Minor Exhaust Manifold Leak

[arwriter]

I have a 1999 Silverado 2500 with the 6.0 liter engine. It has a slight exhaust leak when the engine is cold that goes away once the engine is warm. Once I noticed the leak, I inspected the engine to find the the manifold bolts closest to the fire wall are missing their heads. Having extracted manifold bolts before from one of our tractors, I am too familiar with the difficulty of the job.

 

Is it crucial to have these bolts extracted and to fix the small leak, or can I go a long period without the threat of long term harm to the engine?

 

Please advise.

[Jsdirt]

First off, THANKS for your service!

 

In the past I've driven vehicles for years with header/manifold leaks without any issues besides the annoying sound. On these newer vehicles you'll probably get a check engine light for being lean ... and if the leak is large enough to affect the o2 sensor you will burn through quite a bit of fuel, since the computer will try to richen the mixture to compensate for the additional air (and thus lack of fuel) it thinks the engine is pumping out. If you don't have the light on, I wouldn't worry about it for now.

[arwriter]

First off, THANKS for your service! In the past I've driven vehicles for years with header/manifold leaks without any issues besides the annoying sound. On these newer vehicles you'll probably get a check engine light for being lean ... and if the leak is large enough to affect the o2 sensor you will burn through quite a bit of fuel, since the computer will try to richen the mixture to compensate for the additional air (and thus lack of fuel) it thinks the engine is pumping out. If you don't have the light on, I wouldn't worry about it for now.

 

 

Thank you for your gratitude; it is my distinct honor to serve.

 

No check engine light has come on yet. Listening to it this morning, it is almost indistinguishable with a cold engine at idle. It is accentuated when accelerating with a cold engine, but once the engine temp reaches about 160 degrees the noise goes away and it appears that it seals. On our farm, we have a 98 1/2 ton with a 5.7 liter engine that the previous owner put headers on, and it has a much more pronounced leak that doesn't go away warm or cold. The check engine light is not on and the power seems to be unaffected thus far. Because it is a farm run around truck, we have no immediate plans to fix the leak either. I am more inclined to fix the 99 3/4 ton, however, because it is used more often and for longer trips carrying much larger loads. In short I am in greater need of it and ensuring its reliability as the truck only has 87K on it and I intend to drive it for a long time.

 

Obviously the truck is not under warranty and from my limited research there is no recall to fix this common issue with the 6.0 liter engines. I am curious to know from someone who has paid to have the bolts extracted and all new bolts and gasket and possibly manifolds installed; what the cost was.

 

Please advise.

[ride65]

The exhaust manifold bolts head shearing are a problem that also occur on the 5.3L, I found the problem and the fix while rebuilding my 5.3L. The new harder bolts with a bigger head are GM part number 11518860, about a buck and a half each. Wouldn't know about the cost of labor, but the bolts that were sheared in my heads(4) turned out with a pair of vice grips, pretty lucky.

[ChevyTech77]

First off again, thank you for your service Marine.

 

Second, most of the local exhaust shops in my area are well versed at this repair and usually charge about $150-200 to do both manifolds and install the new bolts. Pretty resonable if you ask me but I've been privy to doing this job and if it wasn't for the large

tool box and shop that I have at my beck and call, I'd hire it done myself.