I'd expect to see exhaust soot from a leak, how many miles have you put on since you replaced the gaskets?. People tend to use smoke machines to see leaks, but I don't know that heard of people smoking the exhaust system.

BTW the locking header bolts I was thinking about are Stage 8. Available at SummitRacing and many others.

 

I have about 20,000 miles since the last time I changed the gaskets and bolts, and it did have soot at a spot where it was leaking, it was quite small though and had several broken bolts at the time, at least the bolts will be easy to get out since I've already dealt with them not too long ago. I'll update on the findings when I'm able to get it checked out. Thanks for the suggestion to use locking header bolts, do you think they're necessary and/or worth it? I don't mind re-torqueing bolts. Anyone use hi-temp RTV around the ports around their manifolds/headers?

I thought I posted this response way earlier but somehow I managed to fumble sending it lol.

 

I think 20k miles would show soot if it were leaking, but not 100% sure. The problem with retorquing, is if they get loose enough it'll blow the gasket then you'll be taking them off again. Put those lockers in there, and never lift the hood for that again.

 

So small update, exhaust guy fixed muffler and one leak down the exhaust, but says the manifolds seem fine, and when I asked him about the noise he said he could hear it and that he thought he heard it coming from the bell housing of the transmission and that "seems normal" because of the "rotating assembly". I've had the trans off and used loctite and torqued the bolts down on the flywheel and TC, so none of them are loose or backing out. Of course once I got home I tried to listen to the bell housing and of course the truck refused to make the noise all together now so I'll try again later. I did have a powertrain reman transmission installed at 225k miles if that's relevant.

 

I think I've had sort of a breakthrough with the hose method considering what the exhaust guy said, if I put it right against the area where the engine mounts to the transmission I can hear it, only if I do it from the engine side though right at the back of the oil pan, around the flexplate area. But I've inspected the flexplate and it didn't seem damaged/loose/cracked/any bolts missing... It also seems straight and doesn't waver when the engine is running. I asked a mechanic friend about it and he told me that it can have micro cracks that you can't really see unless if you hold it up to the light to see, which I did not do, not sure how true that is.

Got some photos of the mounting points


One side..

180 degrees on the other side..

 

I don't see anything wrong there...... there any shiny spots on the flexplate anywhere??

 

Nope... This was a little while ago so I'll drop the inspection plate and check it out again, maybe I missed something...

 

What you are looking for is obvious signs of contact. Thus, 'shiny spots'. Cracks and missing pieces might be a clue as well......

 

Okay, after fumbling around underneath the truck for a while and cleaning some stuff up (rear main seal's been leaking for a while), the noise is definitely louder with the inspection cover off, and when I use the hose trick it's right on the flexplate, not sure if it's louder around the TC bolts or the FP bolts, just kinda all over.. Would make sense why I couldn't find the noise if it was buried in the bellhousing.

I can't really find anything visually wrong with the bolts or mounting points, is there a certain procedure to bolt up the TC that I may be unaware or a certain orientation to the bolts? I didn't think about it before but these bolts never had washers on them. They're all tight and have threadlocker on them. Flexplate doesn't wobble or seem loose, even when prying it gently with a screwdriver.

Right at startup. Sound is there then it goes away.

https://youtube.com/shorts/WKW8eb-ta30 Hot idle.


Bolt looks okay, the shiny circle around the bolt is when I tightened it down with a socket when I originally reinstalled it.

The wet spots is brake parts cleaner overspray from me trying to wipe away a lot of oil residue. FP looks fine and no shiny spots all around.


This bolt *maybe* looks slightly uncentered a little to the left??

 

I can hear something, but, no clue what it could be.

The bolt being not quite centered is ok. They likely all look like that.