Leak where the engine and transmission meet

I’ve had a slow leak for awhile now... been trying to find the source for awhile... today while changing my oil I found a missing bolt on the transmission bell housing (I think)... I would prefer a part number so I can buy a OEM bolt, however an exact size so I can find one at a hardware store would work also... I don’t want to take out one of the other bolts and match it up bc I’m scared to make the leak worse... here are a few pics of what I’m seeing...

The 1st pic is zoomed out for orientation, so you can see what where I’m looking...

The 2nd pic is zoomed on the missing bolt/screw... it’s at the 6 o’clock position of the transmission...

 

Rear main seal.

One 6mm bolt ain't going to help you here. You're going to have to pull the transmission and change that seal out.

 

My question is why is that bolt completely missing? We can agree most likely that is did not just fall out on its own right? Or do bolts like that come out sometimes?

 

I don’t think anyone is going to be able to give you an evidence based answer. It’s just going to be speculation. It could be anything from road vibration, someone didn’t tighten it enough, who knows.

 

All that plate is is a service plate to keep fingers from contacting the flywheel is the engine is running, it has no sealing surfaces or sealants, it's effectively a saftey/vanity plate, you'll notice the squared off hole to the left of the bolt you're missing, that's a weep hole fore water and primarily oil if either the trans or engine rear main seal begin to leak and yours obviously has.

That bolt being missing isn't a big deal, and yes sometimes bolts do just back out, vehicles see a lot a vibrations especially the engine (and notibly V6 engines) and transmissions and heating and cooling cycles differing from simply the materials being different (the bolt mild steel where as the casement it fastens to is magnesium/aluminum alloy) and most likely it wasn't tightend to spec.

Small fasteners should stil be torqued, overtightened and they snap off, under tightened and they back out.

Pretty common for that bolt to be missing though.

 

I zoomed in and it looks like the head came off. You'll hafta have it trapped out if that's tha case.

 

Probably (hypothetically really) the dude that saw the leak the first time that snapped it off.

 

Gotta agree it does look snapped off.

The real question engine oil or Transmission fluid ??

Then just what fluid have you needed to add to keep things at the correct level??

 

My truck has the same hole without a bolt. I don't think it's ever been there.

 

Are you positive that is where it is actually leaking from? My project truck looked like that when I bought it and I thought it was the rear main seal. I cleaned up the engine bay and underside really well, drove it a bit, and inspected for leaks. Turned out it actually just needed a valve cover job and related seals/plugs. Pretty simple job, just takes a little time and careful part tracking.

 

Was that on a 3.4?

 

As mentioned, a leak between both components would mean your rear main seal needs replacing.

Before going that direction however, you should check the rear of your valve covers as they can leak enough to drip down and give you a similar effect.

 

yeah. The oil leaks out the back by the cam and half moon seals and runs down in the area between the transmission and block. Not saying that is the issue in this case, but no matter what the issue is, some seal needs to be replaced and it will be 100X easier to do that with a clean engine. Might as well start there.

 

Engine oil... I haven’t needed to add any fluid... The leak doesn’t even drip to the ground... It just drives me crazy bc every time I drop my skids there is oil on them...

 

My '03 is the same. No bolt there.

 

This was the case on my 3.4l. Leaking cam / half moon seals and ran down that same path.

 

Had a valve cover job done last year before I started working on my own truck... 99% positive they did not do the job correctly and reseal the moons/cam plugs... however this leak looks like it’s dripping right out of that service cover on the trans...

 

Good to know

 

Hey everyone thanks for the replies... I think I’m going to start with redoing the valve cover gaskets... This time I’ll do it myself and give the job the detail and care it needs since it’s my truck and not just another job for someone... I’ve come a long way with my knowledge on this motor in a year and have a FSM on hand to back me up... Hopefully the leak is from the cam plugs that I’m 99% sure were not addressed last time... If not at least I’ve narrowed it down and will gear up for a possible RMS service and/or oil pan service...

 

I have an oil leak somewhere; haven't done the dye thing yet and my initial thought is rear main seal as there is a lot of oil between my engine and tranny. When I did my valve cover gaskets about 1 1/2 years ago, I was unable to remove the cam plug bolts. They are hecka tight! I am wondering if they might be leaking as well?? I have the parts. I guess when I have the time I will do the dye test first, then go from there.