I put about 50 miles on my 6.2 every weekend lately,mostly on back roads ..
The subject is the noise the 6.2's all seem to make..
I've noticed the usual diesel "clatter" the 6.2's make (like hailstones on a tin roof) is most pronounced at a fast idle,when you are cruising along between 30 and 45 mph..
When I let off the throttle and coast,it gets almost silent in comparison..that isn't unusual really,its always been that way..
This engine in my pickup is a lot noisier than the 6.2 in my '85 K-10 Suburban for whatever reason...I looked at the injector pump timing marks ,and its dead on the scribed lines,so I doubt it's been fooled with..sounds like it is advanced more than the Suburban's engine though,that one is much less "clattery"..it also doesn't seem as peppy or responsive as the pickup either..
What puzzles me is on the ride I take ,there is a long downhill grade about 1/8th of a mile long,and I have to make a 90 degree turn at the bottom of it,so I must slow almost to a complete stop to take the corner..
I often pull the TH400 down into second gear so engine braking keeps the truck from gaining a lot of speed down the hill..then I take the corner,put it back in drive,and go on my way..
Then comes the puzzling part--the engine always quiets down after that,to the point its almost silent!--no "clatter" at any rpm/ speed,for at least 2 miles,then the clatter gradually returns,and remains "noisy" as it always sounds the rest of the ride..
Makes me wonder if the engine gets a lot of oil puddling in the timing chain area while it is pointed downhill and I had downshifted it,or maybe oil gets sucked past the valve guides and lubes them up better temporarily--there is no oil smoke while coasting ,and no difference in how it runs,I would expect any excess oil getting sucked in the combustion chamber would make it rev up for at least a few seconds as it got burned if that was the case..
It does this at the same hill every time,so it isn't just a fluke that happened once or twice..I'm taking dozens of times..
Just seems weird to me,like maybe the engine isn't getting oiled somewhere enough..but it has at least 25 psi at idle and over 40 psi above idle,just as it always has..engine has no other knocks like a loose bearing or rockers,lifters,etc either..so it's not like its going to pop or anything,its just puzzling to me why it can get so quiet temporarily..
Any one have a theory ?..
...
The subject is the noise the 6.2's all seem to make..
I've noticed the usual diesel "clatter" the 6.2's make (like hailstones on a tin roof) is most pronounced at a fast idle,when you are cruising along between 30 and 45 mph..
When I let off the throttle and coast,it gets almost silent in comparison..that isn't unusual really,its always been that way..
This engine in my pickup is a lot noisier than the 6.2 in my '85 K-10 Suburban for whatever reason...I looked at the injector pump timing marks ,and its dead on the scribed lines,so I doubt it's been fooled with..sounds like it is advanced more than the Suburban's engine though,that one is much less "clattery"..it also doesn't seem as peppy or responsive as the pickup either..
What puzzles me is on the ride I take ,there is a long downhill grade about 1/8th of a mile long,and I have to make a 90 degree turn at the bottom of it,so I must slow almost to a complete stop to take the corner..
I often pull the TH400 down into second gear so engine braking keeps the truck from gaining a lot of speed down the hill..then I take the corner,put it back in drive,and go on my way..
Then comes the puzzling part--the engine always quiets down after that,to the point its almost silent!--no "clatter" at any rpm/ speed,for at least 2 miles,then the clatter gradually returns,and remains "noisy" as it always sounds the rest of the ride..
Makes me wonder if the engine gets a lot of oil puddling in the timing chain area while it is pointed downhill and I had downshifted it,or maybe oil gets sucked past the valve guides and lubes them up better temporarily--there is no oil smoke while coasting ,and no difference in how it runs,I would expect any excess oil getting sucked in the combustion chamber would make it rev up for at least a few seconds as it got burned if that was the case..
It does this at the same hill every time,so it isn't just a fluke that happened once or twice..I'm taking dozens of times..
Just seems weird to me,like maybe the engine isn't getting oiled somewhere enough..but it has at least 25 psi at idle and over 40 psi above idle,just as it always has..engine has no other knocks like a loose bearing or rockers,lifters,etc either..so it's not like its going to pop or anything,its just puzzling to me why it can get so quiet temporarily..
Any one have a theory ?..
...
