Exhaust manifold gasket leaking

Scoopy G

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Hello gents, My exhaust manifold is leaking on the driver side. I can hear it tick on startup, and I've used the old rubber hose stethoscope to isolate the spot. When it warms up, the ticking stops, but I'm thinking that I smell exhaust fumes in the cabin.

So what is the method of replacement for this issue? Will the manifold bolts back out without shearing off? Can I even access the manifold bolts without having the car on a lift?
Does anyone want to buy a '67 Newport Custom? I joke of course.

Any help will be appreciated.

Rich in Tampa, where it will be 75 degrees and sunny tomorrow!
 
Hello gents, My exhaust manifold is leaking on the driver side. I can hear it tick on startup, and I've used the old rubber hose stethoscope to isolate the spot. When it warms up, the ticking stops, but I'm thinking that I smell exhaust fumes in the cabin.

So what is the method of replacement for this issue? Will the manifold bolts back out without shearing off? Can I even access the manifold bolts without having the car on a lift?
Does anyone want to buy a '67 Newport Custom? I joke of course.

Any help will be appreciated.

Rich in Tampa, where it will be 75 degrees and sunny tomorrow!

Mopar did not use exhaust gaskets on 383/440 engines, the head ports and exhaust manifolds are a machined surface the did not need a gasket. There is a flat style gasket on the manifold exit where it hooks to the header pipe. If your leak is at one of the exhaust ports on the head, likely the manifold studs have stretched from repeated heating and cooling. Usually if they have done that, they will break off if you try to remove the fasteners. You would probably be better served to just leave it alone as you will probably need to remove the heads to replace the studs.

Dave
 
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Mopar did not use exhaust gaskets on 383/440 engines, the head ports and exhaust manifolds are a machined surface the did not need a gasket. There is a donut style gasket on the manifold exit where it hooks to the header pipe. If your leak is at one of the exhaust ports on the head, likely the manifold studs have stretched from repeated heating and cooling. Usually if they have done that, they will break off if you try to remove the fasteners. You would probably be better served to just leave it alone as you will probably need to remove the heads to replace the studs.

Dave
Are you sure about the donut for a '67? My '68 has flat manifolds (HP manifolds) and I know the log manifolds are flat as well (now I'm wondering).
 
Are you sure about the donut for a '67? My '68 has flat manifolds (HP manifolds) and I know the log manifolds are flat as well (now I'm wondering).
You are right flat gasket for '67- '68, I will fix the post

Dave
 
Hello gents, My exhaust manifold is leaking on the driver side. I can hear it tick on startup, and I've used the old rubber hose stethoscope to isolate the spot. When it warms up, the ticking stops, but I'm thinking that I smell exhaust fumes in the cabin.

So what is the method of replacement for this issue? Will the manifold bolts back out without shearing off? Can I even access the manifold bolts without having the car on a lift?
Does anyone want to buy a '67 Newport Custom? I joke of course.

Any help will be appreciated.

Rich in Tampa, where it will be 75 degrees and sunny tomorrow!
Rich, is the exhaust system hanging properly? I've had issues with the pipes sagging and the head pipe not lining up correctly, and have had gaskets blow out until everything was straightened out.

You won't know about the bolts until you try. After the engine warms up it may be easier.

You should be able to get to the bolts with the car on the ground, they're easy to get to.

If you have shouldered bolts, which I think you should, they do make replacement sets, so if you have to get a replacement for you can.
 
Just my two cents having tried most exhaust manifold gaskets, copper spray, as well as the no-gasket approach...Cometic MLS exhaust manifold gaskets are fantastic.
 
Big blocks have studs in the head and nuts tighten the log down.
Keep in mind the nuts are a fine thread and the studs that go into the heads are coarse thread.
The outer end studs are "wet" and go into the water jacket so have a drip tray handy,some coolant, and thread sealant.
If the stud comes out with the nut,replace it with just a bolt roughly same length and thread pitch as the head-kinda cheat that way without having to remove the log.
However,in a "perfect world" best to remove the log and replace any broken studs.
Once the manifold is off, double nut the stud to extract it from the head--if you have enough threads!!
Double check the manifold for any cracks,replace if cracked.
You can get stud and nut kits for your 383 no problem.
Mancini Racing Exhaust Manifold Stud
Mancini Racing Standard Style Nut
As mentioned,the factory does not use gaskets between the exhaust manifold and head.
People used cheap parts jobber gaskets in the past and they tend to blow/burn out.
I use these gaskets on the BoaB..
No leaks and no more burnt valve cover gaskets!!
http://www.moparaction.net/
For Mopars: Big-Block Heat Shield EXHAUST GASKETS Upgrade Charger Cuda 383 440 | eBay
Hope this helps.
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boab 2018 006.JPG
 
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When we got our '66 Newport in the fall of '67, with 7100 miles on it, it had a "tick" on the rh side of the engine. Even when it was hot, but only on acceleration, then it got quiet at cruise. The rear exhaust nut just needed about a 1/4 turn to tighten it back up. When it happened again, years later, just a little wrench action was all that was needed to snug it up and make it quiet again. Seems like the rear nuts are more prone to this that the other ones?

As noted, the factory did not use gaskets between the cyl head and exhaust manifold. Although the aftermarket does make such things, if desired.

