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Exhaust manifold replacement disaster!! *help!*

gigantor919

NAXJA Forum User
Yesterday I thought I would be ambitious and replace my leaking exhaust manifold on my 89' 4.0l auto. It's been getting progressively louder the last few weeks and I finally broke down and started tearing it apart.

Yesterday I got both the manifolds off the car, and all the hoses disconnected. When I took the old exhaust manifold it off I noticed it had actually broken in two pieces!!

Today I spent the better part of the day trying to get this piece of s*%& back together. I had a hell of a time getting manifolds back on and all the bolts and nuts back on (I still have 3 I can't get back on). The egr pipe cracked so I put a plug in on the manifold and some of the vaccuum hoses have broke!!

I wanted to at least get a test drive in to see if the sucker was drivable. Needless to say it's pretty damn far from it. It idles at about 3000rpm, it's spitting raw gas and smoke from the tail pipe and the exhaust leak actually sounds worse.

Any ideas as to what I have done!?! Why is this thing idling so high? Why won't this exhaust/intake manifold line up right, why is it spitting smoke and raw gas out (my nose is still burning!).

Help.
 
Well........ if you've got 3 bolts that you can't get in, you've got a leak, in either the intake or the exhaust. Yes, I know. The lower bolts are a PITA. Don't remind me, I've had my header off something like 5 times now. Crow foot wrenches may help, as well as a socket with a built-in universal joint.

When I first put my Borla header on, I didn't get it seated quite right. The floating washer hung up on a rough spot on the flange, and then hung up on the bolt threads. This caused an exhaust leak, running very rich, and with a noticeable POP in the exhaust. Leaks in the exhaust cause the O2 sensor to read high apparently, which leads to dumping in more fuel.

Short story is that without all of the fasteners in place, all bets are off.
 
I have a exhaust manifold from an 87 I would sell ya

It's in one piece and I don't see any cracks in it. Let me know if you are interested. I don't know if it will fit a 89 though. Someone here should be able to tell you. I also have a bunch of the hard vac lines. Let me know.

BrianC
 
Re: I have a exhaust manifold from an 87 I would sell ya

BrianC said:
It's in one piece and I don't see any cracks in it. Let me know if you are interested. I don't know if it will fit a 89 though. Someone here should be able to tell you. I also have a bunch of the hard vac lines. Let me know.

BrianC


I already have one that's I installed this weekend. Thanks though.


What about the EGR? Would that cause these kinds of problems?
 
I don't think the EGR will cause a rich mixture but a disconnected MAP sensor sure will. Make sure you have the vacuum line connected to the MAP sensor. The MAP sensor is on a bracket mounted to the firewall and there is a vacuum line between it and the throttle body.
 
You say you put the Manifold back on, but didn't say you replaced it with another. I hope you did. The "manifolds" are actually connected and would come off as one unit. The best way to get those 3 bolts on would be to take off the head. But that is a bit of work. You did put in a new manifold gasket right?
 
RookieJeeper said:
You say you put the Manifold back on, but didn't say you replaced it with another. I hope you did. The "manifolds" are actually connected and would come off as one unit. The best way to get those 3 bolts on would be to take off the head. But that is a bit of work. You did put in a new manifold gasket right?

HUH?!!!!

You're right on the replacement manifold. And apparently, he has replaced. And actually, if you leave the outer 2 bolts in place, the intake manifold lifts out before the exhaust.

Pulling the head? HAVE YOU EVER DONE THIS? I have, and NEVER again! Yeah, those lower bolts are a bunch easier to get to with the head off. But that's offset by that gawdawful heavy head and manifold assembly.
 
RookieJeeper said:
You say you put the Manifold back on, but didn't say you replaced it with another. I hope you did. The "manifolds" are actually connected and would come off as one unit. The best way to get those 3 bolts on would be to take off the head. But that is a bit of work. You did put in a new manifold gasket right?


I did put a new manifold on, and I did replace the gasket. I think I'm just going to burn this thing in my front yard.
 
RookieJeeper said:
You say you put the Manifold back on, but didn't say you replaced it with another. I hope you did. The "manifolds" are actually connected and would come off as one unit. The best way to get those 3 bolts on would be to take off the head. But that is a bit of work. You did put in a new manifold gasket right?

One other thing...... don't forget about draining and refilling the coolant. And dealing with the bubble in the head afterward.

BTW, new head gaskets are $40. And new headbolts (only reusable ONCE.)
 
Nobody mentioned, taking the heat shield off of the intake manifold. Makes things a bunch easier. I don´t believe it´s cooling advantages (maybe keeping the throttle body a bit cooler), are worth the effort of having it on there (had mine off for ten years or more). Sure makes installing the exhaust/intake manifold a bunch easier and future inspections of the exhaust, much more productive (find the cracks while they are small).
When I break a hard vacume line. I just replace it with a soft vacume line, thick wall line, that doesn´t crush between your fingers, easiely. Works just as well. Just requires a couple of cable ties to prevent it from floppin around, burning or rubbing.
I sure enough tighten the intake/exhaust bolts from the center out. Even new, the warpage on the exhaust and sometimes the intake are substantial. A really light/small bead of high temp silicon can´t hurt much, especially around the intake ports.
 
RookieJeeper said:
My manifolds have a metal tube connecting each other. When I did my head gasket last winter, it came off together.


That's called the EGR tube which connects the Header to the EGR bung in the intake manifold. If you replace your header then you have to remove this tube.

The main problem here is that you didn't finish the job. YOu have to properly tighten all the bolts and make sure all the vac lines are good. If you don't it will run like crap guaranteed. Go get some hose like they said and rerun all your broken vac lines. The bolts on teh bottom aren't that hard to get to from the bottom of the vehicle with a standard wrench.
 
Thanks to everyone for their help and advice on this. I took everything apart and retorqued the manifolds down with ALL the bolts, traced all the vaccuum lines and made sure all the sensors were hooked up properly.

I found the map sensor was unplugged and the manifold was for sure not tightened down right. now it runs like a champ.
 
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