Noob Installs a Manifold Gasket . . .

[NC Tom]

almost.

 

As usual, I dove feet first into something I know little about. What I have read here really is the extent of my experience/knowledge about MJs. Having said that and while I am not finished, installing a manifold gasket IS difficult, but completely doable for a non-mechanic. IMO.

 

I had to stop because I need a few extra pieces, I didn't expect to need, to finish.

My biggest concern is actually getting it all back together correctly. I think that will be a more difficult task than the removals. You have to remove and disconnect A LOT of things. I tried to keep a photo record of items removed, but I'm sure I missed some.

 

I have been fortunate so far as none of the manifold nuts/studs/bolts were seized or broke. All came off nice and easy. Which brings me to another point. For anyone who has been refusing to check their intake/manifold bolts, like i was, DO IT!!!!! I had a few that were actually just hanging on. Not even finger tight! While I still needed a new manifold gasket, my MJ running problems are likely due to the very loose bolts.

 

The only issue I am having is removing the exhaust pipe from the manifold.  I can't tell if the bolts are welded to the manifold? The nuts underneath are completely rusted and won't budge. I'll be cutting the bolts off unless someone here has another option.

 

 

 

 

[ratrapp]

Pretty sure they're studs installed in the manifold.They shouldnt be welded.

[Strokermjcomanche]

Normally I get a small cut off wheel and cut the bolt in between the manifold and the head pipe. Those bolts are spline pressed in and will come out with an air chisel or ball joint press.

[Salvagedcircuit]

Those are pressed in studs. They look like this:

You will have to cut the heads off then tap them out.

 

[ratrapp]

An easier fix would be to just knock out the studs and just replace them with regular nut and bolts if the studs arent readily available.

[cruiser54]

What's the issue? Nuts hard to remove?

 

If so, spray that area with Freeze-Off first. You may be pleasantly surprised. 

[NC Tom]

On 5/22/2023 at 6:03 AM, ratrapp said:

An easier fix would be to just knock out the studs and just replace them with regular nut and bolts if the studs arent readily available.

I ended up adding new bolts. I had to drill, cut, grind, twist and chisel the old ones off. I swear they were welded. I had to drill new holes in the header!

 

And it's all back together but still runs a bit rough. Not as crappy as before. Idles really well, but adjust the throttle and it begins to cough a bit and the engine has a surging sound. I tightened the intake bolts as best I could. I may have a vacuum leak I cannot find. Another odd thing was I sprayed some carb cleaner in the TB and the truck shut off? I can spray and rev, but it will shut off without revving.

Any Ideas.

[NC Tom]

On 5/21/2023 at 7:49 PM, Strokermjcomanche said:

Normally I get a small cut off wheel and cut the bolt in between the manifold and the head pipe. Those bolts are spline pressed in and will come out with an air chisel or ball joint press.

Did that some. My cutoff wheels were a bit too small. Mostly I cut with a RotoZip. That took some serious finagling!

[NC Tom]

On 5/22/2023 at 8:02 AM, cruiser54 said:

What's the issue? Nuts hard to remove?

 

If so, spray that area with Freeze-Off first. You may be pleasantly surprised. 

 

I would liked to have tried this, but I serious doubt it would have worked! This thing was uglier than Nancy Pelosi!!!

 

 

[cruiser54]

I thought that would be impossible. 

[ratrapp]

its not odd that it cuts off spraying cleaner down the tb at idle.its simply getting too much fuel and not enough air.

[NC Tom]

7 minutes ago, ratrapp said:

its not odd that it cuts off spraying cleaner down the tb at idle.its simply getting too much fuel and not enough air.

Oh. My mistake

[ratrapp]

Did you ever reinstall your original unmodified cps and just hard wire it?Once again if it ran fine before go back and look at your previous repairs.

[NC Tom]

On 5/27/2023 at 12:32 PM, ratrapp said:

Did you ever reinstall your original unmodified cps and just hard wire it?Once again if it ran fine before go back and look at your previous repairs.

Nope. I know I should have when I had the engine half taken apart. I even thought about it. Dang it!

[ratrapp]

DId you try removing the o2 sensor out of the pipe and seeing if it runs better?You could have clogged the cat up when it was running so bad.If it revs up fine with the o2 removed then you know the cat is clogged up.Thats something easy to check and eliminate a possibility.

[NC Tom]

4 minutes ago, ratrapp said:

DId you try removing the o2 sensor out of the pipe and seeing if it runs better?You could have clogged the cat up when it was running so bad.If it revs up fine with the o2 removed then you know the cat is clogged up.Thats something easy to check and eliminate a possibility.

I don't have a catalytic converter. Should I unplug the O2?

[cruiser54]

No

[Eagle]

47 minutes ago, NC Tom said:

I don't have a catalytic converter. Should I unplug the O2?

 

The O2 sensor tells the injectors how much fuel to inject. Don't unplug it.

[ratrapp]

If you don't have a converter that rules that out.If you have an o2 sensor thats stuck either full rich or full lean it'll run like crap.When you unplug it when its cold it will go to neutral usually and tell you if its the problem.

[NC Tom]

29 minutes ago, ratrapp said:

If you don't have a converter that rules that out.If you have an o2 sensor thats stuck either full rich or full lean it'll run like crap.When you unplug it when its cold it will go to neutral usually and tell you if its the problem.

I don't understand. I have two guys saying don't unplug it because it will run bad and your saying unplug it cold. If I unplug it cold will it not run bad? What will that tell me? It's already running bad.

[ratrapp]

I worked for a jeep dealer from 96 thru 02 so i do have alittle experience working on 4.0 jeeps.If you unplug and it runs better then look at the o2 sensor,if it runs the same then its probably doing its job.I'm sure you don't have access to an obd 1 scanner to verify if its working right or not so this is the easiest way to do it.

[NC Tom]

2 hours ago, ratrapp said:

I worked for a jeep dealer from 96 thru 02 so i do have alittle experience working on 4.0 jeeps.If you unplug and it runs better then look at the o2 sensor,if it runs the same then its probably doing its job.I'm sure you don't have access to an obd 1 scanner to verify if its working right or not so this is the easiest way to do it.

No Obd 1 scanner. Thanks for the clarification. I wasn't suggesting you didn't know what you were talking about. I had conflicting suggestions.

 

So, ultimately it will run worse without the O2 Sensor, but temporarily may run better?

[ratrapp]

If it runs better unhooked then thats your problem.If it runs the same then probably not.Unhooking an o2 sensor won't suddenly flood or lean out a vehicle.I worked on a toyota tacoma that idled like it had an oversize cam in it.Fuel trim was crazy numbers.I unhooked it and within 15 seconds it idled smoothly and i drove it around 10 miles.I replaced the o2 sensor and ran fine.I'm trying to give you as many suggestions as possible but not being there to see it all any of us are doing is giving you opinions and best guess's.

[NC Tom]

23 hours ago, ratrapp said:

If it runs better unhooked then thats your problem.If it runs the same then probably not.Unhooking an o2 sensor won't suddenly flood or lean out a vehicle.I worked on a toyota tacoma that idled like it had an oversize cam in it.Fuel trim was crazy numbers.I unhooked it and within 15 seconds it idled smoothly and i drove it around 10 miles.I replaced the o2 sensor and ran fine.I'm trying to give you as many suggestions as possible but not being there to see it all any of us are doing is giving you opinions and best guess's.

Turns out the O2 wasn't plugged in. Plugged it in and no change. I let it warm up and no change.

[ratrapp]

Thats one less thing that it can be then.Have you actually tried to drive it yet?