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Old 07-06-2013, 10:57 PM   #1
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Intake/Exhaust manifold torque specs?

1989 4.2. My Haynes manual says 10-25lbs, but I have read other places that different bolts have different specs. Does anyone know what is correct and the bolt numbers? Thanks in advance.

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Old 07-07-2013, 12:08 AM   #2
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Column one is "Service set too" torque
Column two is "Service recheck" torque

Do you have the torque sequence?

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Old 07-07-2013, 07:09 AM   #3
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I so not have the torque sequence
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Old 07-07-2013, 09:14 AM   #4
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I should add that I just put in a MC2100 carb. While the carter was off I had a couple of loose bolts causing a vacuum leak on the intake. The loose bolts felt like they were slightly more than hand tight. So I set the torque wrench to 22ft lbs to make sure everything was to spec and now I have black smoke pouring out of the manifold somewhere. I haven't fine tuned the carb yet so its rich. I don't know if I always had the exhaust leak or if I created it torquing down the three loose bolts I found.
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Old 07-07-2013, 10:52 AM   #5
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Quote:
Originally Posted by Cashcrazy View Post
I should add that I just put in a MC2100 carb. While the carter was off I had a couple of loose bolts causing a vacuum leak on the intake. The loose bolts felt like they were slightly more than hand tight. So I set the torque wrench to 22ft lbs to make sure everything was to spec and now I have black smoke pouring out of the manifold somewhere. I haven't fine tuned the carb yet so its rich. I don't know if I always had the exhaust leak or if I created it torquing down the three loose bolts I found.


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Here's the sequence. You may want to pull those manifolds and check to make sure they aren't warped and you have no broken bolts. A fresh gasket is always nice too.I just replaced both of mine when I put the new motor in.
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Old 07-07-2013, 12:17 PM   #6
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I am going to start pulling the manifolds this evening. Sooner or later there will be nothing left to replace at the pace I am going.

I really appreciate you sharing this info.
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Old 07-07-2013, 06:58 PM   #7
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I got all the bolts from the intake and exhaust off and have it pulled loose. My power steering pump has had a slow leak so ill probably go ahead and replace it since I have it all unbolted. Tomorrow evening I am going to disconnect the coolant hoses, wiring, etc from the intake and pull it completely out for a thorough inspection. The bottom bolts were a real PITA to remove.

All of this is happening for my quest to have a smooth idle.
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Old 07-08-2013, 08:11 AM   #8
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Does anyone have any secrets for tightening the bottom bolts? I used a long extension, a wobble joint, and accessed them by going under the intake. I'd love to know if there is an easier way.
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Old 07-08-2013, 08:40 PM   #9
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I guess I will keep this thread going with my progress.


I removed everything and now I have a couple of questions. First, the pic below is the exhaust manifold. Is this a crack and needs replaced or a common sight from years of heat? If this needs replacing has anyone purchased lately? I am looking for the cheapest option to get it running. It has broke me...



Last questions for now.... Can someone explain what purpose the metal flex hose that runs from the exhaust manifold to the air cleaner serves?? Also the metal tube on the intake below the carb that connects to the exhaust manifold.
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Old 07-08-2013, 08:56 PM   #10
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Answers

The flexible hose from the exhaust manifold to air cleaner is a preheated hose for when the engine is cold. The exhaust to under the carb is the EGR bypass tube. If you have to get smogged you need it. And yes your exhaust manifold is cracked.

I'd suggest replacing it with headers, but mine have been a royal PITA.
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Old 07-08-2013, 08:58 PM   #11
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Metal hose between manifolds is the EGR tube.

Flex hose is a preheated hose. It allows the engine to pull some warm air in. I've talked to guys who have been in extreme cold and had the carb ice up because that hose was disconnected. Doesn't serve too much of a purpose in warm environments. It's part of emissions here in California.

And that manifold may be able to be welded but that's just buys some time. You want to make sure it's not warped if its warped you may as well replace it. Not too expensive.
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Old 07-08-2013, 08:59 PM   #12
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Quote:
Originally Posted by sfhusser View Post
The flexible hose from the exhaust manifold to air cleaner is a preheated hose for when the engine is cold. The exhaust to under the carb is the EGR bypass tube. If you have to get smogged you need it. And yes your exhaust manifold is cracked.

I'd suggest replacing it with headers, but mine have been a royal PITA.
Guess I should of read before I typed
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Old 07-08-2013, 09:40 PM   #13
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Thanks for the info. The cheapest new manifold I can find is at jcwhitney for $70. Does anyone have experience with their cheap cast iron manifolds? Are they truly OEM quality?

Also, I found the reason for the exhaust leak... There was no gasket on the exhaust manifold.
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Old 07-08-2013, 10:15 PM   #14
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Not all manifolds have gaskets. Some are machined surfaces that are sealed by carbon. I'd run a gasket. And $70 sounds good but not sure on the quality. I paid $40 for a used one.
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Old 07-08-2013, 10:36 PM   #15
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A 2.5l you can use the straight cast manifold no problems. But for the 4.0 you need to look at the replacements that have the flex part where they usually crack.

