AMC Eagle Den Forum
The Mighty 258 => Exhaust System. => Topic started by: blk-majik on January 11, 2013, 07:56:06 PM
-
Howdy all. I'm working on removing the head from my 258, but am having some difficulty getting the exhaust manifold out of the way. It's technically disconnected from the head, but I can't get it separated from the exhaust downpipe to remove it from the engine bay.
I see there's 3 bolts between the manifold and the pipe. There's one big horizontal bolt head on the front of the pipe, and two smaller vertical bolts that clamp the pipe and manifold together. I cant see a way to get the 2 vertical bolts out without removing a bunch of stuff from under the engine. I assume they need to come out, some how? Is there an easier way?
What's the story with the big horizontal bolt? Does it need to come out at all? I've tried turning it and hit it with more penetrating oil that I care to admit, yet it hasn't budged. Instead the corners of the bolt are starting to get rounded off from the struggle.
In a lot of photos I've seen, it looks like people just cut the downpipe in half. I've been tempted to do the same, but once that's done, there's no going back. Why are so many people cutting the pipe?
I've attached some photos to make it clear what I'm talking about. Horizontal bolt = green, vertical bolts = yellow.
Thanks!
(http://i.imgur.com/XckIG.jpg)
(http://i.imgur.com/qODqi.jpg)
-
My knowledge is limited, and i'm sure someone else will be along shortly to correct me but....
I think what you have circled in red in the 2nd picture shouldn't matter. The flange with two bolts should be all that is holding the downpipe to the manifold. If you're not *too* worried about saving the downpipe since it looks pretty rough already, break the bolts loose using a long extension if you have to. They look like they may shear off as it is though. Once the bolts are broken loose (or just broken) a good whack with a hammer should result in two separate pieces.
*EDIT*
Pretty sure what you have circled in red is/was for EGR valve. It's just a plug on yours. Don't worry about removing it.
-
I took these off not long ago and they can be a challenge, and rusty!
Don't be afraid to soak them in a lot of penetrating oil btw
I couldn't get a regular wrench on them due to the lip, and a socket wrench wouldnt fit straight to get a good enough grip to not round off the bolt
I bought a 3/8 inch drive small breaker bar, used a small shallow 1/2" socket and made sure it was on there real good and then wasmable to break them free, they fought me all the way off with small turns, reposition wrench, small turn, repeat several times
You dont need to take off the big bolt
It's a pain but it will come loose eventually
Good luck
Rob c
-
Thanks guys! The plan is actually to do 4.0 head swap, so I'll probably junk the manifold and downpipe, anyway. I think a sawz-all might be my best bet.
Before I commit to that, did you get to he 2 bolts from under the car? The axle is under them, so I dont see a good way to do that without a mess of extentions and swivels. I tried from above, but didn't have any luck. Maybe putting some plywood over the passenger half of the engine to lay on might make it easier?
-
I was able to get them from above, it's a tight fit but can be done
It was one of those times I wished I had an extra set of elbows......
-
I've been able to reach the front one from above, but not the back one. I think it required one swivel, maybe a short extension.
-
For the exhaust nuts I went to autozone and bought a three eights drive socket that had a hex head end on it. After soaking the nuts with pb blaster I put the socket on the exhaust nuts and used a box end wrench on the socket. Worked really well. Installed the new pipe and nuts the same way. Gotta tell ya it sure beat using all these extentions and swivel joints.
-
After soaking in penetrating oil and finding a combination of a six point thin walled socket and swivel and extensions, I have found that rusty exhaust manifold bolts tend to come off with a fight to the last turn! I have always accessed them from under the car. I found it best to try to tighten the nut at first to break it free, then back it off a bit, then tighten it back the same amount, then back it out some more, repeating the process until the nut is backed all the way out. On rusted out down pipes that look like they'll need replacement anyway, I prefer the Sawzall to all that wrenchin.
If you're planning to swap in a 4.o head, you will have trouble getting the stock manifolds to line up on the 4.o head's ports(it can be done, though), and might consider using a 4.o exhaust "header" manifold instead of the stock one, but the 4.o header will be a tough fit with the front axle, unless you modify the front axle's pinion mounting bracket or modify the header. I chose to modify the header, and used a late 80's Renix log-style header, cut off the flange, cut out the section with the EGR tube port, and welded the flange back on angled back to allow the downpipe to clear the front axle's pinion bracket with some creative tubing bending. I have yet to build the downpipe to finish the installation. I swapped in MPI injection, and haven't finished the project, life(other projects and BS) got in the way.
