New noise - is this ok?

[rivcokid]

Hi all - after we replaced the manifold-to-engine gasket on my stock 31 Fordor, the car now has a very throaty sound to it, both idling and under load. Generally, the car runs fine, but this sound is very noticeable and quite prevalent at times, mostly under load. Is this normal? It seems to be coming from the area of the manifold, towards the rear.

I'm including links to two videos - one is the car idling with me opening the hood for better sound, and the other is one of me driving to show how pronounced the noise is.

I'm still too new to this to know if this is normal, too much, or what is the issue.

Thanks as always!!

https://youtube.com/shorts/j_v5VRyROzE

https://youtube.com/shorts/v4XGizK433Q

[Brentwood Bob]

Is it leaking around the clamp?

[Gary WA]

Originally Posted by rivcokid

Hi all - after we replaced the manifold-to-engine gasket on my stock 31 Fordor, the car now has a very throaty sound to it, both idling and under load. Generally, the car runs fine, but this sound is very noticeable and quite prevalent at times, mostly under load. Is this normal? It seems to be coming from the area of the manifold, towards the rear.

I'm including links to two videos - one is the car idling with me opening the hood for better sound, and the other is one of me driving to show how pronounced the noise is.

I'm still too new to this to know if this is normal, too much, or what is the issue.

Thanks as always!!

https://youtube.com/shorts/j_v5VRyROzE

https://youtube.com/shorts/v4XGizK433Q

or cracked.

[Ordsgt]

Use muffler cement on the pipe connection and you will get a good seal. Have also seen the exhaust header warped at #4 so a good seal is not obtainable

[Brentwood Bob]

I have smoothed the receiving surface of the intake manifold with a file, and refined the end of the muffler with a ball pean hammer to improve the mating up. Also check that both halves of the clamp are assembled correctly. I held the muffler in place with a floor Jack.

[rivcokid]

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We inspected both the manifold and the muffler and saw no cracks.

It has been tightened three times - both the muffler/manifold connection and the gasket nuts

Muffler cement was used in the joint, but not the copper exhaust seal.

[Lawrie]

I know its a few bucks, BUT, replacing the manifold ,pipe and clamp you will have a nice leak free exhaust,.
Lawrie

[nkaminar]

I am guessing that the manifold to exhaust pipe connection is leaking. This is a really hard place to seal. Hammering with a ball point hammer may have distorted it. When you use the jack to make the connection, leave the clamp a little loose and take the jack away. Then wiggle the exhaust pipe while you tighten the clamp. The jack can cause the connection to not line up correctly and cause a leak. Use some kind of high temperature sealant at the connection. Do not use the copper gasket at the manifold to exhaust pipe joint as the gasket can leak.

[Gary WA]

Originally Posted by nkaminar

I am guessing that the manifold to exhaust pipe connection is leaking. This is a really hard place to seal. Hammering with a ball point hammer may have distorted it. When you use the jack to make the connection, leave the clamp a little loose and take the jack away. Then wiggle the exhaust pipe while you tighten the clamp. The jack can cause the connection to not line up correctly and cause a leak. Use some kind of high temperature sealant at the connection. Do not use the copper gasket at the manifold to exhaust pipe joint as the gasket can leak.

loosen the rear clamp too

[Gary WA]

If its leaking around the clamp or manifold gasket you will see black after driving ' That is your leak. Never had a leak by taking aluminum foil fold about 4 layers to about 3/4" wide, once muffler and manifold are lined up by using jack wrap foil around the two surfaces and install clamp keeping foil aligned.Tighten clamp, rear too. No need for gaskets pipe dope etc.

[JayJay]

I use Permatex Muffler and tailpipe sealer between the pipe and the manifold. Thin coat inside the bell of the pipe, press the pipe to the manifold with the jack, wipe off squeeze out with a finger, then install clamp. Works great.

[Big hammer]

Is the clamp on correctly? Large opening on the manifold, smaller opening on the pipe

[CT Jack]

I agree it sounds like the pipe to manifold is leaking. If the noise just started the cause is most likely due to movement in the pipe at the manifold. As indicated by others I use a liberal bead of red RTV on the inside of the pipe flange. Then slowly raise the jack and align the pipe as central to the manifolf flange as possible Then engage the clamp, lower the jack, and tighten the clamp fully.
I would also use a small mirror and inspect the exhaust manifold gasket for signs of black marks on the block. This would indicate a leaky exhaust gasket which will produce a similar sound.

[rivcokid]

Thanks for the tips everyone. I didn't think the sound was correct. We did use the muffler sealant but apparently not well enough. I like the foil trick - may use that instead. Off to the garage this weekend!!

Thanks again

[Planojc]

You should be able to see any leaks around the flange from under the car. Look for black soot.

[rivcokid]

** UPDATE ** - Hi all - well, I took the clamp off and it was full of soot and the back bolt had quite a ring around it, this despite using some muffler seal recommended in many places. So, I tried the foil method mentioned by Gary WA and Voila! It worked like a charm! The car is quiet now like when I first got it!

Thanks again everyone for coming through!!!!

[Gary WA]

Originally Posted by rivcokid

** UPDATE ** - Hi all - well, I took the clamp off and it was full of soot and the back bolt had quite a ring around it, this despite using some muffler seal recommended in many places. So, I tried the foil method mentioned by Gary WA and Voila! It worked like a charm! The car is quiet now like when I first got it!

Thanks again everyone for coming through!!!!

Thanks for update also the foil will seal once driven making even a better seal.And if it sticks above cut off for a cleaner look