Hi Guys. Got my Stato back with its new engine yesterday arvo. (5.0) Took it for a drive, runs perfectly, shifts perfectly etc When it's at idle I can feel a thumping sensation through the floor pan of the car, It also has a bit of a knock at low idle and when the engine kicks back to fist right before it drops back to idle as I am pulling up to go with the vibration that can only be heard from within the cabin. I have run the stethoscope over the engine and trans to make sure there is nothing mechanically wrong there and they are fine, the vibration and clunk/knock can not be heard from the outside of the car, only in the cabin with windows up and stereo off....The only time the sound gets worse is right before I pull up at the lights when the trans shifts back to first it has a bit of a rattle/knocking Engine mounts look ok, engine isn't sagging on crossmember etc Transmission mount is looking pretty poor, chunks of rubber etc falling out of it (I first thought through my head well this is obviously it but have never seen a trans mount cause a clunk/thump at idle only when accelerating/going over bumps etc.) The Catback is also another possibility, the mufflers are packed full of rust & crap due to poor maintenance from previous owner (to the point where the exhaust pops and farts and the gasses don't even make it all the way to the tail pipe half the time), the mufflers rattle when I give them a bash with a stick so thinking this could be it but I can hear it more from the front footwells than the rear......Catalytic converter is fine I have already removed and inspected that. Just wondering if anyone has ever had anything similar? if someone could help me narrow it down then I will know what to replace first be it exhaust or mounts etc but after spending almost $2k on a new engine etc I don't have much left to do the whole lot in one go. I have also checked that the engine/trans/headers isn't fowling on anything after the engine swap. Any help would be appreciated.
Thanks mate, yeah, had a poke at it with my fingers and huge chunks of rubber started falling out the mount so wouldn't be surprised if there is no rubber absorption in the mount anymore.....the mechanics probably had finished what was left of the mount off when dropping engine/trans back in......a little annoyed they didn't ask me if I wanted new mounts etc while it was out but oh well, its an easy job anyway I tried prying the transmission off the crossmember with a pry bar to check for any movement and there wasn't any up/down movement or play, so I assume this would mean the mount is still holding the trans down but there is no rubber to cushion it?
Well update time: Fit the new transmission mount, it has smoothed the car out when driving and stopped the knocking around when going over bumps but hasn't fixed my thumping/tapping/ticking sound from the cabin. Went over the car again with the stethoscope to try and pinpoint it but still no good, nothing audible from under the car or the engine bay. I had a thought though, the vibration is coming through the floorpan at the same interval as the fuel system pulsing, could I be feeling the fuel lines/injectors pulsing through the floor?.......I have felt the fuel lines in the engine bay and it feels like its at the exact same interval/sequence Once again it makes a slight tapping/thud thud thud from inside the cabin at idle only when the windows are up and the radio is turned down.....could it be as simple as the fuel system pulse? I have decided just to get a louder exhaust due to the poor state of the factory one mentioned in the first post so once thats in I won't be able to hear the problem but me being paranoid would still like to get to the root of it one of the lines vibrating on the firewall/floor could be the explanation as the noise has only been noticeable since the new engine has been fit so maybe something was knocked/moved? Any thoughts?
The 'pulse' you feel is also the same speed as the exhaust or the same as every firing of a cylinder. Check the exhaust manifolds closely around the gasket edges for leaks. As a way outside the square thought, check flex plate bolts.
Thanks Hako. Will check TC to Flexplate bolts tomorrow, obviously can't check flywheel bolts as they are inaccessible from under the car but I did check them before the engine went in. Will have a look around the gaskets tomorrow, they are factory headers so wouldn't surprise me if there was a crack etc somewhere.
