Replacing exhaust manifolds this weekend

[marcus550]

I'm more than half-way in to this project after about 4 hours of work. It certainly isn't for the timid. CDan was kind enough to hook me up with new parts (thanks!). I have the right side manifold off with not too much trouble. The left (driver's) side is looking damn near impossible.

Can someone with a service manual give me advice on:

1. What is the torque on the manifold studs. 7 out of 8 studs came out of the head vs. the nut coming off the stud. So, I have to separte the nut from the stud and re-insert the studs in the head. They came out clean and the studs have a Torx fitting on the end to allow installation. I just don't want to torque them too much!

2. Required torque on the exhaust manifold nuts.

3. How in the %&*/#$^%@#$ does the steering flex-shaft come off? Is it even possible to remove this with the steering gear still in the car? I can pry it back about 1/2" with a long steel bar, but it isn't enough clearance to even allow the shield to be removed. I'm afraid the manifold will be a similar story. I have the shield bolts out and the top four manifold studs out and had to quit. Bleeding too much from all my wounds.

I'll post some pictures and type a few pointers if I'm actually able to pull this off.

Oh, and the passenger side manifold that I pulled off looks fine to me. I can't see black marks that would indicate where it was leaking. Maybe just the gasket was leaking or the flange is warped? Either way, the new parts should solve that. I was just expecting to see something obvious for all that noise it was making!

Last, how clean does the mating surface at the head have to be? There is quite a bit of crusty oxidized aluminum (?) caked up around the exhaust ports. I cleaned most of it with a brass brush but it will take hours to get it all nice and polished. Ugh.

Mark

 

[100 TD]

Sorry, can't help with the torque specs, but if you don't want to do this job again, I would really ensure the mating surfaces are clean and smooth, sharpen up a 2" barbque scraper and get rid of anything off the heads until smooth then a small sanding block to finish cleaning up, then a wipe with a rag soaked in acetone to remove all traces of grease and crap before assembly. My personal thoughts only!

 

[spressomon]

I'm more than half-way in to this project after about 4 hours of work. It certainly isn't for the timid. CDan was kind enough to hook me up with new parts (thanks!). I have the right side manifold off with not too much trouble. The left (driver's) side is looking damn near impossible.

Can someone with a service manual give me advice on:

1. What is the torque on the manifold studs. 7 out of 8 studs came out of the head vs. the nut coming off the stud. So, I have to separte the nut from the stud and re-insert the studs in the head. They came out clean and the studs have a Torx fitting on the end to allow installation. I just don't want to torque them too much!

2. Required torque on the exhaust manifold nuts.

3. How in the %&*/#$^%@#$ does the steering flex-shaft come off? Is it even possible to remove this with the steering gear still in the car? I can pry it back about 1/2" with a long steel bar, but it isn't enough clearance to even allow the shield to be removed. I'm afraid the manifold will be a similar story. I have the shield bolts out and the top four manifold studs out and had to quit. Bleeding too much from all my wounds.

I'll post some pictures and type a few pointers if I'm actually able to pull this off.

Oh, and the passenger side manifold that I pulled off looks fine to me. I can't see black marks that would indicate where it was leaking. Maybe just the gasket was leaking or the flange is warped? Either way, the new parts should solve that. I was just expecting to see something obvious for all that noise it was making!

Last, how clean does the mating surface at the head have to be? There is quite a bit of crusty oxidized aluminum (?) caked up around the exhaust ports. I cleaned most of it with a brass brush but it will take hours to get it all nice and polished. Ugh.

Mark

Exhaust manifold nut torque (per '99 FSM): 32 ft-lbf

 

[LandCruiserPhil]

I'm more than half-way in to this project after about 4 hours of work. It certainly isn't for the timid. CDan was kind enough to hook me up with new parts (thanks!). I have the right side manifold off with not too much trouble. The left (driver's) side is looking damn near impossible.

Can someone with a service manual give me advice on:

1. What is the torque on the manifold studs. 7 out of 8 studs came out of the head vs. the nut coming off the stud. So, I have to separte the nut from the stud and re-insert the studs in the head. They came out clean and the studs have a Torx fitting on the end to allow installation. I just don't want to torque them too much!
No specific torque found for exhaust studs. In order to use the chart for Specifed Torque For Standard Bolt you will need to know what the markings are at the end of the stud to determine its class to come up with the specified torque.
2. Required torque on the exhaust manifold nuts.
Uniformly tighten 8 new nut to 32 ft.lb
3. How in the %&*/#$^%@#$ does the steering flex-shaft come off? Is it even possible to remove this with the steering gear still in the car? I can pry it back about 1/2" with a long steel bar, but it isn't enough clearance to even allow the shield to be removed. I'm afraid the manifold will be a similar story. I have the shield bolts out and the top four manifold studs out and had to quit. Bleeding too much from all my wounds.
Not for sure what you are asking but if you are trying to remove the no.2 intermediate shaft, it looks like the column needs to be loosened up. There is another joint where the no 1 shaft attaches to the steering assembly you MIGHT be able to also loosen to get a little more room without removing the assembly.

I'll post some pictures and type a few pointers if I'm actually able to pull this off.

