Exhaust/intake manifold gaskets

Hammerhead · Post by **Hammerhead** » Sat Mar 07, 2009 11:54 pm

My truck has slowly but surely developed a worsening leak at the exhaust/intake manifold gasket over the last few months. Besides sounding like a baaad Hemi is was also losing power with the vacuum leak. This was the last gasket I had not not changed yet. When the manifolds were removed, I swear the gasket was the original from it's 1959 rebuild. I took sandpaper and cleaned carefully the face of the manifold but noticed there was a slt. uneveness of the face even after working on it. Unfortunately when everything was reinstalled and the ol girl was fired up it still had a leak at the manifold even with the new gasket.
Question: is there some process/treatment for the face of the manifold to make it uniform or should I just start looking for a replacement one (if there is one to be found)? Besides this problem she runs like a dream.
Thanks for any suggestions.

SpookyDad · Post by **SpookyDad** » Sun Mar 08, 2009 11:51 am

The unevenness is on the manifold, not the head, correct?

The manifold has probably warped slightly due to heat. An engine rebuild shop could reface the manifold for you.

Another option is to get a granite block. similar to this one:

http://www.grizzly.com/products/9-x-12- ... hick/G9648

You can use an offcut from a granite countertop as well but check the flatness with a straightedge.

Tape down some fine emery paper. If you have a long piece of granite, some of the rolled stuff works best. Wet the paper and sand the manifold face by moving the manifold back and forth along the granite slab. You might want to get some blue machinist die and paint the face of the manifold first. As that gets removed, the clean spots will tell you where the high spots are. If the edge gets clean first make sure you aren't leaning on that edge when you are sanding. The pressure must be even. Take your time.

Neil

robc · Post by **robc** » Sun Mar 08, 2009 12:12 pm

Normally you will find the 2 centre sections of exhaust manifold are the problem, put a straight edge across the whole manifold, once removed, this will show where the problem is.
Also check the square gasket between the manifolds, this can also blow and ensure locating rings are fitted to inlet manifold/head on assembly.

I did have a manifold machined flat, it worked well.

Rob

Hammerhead · Post by **Hammerhead** » Mon Mar 09, 2009 8:43 pm

Thanks guys for the input. Rob you're right: it's the center two sections on the manifold. I'll find a shop and have the face machined flat. Good driving weather is coming and I want to be ready!! Thanks again!

Ken Blythen · Post by **Ken Blythen** » Fri Mar 20, 2009 6:00 am

Depending on how much material is removed from the manifolds ( this time or previously), it can be necessary to shorten the guide rings or they bottom out in the inlet ports, preventing a good seal at the gasket.

Hammerhead · Post by **Hammerhead** » Sat Mar 21, 2009 5:40 pm

Hi Ken,

Thanks for the tip about the guide rings on the inlet ports. The machine shop told me yesterday the manifold should be ready Monday. Hopefully I'll be able to put it on that night or Tuesday night. I'm anxious to get Nellie running again! I'll give you guys a report how it turns out. Thanks again Ken.

dr deuce · Post by **dr deuce** » Sat Mar 21, 2009 7:17 pm

Depending upon how your machine shop reworked the manifold(s) will determine how you reinstall it.

If they machined both manifolds while still bolted together, then you can bolt them on as it following part of the procedure in the TM.

If they only machined one or they were separated, you need to follow the procedure in the TM by keeping the manifolds so they can move a bit under the carb.

Absolutely make sure that the intake does not get hung up on the rings if that one was machined.

It has been my experience that if you can find NOS, or old gaskets made out of Asbestos, you will be better off then with new made ones.

Hammerhead · Post by **Hammerhead** » Sat Mar 21, 2009 10:13 pm

Asbestos....what would AL Gore say?? LOL. Unfortunately I've got new gaskets. Do you know anyone who sells the NOS ones? FrankCCKW or VOV?

I took the manifolds to the machine shop still bolted together so I assume he will machine both. I'll definitly make sure that both were done. I'll watch to make sure the intake doesn't hang on the guide rings too.

I put a straight edge on the block and it looked straight and even. Pulling the engine would sure put a damper on my Spring!! I'll know more MOnday. Thanks everyone!

Hammerhead · Post by **Hammerhead** » Sat Mar 28, 2009 10:56 pm

Success!! It took the machine shop several days longer than expected to get the manifold machined flat! But it looked great!! I picked it up Thursday and the first chance I had to put it on was tonight. After putting everything back on it sounded perfect! No leaks anymore!! Thanks for everyone's advice!