I think I'd first soak in in a good penetrating oil for 24 hours, repeat, and then carefully tighten the nut just a bit. How easily the nut might move can tell you if the stud has stretched or if the nut just loosened. Probably might not take more than 1/8 to 1/4 turn, I suspect. Doesn't need/tolerate much more than about 35 lbs/ft torque, similar to a spark plug. Might have been that way for a while, just not noticed?

Just some thoughts,
CBODY67
 
Thank you guys. As Derek with Vice Grip Garage would say "Well I'll be dipped". And CBODY67 is on the right track! Here's what happened just in the hour since I posted this.........

After I posted this topic, I went on youtube to see what videos were available to address the removal of the exhaust manifold bolts (or nuts in my case, as CBARGE correctly points out). I watched a couple of good videos, very informative. I then went out to the compound to have a look at how difficult it would be to access the nuts. I got out the shop light and the mirror and started looking around. When I got to looking at the very last bolt, it caught my eye, as it looked....well....loose! And this is the flange that is leaking, closest to the firewall on the driver side. I grabbed a socket and extender and sure enough, as impossible as it seems, the last nut was finger loose. It just seems impossible that a rusty manifold nut could back itself out that far, but damn if it wasn't loose. SO, I tightened down that nut, and it's neighbor (which was also slightly loose), and voila!, the exhaust leak is fixed! I'm not big on conspiracy theories, but.....

Now I am wondering if it isn't sabotage. I had a shop do some work on the exhaust system a few months back. The manifold leak started around that time, but it would seal up when the engine got warm, so with everything else going on, I figured I wait to take it back there, since there was a 2-year warranty on their work. THEN, there appeared to be a loose hanger, and I could hear a pipe banging on the floor under certain conditions. So I did take the car back, the guys put it up on the lift, then informed me he'd fix the issues, but now there was a gas leak at the tank, so he'd need to drop the tank and repair the leaking fuel hose before he could do any exhaust work. I didn't doubt that, the car is 53 years old, right? But I didn't have time that day, so I made an appointment for the next week. MEANWHILE, over the weekend (last weekend) I jacked the car up, slid under, and observed that there was in fact NO GAS LEAK, and nor was there any evidence of one ever. AND, if there were any leaking fuel hose, it would not require that the tank be dropped. I knew if the tank were dropped, the strap removal probably would start a leak, and then he'd be trying to sell me a replacement tank and labor for $500.

SO, (sorry for the long story), I took the car back at the appointed time, they got it on the lift, and before I could tell the guy I was wise to his gas leak ruse, he calls me into the bay to show me the gas leak! I lost my ****. It was obvious he'd pushed on the rubber fuel line hard enough to cause it to start dripping. I was blind with rage. I told that SOB I knew exactly what he was trying to pull. As he was taking the car off the lift, I informed the guy in the waiting room that these guys were crooks, and I left. I fixed his leak that same day with a 6" piece of fuel hose and 2 clamps, done deal.

NOW, with the most accessible nut on the manifold finger-loose, I can't help wonder if those jokers didn't back that nut off, assuming I'd return for another $500 clip job. And this isn't the first time I've had a muffler shop come into the waiting room and tell me I had a gas leak. The first time about 10 years ago on another classic car. Once under that car, I saw it was a drain plug leaking, so I grabbed his wrench, tightened the plug, wiped the nipple, and told him to keep going.

The moral of the story is..... these muffler guys don't seem to have any morals!! I swear I am going to install a lift at my compound so I don't have to put up with these crooks any more. Thanks again fellas for all your help with these posts, it is most appreciated.

Rich
 
Although sabotage is plausible, not unusual for the flange bolts to back off especially after having exhaust work done.
 
Just curious, were there any shiny areas on the exhaust nut, from recent wrenches being there, before you re-torqued it? Just curious.

Did you also maintain the continuity of the ground between the fuel tank sending unit and the chassis section of the fuel line? Such that the fuel gauge still works properly after you replaced that fuel line section? Just curious.

Glad you got the exhaust "tick" fixed.

Enjoy!
CBODY67
 
Glad you got it licked.
If the shop did not use locking nuts,or lock washers,or Loctite,they will back off.
Happened to me with my TTi system..
cell phine may 26 2018 036.jpg
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Hello gents, My exhaust manifold is leaking on the driver side. I can hear it tick on startup, and I've used the old rubber hose stethoscope to isolate the spot. When it warms up, the ticking stops, but I'm thinking that I smell exhaust fumes in the cabin.

So what is the method of replacement for this issue? Will the manifold bolts back out without shearing off? Can I even access the manifold bolts without having the car on a lift?
Does anyone want to buy a '67 Newport Custom? I joke of course.

Any help will be appreciated.

Rich in Tampa, where it will be 75 degrees and sunny tomorrow!
WHAT BRAND OF GASKET DID U USE? WAS EVERYTHING CLEAN& straight?
 
Then have the manifold refaced so it is flat.

IMHO, if it's warped that bad, you're going to blow out the gaskets anyway.
jegs has3 gaskets for the bb mopar 2 r 100% copper & A fel-pro campsite1 but i think i will have to use the fel-pro it fits my log manifolds i only have the part # of what i ordered from jegs the fl-pro # is37460025 &v the stock fit all copper gasket # is 555210555 they make a bigger one its a match to the mr gasket al copper but i dont have the jegs # for their brand . i have had really good luck with jegs butter than summit (all they have is fel-pro & them gasket . my cousin used the fel-pro on his 70 440 six pack cuda & the bigger mr gasket all copper one on hs 73 satilite sebring + i hope this helps u all
 
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