Vortec 8.1 Loud Under Load, Passenger Side

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drisley

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I've got a 2002 Vacationer on the W22 chassis, Vortec 8.1. We are currently up around the Smokies, from Florida. As we went north of Atlanta, I noticed that the engine (seemingly suddenly) was much louder under load. More so than usual. Here's what I'm noticing...

  • When under load (like climbing a hill or accelerating, it is louder than usual. Almost like a lawn mower.. it has that unmuffled clicking sound coming from the passenger side.
  • It seems to rattle a bit while idling.
  • The exhaust coming out of the passenger side tailpipe is visible and a bit louder than the driver side. Not smoking, but you can see the exhaust.
  • It SEEMS as if I have to open throttle more than usual to get up the hills. I'm going out of memory here, but it just seems not to have as much umph up the hllls. Could just be me being overly sensitive at this point. ;)
  • No overheating or anything. Engine seems to be doing it's job. And when we're flat and level and the engine isn't under any load, it sounds perfectly smooth and normal

I've done some reading and some people say spark plugs. I'm not exactly a mechanic here. :) And I don't have a mechanic's set of tools with me here (just standard stuff). But, is there anything I can check easily?

Some have talked about the donut gasket where the exhaust pipe begins (out from the manifold). When I look there, I see no weird discolorations or anything. Interestingly, though, we can smell some exhaust fumes from the engine when we're sitting still. When we pulled into our current campground, we even had the gas alarm go off inside while the rig was sitting still. No odors or anything while traveling because the airflow is higher, most likely.

Hoping somebody can help point me in the right direction.

We're heading to Anchors Down from here and I'm sure I can get there without issue, since I've probably put 150 miles on the rig since I noticed this. But, there's a lot of up and down around here in the mountains, so this noise is nerve wracking and I'm concerned if it is hurting anything.
 
A couple of other possibilities are leaking manifold gasket caused by broken bolts, or a worn out muffler.  Does the check engine light come on?
 
Paul & Ann said:
A couple of other possibilities are leaking manifold gasket caused by broken bolts, or a worn out muffler.  Does the check engine light come on?
No. We have a Scanguage in it, too, and there's no codes or anything. And it doesn't sound as if there's a muffler issue. The noise is coming from the front, not the tailpipe.

I also checked the bolts I can see around the engine and nothing looks to be blown or broken, that I can tell.
 
How many miles on it?

Have you ever had exhaust manifold problems? Usually the  bolts will break after a while. I've had mine in several times over the years for that.

Exhaust manifold leaks will make many and various sounds that will come and go. Sometimes only at startup and go away when warm, some not.

I didn't notice any loss of power when mine were bad.

The leaks didn't seem to hurt anything as I ran cross country with mine before I knew what it was.

Are you getting a Check Engine Light? Visible exhaust on one side is a bit strange, maybe unburnt fuel.

Have you ever replaced the plugs and wires? 
 
About 42k miles on it. No bolt issues that I know of, but I don't know the history of the rig before I owned it. And no, no codes or check engine light.

I just took a couple photos of the top of the passenger-side cylinder bank. I notice some staining there. Don't know if that's a concern. Doesn't seem new to me, tho.
 

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I went out and looked through the wheel well and up from underneath. It SEEMS as if the manifold bolts are intact, if I know what I'm looking at. Although, there are some holes that appear to have nothing in it. A few images attached. Hope you can tell what it is, since it is from weird angles.
 

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X3 on exhaust manifold. Actually have that exact issue that's getting fixed in a couple days. Sounds exactly as you describe. That "click" is actually a little spurt of exhaust from the one cylinder closest to the broken bolt.
 
Arch Hoagland said:
I think I'd take it to a Workhorse dealer. Looks like you need plugs and wires to me and have them check the exhaust manifolds.
How would I know if I need new plugs and wires? None of the wires look back to me.

And in terms of the exhaust manifold, if I do indeed have an issue with that, is it hurting anything for me to drive it around? It'd obviously be easier to deal with a repair back home in Florida than out on the road. If it is only a noise issue and otherwise not a big deal, I'll just drive it home like this.
 
Suspect list includes bad manifold to exhaust pipe gasket

Bad manifold mounting bolt
Bad manifold gasket
Cracked manifold
and. from there it gets real expensive.

Also you should inspect the pipe and muffler.
 
OK, so can I continue to drive it like this until I get home without worrying about anything?
 
Not sure which years involved but some Vortec 8.1 engines had a history of wires and plugs overheating due to a design problem.  Apparently not enough clearance from some hot surfaces.  Discovered this while researching our 2005 Pace Arrow with the same engine.  When I reviewed the service records of the original owner, I noticed one or two times when the plugs were replaced.  Motorhome only had 32,000 miles on the Odometer when we purchased it two months ago.  A lack of power is one of the symptoms. 
 
Sounds like a bad exhaust gasket. Especially if you are missing bolts. Sometimes the gaskets get super brittle and a small piece can get blown out where
the bolt is missing/loose. The rest of the bolts will seem tight still. About driving if that is the problem I'm no help there.

 
I say small hole in exhaust manifold. Here's a pic of mine. It was behind a tin shroud. The air would bounce off that. It progressed to different sounds. One like marbles in a can rattling around and a ping. Then it would only make a noise under load. 

 

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With the engine stone cold, have someone else fire it up as you feel around the manifolds / exhaust for the leak.

You have only moments for this process before it gets too hot.

 
SkateBoard said:
I say small hole in exhaust manifold. Here's a pic of mine. It was behind a tin shroud. The air would bounce off that. It progressed to different sounds. One like marbles in a can rattling around and a ping. Then it would only make a noise under load.
SkateBoard...your manifold is cracked,  it will expand and get louder as it heats up. you can try to have it welded but cast iron is difficult to weld correctly. 

Big block Chevy's are famous for that.  It's time for a set of headers or a new manifold.
 
TonyDtorch said:
SkateBoard...your manifold is cracked,  it will expand and get louder as it heats up. you can try to have it welded but cast iron is difficult to weld correctly. 

Big block Chevy's are famous for that.  It's time for a set of headers or a new manifold.

Started out as a hole and that's why I posted that pic
 
I had a Class C 25 years ago with a 360 Dodge. It had been run so long with a small section of the manifold gasket blown out that a V groove eroded in both manifold and head. Both had to be milled to repair.

I wouldn't drive thousands of miles but would drive hundreds.

Tom
 
I've got an appointment locally here on Tuesday AM to have it looked at. Decided I'd rather get it checked out sooner rather than drive several hundred new miles with it like this.
 

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