Installing Headers on a W22

[yeloduster]

I started a similar thread a few weeks ago. That thread got hi-jacked in several ways. My intent for this thread is to document the parts, supplies, tools and methods to install headers on my W20/W22 including new mufflers. My MH has true dual exhaust. I think that some chassis have a single exhaust. The single exhaust versions would be somewhat different than my installation.

I tried to anticipate all parts needed and problems I may encounter. See the attached document for my list of parts and special tools. I also attached a picture of all my parts. I will buy a few bolts and other hardware locally. The only real problem that may occur is breaking off 1 or more of the studs that attach the exhaust manifold to the cylinder head. I intend to get all the nuts off without breaking a stud!

Parts Discussion:

• I am installing Doug Thorley Headers. I am quite sure that the installation process would be very similar regardless of brand of headers.
  
• I am also replacing the stock mufflers. The stock mufflers are starting to leak so now is a good time to replace them. The stock mufflers are really expensive. The word on the street is they are restrictive and other mufflers yield better performance. There are several discussions on mufflers on the forum. The general consensus is MagnaFlow P/N 12589 is the muffler to get so I got 'em.
  
• Thorley had mixed messages relative to the use of gaskets between the header flange and the cylinder head. Their on-line installation document does not mention gaskets...the installation document included in the box says to re-use the existing gaskets. I am a little skeptical of re-using gaskets so I order some that are identical to the OEM gasket.
  
• If I were not changing the mufflers everything I needed was supplied by Thorley. The mufflers and associated gaskets and hardware added about $550 to the cost for parts.

Method:

My plan is to change the mufflers first. After the new mufflers are installed I will then change the headers. See this THREAD posted by Civdiv99. Civdiv99 documents very well the steps he took to replace the mufflers on his W22. I am shamelessly plagiarizing his work. Thanks Civdiv99!

With the exception of possible broken exhaust manifold studs the header replacement looks rather straight forward.

The weather is not conducive to working on the MH now. The forecast looks promising for the week starting Monday March 14.

As I work through each stage of this process I will take some pictures and post as I go along.

PLEASE!: Let's keep this conversation to the installation. The parts are ordered. Brands are selected. Performance will be what it will be.

I welcome questions on the installation. Suggestions to make things easier are much appreciated!

So long until my next installment on this thread.

[jeff0210]

When i was young I believed in brute force and leverage. Now days, not so much. Those exhaust bolts have been in there 20plus years. Same as the clamps on the mufflers. Get a torch and use heat. Heat them up let them cool, repeat, use wd40 in between. The clamps no big deal if the break, might even just cut them off. You got to baby those exhaust head bolts. Probable repeat three times. Better than having to drill and tap. Using new gaskets always a good idea. Newer gaskets in general are better than 20 years ago. The rest is all measure twice and cut once if applicable.

[yeloduster]

Thanks Jeff, I plan on using heat and the method that you outlined. Although I am a very experienced amateur auto builder I have never used heat on exhaust bolts...and never broken one!

If you have personal experience I would like to ask if you used a propane torch intended for copper pipe sweat soldering or have you used acetylene. I have both. It seems the acetylene can provide a much smaller flame and make it easier to heat only the nut and not the surrounding area.

What do you think?

[rollinj]

I considered putting on headers but I'm terrified I'll have studs break! 2003 w22 43k miles.

[jeff0210]

Not an expert with either. I use the weld tips most often when working in tight places. I can control the flame better that way. Not sure which one gets hotter though. I put the flame to everything in area. Nut, flange, any part of the block I can get to around the bolt. Let cool a while then the WD or what ever. After a couple of treatments I'll go tight, loose , tight back and forth till i'm sure it's on it's way out. After the first one you can see how the others will be. Good Luck.

[sploke]

I have found a great penetrant is a home-made blend of 50/50 acetone and ATF. I keep a mix in a small spray bottle in the shop. For stuff like exhaust bolts I'll start dousing them a few days before working on them. Usually a few days of soaking, then hitting it with a torch is enough to break nuts loose.

[yeloduster]

Thanks sploke,

I've been dousing the studs with PB Blaster for the last few weeks occasionally. I haven't tried to break a nut loose yet. I have put a nut on an existing stud. Although the stud looks rusty, the threads seen clear because the nuts goes on all the way easily with just finger pressure.

I'm optimistic that if I can successfully break the nuts loose they will come right off.

We will see. The start of my project may be delayed. We have an unexpected family commitment next week that may preclude me working on the MH.

[exrench]

Since most people who have replaced exhaust manifold gaskets on 8.1 engines, have been prompted to do so when one or more studs have broken, causing a noise which they investigated. The question is, how long do you think your exhaust manifold studs will last? Why would you not wind them all out while you can grip them with a stud extractor and not wait until one or more are broken off flush with the cylinder head? In my experience, the whole studs come out without a problem; the broken ones-not so much!

[yeloduster]

Things have not gone as planned! Many of the weather friendly days have been used going to a family funeral! The daytime temperatures on many days have been in the 20's and/or 30+ MPH winds. Today the wind is +50 for example!

I got the flu! No, not the 18 hour flu...the 7-14 day flu.

In spite of that I have moved the MH to the pad in front of the shop. After crawling under it I have modified my plans from Civdiv99's plans a little.

At this point I have both mufflers removed and I am ready to install the new mufflers. Everything is on hold until I recover. However...a new weather front may be rolling through about the same time I am feeling better! I'm really glad I'm not planning on going anywhere soon!

I will post some pics once I get back to the job.

