Exhaust to header bolt issues

[MolassesHill]

The nuts holding the header and the exhaust downpipe together keep loosening.

I've tried old rusty bolts with old rusty nuts, old bolts with new nuts, new bolts with rusty nuts, new bolts with new nuts, various types of lock washers, using two nuts per bolt and still loosen.

I can't get a drill in to use a cotter pin. I could spot weld it but it would be very difficult to grind the spots off should I ever need to drop the exhaust. I wasn't aware of a locktite product that would hold under the heat of the exhaust system.

Any suggestions?

 

[73CJ]

Have you tried the metal style lock nuts? Not Nylocs.

 

[jamie]

what about locking header bolts from a company like jegs or summit? i used some on my bronco a few years ago, and i have had no problems.

 

[MolassesHill]

Yes I've tried those nuts and had the best luck with them holding. Never tried the nylon insert ones, I figured they'd melt rather quickly.

 

[MolassesHill]

Locking header bolts, hadn't tried them yet. Thanks!

 

[IOPort51]

lock washers??

 

[MN CJ7]

How do how to torque up the CJ intake & exhaust manifold

Not mentioned yet.... but the AMC 258 i6 / 4.2l Manifolds are long long long and love to loosen up and cause issues. NOT to mention you have a early CJ with a cast iron intake and exhaust manifold. Are you still using the cast manifolds.. those puppies weight 75#. Something that heavy is going to shake if not installed correctly.

The manifolds need a premium gasket. The alumium intake uses a different gasket set than the cast iron manifolds. They are not interchangeable.

Once all the bolts are screwed in. Hold the manifold up and try to hand snug the bolts. do it a few times. Gently snug up the center bolts adn work you way out to the ends in a circular pattern. Go slow and then snug up a bit more...... SNUGING UP THE MANIFOLD BOLTS A BIT AT A TIME TO REACH THE TORQUE SPEC OF 23fT# IS VERY IMPORTNT.....use a torque wrench once past the first snug up. Start in the center of manifold and circle pattern is true for manifolds, valve cover, oil pan.... and important when you have such a long engine.

Torque value is 23 ft# (alum and think cast same)
I like the idea of the lock washers... not sure if I used them or not.
I did use antiseize on the bolts..... heck put antiseize on everthing CJ

 

[Cheepjeep85]

Re: How do how to torque up the CJ intake & exhaust manifold

he's not having problems with the manifolds to head, anyhow he also has a 4.3 v6 not a AMC 258 i6 / 4.2l so that isn't even gonna be a problem. check these folks out World's Best Locking Fasteners & Locking Nuts and Bolts STAGE 8

 

[MN CJ7]

Re: How do how to torque up the CJ intake & exhaust manifold

he's not having problems with the manifolds to head, anyhow he also has a 4.3 v6 not a AMC 258 i6 / 4.2l so that isn't even gonna be a problem. check these folks out World's Best Locking Fasteners & Locking Nuts and Bolts STAGE 8

sounds like you are correct.

But... the manifold to head also holds the intake and exhaust together when intalled. so still have doubts.

Solution... then find some soft metal and make a washer so that it can fold over the edge of manifold and then fold up another part of the shaped washer sheet metal so that it is flat against one face of nut and do one for the bolt.

The alternative is a high temp thread lock... max temp of 500F or maybe as low as 400 should do
Permatex Red High TEmp 450F max will work
10 mil bottle is #27210

OR both locktite and flex metal folder over on flats of both the nut and bolt.

Make sure your exhaust pipe is supported and is not adding to your manifolds comming apart.

 

[Cheepjeep85]

But... the manifold to head also holds the intake and exhaust together when intalled. so still have doubts.

no it doesn't a 4.3 is a v6 the intake bolts on top of the motor against the top side of the heads, in the "valley", and the exhaust bolts to the bottom side of the head like a small block chevy. The 4.3 v6 is in a sense a 350 with the back 2 cylinders removed.


Sent from my DROID2

 

[DHugg]

The nuts holding the header and the exhaust downpipe together keep loosening.

I've tried old rusty bolts with old rusty nuts, old bolts with new nuts, new bolts with rusty nuts, new bolts with new nuts, various types of lock washers, using two nuts per bolt and still loosen.

I can't get a drill in to use a cotter pin. I could spot weld it but it would be very difficult to grind the spots off should I ever need to drop the exhaust. I wasn't aware of a locktite product that would hold under the heat of the exhaust system.

Any suggestions?

Airplane fixers, where having a nut loosen and a bolt fall out is REALLY bad news, drill a hole in the nut margin and another through the bolt threaded end, and twist safety wire through the holes. MILSPEC bolts are made that way in certain system areas. Might be a PITA to drill 'em yourself, but a specialty house might could source them for you.

 

[73CJ]

Safety wire will do the trick. They make a jig to drill the nuts with a .062 drill. Not too expensive. At Safety Wire Nut Drill Jig

Locktite will never work. You use heat to break it loose. . . .

 

[MN CJ7]

Re: How do how to torque up the CJ intake & exhaust manifold

Permatex Red High TEmp 450F max will work
10 mil bottle is #27210

Exhaust temp measured with optical temps read in the 260 to 350F and in the 400 range on the shared port center on the AMC 258 i6 / 4.2l . The V6 will not share ports will be in the cooler range... and the

manifold to pipe connection will be cooler and is external fasteners on a ring clamp mechanism. Snugg up evenly add a second nut with the high temp locktite.

The external stud and the second nut will be even cooler and on a external ring..

The high temp locktite... it can take 450F for operational temp... would most likely see temps in the 250-350f range. For normal exhaust it should be fine... RACE Car ye than the exhaust will be 500 but not the passenger cars.

The part # above is not std blue and red locktite is a special high temp that I looked up in the permatex appl guide. Nice to look before saying it will not work.

Also suggest a grade 5 or 8 so no using pot metal fasteners. Consider using a finer thread count. The detent nuts also work pretty good try to apply once since they deform threads some. Use the high temp locktite on #1 and #2 nut.

Ck the exhaust support and the motor mounts to make sure operation is not adding more than normal stresses. If you have the ring collars I have in mind and on many exhausts manifold to pipe. The collars do not bottom out and use some of the spring energy in the collars to take up play in the heat & cool cycles. If they were over torqued and really went after they will be bent and bottom out on each other. Bent up collars may not keep the tension on the fasteners that keep the nuts from loosening up. HT Locktite would keep the second nut from rotation if if the tension of the collar/fasteners is realeased. The bent up collars could also possible leak exhaust. If the collars are all bent up straighten them up or fix and torque up to the field service torque specs.

I have never seen one of these loosen up repeadly, something is being missed.

Fred



coule even
bend the bolt with a punch/chisel and hammer so the nut cannot back off. Use a longer bolt for leverage.
OR....Can use a pipe or old deep well socket of the fastener with long ext and might work to bend the bolt a bit. A nut cannot back up on a bent bolt