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Exhaust manifold replacement advice

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Old 04-13-2018, 11:33 PM
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Default Exhaust manifold replacement advice

Hey guys - so I'm gearing up to replace my exhaust manifold and I've never done one before so I was hoping to get some expert advice.

I'm replacing the front pipe as well while I'm at it.
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My questions are:
1 - Hardware - should I replace it or reuse the old fasteners?
2 - Vacuum lines - are there any tricks or pitfalls with disconnecting these that I should be aware of. They seem very fragile and I'm worried about breaking them. If I do, how hard is it to replace? (Could I use rubber hose, etc.)
3 - The FSM mentions that the fuel line quick disconnect o-rings should be replaced, but other sources indicate that they are not replaceable. The couple write-ups I've seen make no mention of it. What's the deal and if I should replace them does anyone know the part number?
4 - Torquing the bolts. The FSM indicates they should be torqued in order - is this number 1, then number 2. The FSM had a grouping box so I just want to be sure that they mean literally 1 first, 2 second. I'm assuming you get everything hand tight and then do a turn or two on each in the correct order and repeat until the proper torque is reached.

I think that's it, but I'll add any further questions I come up with. Please also jump in with any advice that might be helpful.
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Old 04-14-2018, 07:26 AM
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Originally Posted by PatHenry View Post
1 - Hardware - should I replace it or reuse the old fasteners?
They are just nuts and washers, so not a big deal either way. But if they are at all suspect, for the few bucks involved, replace. The labor to do it over is not worth taking a chance.

Originally Posted by PatHenry View Post
2 - Vacuum lines - are there any tricks or pitfalls with disconnecting these that I should be aware of. They seem very fragile and I'm worried about breaking them. If I do, how hard is it to replace? (Could I use rubber hose, etc.)
If you get one that is stubborn, warm it up well with a blow dryer. If you have a heat gun, use it very carefully, as it's easy to melt rubber and plastic with one of those.

Yes, you can replace with rubber hose.

Lube with dielectric grease as needed to reassemble. Don't use any kind of vegetable oil. It polymerizes when exposed to air, and creates varnish. You will basically be gluing the hoses in place. Not good.


Originally Posted by PatHenry View Post
3 - The FSM mentions that the fuel line quick disconnect o-rings should be replaced, but other sources indicate that they are not replaceable. The couple write-ups I've seen make no mention of it. What's the deal and if I should replace them does anyone know the part number?
Hmm... I seem to remember replacing them, but I don't have a record of a part number.

This thread might help.




Originally Posted by PatHenry View Post
4 - Torquing the bolts. The FSM indicates they should be torqued in order - is this number 1, then number 2. The FSM had a grouping box so I just want to be sure that they mean literally 1 first, 2 second. I'm assuming you get everything hand tight and then do a turn or two on each in the correct order and repeat until the proper torque is reached.

Correct.
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Old 04-14-2018, 07:52 AM
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FYI. Manifold bolts use conical washers that allow for expansion/contraction. Reuse or replace but I would not substitute for flat washers.
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Old 04-14-2018, 09:22 AM
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why are you disconnecting the fuel line?
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Old 04-14-2018, 09:48 AM
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Originally Posted by s346k View Post
why are you disconnecting the fuel line?
You beat me to it.

And, remove the air cleaner assembly to allow better access.

Let me know how using a torque wrench works for ya.....

Use the sequence for sure. But getting a torque wrench up there? Ha!!

I've never used one there.
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Old 04-14-2018, 11:26 AM
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I torqued the bolts to a setting I found somewhere online, put it all back together and it was idling about 1500 over normal. Tightened them snug using a regular wrench and the idle dropped immediately. Just my experience. Good luck.
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Old 04-14-2018, 11:32 AM
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Originally Posted by esteem View Post
I torqued the bolts to a setting I found somewhere online, put it all back together and it was idling about 1500 over normal. Tightened them snug using a regular wrench and the idle dropped immediately. Just my experience. Good luck.
You have to use an extension, and that screws up the reading....

Been wrenching for 50 years and only used torque wrenches on critical components like head bolts or nuts, crankcase halves, rod bolts or nuts, crankshaft bearing caps, etc.

