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I recently got a 2015 c7z06, the car has 4k miles on it and it does sound like this at cold start. It’s like a tap pause tap tap noise, it seems to start after 20 seconds after cold start, the sound goes away after the car is warmed up. Oil level is correct, new oem spark plugs and wires, double checked gap and wires to be correct. I checked under the car nothing seems to be missing or loose. I don’t know what else to check. Any help would be appreciated.
the sound is identical to the one on this video.
https://youtu.be/iEIdVZZKDzI?si=UZMdtNtIYUq5N238
Last edited by GunnerFox19; 05-13-2024 at 08:26 PM.
Could be the flex plate. There were problems with the old flexplate and GM made a revised one and issued a TSB. The rivets that were in the old flexplate caused for wobble in the plate it self and had the potential to hurt the thrust bearing. This was revised with bolts as opposed to rivets. This doesn't sound overly bad and may not have anything to do with what I'm saying, but it would be worth looking into and from where you are recording, that is where it would be coming from. Could also be that it is just starting and not bad yet. Hope this helps a little.
Ah, no you do not you have a flexplate since it is manual (You have a flywheel, the equivalent of a flexplate on a manual car). Totally disregard what I said here, it does not apply to you in this case. Good luck with diagnosing the issue
So I removed the supercharger belt and the noise is not there anymore, so I replaced the supercharger belt tensioner and installed a new belt on it and the sound is back. I’m really out of ideas.
Last edited by GunnerFox19; 06-01-2024 at 04:53 PM.
OP.
The bearing in the snout of my sc failed....diagnosed with a stethoscope...but it was a Maggie 2650.
Spray water on the belt while running.
Check the idler bearings.
There have been small instances that the supercharger pulley itself makes a clicking noise. Look around the forum & you may find the post.
Well l removed the idler under the supercharger and its destroyed, It taps just like the noise the car is making while spinning by hand. I already order a replacement and I’ll update yall if the noise is gone with the new idler.
OP.
The bearing in the snout of my sc failed....diagnosed with a stethoscope...but it was a Maggie 2650.
Spray water on the belt while running.
Check the idler bearings.
yeah idler under the supercharger taps/ clicks. i think the bearing is destroyed, i removed it and it does click/ tap loud while spinning it.
OP: Use a stethoscope or a 3 ft long wooden dowel to listen to the Supercharger snout bushing. It is located in the snout where the pulley shaft comes into the SC. If you hear the noise there the SC isolator may be going bad. The isolator provides a flexible coupling between the input shaft and the SC main shaft that turns the SC rotors. As the engine changes speed the isolator provides some slop so the SC rotors turning 4 or 5 times engine speed won't be subjected to as much of a shock load as engine speed changes.
To fix this the SC has to be removed from the engine and the snout from the SC. Once the snout is removed from the SC you will see the isolator. The snout can't be removed from the SC while it is mounted on the engine due to one of the bolts only being accessible from the rear of the snout under the SC.
The first three pictures show the snout and the isolator from different points of view:
Note the unthreaded bolt hole under the snout just above the red emblem, that is where the rear-mounted bolt that threads into the snout is located.
The final picture shows where the isolator fits into the SC.
Here is my Youtube video of what my isolator sounded like when it went really bad.
This can be a DIY repair if you can lift the SC off the engine. The SC weighs in the range of 65 pounds by itself and you have to lean over the fender to lift it and move it forward so it clears the rear of the hood opening. I used some sheet metal angle brackets with holes punched in them to make a lifting fixture then used my neighbor's engine hoist to lift the SC, that way there were no doctor bills for reinjuring my back.
Supposedly, there is a metal Vs plastic isolator that is available now to replace the failure-prone plastic installed in the production units. There is one location in the US that is certified to rebuild Eaton SCs and that is SuperChargers Online located in CA. Kong and Jokerz will rebuild them as well but as far as I know they aren't certified.
OP: Use a stethoscope or a 3 ft long wooden dowel to listen to the Supercharger snout bushing. It is located in the snout where the pulley shaft comes into the SC. If you hear the noise there the SC isolator may be going bad. The isolator provides a flexible coupling between the input shaft and the SC main shaft that turns the SC rotors. As the engine changes speed the isolator provides some slop so the SC rotors turning 4 or 5 times engine speed won't be subjected to as much of a shock load as engine speed changes.
To fix this the SC has to be removed from the engine and the snout from the SC. Once the snout is removed from the SC you will see the isolator. The snout can't be removed from the SC while it is mounted on the engine due to one of the bolts only being accessible from the rear of the snout under the SC.
The first three pictures show the snout and the isolator from different points of view:
Note the unthreaded bolt hole under the snout just above the red emblem, that is where the rear-mounted bolt that threads into the snout is located.
The final picture shows where the isolator fits into the SC.
This can be a DIY repair if you can lift the SC off the engine. The SC weighs in the range of 65 pounds by itself and you have to lean over the fender to lift it and move it forward so it clears the rear of the hood opening. I used some sheet metal angle brackets with holes punched in them to make a lifting fixture then used my neighbor's engine hoist to lift the SC, that way there were no doctor bills for reinjuring my back.
Supposedly, there is a metal Vs plastic isolator that is available now to replace the failure-prone plastic installed in the production units. There is one location in the US that is certified to rebuild Eaton SCs and that is SuperChargers Online located in CA. Kong and Jokerz will rebuild them as well but as far as I know they aren't certified.
Before ordering parts call and talk to vendors about what should be done and to make sure you are getting the correct parts.
Bill
Thanks for the info, my builder was thinking maybe the same thing. I will definitely take a listen to the area. Thanks a lot for replying, this thing is driving me 🤪.
05-13-2024, 08:01 PM
Is this a normal tap at cold start ??
