Right muffler for quiet ride?

[AWickman]

Hallo, I am new on this very interesting page. I have a 1983 Silverado with 6.2 and TH700. I have been driving the car daily since 15 years. Engine was rebuilt 3 years ago and the last year the car have been in small pieces - frame of restoration. I am now getting close and I am really looking forward to have the truck back on the road again. One thing I had as an aim was to have the cab quiet. I have insulated with Hush mats, new fire wall insulation, all rubber sealing new and new - what I thought - right type of muffler. But now when Im doing the first test rides I am disappointed. Still some kind of resonance - not a good sound level in the cab.
First I tried Walker muffler 18124, not good at all. Now I have Walker 17845 which I was told should be the right one for the 6.2. But no, not good. I can see that P/N 14063795 is GM part number. Anyone that have any idea how I can have a quiet ride?
Andreas Wickman, Gotland Sweden

[sctrailrider]

Build a resonator


https://www.performancetrucks.net/forums/gm-engine-exhaust-performance-21/how-build-exhaust-resonator-tube-eliminate-drone-489463/

[DmaxMaverick]

Welcome aboard!

A resonator is one option, but can be complicated, requiring repeated attempts. If you have dual exhaust, a crossover pipe (x-pipe, H-pipe, balance pipe, etc.) is much more simple, and often more effective for your V-8 Diesel.

[Robyn]

What Maverick said.....

The 6.2 with the dual pipes from the factory were very quiet.

Install a balance pipe between the two exhaust pipes ahead of the mufflers.

This will stop the "Rapping noise" and should stop the droning as well.

If you have large tail pipe tips (ENDS) THESE CAN CAUSE DRONE.

I installed a set of 5 inch chrome tips about 16" long on one of my trucks and it looked nice, but the drone was horrible.

The factory set up was the best as far as quiet.

[More Power]

What DmaxMaverick said about an H-pipe. Not only will it reduce the noise, it'll also allow the engine to produce more power. It's a big deal.

Generally, the larger the muffler the quieter it will be. A larger muffler more effectively cancels sound better for a diesel because of the engine's lower rpm nature. The quietest mufflers I've been around are those made by Banks - they're usually larger than most. I'd look for stainless steel exhaust system components if you live in areas where they use road de-icer during the winter months.

[AWickman]

Thank you a lot for the tip. I have seen those cross pipes and heard that they boost power, but not that they also helps against the drone. I have original pipes, one for the left bank and one for the right. 2.5 inch before the muffler. When I look for a good location for a H-pipe, it seems to be right behind the frames cross member. My truck is 2WD so there are quit good space just behind the transmission. Can I make it easy and just let the H-pipe joint be 90 degrees perpendicular attached? I have seen sophisticated cross systems more X-shaped, but that seems quite complicated to make. Will it be any different if I make the cross-pipe 2 inch instead of 2.5?

Once again. Happy I found this page!

[More Power]

If you have a light-duty engine, there is an exhaust passage through the intake manifold that effectively acts like an H-pipe. The HD 6.2L diesels from that era did not have that EGR passage in the intake manifold and the intake manifold gaskets included blocking plates for those passages. This is why using an HD intake manifold gasket set on an LD engine can result in a drastic change in exhaust noise and engine performance.

Otherwise, the best place for an H-pipe is as close to the engine as you can get it, while compromising a little for convenience's sake and future maintenance.

But... if you have a light-duty 6.2L diesel with an EGR equipped manifold, you may not need an H-pipe... That's why the factory didn't use one.

[AWickman]

No EGR valve on the engine today at least. If EGR-system is installed, should it then be an exhaust outlet just below the "iron header" (i dont know the english word)?

[DmaxMaverick]

No EGR valve on the engine today at least. If EGR-system is installed, should it then be an exhaust outlet just below the "iron header" (i dont know the english word)?

If your truck is a light duty model, and has an originally equipped TH700R4 transmission, it should have been originally equipped with EGR. There were exceptions, including fleet export models, which may apply to yours.

Below the "iron header" (cast iron exhaust manifold?), if it has EGR, would be the EPR (Exhaust Pressure Regulator valve, which is a simple butterfly valve). The EGR valve, if it has one, is located inside the intake manifold. It is obvious if it has one, being a large vacuum operated valve right in the middle of the intake, inside the air cleaner, with a vacuum line going to it through the bottom plate of the air cleaner.

It was quite common to defeat or delete the EGR system on these, and there are a few ways to do it. One is simply to remove or plug the vacuum line at the EGR valve (valve stays closed all the time). The second method is to remove the EGR valve and plug the holes in the manifold. The third is to replace the EGR manifold with a non-EGR manifold. It's simple to determine which you have. Remove the air cleaner and look into the intake. An EGR manifold will either have the valve in place, a mounting surface with threaded bolt holes and a large plugged hole (like a freeze plug on the side of the block), or a plain floor with only the air cleaner studs in place.

The EPR can be removed, forced fully open ("wired"), or the valve removed with shaft holes plugged.

[AWickman]

Thank you a lot for all this information. below the cast iron exhaust manifold (nearly as a long German word - is this what you use?) there is no valve today at least, and there is nothing under the air cleaner. I have today ordered a couple of 21/4 inch pipe pieces at my local shop that I will form to a H-pipe on Saturday. It should really be interesting to see if it will help.

[AWickman]

I spend some time to look into GM part catalog and I am really confused how many different mufflers there are for the 6.2 engine year 1983. This is what I found:
”C107(03)” 6.2 EXHAUST (LH6 DIESEL)
RH 14063876 LH 14067425

”C109(03), C2(03)” 6.2C/6,2J EXHAUST (LH6/LL4)
RH 14045002 LH 14045001

”C2(43), C3” 6.2J EXHAUST (LL4 DIESEL)
RH & LH 14063795

”C(06)” 6.2C/6.2J EXHAUST (LH6 DIESEL)
RH 14063876 LH 14067425

”C(06)” 6.2C/6.2J EXHAUST (LH6/LL4 DIESEL)
RH 14044998 LH 14044997

”K3(03-43)” 6.2J EXHAUST (LL4 DIESEL)
RH & LH 14063795

”K(06)” 6.2C/6.2J EXHAUST (LH6/LL4 DIESEL)
RH 14044998 LH 14044997

”K1,2(03)” 6.2C/6.2J EXHAUST (LH6/LL4 DIESEL)
RH 14063876/14063878 LH 14063875/14063877

”K(16)” 6.2C EXHAUST (LH6 DIESEL)
Rh 14067430 LH 14067429


Anyone who have the knowledge and time to explain the differences between all these versions?