Exhaust Manifold Bolts... Revisited

[Marshmountain]

Ok, I'm planning on pulling my exhaust manifolds this coming weekend to replace the gaskets, and to drill out and retap 2 broken bolts. I know from prior posts, that the bolts needed are as follows:

J4004538 3/8" (four)
J4006311 5/16" (eight)

I would like to get everything in advance, so my time in the frigid weather can be spent working outside, not driving around in the comnfort of a warm car chasing down proper length bolts...

so what length/pitch/etc do I need for the 3/8" and 5/16" bolts? I will be going with grade 8 and using lock washers.

Thanks in advance.

Peter

[Marshmountain]

anyone???

[Joe Guilbeau]

Check out the Allen Head Stainless Steel version of those units, just take the existing bolts down to a Bolt Supply shop and they should be able to match them with Allen Head in Stainless Steel.

Looks cooler and you can better torque them down with a Allen Head Ratchet on you trusty Craftsman 3/8-inch drive ratchet.

Use some anti-seize on them an all will be well.

[mdill]

Lock washers are a waste of time on exhaust systems
they loose temper due to the heat, same with grade 8
bolts, grade 5 is fine. I don't have the lenght
spec, but do remember the thread pitch is NC.
Do not crank down on the outer 5/16 bolts the
manifold has to move in relation to the head due
to the vast temp differents between the watercooled
head and the no cooled manifold, so the manifold
has to expand in relation to the head, and move
under the out side bolts, as it goes though hot-cold
cycles. Just snug them up, and then check snug them
up a few more times in the weeks after you do the
job.

Mike D.

[tgreese]

Marshmountain -
-Grade 8 is overkill IMO - Grade 5 is fine unless the Grade 8s are cheap or free. I hear that Tractor Supply is a good source for Grade 8 bolts, if you feel that you need them.
-Use anti-sieze paste for reassembly.
-You've read prior posts about redrilling in situ I presume.
-I believe they are all 3/8"-16 - if there are any 5/16" bolts, they'll be 5/16"-18 (USS).
-If it were me, I'd pull off both manifolds and use the old hardware as samples to buy the new stuff. Use flat washers too if that's what's there now. Either that or I'd wait for warmer weather - the weekend is supposed to be warmer.
-The exhaust manifolds didn't have gaskets at all from the factory. You can buy aftermarket gaskets, but if the condition of the manifold-to-head mating surface isn't good, they won't seal for long.

Not exactly what you asked, but I hth :cool: Tim

[Marshmountain]

Thanks all, have been putting this off, but the noise and the fumes are finally motivating me to do it.

Appreciate all of the advice.

Peter

[fitron74]

marshmountain,
There are torque specs for these bolts in the Haynes manual as well as the proper tightening sequence to use for snugging the bolts down.It worked fine for me when I changed my manifold gaskets 2 yrs. ago. No problem with leaks.
Fitron74

[Marshmountain]

Thanks all, have been putting this off, but the noise and the fumes are finally motivating me to do it.

Appreciate all of the advice.

Peter

[Rich 89 Gr. Wag]

How about driving your nice quiet Jeep to Boston and doing my exhaust gaskets? -6 degrees this morning, man that's cold.