Exhaust Manifold Gasket Replacement - TCCoA Forums
 
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post #1 of 7 (permalink) Old 06-20-2015, 12:24 AM Thread Starter
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Exhaust Manifold Gasket Replacement

I've had an exhaust leak for a few months now and it has gotten worse and worse and I finally decided to use a smoke machine to see where it was, it seems to be leaking from the exhaust manifold gasket. To change the gasket I know you have to pull the manifold, make sure it's not warped, and replace the gasket. The problem is the forever fight on a 4.6 T-Bird, there is no room for anything. I've had the car on a hoist a few times and it looks like you can get to the bottom bolts kind of, but the top bolts look like a b**** due to the strut tower being right there. (Passenger side manifold). So my question is what do you guys usually do, do you pull the engine? Do you let it cool down and use a bunch of pb blaster and a combination of wobbly sockets, extentions, and an impact gun? Or is it even worth doing? I appreciate the input.

- Note, I would have access to a hoist and a shops worth of tools.
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post #2 of 7 (permalink) Old 06-21-2015, 11:31 AM Thread Starter
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post #3 of 7 (permalink) Old 07-03-2015, 05:30 AM
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Originally Posted by 1996 Spencer 4.6l View Post
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Spencer I've not done one of these myself and I've been watching the thread hoping some one with some real world experience would answer you. So I can't help much. If you want me to look and see what the manual says I'll post back.

It's just a guess but you may be able to loosen one or both of the engine mounts and possibly the trans mount and then jack the motor up enough to gain some clearance. That what we would have done in the old days. On one of these that might be as much work as just wrestling with the bolts from the top and the bottom. Manifold bolts can be notorious for being rusted and seized. Prior experience with old fashioned cast iron heads and manifolds has taught me that having a oxy acetylene torch handy goes a long way toward towards getting the bolts out without snapping a bolt off. But with the 4.6's aluminium heads that may not be a good peice of advice. And even with a a lift and a torch and a impact gun it's wasn't uncommon to bust at least one bolt back in the day. Then you get to drill out the busted stud. Which is NOT something I'd want to do in in one of these cars with the motor still in.


So BUMP!

Can any one offer this guy some better advice?
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post #4 of 7 (permalink) Old 07-03-2015, 11:54 PM Thread Starter
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Spencer I've not done one of these myself and I've been watching the thread hoping some one with some real world experience would answer you. So I can't help much. If you want me to look and see what the manual says I'll post back.

It's just a guess but you may be able to loosen one or both of the engine mounts and possibly the trans mount and then jack the motor up enough to gain some clearance. That what we would have done in the old days. On one of these that might be as much work as just wrestling with the bolts from the top and the bottom. Manifold bolts can be notorious for being rusted and seized. Prior experience with old fashioned cast iron heads and manifolds has taught me that having a oxy acetylene torch handy goes a long way toward towards getting the bolts out without snapping a bolt off. But with the 4.6's aluminium heads that may not be a good peice of advice. And even with a a lift and a torch and a impact gun it's wasn't uncommon to bust at least one bolt back in the day. Then you get to drill out the busted stud. Which is NOT something I'd want to do in in one of these cars with the motor still in.


So BUMP!

Can any one offer this guy some better advice?
Thank you for the input but actually I think I figured it out! At work today we finally had a hoist open. (We've been slammed for almost 2 weeks straight so I havent had time to put the car on a hoist and make a game plan on what I'm going to do.) I think there is enough room for the top and bottom bolts if I use a swivel socket, some extensions and some ratchets/impacts. If you wouldn't mind looking in the manual if you have one and see what they suggest I would greatly appreciate it.

P.S. At our work we have a program that we are able to look up certain precedures for cars and for one side it calls for 5.8 hours and all it says you have to do is unbolt the flange that hooks the cat onto the manifold, and take the bolts out. So yeah hopefully with some patience and swivel sockets, next weekend I will be able to take off the manifold and possibly get it machined or get a new one.
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post #5 of 7 (permalink) Old 07-05-2015, 07:52 PM
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Q: Once you have the exhaust manifolds off the heads, are you planning to use Copper RTV or that metal gasket you sometimes get in the kit from FELPRO.

