Xj423

any tips and pointer about getting the old mani off? the bolts are a little rusty what shout I be spraying on them for prep. thinking liquid wrench on em for a week or two once or twice daily would work....
also to be prepared what bolts do I buy if the old ones break....is it any help to just replace them anyway?...

ZINGGG

Penetrating oil for a couple weeks would definitely help. I know Dorman makes a set of bolts specifically for the exhaust manifold.

Xj423

dorman ok thanks. thinking of just replacing all the bolts anyway. why not if I've got the old ones out anyway

XJ-92

let the engine run till the block is nice and hot, then put your wrench on the bolts and turn them out. ofcoarse this way is more dangerous and wear protection. using a penetrating oil should work just fine.

Programbo

I've taken off a lot of manifolds in junkyards and while they may look like the rust will be a problem they are held on by very little torque, maybe 25 lbs., so they break free without much difficulty and once popped they come off easily. As mentioned it won't hurt to spray them down but I haven't even had any not come loose in a junkyard.

5-90

Use a 9/16" "flex" socket (shorty socket with inbuilt universal joint,) to reach around corners, makes the lower rear ones a lot easier to get to!

Penetrating oil of choice will serve.

DO NOT reuse those screws - they're wrecked. Replace with silicon bronze, aluminum bronze, or SAE5 carbon steel. Reuse the bowl-shaped washers, or replace with Belleville spring washers.

The screws are, I believe, 3/8"-16x1-1/2", but I wouldn't swear to it. Check my site (www.kelleyswip.com/tech.html) and the listing should be there. ("I wrote it all down in my diary so I wouldn't have to remember it!")

Screws are generally torqued to 20-22 lb-ft. Don't bother with LocTite - the regular stuff won't hold up to the temperature. #271, I think, is the one you want - it's the one formulated to hold up to exhaust heat. Anything else, don't bother.

I prefer to use copper alloys, as they won't seize against the iron with temperature. Also, they'll do a better job of retaining strength (see my notes on this subject elsewhere.)

You'll probably have a bigger problem taking the collector nuts off - the earlier ones are threaded 3/8"-16, and I replace these with brass. Check the thread before you get replacement hardware - you're probably going to need to go to Fastenal or order from MSC Direct if they're ISO threads (but replace with brass or bronze as well.)

Xj423

great info thanks!

Bossokee

Yeah I wouldn't worry about the torque, the worst part is just getting a wrench on the exhaust and intake manifold bolts. I would let the thing cool off first also so you dont have to worry about leaving any of you skin on the old manifold. Be careful when putting the intake manifold back on - there are alignment tabs that it sets on. I didn't notice these at first and the intake manifold wasnt set properly, when i fired the thing up I almost blew the engine because of the massive air leak... Live and learn, lol

Scott_Sport99

I used ratcheting swivel head wrenches for the lowers and they are the best tool to use for this job. lowes sells the set for $40 lifetime warranty.
I have a link somewhere..brb
https://www.cherokeeforum.com/f51/je...91-98-a-80445/

I used the APN header.

5-90

There should be two (each end) or three (each and and top center) studs there when you take it all down. They probably want replacing as well - I cut new ones from 3/8"-16 brass threaded rod, cut 2-1/2" long and dressed. Any nuts will serve, steel won't seize against brass.

Malik3404

Yea Im about to do the same job, swapping the cracked oem with APN.

I got new bolts and fel pro gasket (apn gasket is flimsy as heck).

Figured Id knock off the motor mounts (brown dog) and oil filter adapter rings.

Everything once same time...

bilzhorse

I don't believe I have ever been told "don't re-use the bolts". If they are in good shape why not re-use them? I have done two exhaust/intake gaskets using the original bolts on two diff. Cherokees with no ill effects.

Malik3404

I dont think I would want to re-use a 20 yr old bolts. But then again my xj was a rust bucket.

The world wont come to a end if you do, but why not replace everything while your in there.

DFlintstone

I'm with you in principal, but exhaust manifold bolts/studs can really mess up your day. Just cheap insurance to not have a headache down the road.

5-90

Corrosion, seizure, gradual annealing of the metal. I have not reused exhaust hardware, if I've had the option.

Granted, I've worked on pretty much everything - which means I've run into more headaches than most. "I don't look for trouble, it finds me with alarming regularity..."

Some screws should not be re-used. Any carbon steel screw that is partially/wholly immersed in water, any steel screw subject to exhaust head, any fastener that locks through a deformed component (Nylon collar, deformed threads,) should not be reused if you have a choice.