2005 Denali XL Engine rattle/Knock when cold

[MnBry1]

Last week my 05 denali Which has always run good and then maintained well Started having a rattle/ knock on start up and during warm up... Having a bit of trouble trying to pinpoint, I'm going to get my mechanics stethoscope from my work in the next day or so and check it out with that.
Once the truck is warmed up there is no rattle, no knock it runs perfectly well full power and you would not know there's an issue come up but once it cools off a bit that knock will be there until it's warmed up again. Oil pressure gauge goes right up near 80 rate were it has always been and I have No check engine light.... But the noise on start up is very loud and Obvious. Has little over a 1000 miles on the current oil change and I have been using Full synthetic for 3 years And also always add a bit of motorkote.
267,000 miles on truck, And again has been maintained well and runs perfectly good once at temp.
Any thoughts would be Appreciated, thank you

 

[Mechanic421]

Almost sounds like maybe a catalytic converter or maybe a lifter . Hard to say with out hearing it. A long thin screwdriver works well also.

 

[Joseph Garcia]

Does the rattle/knock become more pronounced or louder, when you accelerate, when the engine is cold, versus sitting at idle?

 

[MnBry1]

Does the rattle/knock become more pronounced or louder, when you accelerate, when the engine is cold, versus sitting at idle?

Yes, sorry about that I had Intended to mention that in the original post…. It is rotational with the engine , what Is kind of making me think is that it goes away entirely once the engine is warmed up.

 

[wjburken]

While you have your stethoscope, might check around you exhaust manifolds. If the noise you are hearing just started all of a sudden, you might have had a manifold bolt break and create a slight exhaust leak that closes up when everything gets hot.

 

[OR VietVet]

Sounds like the dreaded lifter rattle and with that many miles on that engine it could be other things like the exhaust leak Wade mentioned, cat converter noise that David mentioned but one thing is for sure. The stethoscope will help pin it down.

 

[MnBry1]

I am very familiar with the exhaust manifold bolts breaking and what that sounds like.... When through that on my 04 which was an identical truck to this one. This is much more of a pronounced knock or rattle.

Lifters were mentioned do these engines have an issue with that? I have had several GM Trucks but I've never had Any deep engine issues so something like this is new to me

While you have your stethoscope, might check around you exhaust manifolds. If the noise you are hearing just started all of a sudden, you might have had a manifold bolt break and create a slight exhaust leak that closes up when everything gets hot.

Sounds like the dreaded lifter rattle and with that many miles on that engine it could be other things like the exhaust leak Wade mentioned, cat converter noise that David mentioned but one thing is for sure. The stethoscope will help pin it down.

 

[OR VietVet]

Many threads here about lifter noise and even piston slap. Read thru them because it would take some time for others here to duplicate what has already been discussed. Watch some you tube about it as well.

 

[petethepug]

Wonder why no one referred him to the 00-06 NBS section? Nice crowd [emoji2]


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