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Exhaust/intake manifold bolts

egon

Dunlop Slayer
NAXJA Member
Location
New Jersey
Can these be reused as long as they are not damaged? With the amount of heat cycles they see makes me wonder. Which threadlocker is prefered on these bolts, blue or red? Thanks.

--Matt
 
I've had my manifolds off 3 or 4 times, still using the original fasteners.

I wouldn't use a threadlocker on them. The fasteners are also relatively lightly torqued, only 23-24 ft./lbs. on the 4.0l manifolds.
 
Not only is threadlocker not needed, but the temps that a manifold bolt will see will neutralize any "Loctite"-type anerobic thread locker, as they all fail at below 500 degrees F.
 
AZ Jeff said:
...as they all fail at below 500 degrees F.

Don't you mean fail above 500*?

--Matt
 
If you have the engine out of the vehicle, I highly recommend attaching the manifold back prior to engine install. I just went through this a couple days ago, foregoing my own advise. Took me the better part of the day to torque the bolts in the sequenced stated in the FSM. I was never able to get a torque wrench on the lower right manifold stud (by the firewall), as something was in the way no matter what direction I approached it from. The best I could do was snug the bolt using a universal adapter. This is on an 88 4.0.
 
Kind of an antique mehtode, but copper grease (or copper paste) cooks and makes a bond, the copper keeps it from seizing completely. Old fashioned methode, I`ve used. Imagine there are high tech. alternatives now. Though I did waste some $ on some extremely high temp. grease recently, that didn´t perform as advertised, guess I´ll use it as a preservative on my garden tools.
 
Well...
Whenever I pull an exhaust, I replace the hardware with non-ferrous alloy, to prevent galling and heat siezure. Brass will work nicely (if you can find hex caps or socket heads easily enough,) but I usually end up getting silicon bronze from Fastenal. Retain the steel Belleville spring washers (the little dishes,) as they spread clamping force and promote sealing.

For a threadlocker, I use LocTite #272. It is designed for high heat applications, and it is fairly common for the long manifolds on the I6 to work loose over time without a little help (I've seen this on Big 3 iron as well - it's not peculiar to the AMC six.) You may have to do some looking to find it, but it's worth the effort IMO.

5-90
 
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