Oh, and the passenger side manifold that I pulled off looks fine to me. I can't see black marks that would indicate where it was leaking. Maybe just the gasket was leaking or the flange is warped? Either way, the new parts should solve that. I was just expecting to see something obvious for all that noise it was making!
White paint on new gaskets goes to manifold side
Last, how clean does the mating surface at the head have to be? There is quite a bit of crusty oxidized aluminum (?) caked up around the exhaust ports. I cleaned most of it with a brass brush but it will take hours to get it all nice and polished. Ugh.
3m scotchbright disc on an 1/4" angle grinder
Mark

HTH

 

[marcus550]

The pain

Well, I found the problem. The flange itself is cracking around the lip. The passenger side was bareley cracked but the driver's side had split open. Just the ports furthest from the cat (closest to the front of the engine) looked cracked.

Prep: Truck on jack stands, front wheels off, hood up, and wheel well plastic shields removed.

Passenger Side Removal: This wasn't that bad. I removed the cat flange nuts first, then the four bolts holding the shield on. It is possible to wrestle the shield off. With an assortment of 1/2" extensions, breaker bar, ratchet and universal I got all of the studs out. One actually remained in the engine and the nut came off instead. I was able to get the manifold out without removing the cat. Two of the front top studs are best reached from above. All others could be reached from the wheel well. You WILL need a breaker bar to get these broken free. 3/8" universals explode violently, so 1/2" or better is required. I've got a busted lip to prove it.

Driver's Side Removal: First I removed the three nuts holding the manifold to the cat, then removed the four small screws holding the shield to the manifold. There is no way to get the shield out, even with shoving the steering shaft to the side with a steel bar! I had to leave it in place and just move it around to reach the manifold nuts. It has nice sharp rusty edges to make the job even more entertaining. Only the insanely patient should attempt this! The two front/bottom studs were reached from underneath, one middle/top stud had to be wrenched, all others could be reached witht the ratchet and extensions from the wheel well.

With all studs removed, it became obvious there was no room for the manifold to exit either. The cat had to go. It was pretty easy with that out of the way. Now I have to get another gasket...

Now I had 15 studs with nuts on them that needed separating. I used jam-nuts to attempt to hold the stud in a vice while backing the nut off with an impact gun. No luck. I found that running the nut in then running a 10mm-1.25 die down the stud allowed the nut to come off easily. The ends of the studs were pretty corroded so there was no way these were coming off without this method. If you are planning this project, maybe a good investment would be new studs and nuts.

Driver's Side Install: With all the studs out, there was nothing to locate the manifold/gasket/shield. Yep, you have to have all three of these shoved in to the tiny cavity at once. I found that the top stud closest to the cat flange could go in without getting in the way. This at least located the back side so you can get a nut on it. It's painful and you have to be a contortionist, but the rest of the studs went in with no problem. The studs have a torx head so you need a torx socket to allow running these in to the head. I bought a set from Sears for $20. Re-install the cat (don't forget the new gaskets!)

Passenger Side Install: Similar to the Driver's Side, except you can leave the shield out until all of the manifold nuts are torqued. Again, wrestling this back in is fun, but better than the alternative.

My manifold gaskets were painted dark gray on one side, polished on the other. The polished side apparently goes against the head with the gray facing the manifold. The head was corroded so I spent hours trying to clean them up with a razor blade (not recommended), screwdrivers, a wire brush and scotchbrite pads from Home Depot. If you could get a tool in there to polish this area, go for it! I could hardly see it much less reach it by hand.

I attempted to torque the nuts to 32 ft.lbs., but ended up winging it for most of them. It's impossible to see some of these much less get a direct path for a socket. One on the driver's side had to be wrenched. Only two or three of these are easy.

I would assume the cuts and bruises and one lost weekend are cheaper than paying my dealer to do it. They quoted $2500 to do the job and said the engine had to come out. After I said I would do it myself, they corrected their statement but didn't lower the estimate. The parts were around $600 (manifolds, nuts, studs, gaskets and two O2 sensors) plus $130 in new tools.

Mark

 

[vcheng]

Thanks for great write up.

A question (may be stupid): What about the old manifolds? Isn't the crack amenable to welding once it is out? That would greatly reduce the cost of the repair if possible (bloody knuckles notwithstanding).

 

[marcus550]

I suppose it could be welded but there is no guarantee that the flange would still be perfectly flat when you're done. The best place to weld it would be on the outside of the flange, but this is where the holding plate nestles. Welding then grinding may work.

Regardless, the manifolds alone are fairly cheap at less than $250 / ea. I would hate to go to ALL this effort only to find out the weld failed or the flange wasn't flat (IMO.)

I buttoned it all up tonight, changed the oil and filter and took it for a test drive. Quiet as a new truck!

 

[vcheng]

You, sir, are to be commended for your effort. I hereby enter you in the Golden Order of the Bruised Knuckles, and salute you!

PS: I think you are right about putting in new manifolds for the amount of effort involved.

 

[hoser]

marcus, don't throw those old manifolds away. I'm sure somebody here wants to use them as templates for a pair of headers.