[EyezOpen]

Did you use a torch? If so what type? I cannot imagine getting lucky enough to do that job without a torch...but hey things happen..

[yeloduster]

Well, I've mostly recovered from the flu. We had a couple days of nice weather so I finally got back to work.

My motorhome has a true dual exhaust. I think there may be some variants so I thought I would define what I have. Each bank of the engine has a separate exhaust system. The two systems are roughly mirror images and exit in front of the rear axle. The catalytic converter assembly has a large flange on each end and the muffler assembly has a identical flange on the inlet end. This is a total of 3 flanges per side.

Each of these flanges is a potential source of leaks. I know a couple if mine were leaking. Maybe yours are leaking too!

I told you I was going to plagiarize Civdiv99 work. I decided to deviate in 2 ways from Civdiv99. First I removed the mufflers by removing the clamp on the pipe in front of the flange and separating the pipe. By doing this I eliminated 1 flange from each side. See the first image below. It shows the original muffler with the front flange still attached. It shows the comparison of the original muffler with the replacement muffler with a section of pipe to match the length with the original. If you click on the photo you can see the annotation where I indicated where Civdiv99 cut the muffler out. The next picture shows the muffler installed on the drivers side. You can see the jack stand holding the exhaust system in place as I have not added hangers yet.

The second way I deviated from Civdiv99's installation is my choice of hangers. Civdiv99 used flat strap to fabricate his hangers. I chose to use 1/2" bar stock that fit into the factory rubber isolators. I bent each one to fit, threaded the end that went into the isolator and double nutted it to assure that it wouldn't come out. The other end I braised to a clamp. See picture 3. My braising doesn't look very elegant but I tested my braising by trying to break a joint with a hammer. I couldn't do it! I think the welds will last longer than I will.

The finished project took a long time with the bad weather and the flu. However, the finished product looks good. With the engine idling I measured the noise level 3' from the left exhaust pipe and found ~70db before the installation and ~70db after the installation. I can't tell the difference in sound. These Magnaflow mufflers have a 3" hole directly through them. You can look in one end and see out the other end. How they can be so quiet and be straight through is beyond me! The exhaust may be much louder under load!?

Next installation of the headers. Wish me luck.

It is currently 26° F with snow flurries! I guess I won't start that project today!

[yeloduster]

Originally Posted by exrench

Since most people who have replaced exhaust manifold gaskets on 8.1 engines, have been prompted to do so when one or more studs have broken, causing a noise which they investigated. The question is, how long do you think your exhaust manifold studs will last? Why would you not wind them all out while you can grip them with a stud extractor and not wait until one or more are broken off flush with the cylinder head? In my experience, the whole studs come out without a problem; the broken ones-not so much!

Sorry to have taken so long to respond.

I have oscillated back and forth on this issue. I have studs and an extractor in my parts/tool list for this project but haven't ordered either. My thoughts are: I live in a semi-arid region and the motorhome has lived here all it's life. We have less moisture so the rust on the bolts seem less. I had to remove the oil dipstick recently. It is retained by an exhaust manifold stud. It came right off without using any penetrating oil. If all the nuts come off it indicates that limited corrosion has occurred on the studs. Adding any additional steps increases the chance of creating a problem that did not previously exist.

So, the current plan is this. If all the nuts come off without breaking a stud I will just use the old studs with new nuts. If any stud breaks I will replace them all.

[yeloduster]

Originally Posted by EyezOpen

Did you use a torch? If so what type? I cannot imagine getting lucky enough to do that job without a torch...but hey things happen..

I did not use a torch to disassemble the system. I used a sawzall and a small angle grinder to cut off the hangers, clamps and pipes.

I used a Acetylene torch to bend the hanger rods and to braise the hanger rods to muffler clamps to make my exhaust hangers.

I plan on using the same torch to heat each manifold nut before I try to loosen it.

[yeloduster]

I didn't want to just take anyone's word on choice of mufflers without doing some investigation. From the info available it seemed the MagnaFlow had the reputation for the best compromise between maximizing vehicle performance and minimizing noise. I liked those qualities.

The stock mufflers are made by Donaldson and are ≈8.5" x 11.5" oval x 24" long. They have a center inlet and on offset outlet. Both inlet and outlet will fit inside a 3" exhaust pipe for clamping. They are not a straight through muffler. If you look in one end you can't see out the other. Other than that I don't know how they are constructed.

The MagnaFlow 12589 mufflers are 5" x 11" oval x 22" long and also have a center inlet and offset outlet. Both inlet and outlet fit OVER a 3" exhaust pipe for clamping. They are a straight through design. Looking in one end you can see out the other. Larger interior volume helps reduce noise. The original muffler is significantly bigger than the MagnaFlow 12589. I went looking for a larger straight through design muffler and couldn't find one. So the MagnaFlow 12589 it is! Because the MagnaFlow is a straight through design I am presuming that it will pass more exhaust with less backpressure than the Original equipment muffler.

The results. I haven't driven the motorhome so I don't know about the sound under load. I measured the noise 3' from the tailpipe at idle. A decibel meter says old muffler sound was ≈70db, the new muffler measured the same way is ≈70db. My ear can't tell the difference either.

I will never determine if just the mufflers added any performance because I will install the header before I ever drive it.

PS: I looked into Donaldson mufflers. Donaldson specializes in mufflers for diesel equipment. I think their technology looks pretty impressive. I'm not sure the MagnaFlow mufflers offer any improvement in back pressure reduction. If your mufflers are not leaking you might not want to spend the money changing mufflers.