Help with magical squeal. Not coming from belt. Maybe crank pulley/bearings/oil pump?
12-10-2015, 06:39 PM
#1
Help with magical squeal. Not coming from belt. Maybe crank pulley/bearings/oil pump? I have no idea where this squeal is coming from. Want to see if anyone has seen anything like this before I pull the crank pulley off, or possibly tear down further than that. I'll go ahead and say its a LQ 408 with about 15k miles on it and melling oil pump and LS2 timing set.
I thought it was the belt so I replaced it with a new one. Didnt fix it. Then I took the belt completely off and its still there with only the crank pulley turning.
This isnt a new build or anything. Drove the car one day and it was fine, drove it again the next day and it started doing this. No changes is parts or work done. Nothing has changed.
The crank pulley is on tight and is not wobbling any. Its an aftermarket 25% UD pulley with ARP crank bolt. Have had it for years with no issues. There are no oil leaks from the seal. Oil level and oil pressure is fine. Car runs 100% just fine.
I dont see how the pulley could be doing this. Could it be something inside the engine? Maybe crank, or crank bearings, or oil pump or something?
Here is a video I took. You cant see much but just listen to the squeal. Like I said there is no belt, only crank is turning. I'm turning the throttle body by hand just a little. It doesnt make the squeal when I give it a good amount of gas or full throttle. Only squeals a little a idle and the most just past idle. Also doesnt squeal at all when cold, only starts when at normal temperatures.
I thought it was the belt so I replaced it with a new one. Didnt fix it. Then I took the belt completely off and its still there with only the crank pulley turning.
This isnt a new build or anything. Drove the car one day and it was fine, drove it again the next day and it started doing this. No changes is parts or work done. Nothing has changed.
The crank pulley is on tight and is not wobbling any. Its an aftermarket 25% UD pulley with ARP crank bolt. Have had it for years with no issues. There are no oil leaks from the seal. Oil level and oil pressure is fine. Car runs 100% just fine.
I dont see how the pulley could be doing this. Could it be something inside the engine? Maybe crank, or crank bearings, or oil pump or something?
Here is a video I took. You cant see much but just listen to the squeal. Like I said there is no belt, only crank is turning. I'm turning the throttle body by hand just a little. It doesnt make the squeal when I give it a good amount of gas or full throttle. Only squeals a little a idle and the most just past idle. Also doesnt squeal at all when cold, only starts when at normal temperatures.
Last edited by Jc803; 12-10-2015 at 07:50 PM.
12-11-2015, 04:25 PM
#4
Mongo510, I feel like I barely know you, and we've never met, but I love you.
Problem is fixed. Turns out there was too much vacuum in the crank case. I forgot that a few weeks ago I switched from a Rx catch can with a fresh air source to a MM "Draft" can with no fresh air source. With no air entering the crank case the vacuum from the manifold was creating so much vacuum that air was actually entering through the front main seal making the seal basically whistle like sucking air in through your lips instead of blowing out. The lower the KPA (more vacuum) the louder it would be. Deceleration with the manual trans created the most vacuum and made it the loudest.
I never thought air coming in through the seal was possible so I overlooked it and explains why I was thinking oil pump or bearings as unlikely as that sounded.
To temporarily fix the problem I just uncapped a port on a valve cover. I'm going to run a line from the intake piping to driver side valve cover to filter the air entering.
Problem is fixed. Turns out there was too much vacuum in the crank case. I forgot that a few weeks ago I switched from a Rx catch can with a fresh air source to a MM "Draft" can with no fresh air source. With no air entering the crank case the vacuum from the manifold was creating so much vacuum that air was actually entering through the front main seal making the seal basically whistle like sucking air in through your lips instead of blowing out. The lower the KPA (more vacuum) the louder it would be. Deceleration with the manual trans created the most vacuum and made it the loudest.
I never thought air coming in through the seal was possible so I overlooked it and explains why I was thinking oil pump or bearings as unlikely as that sounded.
To temporarily fix the problem I just uncapped a port on a valve cover. I'm going to run a line from the intake piping to driver side valve cover to filter the air entering.
