So my 99 5.3l Sillverado has a grumble of sorts at part throttle (about 5%). It kinda sounds like an exhaust leak but it goes away once I actually get on it.
Any ideas?
vacuum leak? Any hesitation or misfire?
Didn’t even have to read the OG post.
All of them do it. It’s the “Seamless” transfer between 4 cylinder operation and 8 cylinder operation.
prolly an exhaust leak, hard to diagnose yourself, get a buddy to lay under the truck while you fuck around with the gas
It’s too low of a noise for a vacuum leak, i’ll check for hesitation tonight, but its only at like ‘cruising’ speed, not accelerating. And I don’t think i can get it to make the noise at idle…
Try seafoaming it next time you change the oil. The white smoke will easily let you find the leak.
you can seafoam without changing the oil, put it through the vacuum line, otherwise, the cold should let you see where a would be exhaust leak is from
hmm, good idea. I think we have some in the shop too.
I’m going to go out on a limb here and say either a cracked manifold or a bad exhaust manifold gasket
Manifolds usually have a very telltale tick though.
The cracked manifold thing is usually ford trucks
It definitely has a manifold gasket tick, I can hear that at idle. The grumble is a totally different noise but from what you guys are saying its the same issue just different frequencies/rpm’s? I couldnt replicate it with no load and it only does it about 1500 rpm.
You sure it’s not a misfire and giving it more gas clears it up?
Not sure at all, but the exhaust tick is there at idle. the grumble does sound like a misfire. I’ll check plugs in a bit