Manifold bolt question
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More Turbo
Joined: Jun 2015
Posts: 578
Likes: 111
From: New Hampshire
Manifold bolt question
1975 F250 Highboy, 360FE C6, all stock.
I have diligently located and corrected the leaking exhaust manifolds on my truck.
I used NOS manifolds, had the machine shop grind them flat before installation, used Remflex gaskets, FORD NOS steel exhaust donuts in properly formed and sleeved exhaust pipes.
I did reuse the old bolts but they appear fine with no thread damage.
I finally have no exhaust leaks!!
Why cant I keep the manifold bolts tight??
I initially torqued them to 23 FT-LBs as Remflex suggested, but I have to re-torque them so many times in the past month , I'm sure they are beyond 23 ft-lbs now.
Basically after each ride I am able to get a half to almost full rotation on each manifold bold..its almost as though they are backing themselves out.
I like the truck with no exhaust leaks and am wondering if new bolts with locking washers and loctite would do the trick??
Appreciate any suggestions
Thanks
Tbruz
I have diligently located and corrected the leaking exhaust manifolds on my truck.
I used NOS manifolds, had the machine shop grind them flat before installation, used Remflex gaskets, FORD NOS steel exhaust donuts in properly formed and sleeved exhaust pipes.
I did reuse the old bolts but they appear fine with no thread damage.
I finally have no exhaust leaks!!
Why cant I keep the manifold bolts tight??
I initially torqued them to 23 FT-LBs as Remflex suggested, but I have to re-torque them so many times in the past month , I'm sure they are beyond 23 ft-lbs now.
Basically after each ride I am able to get a half to almost full rotation on each manifold bold..its almost as though they are backing themselves out.
I like the truck with no exhaust leaks and am wondering if new bolts with locking washers and loctite would do the trick??
Appreciate any suggestions
Thanks
Tbruz
Lead Driver
Joined: Oct 2018
Posts: 7,826
Likes: 2,339
I love the remflex gaskets on headers. they've held up great in my '76 high boy 428 Cobra Jet . I've never tried them on stock manifolds.
my guess is this, Remflex gaskets are pretty soft and fragile. on headers you have a larger surface area to spread the compression from the bolts. on stock manifolds you don't. so maybe the gaskets are letting things loosen up and back off.
This seems logical to me, but if I'm wrong there is one thing I'm sure of. the stock gaskets work fine and with new manifolds they will seal and your bolts won't back out. I'd put some in and ditch the graphite gaskets. .
my guess is this, Remflex gaskets are pretty soft and fragile. on headers you have a larger surface area to spread the compression from the bolts. on stock manifolds you don't. so maybe the gaskets are letting things loosen up and back off.
This seems logical to me, but if I'm wrong there is one thing I'm sure of. the stock gaskets work fine and with new manifolds they will seal and your bolts won't back out. I'd put some in and ditch the graphite gaskets. .
Lead Driver
Joined: Oct 2018
Posts: 7,826
Likes: 2,339
The only reason they would back out is they're not staying tight. the only reason they're not staying tight is they're getting slack. the only place to get slack is the gaskets. new manifolds + new bolts + graphite gaskets that don't belong .
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,095
Likes: 5,756
From: S/W Missouri, Polk county
Maybe try Wedge lock or Nord lock washers....Fastenall has them https://www.nord-lock.com/nord-lock/products/washers/ I agree with the slack coming from the soft gaskets. And only after you compress all the compression out of the gaskets, then they will hold torque.
A long drawn out, but very good explanation of how the washers work.
A long drawn out, but very good explanation of how the washers work.
Lead Driver
Joined: Oct 2018
Posts: 7,826
Likes: 2,339
I doubt they will stop compressing until they're gone. like I said headers are what they are for .. they will smash out and break up I've done it.
graphite gaskets are great under the right conditions and worthless in the wrong ones.
graphite gaskets are great under the right conditions and worthless in the wrong ones.
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Thread Starter
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More Turbo
Joined: Jun 2015
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From: New Hampshire
I’ve ordered a set of the steel gaskets and will replace the Remflex gaskets at the first opportunity.
Thanks
tbruz
Thanks
tbruz
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Laughing Gas
Joined: May 2006
Posts: 1,140
Likes: 13
From: Port Orchard Wa
Quess it's worth a try, but I've used REMFLEX gaskets with stock manifolds on 390's and a 460 with no problems. Of course, I've also never heard of manifold bolts coming loose without PB blaster, impact wrench and a torch!
Mountain Pass
Joined: Sep 2018
Posts: 136
Likes: 25
For the steel gaskets, will you use Graphite Grease as specified in the factory manual?
Thanks..!
Mountain Pass
Joined: Sep 2018
Posts: 136
Likes: 25
I'm not exactly sure what graphite grease is, but it is specified in the 1975 Shop Manual.
I had the passenger side exhaust manifold gasket replaced last summer at an old school truck repair shop, they used the steel gasket, and coated it with something that oozed out from the joint. Not sure what they used, should have asked.
Tuned
Joined: Mar 2010
Posts: 387
Likes: 25
I use Permatex anti-seize compound that contains graphite. I don't know the technicals of what the graphite does. I suspect that it may help with heat transfer, fill minor imperfections, and possibly provide some degree of rust protection to the mating surfaces. Over time, carbon deposits may also help fill the joint after the graphite has done it's job initially. I have a 1979 F150 (400 engine) with 375,000 miles and it has never had exhaust manifold gaskets installed--no leaks! Manifolds installed directly on the heads seem to stay flat and rarely (maybe never) need machining to true them up.
Many Ford engines did not come from the factory with exhaust manifold gaskets. I can't figure out why so many Ford truck lovers feel the need to install some sort of composite gasket with the manifolds. The 360/390 in our trucks did use a heat shield from the factory which is what Ford called them in the parts manuals (likely the same as the "metal gaskets" that you have). I think you are on the right track with what you are doing by installing the manifolds the way Ford did it originally. Headers are a different story.
Many Ford engines did not come from the factory with exhaust manifold gaskets. I can't figure out why so many Ford truck lovers feel the need to install some sort of composite gasket with the manifolds. The 360/390 in our trucks did use a heat shield from the factory which is what Ford called them in the parts manuals (likely the same as the "metal gaskets" that you have). I think you are on the right track with what you are doing by installing the manifolds the way Ford did it originally. Headers are a different story.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,095
Likes: 5,756
From: S/W Missouri, Polk county
And at least some anti-seize on the bolts. https://www.permatex.com/products/lu...e-lubricant-2/
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
1975 F250 Highboy, 360FE C6, all stock.
Why cant I keep the manifold bolts tight??
I initially torqued them to 23 FT-LBs as Remflex suggested, but I have to re-torque them so many times in the past month , I'm sure they are beyond 23 ft-lbs now.
Basically after each ride I am able to get a half to almost full rotation on each manifold bold..its almost as though they are backing themselves out.
I like the truck with no exhaust leaks and am wondering if new bolts with locking washers and loctite would do the trick??
Appreciate any suggestions
Thanks
Tbruz
Why cant I keep the manifold bolts tight??
I initially torqued them to 23 FT-LBs as Remflex suggested, but I have to re-torque them so many times in the past month , I'm sure they are beyond 23 ft-lbs now.
Basically after each ride I am able to get a half to almost full rotation on each manifold bold..its almost as though they are backing themselves out.
I like the truck with no exhaust leaks and am wondering if new bolts with locking washers and loctite would do the trick??
Appreciate any suggestions
Thanks
Tbruz