Never had a failure. The rest I used my internal torque wrench.
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Old 04-14-2018, 01:12 PM
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i am thinking i used a ratcheting end wrench on all but 1 of the bolts. been a couple years since i’ve had that manifold off. but the time is coming as i’m a bit anxious to get that pacesetter long tube and new exhaust on there.
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Old 04-14-2018, 01:46 PM
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Originally Posted by cruiser54 View Post
You have to use an extension, and that screws up the reading....

Been wrenching for 50 years and only used torque wrenches on critical components like head bolts or nuts, crankcase halves, rod bolts or nuts, crankshaft bearing caps, etc.

Never had a failure. The rest I used my internal torque wrench.
Yep I never use a torque wrench except for critical parts on the engine. It's like Eric the Car Guy says; once you've been wrenching for so many years you know how tight stuff needs to be just by hand. I tried using a torque wrench for tires but apparently the wrench was off or the spec was wrong because the nuts came loose
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Old 04-14-2018, 03:13 PM
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On my last XJ I never went wrong with this, especially where there's a differential in the torque for different bolts on the same part:



Numbers from TorkSpec

Jeep 4.0-specific specs

Cherokee XJ-specific specs


The original conical washers are not easy to find and have a purpose I wouldn't trust to flat washers.

My 2
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Old 04-14-2018, 11:56 PM
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One tip I"ll pass on for when you put everything back together. You will need to remove the intake as well. When you put it back together, put the bolts/washers in the hole prior to putting the intake manifold back on. I tried for a long time to to get them in after the intake was in place and got really frustrated. I finally figured out you can put them in and then set the intake manifold on top of them and then start tightening them.
Another tip is to make 100% sure you get the intake onto the cylinder head dowels. If the engine revs up when you start, you most likely missed the intake positioning on the dowels. It can feel like it is in the right place, but actually sitting on top of the dowels.
I have replaced the exhaust manifold on both of my XJs (98 and 99) and was able to reuse the hardware with no issues. I have had the fuel line disconnect off several times on both XJs and have never replaced the orings. I highly recommend getting a fuel line disconnect tool for when you remove it. That will save you a ton of time. I bought the metal set from harbor freight and it has worked great.
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Old 04-15-2018, 06:34 PM
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Originally Posted by cruiser54 View Post
You have to use an extension, and that screws up the reading....

This needs to be highlighted for the young guys who haven't run across this yet.

If you use any adapter, u-joint, or anything like that on a torque wrench, your torque will not be accurate. In fact, it can be pretty far off.

Extensions can be used, but you have to know what you are doing. Your reading will change.

https://www.norbar.com/en-gb/Home/To...ion-Calculator


Here's a pretty good general article.

http://www.hotrod.com/articles/ctrp-...-wrench-myths/


https://duckduckgo.com/?q=can+you+us...&t=ffnt&ia=web
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Old 04-15-2018, 10:00 PM
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Wow, lots of great advice. Thanks guys!

So if I didn't remove the fuel lines, how does that work? Everything I've read indicates you have to take the lines off to get the intake out of the way, plus the gasket is one piece, so both intake and exhaust have to come out, right?
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Old 04-16-2018, 01:06 AM
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Originally Posted by PatHenry View Post
Wow, lots of great advice. Thanks guys!

So if I didn't remove the fuel lines, how does that work? Everything I've read indicates you have to take the lines off to get the intake out of the way, plus the gasket is one piece, so both intake and exhaust have to come out, right?
leave the injectors in the rail pull them out of the intake manifold, lay the entire thing over out of the way. and yes, both manifolds come off.
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Old 04-16-2018, 11:01 AM
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Originally Posted by s346k View Post
leave the injectors in the rail pull them out of the intake manifold, lay the entire thing over out of the way. and yes, both manifolds come off.
Ah, that makes sense.

I think what I'm going to do is hit HF and grab a quick disconnect tool and maybe a few supplemental flex/crows feet tools. Then when I go to do the replacement this weekend I'll have the option to go the fuel line removal route or the fuel injector removal route - whichever seems easier. I like having options.
The fuel lines look similar to the ones I had to disconnect to drop the gas tank on my TJ and I disconnected and reconnected those a couple times without any problem. I guess worst case scenario if I disconnect the lines and they start leaking once I have it back together I can just deal with it then and wouldn't have to redo the entire disassembly a second time.

I'm assuming that once I have the intake off and set aside that I can clean the inside areas of it with Throttle body cleaner, right? For the exterior, I'm thinking that some degreaser sprayed on blue shop paper towels to wipe it down will work - or is there a better option?
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