While I cannot speak for 4.6L engines specifically, I've always found the copper gasket to seal better on other engines.
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post #6 of 7 (permalink) Old 07-06-2015, 06:29 AM
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Originally Posted by 1996 Spencer 4.6l View Post
Thank you for the input but actually I think I figured it out! At work today we finally had a hoist open. (We've been slammed for almost 2 weeks straight so I havent had time to put the car on a hoist and make a game plan on what I'm going to do.) I think there is enough room for the top and bottom bolts if I use a swivel socket, some extensions and some ratchets/impacts. If you wouldn't mind looking in the manual if you have one and see what they suggest I would greatly appreciate it.

P.S. At our work we have a program that we are able to look up certain precedures for cars and for one side it calls for 5.8 hours and all it says you have to do is unbolt the flange that hooks the cat onto the manifold, and take the bolts out. So yeah hopefully with some patience and swivel sockets, next weekend I will be able to take off the manifold and possibly get it machined or get a new one.
I helped some one pull their trans this weekend. Step one was pretty much getting the the converter bolts out. You'll need a nice long extension bar your not in the rust belt belt but I'd still suggest soaking as many of the exhaust and bolts as you can get to with Blaster several times before you start the job. Especially the EGR tube nuts.

I don't have any advice as far as gaskets or gasket materials other than this seems like a bad area to save money unless you want to to do it over again down the road. While I've never used RTV on exhaust manifolds people do and have good results. Hopefully some one else will chime in on what's a good brand of gasket or sealer. I've always gravitated towards FelPro personally but haven't done a exhuast or header gasket on a MN12. So I'm in the dark here. As far as I know leaking exhaust gaskets on these are not exactly a common problem. If you suspect the manifold itself is warped or possibly pitted or eroded in the area where the leak is you might want to have a better manifold available from your local pull a part. I'd be willing to bet that if you put a ad in the wanted section here you could find some one willing to sell you one very cheaply or perhaps even free for the cost of postage.

On the the main event.

1) Disconnect battery ground.

2)Raise vehicle on hoist.

3) On left hand exhaust manifold remove bolt retaining dipstick tube.

4) Disconnect wiring from heated Oxygen sensors.

5) Remove EGR valve to exhuast manifold tube line nut from right hand manifold and remove EGR tube.

6) Disconnect converter from LH and and right hand exhaust manifolds.

7) Lower converter assembly and secure to trans cross member with wire on either side.

8) For left hand manifold disconnect steering shaft and position out of the way.

9) Remove 8 nuts retaining left hand manifold and remove manifold and two manifold gaskets.

10) For right hand manifold remove 8 retaining nuts and remove manifold and gasket from engine.

Installation is the reverse.

Some added notes. Exhaust manifold bolts are torqued to 14-16 foot pounds. And torqued in sequence starting at the manifold to down pipe outlet and working your way forward to the front of the motor. Upper bolt then the lower bolt. It looks like your chasing the manifold flat from the back to the front as far as torquing it down. Since you had a leak I'd follow this rather than tightening the bolts at random. I'd go with the higher torque number for the same reason. And might add a few few foot pounds just to be safe depending on how the gasket was compressing and how it felt. The more experienced members here might have an opinion. But being a aluminum head this may or may not be a good idea. I wouldn't go more then 2 pounds over the max torque. I'd also inspect the cylinder head closely at the leak just to make sure it wasn't pitted or eroded from the exhaust gasses. If it was I'd probably use the RTV as mentioned. The EGR tube to manifold torque spec is listed at 34-47 foot pounds. The EGR tube to EGR line nut torque is listed as 26-33 foot pounds. To add some confusion to the mix the reassembly steps mention engine isolator bolts which I assume are the engine mounts but makes no mention whatsoever of removing the mounts during disassembly. So you may have some additional fun if you need to pop the mount loose.

I hope that helps. It's about all I can offer as far as help and if I've offered any bad advice regarding inspection and gasket materials hopefully some one will school me here since your only doing one side this may just come down to removing the down pipe bolts the EGR tube and your knuckles on the actual exhuast manifold bolts. I listed all the steps for both sides in case some one stumbles on the thread from 2025.
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post #7 of 7 (permalink) Old 07-11-2015, 11:58 PM
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To complete my PI intake swap I had to remove the pass. exhaust manifold in order to remove the old EGR tube. In fact I'll have to do it again real soon to finally replace the EGR tube adapter and fix my exhaust leak. No, you do not have to pull the engine to get the manifolds off but you will need a 1/4" ratchet with multiple lengths of extensions. It's a pita and it may take a bit of time but it is possible. Just be prepared to have a stud or 2 break.
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