Leaking exhaust

[Bryce Mcclintock]

Hi guys , ive had to replace the exhaust gasket between manifold and exhaust pipe twice now on my 52 plymouth . Bith times it worked fine for a while then they both ended up leaking and cutting a piece out if gasket is there a trick to putting these in yo stop this happening ? Ive  een told this point in exhaust is renowned for leaking .

[maddmaxx1949]

Is there any chanceit is not flat or has a low spot? Maybe try draw filing both flanges til you get a nice smooth shiny flat surface. Can't say on if there is maybe a shellac or liquid product you could put on it to get a better seal. Someone else on the forum probably has a good idea.

[DJ194950]

Was the manifold/s  checked for flatness?

 

Intake and exhaust manifolds set on separated and tightened down  and  slowly pulled in? Bolt between intake/exhaust tightened together last?

 

DJ

[Bryce Mcclintock]

No its not where its bolted to engine its the outlet of exhaust mainfold to exhaust pipe where its leaking 

[kencombs]

Both mating flanges must be flat and mate with no gaps.   Once you get that to happen add the gasket. 

[Sniper]

Best Gasket gets good reviews here, they show flange gaskets for your application.  PN 4073 and 4074, you can't buy direct so I included a link to a vendor.

 

https://hagensautoparts.com/plymouth/28-engine-gaskets/5927

[DJK]

14 hours ago, Sniper said:

Best Gasket gets good reviews here, they show flange gaskets for your application.  PN 4073 and 4074, you can't buy direct so I included a link to a vendor.

 

https://hagensautoparts.com/plymouth/28-engine-gaskets/5927

Didn't Hagens close up shop? I used 2 gaskets with muffler sealer, so far so good.

[Sniper]

Hmm, well if Hagen's closed up their website is still online, I dunno

[busycoupe]

what do you mean by "cutting a piece out".  Do the exhaust gases blow a hole in the exhaust donut gasket?  If so, then there is somthing wrong with the way the pipe is seating into the manifold.  Check the end of the pipe and how it slides onto the manifold, then fit a new gasket on it. The pipe should extend past the gasket slightly.  Then make sure that flange bolts up squarely and securely to the manifold.  I suspect that your exhaust pipe does not line up squarely to the manifold.

[Plymouthy Adams]

insert an inside sleeve/liner here or if fitted to the pipe already it is in good repair....

[greg g]

You can also double up gaskets or go to the hardware store get a piece of brass flat stock and make a replica to add to the new one.  You Could also get a couple of the spring style exhaust bolts add some sealing paste to the mix and don't over tighten. You are bolting steel to cast iron which have different expansion and contraction rates so the connection actually needs some slack to accommodate the different movement.

 

https://www.amazon.com/Permatex-80335-Muffler-Tailpipe-Sealer/dp/B000BOAZM8/ref=asc_df_B000BOAZM8/?tag=hyprod-20&linkCode=df0&hvadid=312147482150&hvpos=&hvnetw=g&hvrand=7066428950796512983&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9005090&hvtargid=pla-435208118337&psc=1&tag=&ref=&adgrpid=65039680554&hvpone=&hvptwo=&hvadid=312147482150&hvpos=&hvnetw=g&hvrand=7066428950796512983&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9005090&hvtargid=pla-435208118337

[Dodgeb4ya]

As mentioned the pipe should extend 1/2" up into the manifold as originally designed.

Also the original flange was approximately 1/2" thick steel not 3/8" typically supplied today in the repop market.

Without the pipe extension into the manifold and the thinner flange steel which curls when tightened both cause the gasket to leak.

[kencombs]

8 hours ago, Dodgeb4ya said:

As mentioned the pipe should extend 1/2" up into the manifold as originally designed.

Also the original flange was approximately 1/2" thick steel not 3/8" typically supplied today in the repop market.

Without the pipe extension into the manifold and the thinner flange steel which curls when tightened both cause the gasket to leak.

Yes to all of that.  Especially the thin flange part.  I've seen a lot of cases in the past where guys used extra thick gaskets or double gaskets and tightened them really well, thinking that was the fix.  Just makes things worse as the thick gasket compresses at the bolt location and bends those thin flanges.  Better to start with a really good flange to flange joint,  and correct gasket.   If the old flange is bent already it can be straightened with heat.  Lots of heat, cherry red.   Then, file or grind to finish it.

 

Most any gasket will work if the fit is tight to begin with.

[DJK]

On 6/27/2021 at 8:26 AM, Sniper said:

Hmm, well if Hagen's closed up their website is still online, I dunno

Sniper, called them yesterday, they are barely hanging on, inventory is almost gone, doors were supposed to be closed back in April.

[Dodgeb4ya]

Yes it's true...Darrel the owner closed it up....older and retired.?