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I recently had the clutch replaced on my 81 Manual, all with the clutch good but after about now 300 miles I picked up an exhaust Tick. Ok I climb under the car Left side Factory manifold the 3 flange bolts are loose so I put the wrench and socket to them they snug up. Great another 80 miles and the tick is back
So back under I go again their loose again, but this time I back off the bolts put a socket to the studs to make sure I'm not pulling the new studs out, they weren't loose but I got some more out of them.
Now the question I know the Flange on the pipe floats, does the one on the manifold float too because it to can be rotated and rattle it, also is there an Exhaust donut/flange gasket used (I don't see 1) so after seating and tightening I now have a far worse leak now so over the weekend I will get the car higher and reattack it.
Auto Zone shows a Donut but the car has flanges that look like they would fit together without.
I recently had the clutch replaced on my 81 Manual, all with the clutch good but after about now 300 miles I picked up an exhaust Tick. Ok I climb under the car Left side Factory manifold the 3 flange bolts are loose so I put the wrench and socket to them they snug up. Great another 80 miles and the tick is back
So back under I go again their loose again, but this time I back off the bolts put a socket to the studs to make sure I'm not pulling the new studs out, they weren't loose but I got some more out of them.
Now the question I know the Flange on the pipe floats, does the one on the manifold float too because it to can be rotated and rattle it, also is there an Exhaust donut/flange gasket used (I don't see 1) so after seating and tightening I now have a far worse leak now so over the weekend I will get the car higher and reattack it.
Auto Zone shows a Donut but the car has flanges that look like they would fit together without.
On my 77 manual. Back when I had the factory exhaust manifolds but aftermarket true duels exhaust. It was always the drivers side that would come loose. That's the side that lifts up when you drop the clutch and hammer on it.
Anyway, with the factory manifolds, yes there is a exhaust donut between the manifold and the pipe, there is also a sleeve that fits through it if I remember correctly. I think I still have a few of those donuts laying around.
They no doubt had to at least loosen if not remove that pipe to pull the transmission. And perhaps, just maybe, they didn't put a new donut in when they reinstalled the exhaust. They may have thought it looked fine. It's never fine to reuse these. And they are cheap.
They sure look like tubular manifolds to me !
Okay that is probably why you have a loose flange on the "manifold" because it's not a cast manifold.
Pipe probably has a ball end that mates with a matching seat on the manifold or vice versa.
Need to be undone to clean the mating surfaces and put some hi-temp RED RTV on - but not to much to get inside the pipe and mess up any sensors ?.
Well sorry to new for this old guy as far as gasket or donut - sorry !
They sure look like tubular manifolds to me !
Okay that is probably why you have a loose flange on the "manifold" because it's not a cast manifold.
Pipe probably has a ball end that mates with a matching seat on the manifold or vice versa.
Need to be undone to clean the mating surfaces and put some hi-temp RED RTV on - but not to much to get inside the pipe and mess up any sensors ?.
Well sorry to new for this old guy as far as gasket or donut - sorry !
Ok so don't buy the Donuts, which confirms my thoughts because I wasn't seeing any place for them to go looks like a ball and socket faces. I probably have 1 side too right and off center. I may may throw some springs I have left over from my C4 exhaust will see after I try to reseat it
Yeah good idea with the springs as long as they are strong enough.
I was always amazed those ball and seat connections worked as well as they did on my daily cars LOL
Good luck with it !
The manifold nuts need to be prevailing torque style if you want them to stay tight. They look crimped from the top. Regular nuts will back off quickly under normal use. Some people like to use brass exhaust manifold nuts and those work well too.
Prevailing torque nuts for exhaust manifolds. They are deformed to stay tight under high thermal expansion.
The manifold nuts need to be prevailing torque style if you want them to stay tight. They look crimped from the top. Regular nuts will back off quickly under normal use. Some people like to use brass exhaust manifold nuts and those work well too.
Prevailing torque nuts for exhaust manifolds. They are deformed to stay tight under high thermal expansion.
It has a new set of studs with long Brass nuts on the Left the studs on the right side are generic with the Nuts you showed and No Grief on the right
The question has been raised that possibley the mechanic doing the clutch had left Out a exhaust clapper valve between the manifold & pipe I don't have 1 on the left side and haven't looked at right now DOES IT HAVE THEM or is any used at all
the '81 should have an exhaust heat riser valve on the passenger side only
I will have to look passenger side isn't giving me any problem will look through. So the driver side has none. So it's a flange to flange with or with out a donut?
(It also shows no heat riser, since the 82 didn't use it).
I picked up the called out gasket that is showing in several parts suppliers because it was $6 for a just Incase. But I totally agree there's No gasket needed on Left side I see No place for it to sit. It's the standard wedge shaped male funnel shaped Manifold pipe side, No rims No shelves or other accommodations for a gasket other than a smear or a High temperature sealant
Well I the mystery of the exhaust leak has another chapter, first chapter written and read.
Chapter 2 as Chris Rock once said
THAT AIN'T RIGHT the flange snapped off
so today with the car plenty high enough I went armed with all suggestions, and this what was found the Collector is Supposed to be a welded part of the Manifold and it's not.
So now I'm sure I can find a replacement Left side Factory tube style exhaust manifold so I can keep my totally factory exhaust and do a swap out unless there's a short header that is Direct bolt up.
Odds are I will just pull the manifold and have the flange welded back on.
Last edited by s carter; Apr 11, 2025 at 06:36 PM.
Exhaust question for the masses
