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Stock Exhaust Manifold Leaks - LEAK STOPPED!

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
908
On my 302 the left side stock exhaust manifold leaks at the head. I have a gasket on there from a while ago, however it has been so long since I had the Bronco on the road (passed inspection yesterday!) that I don't remember if it leaked before or not.

Anyway I am looking for suggestions on how to tame this leak. It is at the back of left side.

My questions are...

Should I use studs instead of bolts?
Do I need a gasket at all?
Can these cast iron manifolds warp over time and if so can they be planed?

What have you guys done to seal these at the head.

I am seriously out of money on this so headers are not in the card right now. I am stuck with this setup, and I don't mind it as long as I can get this leak sealed up.

Looking for ideas and experiences!

Thanks

Rich

:cool:
 
Last edited:
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Sporto

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
908
I was going to get a pair of header gaskets maybe FelPro's and try them. From what I can see of the one that is on there it does not look like it is high quality.

Any recommendations on brand or type?:

Did not think of the copper permatex though. That can stand up to the heat?

Anything to get this annoying noise to go away!

Thanks
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
Take a good look at the manifold for cracks. I had one that looked like spider webs. Leaked all over and had to be replaced. You will need an exhaust manifold gasket set unless you have the manifold resurfaced. It will come with a couple of donut gaskets for the exhaust pipes.
 

bmc69

Contributor
Bronco Guru
Joined
Jun 11, 2004
Messages
11,891
Header gaskets are the worst choice for stock manifolds; due to the wide (compared to a header) mating surface, the clamping pressure is low. I have always had the best luck using the thin all steel gaskets with the raised compression ridges around each port.
 

Justafordguy

Bronco Guru
Joined
Sep 26, 2009
Messages
6,253
Header gaskets are the worst choice for stock manifolds; due to the wide (compared to a header) mating surface, the clamping pressure is low. I have always had the best luck using the thin all steel gaskets with the raised compression ridges around each port.

X2, I would not use header gaskets. The regular manifold gaskets work much better on manifolds. Pull it off and make sure it's not warped. Just use a long strait edge. Clean the surface good on the head and manifold and then bolt them back on with the stock gaskets. I always just use bolts because studs make it harder to remove but do use anti-seize on the bolts.
 
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Sporto

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
908
ok manifold gasket it is. I see them on the Advance Auto Parts' site, they come with the donuts like BluBuckaroo mentioned. I think that I will opt for these...

I will check the manifold when I have it off. Is it easy to find someone to plane these? I mean like finding someone to turn a flywheel down is not too difficult, would it be the same kind of thing? Is it common?
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
9,069
Loc.
Memphis, TN, USA, Earth, Milky Way
Do I need a gasket at all?
No.
Can these cast iron manifolds warp over time...
They warp from heat-cycling, like most low-grade metals.
...and if so can they be planed?
Yes.
What have you guys done to seal these at the head.
Read these captions:

Is it easy to find someone to plane these? ... Is it common?
Yes, any machine shop with a head planer can throw a manifold on it for a few bucks.
 
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Sporto

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
908
So the chassis grease mentioned in the photo article is the same as in my grease gun? It looks like that same red/maroon color in the pix.

I think that I will check the manifold to see if it is not warped before I do anything...

Thanks a lot everyone. This has been very informative. I will post my results when I get this taken care of!
 

techlaf

Contributor
Sr. Member
Joined
Jun 28, 2008
Messages
692
Steve, great captions to help me understand what to do to fix the situation. I have a similar issue.

Does anyone have pics or links to see even better what some of these "spider" like cracks look like? Steve's pics and captions show small black marks on the manifold indicating a seal failure, but I'd like to see some pics of actual cracks. They seem small, subtle and require a good eye to discern a hairline cracked manifold vs. 40 years of crust.

I can hear my exhaust leak on the passenger side, but I'm having trouble seeing anything wrong when looking. Are there common locations on the manifold (top, sides, bottom) that are prone to crack first?
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
9,069
Loc.
Memphis, TN, USA, Earth, Milky Way
It works the same way - you can't necessarily see the cracks, but you'll see the soot marks emanating from the cracks, making them fairly obvious, even while installed. You can see a fine crack in the face of the #1 journal both in the main view (lower L corner) and in the bottom L frame of this pic:



The trick is getting an angle to see them, and with an eB's welded wheelwells, it's tricky. Look for a lighted inspection mirror; Snap-On/BluePoint sells a good one with 3 LEDs for ~$25. Another trick that usually works for me is to stuff rags into the tailpipe. With the engine idling, any exhaust leaks become noticeable hisses. Ignore any on the muffler(s) or downstream.
 
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Sporto

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
908
I took the manifold off tonight. Did not see any indication of cracking anywhere. I could see where the leak was from the soot on the lower corner of the number 8 cylinder port. I also noticed a lot of gasket buildup on the manifold all around. I had these on and off several times over the years so it probably built up. After scraping, I measured with the straight edge and they seem to be flat, but I think it is worth the time to have them milled at the local machine shop. Just to be sure.

I scraped the ports on the head, and they are free of any residual materials. I am tempted to try the grease like Steve posted. I just don't feel that I am that lucky when it comes to this kind of thing. :( Gaskets just seem like the better way b/c I am dealing with 40 year old hardware, and even if they are planed, I am certain that it will not seal without them. Just my almost 30 yrs of Bronco experience talking here...

I have a set of FelPro manifold gaskets that I picked up and I may go with them. However I have a few days to mull it around.

Thanks again everyone...either way I am sure that I will get rid of the exhaust leak one way or another!

R
 
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Sporto

Sporto

Sr. Member
Joined
Oct 10, 2005
Messages
908
Leak stopped!

Using a long straight edge and a flat file, I filed down all of the buildup that was on the ports. It took an hour or so of filing, but I got clean exhaust ports on the manifold. I then took a razor blade and scraped the ports on the head. There was not much on there to scrape.

I used a FelPro Manifold Gasket and RTV Hi Temp Red, and I got a Motomite stock manifold stud kit. From there I put a bead of RTV on the manifold and a bead around the ports on the head. I bolted the two ends of the manifold on first and then slipped the gasket in between. It lined up perfectly, so I threaded in all of my new bolts. I put Anti Sieze on the threads of the bolts as well. I then tightened down the bolts in a center out pattern until tight as I could get them.

I used the FelPro donut that came with my gasket set and what I do is tape it to the pipe with blue masking tape so it stays seated as I fit the pipe the manifold. I then cranked down the two bolts that hold the pipe and flange on.

Started it up, and all I could hear was the rumble of the Magnaflow muffler...

Beautiful...

;D

Now tomorrow night I need to readjust the clutch linkage.

Thanks again for the help everyone!

R
 
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