner

 

Keep looking above it. Like all the way to the valve cover.

Just kidding but not really.

 

Yeah, looks like a tensioner bolt. so not a plug of any kind. You can kinda see oil above that bolt anyway. Bet it's coming from higher.

 

Looks like belt tensioner bolt. The one where the arrow below is pointing. Stick your finger around the top/back side and up about 1/4" and see if you can feel the bolt threads after the bolt has passed through the bracket.

If so, likely the oil is coming from somewhere higher up and running down.

 

The valve cover was possibly leaking up until a few weeks ago when I tightened the bolts a tad (some were only finger-tight) and degreased the valve cover area good, and no leaks are coming from there now.

 

Run your hand behind the head. Even if this is a different leak you'll need to stop the huge leak that is the full moon before finding lesser ones.

 

I third or fourth this idea of finding the correct height of the leak. As you drive, the wind will blow the leak all over the place, but not upwards.

 

That was it, belt tensioner bolt! Should I loosen it back to where it was?

After looking some more I think the leak is the oil pan nearby. I think the oil pan gasket is leaking in multiple places.

The transmission pan is also leaking around part of the brim. 10 years ago a friend took off the transmission pan while replacing the trans fluid (I don't know why) and he didn't use the sealer stuff on the pan brim, said it was unnecessary. Maybe it's been slow leaking since then through a couple more fluid changes.

I'm thinking I'll have the shop do the oil, trans fluid, and both pans in January when they reopen. The instructions make the pans seem like a lot of important steps that need to be done right, and if that trans pan is damaged from being smashed into place with no sealer then I don't want to deal with it myself.

 

Tensioner should be snug enough not to fall out as the mounting bolts should have the torque to hold in place.

Pan could be leaking, they are known to at this age. Wash under there well and determine before dropping off and it will be of benefit to both of you.

 

You should always use a gasket or sealant, or yes, you will get leaks.
Transmission pan is probably not deformed just from that, but if your friend pried it off, it might be.

 

I tightened all the transmission pan bolts. I know it wants only 5 ftlb, and they all felt too loose via a gentle open-hand ratchet turn. That will be nice if it's sealed now. Front passenger corner bolt on the pan was stripped! The bolt isn't gonna fall out but it's not snugging. Gonna leave the bolt alone, or alert the shop if relevant.

As far as the oil pan, the bolts were already tight, so I'm expecting a leak still. Still a bunch of gunk above it that the foamy degreaser hasn't gotten yet but it looks like it's the pan gasket to me.

I'll degrease and recheck for leaks on both pans again tomorrow.

 

Ya pan bolts are very sensitive. I actually broke a couple in my oil pan. Somebody has almost guarenteed over-torqued yours.

You can always use a little blue locktite on them though

 

FYI I think I determined the oil leak to be coming from the oil filter. Oil pan is fine. The filter untwisted too easily by hand, and the threading and whole area was pretty grimy. The plastic oil drain plug gasket fell apart in my fingers. New aluminum gasket.

Transmission pan is still leaking enough near the stripped bolt to have fluid on the gasket edge but not enough to be dripping. Bolts I had tightened to 65 in-lb, and I tightened them further today to 70 in-lb.