[Repair] Exhaust Manifold Replacement Guide

DailyDrivenTJ.com · Posted: Thu May 08, 2008 9:35 pm Post subject:

[Repair] Exhaust Manifold Replacement Guide
The Most Comprehensive Guide Available on the Internet!!

<Original> - Written in 11.6.2006
<Revision 1> - Click on the image to see the enlarged version!
<Revision 2> - 4/18/2008: Bigger Thumbnails.
<Revision 3> - 4/22/2008: Minor Spell Check and GearWrench Information Added.

Introduction

Believe it or not, this is my 3rd exhaust manifold swap and 4th manifold! If you own a Jeep, this is one of the things you will HAVE to replace. People look into replacement with life time warranty, namely Borla and Banks performance headers. While they might offer the warranty and some performance gain, they will probably crack too. That was exactly my case. Of the 3 other manifolds that I have gone through, 2 were Borlas. I was getting tired of replacing the headers every two years. This time it only lasted about a year.

One thing with the header cracking is, it just occurs so gradually you won't even realize you have it. Symptoms of cracked exhaust header include: engine making diesel engine like noise, loud engine noise coming under the hood and lack of power with loss of MPG. Little cracks tend to quiet down once things are warmed up making it harder to diagnose.

I confirmed the leak when I was treating the engine with Seafoam. Cracks aren't easy to visually confirm, specially when it is installed on the Jeep.

So I was debating, I could either replace the header with the Borla's replacement or try something else. I decided to try eBay version with expansion joints built in. The reason I chose the eBay over Borla is that there is an inherent problem with the one piece design. The root of the problem is the big long pieces of metal pipes that extended to different directions which are ultimately welded to a single point. When these pieces get hot, they start expanding, pushing, pulling, and ultimately twisting each other. However, they are all welded tight. Something has to give to relieve the stress of the expansion. It is usually the welding that gives. All three of the previous manifolds had crack at the welds. Whlie the eBay version of the manifold is still one piece, but it has the provision built in for the heat expansion, expansion joints. These joints will expand and contract when it gets hot and cold, relieving some of the stress caused by the heat deformation.

This is how eBay exhaust manifold showed up.

Tools and Parts Needed

Basic Socket Set with Extensions (Ratchets too!)
Flexible Head Gear Wrench (This made the job go so much faster!)
Exhaust Manifold (eBay, $60-$80)
LocTite
Copper Spray for manifold gasket
OEM Manifold Gasket

Job Hours
Takes about 2-6 hours.

WARNING
You are dealing with engine's exhaust and intake. This is a job where you cannot do half of a job, get tired in the middle, have left over parts when you are done, or overlook a step or two. Read over this entire guide several times and understand each step and what it takes to complete this replacement/modification. BY NO MEANS, this guide line is error free.

I will not guarantee or take responsibility of the ill outcomes/consequences and/or any process involved.

Procedure

1. Here we go! Remove the negative battery cable. Take a good detailed picture of the engine bay. It can save your some headache if you forget which connection went where. Make sure you got all the parts you need to complete the install without having to make a trip to the part store. This can also help you focus.

2. Remove the air tube since this will be on the way. Loosen the straps on both end of the hose.

3. Pull the vent hose from the hose end. Remove the hose from the engine bay.

4. Remove the vaccum hose from the brake booster.

5. Pull the plastic line from the rubber piece. Then remove electrical connections shown.

6. First loosen the throttle and the cruise control cables from the plastic retainer clip. Remove the metal cable holder. On the next picture, remove 3 connections from the throttle body sensors and 4 bolts holding the throttle body. Move the throttle body out of the way. YOU DO NOT NEED TO REMOVE ANY CABLES ATTACHED TO THE THROTTLE BODY.

7. There are two connections that need to be removed. They are sort of hidden from the view. I marked them with arrows.

8. We are going to remove the connections to fuel injectors. These are electrical connections. Make sure you don't cross them, mark them if you want to be safe. Also on the fuel line (black hard line) is held on the intake manifold via 4 bolts, make sure you remove them. YOU DO NOT NEED TO DISCONNECT ANY FUEL LINE!

9. Now the fuel line and the injectors are ready to be removed as ONE unit. Give it moderate pull, it should pull out pretty easily. Make sure the hard line is free of any other attachments with exception of the fuel line!

