# Silverado "Grumble" **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [November 3, 2011, 8:11pm UTC](https://forums.speedlife.net/t/silverado-grumble/218058 "2011-11-03T20:11:18Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [November 3, 2011, 8:11pm UTC](https://forums.speedlife.net/t/silverado-grumble/218058/1 "2011-11-03T20:11:18Z")
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? ---
**Author:** ![Deathproof](https://avatars.discourse-cdn.com/v4/letter/d/dec6dc/32.png) [@Deathproof](https://forums.speedlife.net/u/Deathproof)\ **Post date:** [November 12, 2011, 11:29am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/2 "2011-11-12T11:29:01Z")
vacuum leak? Any hesitation or misfire? ---
**Author:** ![sobo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/sobo/32/5267_2.png) [@sobo](https://forums.speedlife.net/u/sobo)\ **Post date:** [November 12, 2011, 11:41am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/3 "2011-11-12T11:41:27Z")
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. ---
**Author:** ![ubengineering](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ubengineering/32/5171_2.png) [@ubengineering](https://forums.speedlife.net/u/ubengineering)\ **Post date:** [November 12, 2011, 11:41am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/4 "2011-11-12T11:41:34Z")
prolly an exhaust leak, hard to diagnose yourself, get a buddy to lay under the truck while you fuck around with the gas ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [November 12, 2011, 3:03pm UTC](https://forums.speedlife.net/t/silverado-grumble/218058/5 "2011-11-12T15:03:36Z")
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… ---
**Author:** ![lorge1989](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/lorge1989/32/6153_2.png) [@lorge1989](https://forums.speedlife.net/u/lorge1989)\ **Post date:** [November 12, 2011, 7:11pm UTC](https://forums.speedlife.net/t/silverado-grumble/218058/6 "2011-11-12T19:11:49Z")
Try seafoaming it next time you change the oil. The white smoke will easily let you find the leak. ---
**Author:** ![ubengineering](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ubengineering/32/5171_2.png) [@ubengineering](https://forums.speedlife.net/u/ubengineering)\ **Post date:** [November 12, 2011, 7:59pm UTC](https://forums.speedlife.net/t/silverado-grumble/218058/7 "2011-11-12T19:59:07Z")
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 ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [November 12, 2011, 8:29pm UTC](https://forums.speedlife.net/t/silverado-grumble/218058/8 "2011-11-12T20:29:38Z")
hmm, good idea. I think we have some in the shop too. ---
**Author:** ![Jam](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jam/32/7235_2.png) [@Jam](https://forums.speedlife.net/u/Jam)\ **Post date:** [November 13, 2011, 12:01am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/9 "2011-11-13T00:01:34Z")
I’m going to go out on a limb here and say either a cracked manifold or a bad exhaust manifold gasket ---
**Author:** ![JayS](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jays/32/15375_2.png) [@JayS](https://forums.speedlife.net/u/JayS)\ **Post date:** [November 13, 2011, 5:03am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/10 "2011-11-13T05:03:22Z")
Manifolds usually have a very telltale tick though. ---
**Author:** ![LZ1](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@LZ1](https://forums.speedlife.net/u/LZ1)\ **Post date:** [November 13, 2011, 5:32am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/11 "2011-11-13T05:32:30Z")
The cracked manifold thing is usually ford trucks ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [November 13, 2011, 8:25am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/12 "2011-11-13T08:25:30Z")
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. ---
**Author:** ![LZ1](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@LZ1](https://forums.speedlife.net/u/LZ1)\ **Post date:** [November 13, 2011, 8:27am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/13 "2011-11-13T08:27:35Z")
You sure it’s not a misfire and giving it more gas clears it up? ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [November 13, 2011, 9:09am UTC](https://forums.speedlife.net/t/silverado-grumble/218058/14 "2011-11-13T09:09:35Z")
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