Well 14 years and nearly 90,000 miles have taken their toll on my exhaust system. I'm starting to get exhaust leaks through the muffler where the clamps wrap around it. The tail pipe also has a small hole in it (after the muffler).

The engine is a Cummins 8.3 liter, turbo-charged and after-cooled. The muffler and exhaust pipes are fitted around the turbo and radiator piping with fairly close tolerances.

My question: How complicated is it to replace the exhaust? I'm a fair mechanic, but will need to do this in my driveway. Will the tubing need to be custom bent or are the muffler and other parts available off the shelf?

I hope to defer this job until next spring, but it may not wait. The leaks are fairly small now but I'm sure things will progress quickly at some point.

Once you remove the pipe from the turbo then take that to a truck parts house. Most of the pipes for the exhaust are "off the shelf" with only a few really needing any custom bending.

I have had exhaust systems with all sorts of bends in it and the pipes that's sitting on the shelf usually matches up. Look at what you have there, at each bend you will probably see a welded seam going to the next pipe.

If you can't find the right stuff then bring that pipe to a garage that does custom bending and have then make you another piece. The muffler should be easy to find.

I would add that the exhaust "V Clamp" at the turbo should be replaced instead of being reused. Most truck mechanics don't do this and this is one item that really pays to replace.

Bill N.Y.

One thing to consider is that separation of the old parts can be an issue - an air chisel with a muffler "bit" can make short work of it.

And because of the nasty stuff in diesel exhausts, going with stainless wherever possible is, IMHO, worth the extra cost.

Bill N.Y.:

Why do you say the exhaust "V Clamp" shouldn't be reused? I just replaced the Pacbrake exhaust brake on my 8.3 and when I removed the stainless clamps, they looked good - no rust, pits, lumps, etc. The coach is a '95 and they were there a while. I reused them.

What type of problem(s)might be encountered by reuse?

...Kind of a generic sidebar question relating to this thread:

For our applications, how important is the issue of having custom pieces "mandrel bent"?
I understand the concept & goal (no internal choke-down on the bends), but is it really a factor or more of a hype?

quote:

Originally posted by Relative:
Why do you say the exhaust "V Clamp" shouldn't be reused? What type of problem(s)might be encountered by reuse?

When we chase road call for exhaust leaks we sometimes hear. "I don't understand it - we just replaced that exhaust system." We'll show up and sure enough the "Vee Clamp" were it comes out of the turbo is snapped off at the mounting “Tee bolt”.

For tractor trailers there are several sizes - we carry two. If it's one of those we throw it on and the customer just trucks on down the road. If it's an odd ball we use a large hose clamp around the outer edge and then move our hand in a Up - Down - Right - Left fashion and then reflect. It must help cause no-one ever called back to complain.

We have yet (since 1987) to chase a call were the clamp just breaks off. It has always happened after they were disturbed. The stress from remove and reinstallation is what causes this. Sometimes us truck mechanics just remove everything like it was made for a truck, go figure. That "Tee bolt" isn't very big and it is subjected to a lot of heat.

Collective wisdom only. As stated earlier, hardly anyone does it, so don't sweat it. Out of everything you had off of the exhaust was that the only thing you reused? Did you reuse any other clamps?

I have re-used these clamps many times - I don't anymore. The cost factor to replace it is too cheap ($4.00-$16.00) compared to goodwill lost from something that inexpensive.

I just looked thru the search feature of my QuickBooks for a major breakdown and only found one that cost over $750.00. His exhaust melted most of the airlines (including the steel braided air compressor discharge line) on top of the transmission. Every other call was just a clamp and or a small repair.

Bill N.Y.

The only things I reused when I replaced the exhaust brake were the two clamps. Replacing it was one of the simplest repairs I've done. Disconnected the air line, removed the two clamps and partially undid the straps hanging the muffler to get a little slack. Had a new unit sent UPS to me in a KOA campground in Kentucky.

Actually, the old exhaust brake is now working too. After arriving home a few weeks later, I tore the thing apart and found the shaft that the butterfly mounts on was bent and was the cause of the bind. I thought the shaft was simply seizing in the holes because of crud buildup.

Straightened it out, cleaned the shaft and holes and the butterfly is so free it flops around unless connected to the air cylinder. If I hadn't put 2,500 miles on the new one, I'd return it, even though it is a newer model with supposedly better performance.

Mike

That type of clamp is very common on jetliners. I have never seen one broken except for when it was intentionally overtorqued in hopes of stopping a leak. I never saw that work, either, but every now and then someone thought it would be a good idea. However, they are almost always torqued to specs. More is not better. If they are overtorqued, they would likely fail the way Bill described, sooner or later.

So, I would re-use a clamp that I knew had a good history. I would not re-use a clamp that unknown people had tightened to unknown torque forces.

The most common failure mode was galled threads to to the stainless alloys, high heat and lack of anti sieze. There is a myth out there that a silver-plated nut is a silver bullet. Not so.

So, replace if of doubtful provenance, torque to specs, and use anti-seize.

Relative,

Was your exhaust and radiator on the same side of your coach (drivers side)? everything is fitted together very compactly on my unit. I also have a Gillig chassis. How long ago did you do this job? Do you remember the cost of the exhaust parts?

Bill G

Yes, the exhaust setup and the radiator are both on the left side of the coach. In my case, the only thing I replaced was the Pacbrake. The rest of the exhaust system was fine.

The Pacbrake was the new PXRB model for $710 + overnight shipping to the campground. Now, I would probably order two new V-clamps based on discussion in this forum.

Although it looks compact, by starting at the muffler and working your way back, it looks like a fairly easy job. First couple of parts - muffler, pipe, exhaust brake (if you have one) from the bottom, then continue on top with another pipe, turbo (if necessary), etc.