-
Thanks guys, but it looks like I'm gonna have to break out the sawzall tomorrow :) I was able to get the nuts easy enough with a swivel, but ended up snapping both of them. I spend more time than I'd like to admin trying to drill them out. Screw it, the exhaust is rusted to heck anyway, and I need an excuse to practice my welding and pipe bendnig. Custom exhaust, here we come!
Next question: In the first picture i posted, on the bottom right corner there is a really annoying bracket that prevents the exhaust manifold from being removed from a post. It has to go before I can get the manifold out. It appears to be held on by 4 bolts. As with pretty much everything else on this car, it's pretty well rusted. I've already rounded off one of the bolt heads while trying to get it off. Any tips? Whats this bracket for? Can I just take a cut-off to it?
-
Sawzall will solve the issue no problem, I had to do the same. The bracket that you speak of, looks to be the power steering bracket that bolts to the intake, I would not lob that off, it keeps the pump from flexing. Though, if it's the air injection pump bracket, Which would've been in the same general area, **** it, cut it off.
Was wondering if you were still in project or not... :occasion14:
-
It looks like it bolts into the power steering pump bracket, but isn't actually the bracket for the pump. I can't see it being of any use at the moment. However, i'll be a good mechanic noob and use this as an excuse to get some turbo sockets and to practice using my easy-outs
thanks, project got put on hold for a bit when I had a kid last year. Most of the other people on the team are no longer involved (deployed to the middle east, moved out of state, etc). I found a bunch of other nutjobs to help, so the balls rolling again :D
-
That big one is a plug for an oxygen sensor, I believe.
I have accessed them from underneath. The A-Arm has a hole in it for accessing the front nut with a long extension. The rear is just accessed around the down pipe.
They rust good and solid, that's for sure. Running a die down the remaining thread and then heating the snot out of it with an acetylene torch works.
I usually make a trip down to the parts store for some fresh studs and brass nuts when I'm done. It makes the next time I decide to tear into the engine much easier.
You'll need that bracket to reattach the power steering pump unless you get the correct 4.0 one... then you'll need the holes it's attached to. Heat, and hit the bolt square with a hammer and punch if you can. You may need a specialty socket to grab it rounded off.
-
big one is indeed a plug for the o2
that bracket is for power steering and i have had no trouble removing mine. spray a bunch of pb/wd40/whatever you use on it if it's rusty and wait a bit. u-joints and swivel sockets are your best friend in this car. if i remember right they are a 9/16 and there are multiple other bolts on the motor that you'll be able to use that swivel on (intake/exhaust/etc) so it's money well spent.
-
I'm not sure if anyone has posted or discovered this, but there is an access hole for the front bolt on the downpipe. I found it today while struggling to remove mine. I tried to take a picture but it's a tough spot. If you stick your head under the front diff and look up between the diff cover and front subframe, there is a hole. It is not perfectly lined up with the bolt, but you can see the flange.
A long extension ~10" (14-16 would work better) one swivel on the nut end, and the socket with a breaker bar is all you need. Be sure to get the socket seated properly on the nut to avoid stripping it. The extension will be at ~45 degree angle to the right of the pumpkin (as you're looking toward the front of the car). The front stud actually pulled out on mine which I am actually happy about. I'll probably use a bolt with some never-seize on it for re-installation. I'm going to try to get the other stud out but I'm not sure how well that's going to work.
(http://i.minus.com/iTZVXYoygVb0W.JPG)
(http://i.minus.com/ibyOfLTEkp7wz4.JPG)
-
This was a super helpful post. I got stuck here too. I married two ideas from this thread and the baby resulted in it taking me 5 minutes to remove the downtube. Here's what worked for me. First, soak the crud out of them with penetrating oil. Then, I grabbed my 3/8" drive 14" extension and 9/16" swivel socket. A standard socket and universal would not work. For the front bolt, I inserted it through the access hole in the front crossmember (put your head just behind the pumpkin and you'll see it). Ran it up through there. Then, I rolled to the right side of the car a bit and looked up to ensure it was seated. Then, put a 1/2" adapter on it and hit it with my impact. That was it. For the back one, the same tool reached very easily up behind the axle. Exact same setup. No trying to reach from the top of the car which I could not do. And no mess of universals. Just a straightforward solution that worked a treat. Hope this helps someone!