How hard is it and what is the procedure to replace the intake/exhaust manifold gasket.

83 4.9l Carb'd

Thanks.

 

Not that hard in theory. You just remove stuff and put it back. The problems come when a bolt breaks off. Soak the exhaust bolts especially with PB Blaster for a few day's before you attempt the job. Have access to a torque wrench for putting it back together. Even a simple Haynes manual would be a big help. Take pic's so you know where everything goes back. Buy good gaskets.

 

Procedure:
1. Remove Air Filter
2. Remove and disconnect all vacuum lines in the way from the carb and manifolds.
3. Disconnect fuel lines and remove carb.
4. Unbolt intake/exhaust manifold.

Reverse to install. Pretty straight forward and not very complicated.

Just be glad you're working on a carb engine and not an EFI, or your job would take 10 times as long.

Personally, the most difficult part I find with replacing the manifold gasket is remembering where all of the vacuum lines go. Most of them are all around where the manifolds are, so almost all of them need to be removed. Get some masking tape and mark the vacuum line you disconnect with where it connects to with corresponding letters. A: A B: B C: C etc. That way you can put it back together easily. Get good tape though, or it'll just fall off, which doesn't help.

The intake and exhaust manifolds are bolted together and they are very heavy. Be sure to be ready for that or you can really hurt your back.

While the manifolds are out, check for warpage (which, if they're leaking, is probably why). Take them down to a machine shop and have them planed. If they're warped, and you put a new gasket on, they'll just leak all over again. Definitely important, or you're just wasting your time.

Several of the bolts don't have a lot of room to work with, such as right behind the carburetor. Be sure that you don't use any extensions on the torque wrench (such as 3/8" to 1/4") and have a shallow socket, or you won't be able to get the torque wrench on them.

Lastly, as stated above, use a good gasket and get a Haynes or Chilton's manual so you can get the proper torque sequence and specs (very important).


Take your time, and be glad you have an I6 with plenty of room to work in.

 

Cool thanks. I'll get to it eventually. I just don't have the ambition right now because it has me pissed off at it from an unrelated issue that seems unsolvable. When i do the IM/EM gasket i will be replacing all the vac hoses because they are ALL shot and not routed properly (thanks PO)

 

Replacing all the vacuum lines with new ones was one of the best things I did for my 300. Night and day difference.

 

Ugh. On an unrelated note i can't get this damn valve cover to stop leaking. I tried a new gasket but apparently it was dried out and broke when i installed it. So i tried RTV and now it's leaking in a different place. Still on the manifold side though which isn't pretty.

Any suggestions to get it sealed properly?

 

Make sure the valve cover isn't over torqued and that the bolt holes aren't mushroomed. If they are, be sure to flatten them back out before putting it back on.
It can be a pain, took me a few tries to get mine to stop leaking. I wish they were made of thicker metal.

 

yeah that would be nice. I'll take another look if it's still leaking after my last bout with it.
gotta wait for the RTV to dry at this point.

when this sucker leaks it leaks BAD. it's like a smoke show opening the hood

 

Thanks Abandoned. Got her to stop leaking finally. I wound up buying a cork gasket (the rubber "upgrade" failed immediately after installing) hammered it flat like you said and used indian head sealer to get er done. Torqued to 5ft lbs and done

 

Awesome! Good to hear. That Indian sealer is nasty stuff, but it sure does the trick.
I had a rubber one too, and it just ripped and mushroomed out. The cork seemed to work much better.
It's so temping to torque them down tighter, but they're just such a light metal simple cover, that all it has to do is put a little pressure on.

Stopping leaks always feels good.

 

Especially considering it was leaking so much oil onto the Exhaust manifold that my engine caught fire 4 times .

But it's a 300 so it still runs great LOL.