Can a bad intake manifold gasket make my exhaust really loud?

Are you guys talking about this piece? (see photos) When I replaced the exhaust manifold on the passenger side last November it was connected between the exhaust manifold and intake manifold. When I reassembled it I couldn't get it back on so I just inserted a screw in each manifold where the holes were. The noise wouldn't be coming from there, would it? Also, I made a short video of how loud the exhaust is from under the hood. Thanks again for the help....

https://www.youtube.com/watch?v=MHJtow9y4qU

 

Sound travels, have you rolled under the car to locate noise? Still think it is the muffler or piping connection somewhere.

The pic is your choke heat tube to pull the choke off after warming up. It went to the carb choke device.

 

That tube (choke stove) in the photos does supply heat to the choke thermostat. But, only fresh air travels through it. No exhaust gas goes through there.
I found trouble getting my old choke stove to work again. I bought a Dorman after market choke stove.

No the channels we're talking are cast into the intake manifold.
I cant find a decent picture, all my books are packed up for my move tomorrow

 

I just (listened) watched the video...
I'm guessing you got duals,
so it's not the "Y" pipe. (that's exactly how mine sounded when it needed a "Y" pipe)
I'm pretty sure the leak is ahead of the muffler(s)

I'm understanding why your asking about the intake manifold. You may be on the right track.
Can you reach your hand between the valley pan and intake manifold at the front of the engine?
Maybe you could feel if there is a leak under there

 

Some disassembly required: remove the carb and you should see the exhaust track at the base; remove the intake manifold and look at the bottom. You may find your leak, but at least you will understand the exhaust crossover. I thought about taking mine apart, taking detailed pictures and writing a details explanation --- I got over that thought real quick.

 

Smiley,smiley,like,like!

 

What I noticed is you have TWO things sounding like are going on. 1st. is it sounds like the timing is RETARDED, hence the "POP" from the carb. 2nd.quit messing around & pull the intake. It will be easier than replacing the exhaust manifold. Then you will know POSITIVELY. All this fouling around the job could have been DONE ALREADY!!!!!

 

Here's the top of a 322 head.
the smaller rectangular openings are the exhaust crossovers

the larger squares are the intake ports

 

I already replaced the passenger side exhaust manifold because I thought that was where the noise was coming from. It's still loud so there's $300 wasted plus 3 days in the garage in 20 degree weather last winter.

I discovered a long time ago that it's a lot easier to take things apart than it is to put them back together. I had a '37 Packard several years ago in which the left front brake drum locked up. I don't know anyone around here who is a decent mechanic so I called a "mechanic" on Craigslist. He came over and tried to fix it but couldn't but it still cost me $100. Then I started asking questions and posting pics on the Packard website and after 3 weeks finally fixed it. That's happened several other times but I'm not going to get into all of that here. My point is I don't want to disassemble it and then not be able to reassemble it. There's no proof that the intake is even the actual cause of the loud exhaust. If anyone knows anyone in the Louisville area who is familiar with old Buicks please let me know. Thanks....

 

I am waiting to hear you say that you have been underneath the car from one end to the other to look for that leak.

 

Take pictures when you are removing the intake, then use them as a guide for reinstalling the intake

 

Yes I have. The car only has 7,000 miles on a complete resto and has a very nice stainless exhaust system on it....

 

Are you 100% sure that the problem is with the intake? I already put rags all the way around the manifold and they didn't budge when I revved it up. How can I be sure it's the intake before I go through the ordeal of removing it?

 

Remove it!!!!

 

You know if you drive an old car, no matter how good of shape it's in, you are gonna have to expect to get your hands dirty. You asked for advice as evidenced above and people here with experience have given it to you. I think it's time you $#!+ or get off the pot, to put it bluntly.

I know doing work you are not that familiar with can be daunting, but being on this forum you have some of the most knowledgeable people around who are your friends. Plus you surely have guys wherever you live that own and maintain their own cars to ask for help if needed, it's not rocket science on old cars, just plain ol' common sense. You may not be able to tackle rebuilding a motor, but taking off the intake manifold and reinstalling it is not that difficult.

So grab a wrench and let's get busy!

BTW, I watched your video http://www.youtube.com/watch?v=MHJtow9y4qU and it is pretty loud. The noise is definitely coming from the engine compartment, so I would say the guys who suspected the intake manifold are spot on. Also those roads looked familiar, I used to live in Vevay, Indiana and worked in Carrollton, KY for 19 years. I've traveled that stretch of I-71 from Carrollton to Louisville many, many times over the years.

 

The nice thing with a Nailhead is that you aren't going to get wet. There are no water jackets to worry about. It's an easy job, should take about 10 minutes and 2 beer. Shoot a photo with the aircleaner off showing everything that's hooked up. Carefully remove the wiring plug from the carb, noting which colour went to which post, and then pop the throttle linkages off at the carb. Move them out of the way. Disconnect the coil wires,(noting which colour to what pole) vacuum hoses or lines, the fuel line at the carb and the choke line from the exhaust manifold. Starting at the centre of the manifold and proceeding in a square pattern, (left to right) loosen the bolts holding down the manifold working from inside to the ends. They're at about 40 lbs if memory serves me correct, so loosen them a turn or two at a time, don't just take them out. Once all the bolts have been backed off, remove them and do one last check to make sure the carb and anything on the manifold is disconnected. The coil may have to come off, remove the two anchoring bolts holding the bracket down to the manifold, don't try and unscrew the bracket tensioner bolt, it'll probably snap or strip the head out. The distributor doesn't have to come out, so don't loosen it or back it off. Work around it. Carefully remove the manifold and the carb as one unit, lift it straight up to prevent gas from spilling out. Once out of the car, then you can turn it over and look and see if the plate or plug is burned through. Try not to smoke (if you are a smoker) when doing this, because if you do a leaky exhaust will be the least of your worries. Liquid gas isn't explosive, but the vapours sure are. For best results, photograph each step prior to you taking it apart, that way you'll have a record in reverse.

Insure that you have new gaskets on hand prior to doing this job. Photograph the old gaskets in place, then match up the new ones and place them in the same orientation. When it goes together, do the steps in reverse. You can use silicone on the gasket faces, but I never had much luck with it, so on my car it went on with spray "max-tac" and that was it. No leaks on mine yet.

The best thing you can do for your car is to get a copy of the service manual and /or a Chilton's or Motor manual from the period. These books are indispensable when it comes to easy tips, torque specs, and pictures. They're easy to read and are easy to follow. I got my first one when I was 16 and that is how I learned how to do auto mechanics. Well, okay, I also hated walking, so that was a motivator too.

Hope this helps, Good Luck!

 

I took the plunge. I wasn't too worried about being able to remove it. I took several pics and attached some below. Is that square hole in the bottom where the exhaust leak may be coming from? Do I need to replace that plate on there? Also, do I need new gaskets? The ones on it now are metal and appear to be in good shape. Thanks to all you guys for the encouragement so far....

 

Yep, I would say that is it. And I would replace the intake gaskets also while you are at it.

Can't explain it any better than that. Good luck.

 

So I need to buy a rebuild kit which consists of a gasket for that bottom plate and two intake gaskets? Would NAPA or Advance Auto Parts have it? If not where should I get it?