Good replacement instead of the cheapest and do it once.
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Old 07-08-2013, 10:44 PM   #16
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Joker, what do you mean by flex part? Are you referring to where the flex hose connects?
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Old 07-08-2013, 11:30 PM   #17
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You have the 258 4.2l correct? I think Joker misread your post. The 4.0l 242 has a flexible portion built into the manifold. Not really an option for our motors.
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Old 07-09-2013, 02:48 AM   #18
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Yes I have the 4.2
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Old 07-09-2013, 09:38 AM   #19
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I found a used and the cheap new manifold for about the same cost. I am a little worried about the quality of the new manifold, but also know the used one is 20+ years old and could crack. Any opinions on that? Since it's a cast iron manifold I guess it's a roll of the dice for which will last the longest. I have been a small block chevy man for the last 15-20 years and never had a manifold crack. I have pulled several sets from engines sitting under a tree for years and still never had a cracked one. Maybe I have been lucky and this Jeep is making up for it. Was the 258 manifold prone to cracking? I found a lot of threads about others with the same issue.
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Old 07-09-2013, 10:06 AM   #20
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Is there a warranty on the new one? If so if go with that one. And yes the Jeep inline motors are prone to manifold cracks.
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Old 07-09-2013, 10:44 AM   #21
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One year, unlimited mileage warranty. No name brand on it, I assume it's cast in Mexico.
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Old 07-12-2013, 07:31 PM   #22
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I found one at rock auto dot com for 55.00 oem specs
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Old 07-16-2013, 08:27 AM   #23
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I am ready to start putting this back together. I took my time and cleaned the mating surfaces very well. I picked up the FELPRO MS90949 gasket set and have a couple of questions. The set came with a gasket that is fiber on one side and metal on the other and a regular fiber gasket for the intake manifold. The metal/fiber gasket covers the entire mounting surface on the block for the intake and exhaust manifold. Is the fiber intake gasket supposed to be installed on top of the metal/fiber gasket? That's how I plan to install, but wanted to make sure the gasket set didn/t come with an extra gasket for a 4.0. I have also read the debates on sealer or no sealer on these gaskets. My plan is to install dry unless someone talks me out of it. The PO used a sealer on the last intake gasket and it leaked. Thanks in advance.
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Old 07-16-2013, 09:04 AM   #24
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Just use the one big exhaust gasket. That gasket has the same part number all the way back to 1970 something. Some older applications didn't use the exhaust gasket, just the intake. Again use the one big gasket and do not use sealer.
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Old 07-16-2013, 10:03 AM   #25
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Thanks for the response. I was worried that stacking the two gaskets would create more opportunity for leaks. When I took it all apart the intake had a fiber gasket and the exhaust manifold was mounted directly to the block with no gasket. I hope to have this bolted up this evening.
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Old 07-16-2013, 12:03 PM   #26
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If the head and manifold surfaces are freshly machined you an run no exhaust gasket and that's why it includes two. I found that the intake gasket hit the exhausts bifold and wouldn't lay flat on the head. I just went they this about a month ago. I used the big gasket that seals both and haven't had any leakage.
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Old 07-16-2013, 02:12 PM   #27
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1989 models:

Nos. 1 and 2 = 30 foot pounds
Nos. 3 through 12 = 23 foot pounds
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Old 07-17-2013, 08:55 PM   #28
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I had a productive evening on the Jeep. The manifolds are bolted up and torqued properly. I ran into one problem with the EGR bypass tube(tube that connects the exhaust to the intake manifold). Twenty four years of heating and cooling on the exhaust manifold welded the threaded part to the tube. I let it soak in PB Blaster overnight with no luck. Now I am on the search for another one.
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Old 07-18-2013, 01:08 AM   #29
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Any luck finding the tube? I hear they're getting hard to find.

You may have to loosen up those manifolds to install the tube. The manual says to finger tighten the tube to both manifolds, tighten manifolds to correct torque then tighten down the tube. This prevents the tube from twisting and cracking.

I hang the exhaust manifold by the studs(finger tight), then install the tube on the exhaust manifold. Next hold intake in place and start the threads on the tube. Install and torque all bolts then snug the tube down.
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Old 07-18-2013, 08:20 AM   #30
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I sent a couple of emails and am waiting on a response. The problem is that there is no finger tightening the exhaust side with my current tube. I put heat to it and was able to get it spinning again, but I still need a wrench on it because its hard to turn. I sprayed it out with carb cleaner and then a PB Blaster bath. That helped, but still too much friction for hand tightening. I guess this evening I will take it all back apart, which I really didnt want to do. Then install the tube on the exhaust manifold and reassemble.

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