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Likely exhaust leak locations

SS FORCE

Active Member
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Location
West Jordan utah
Thread starter #1
Good Monday morning all,

I was coming back from vacation Sunday afternoon and I think I have developed an exhaust leak. Looking to have that validated and a couple opinions.
To start off I changed the fuel filters on my fass to the CAT counterparts Saturday before returning home so they are new, Oil change was done Thursday and I am well aware of the ticking noise we experience from that. Now, on to the issue.

Driving at highway speeds (65-80) posted most of the way, when accelerating I would get a progressively louder pft pft pft noise that, from in cab sounded like it was coming from the passenger side. If I was just maintaining speed I get no ticking noise. No power loss, no codes, nothing but the ticking noise under hard throttle. Monitoring my CTS2 when boost would get around 25-28 psi was when the ticking noise was the loudest. I got home and unpacked without time to go investigate anything further. This morning I fired up the truck and at idle I can here what sounds very much like an exhaust leak now. From the outside of the truck it almost sounds louder on the driver side but can also be easily heard from the passenger side as well. I have a blocker plate in the egr showing some oil so I am wondering if it could be that?

I quickly looked at the egt probe and didn't see any soot around it. Several months ago I put in a 3'' downpipe, I don't know if there is something going on there with a V-band clamp.


Any suggestions on where to check for leaks? Or, am I experiencing an injector problem? Could it possibly be related to the fuel filters I just changed?
 

Will L.

Well-Known Member
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Boulder City Nv
#2
If you can here it and it Resembles the sound of a gas engine exhaust leak where you can hear the cylinders firing, it is pre turbo.

Couple of times I’ve been able to find an exhaust leak, providing leak is there when the engine is cold, by mixing up dish soap and water - then spraying it all over the exhaust manifolds, turbo, etc. and watching for the bubbles. It’s Just like you would a tire leaking air. Once the components get hot enough to cook off the water this will obviously not work.
This trick works best with three people. One of the driver seat to rev the engine up for more air volume flow, and one on each side of the truck to watch for the bubbles since you only have a minute or so before it is too hot. Since you will probably be the most observant of the 3, you take passenger side- and it is more spots to leak.

Another variation of this is hooking up shop air compressor or high quality leaf blower to the end of exhaust system.
 

SS FORCE

Active Member
Messages
227
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101
Location
West Jordan utah
Thread starter #3
Thank you Will I will try the soapy water. I'm down to 2 with me and the wife but that should work. It very much sounds like an exhaust leak on a gas truck. I'll report back when I can pull the fenders and get under with the spray bottle.
 

SS FORCE

Active Member
Messages
227
Likes
101
Location
West Jordan utah
Thread starter #6
I think the leaf blower up the tail pipe sounds to be more fun. LOL :happy:
Why did I expect Leroy to respond with something like that involving a “not me”.
I would have to consult the truck on that one.:woot:
First things first. I'm removing/cleaning the egr blocker plate and reinstalling. Then soapy water. Leaf blower enema if all else fails as I don't have one handy and would have to sweet talk the ol girl into taking one for the team.
 

SS FORCE

Active Member
Messages
227
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101
Location
West Jordan utah
Thread starter #7
Didn't get to touch the truck last night but I was able to pull the pass fender this morning before work along with putting a socket on the two egr bolts where the blocker is. I got a 1/4-1/2 turn out of the one on the center side of the engine. No change. Looking at the pass up pipe, manifold, downpipe, all is soot free apart from where the exhaust meets the downpipe. There is a small amount here at the V-band but as Will said, the sound I am hearing would place the leak pre turbo.

I'm starting to be concerned that what I am hearing is something else. the sound is most present at idle, at mid throttle the sound is gone completely. At 3/4+ the sound is a more pronounced ticking. I will hopefully have time after work tonight to give the soapy water a try.

As I mentioned earlier in my posts I am familiar with the oil change typewriter tick, which to me always sounded random. This is constant and seems to vary with RPM, only that the sound is present at idle and 3/4 to WOT. But, maybe I am not as familiar with the sound as I thought???
 

SS FORCE

Active Member
Messages
227
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101
Location
West Jordan utah
Thread starter #12
Will L, MrMarty51, Thank you

I took a soapy bottle to the exhaust on the passenger and back side of the engine, nothing. Drove it to work this morning and had a buddy take a listen, who sent a short video to a fellow duramax owner. He quickly replied it typewriter tick, calm down.

I didn't feel it was as I could hear the noise when I would punch it. and my previous encounters with the post oil change tick were always random. But he assured me if I wasn't having any performance issues that's exactly what it is.

So don't I look like a relieved fool now... :banghead:
 

SS FORCE

Active Member
Messages
227
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101
Location
West Jordan utah
Thread starter #14
Thanks Will L. Thank you all for your expertise. I still don't like the sound and will be more than relieved when it goes away but for now I am happy to know its just a 'normal' noise.
 
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