10. Make sure all of the O rings are accounted for. The first picture shows injectors with no O ring and the second one shows O rings attached. Clean them with some rag, remove all the foreign material.

11. We need to free the pulley of the power steering pump so it can be freed from the intake manifold. Loosen the tensioning pulley as shown on the left, then loosen the bolt shown in the second picture. This loosens up the belt and allows you to rotate the power steering pulley to gain access the mounting bolts through the holes in the pulley. Remove the top two bolts and one on the bottom holding the power steering pump to the intake.

12. Remove this piece from the intake manifold. This is located near the driver side fender above the wheel. Finally, the intake manifold is ready to be removed from the engine bay!

13. Bolt locations are shown in below 4 pictures. Remove the bottom bolts first! Assuming that you are swapping out your factory manifold, yours will look different from mine because Borla header is pictured here. However, the bolt location is the same.

14. The intake manifold is ready to be removed. The picture on the below shows how it looks removed. It is not heavy.

You can see how dirty the intake is. I just did Seafoam treatment about two weeks ago. I doubt this gunk formed during last two weeks.

You can see the intake valves!! You can see how dirty the port is too!!

15. Here is a shot with the intake manifold removed. Remove the bolts that are holding the collector tube to the down pipe.

You can see where the crack is. It is amazing how little of a crack can cause such a big noise.

16. You can see the pictures of the manifold gasket. On TJs, the intake and the exhaust gasket is one unit. There is specific manifold side, be warned. Also notice the thickness of the different gaskets. Near the port area, the both gasket get thicker. I opted to use the Chrysler gasket instead of the eBay version. A bad gasket will cause leak and remember that is the entire reason why you are doing this whole operation! Try using quality gasket. Notice the difference in thickness. OEM is thinner overall!

17. Every time when I swapped the exhaust manifold, I used the gasket dressing on the new gasket. It helps spreading heat evenly across the gasket and sealing minor grooves to seal the mating surface better. It also dries tacky. I also found the old gasket did not stick to the mounting surface since I used the gasket dressing last time; it left very little residue to be cleaned up. DO NOT USE GASKET MAKERS LIKE RTV ON THIS GASKET!!

18. Clean the mounting surface with a carburetor spray and a scrub. Make the mounting surface as clean as you can. Otherwise you are risking the leak! You can also take some paper towel and clean the intake a little. Notice the "side" marking on the third picture.

19. Place the gasket in place.

20. Now place the gasket for the exhaust manifold which goes on the collector. *Borla headers does not require one of these. This creates round surface where the down pipe can attach to and move around.

21. Start bottom bolts for the manifolds as shown. I had to do this because there is no room for my hands to squeeze in once the exhaust and intake manifolds are in place. However, there is just enough room for the wrench to clear towards the bolt. IF you are installing Borla, this step won't be necessary. You will be able to get to all the bolts directly from the bottom since it gives you a lot of spaces to work with. This is one thing Borla did a great job on.

Now, if you like buying new tools, here is something you can buy and make this portion of the job much easier.

It is called GearWrench with Flexible Head. Now it offers the clearance of the regular boxed wrench with the convenience of the socket on a ratchet. You don't have to reset the wrench with every turn on nuts or bolts any more with this! I noticed I started using these a lot lately.

22. Place the intake manifold. Make sure they go between the mating surface and the bolt. There are also two dowels that the intake must mate on. The location of the dowel is shown in the picture below.

23. Install the top bolts and torque them down as shown below.

24. Remake these connections.

25. Reinstall the power steering pump (20ft.lbs) and the belt. Put a right tension on it. You can ball park by put some tension on it and try to rotate the belt at the longest part and it should not exceed 90 degree rotation.

26. Reinstall the fuel injectors and the fuel line. Secure the fuel line with the bolts you previously removed. Remake all the electrical connections to the injectors. If you are not sure which connections are going where, I hate to tell you but you are screwed.

27. Reinstall the throttle body and remake all the electrical connections.

28. Make sure you reconnect these!

29. Reinstall the air hose and tighten up the clamps. YOU ARE DONE! Retorque all the bolts after a few hundred miles.

Disclaimer

I tried my best to document as much as possible along with pictures. I hope you find them useful. However, do use the information provided here "as-is". DailyDrivenTJ.com or the author does not warrant or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, or process disclosed. Use the information at your own risk.