Hello, I have been having trouble with my sr20det redtop. I recently had my new rebuilt T25 turbo installed at a shop along with megan racing manifold, elbow, and circuit sports turbo lines around 5 months ago. All the nuts were tight and nothing was loose. I have been hearing this weird noise, which would make my car sound like a tractor during acceleration and at idle. At first i thought it was a exhaust leak but i took apart pretty much everything that has a gasket and they are all in good shape (downpipe, elbow..etc)
theres a plate on the turbo near the actuator which i THINK is vibrating against the bracket you see on the motor mount (i just bent the motor mount bracket because it was touching the turbo) Has anyone else had this issue and could this be what im hearing?
Another newb question, is that bracket or plate safe to be removed because when i was looking at the piece, it looked like it was just randomly bolted there with no purpose
Thanks for your help
SR20DET strange issue..
Re: SR20DET strange issue.. (S13Redbug)
That bracket has at least one purpose, which is to keep the compressor housing sandwiched together.
Its possible ulterior purpose, being that it's a bracket with an additional 2 anchor nuts on it, indicates to me that it used to have some sort of heat shield that bolted to it from the factory.
It's been a long time since I had a T25 installed and even longer since I got my motor off the pallet so I don't remember what all used to be there... but you shouldn't remove it for the sake of removing it, because it Is helping to keep the compressor housing together. There should be 2 other areas on the back of the housing that have similar measures in place.
It's probably not the source of your noise. It wouldn't be hitting your motor mount there because as the engine rocks back and forth the mount compresses along with it, so the bracket and the shield on the mount are always the same distance from one another. (edit: i just re-read that you had just bent that shield out of the way. I'm guessing it didn't help?)
If you originally suspected an exhaust leak, I'd continue along that route. Get a small telescoping mirror and a light and make sure the 4 nuts on the turbo flange aren't vibrating loose. They're supposed to be held in place with lock-tabs so they don't rotate loose from vibration and heat expansion. Were the lock-tabs installed when changing to the Megan manifold? They are very important to retain. If reused a few times they can break, but you can order a new pair for a 300zx turbo from the dealership.
Also, did you use the tin/paper turbo flange and header gaskets that came with the manifold, or are you using new Nissan gaskets? The tin/paper gaskets can blow out from heat alone, especially at the T2 flange where the turbo bolts to the header.
Have you bottomed out and crushed the bottom of your downpipe? That force can deform your header and/or turbo gaskets and cause a leak, too. I finally realized that recently after trying to fix an exhaust leak that I was sure was my forward downpipe gasket.
Finally, don't rule out that your exhaust manifold may have a hair line crack in it somewhere, most likely to occur along a weld seam. Lots of people use Megan manifolds without any issues but there can't possibly be a 100% success rate.
Its possible ulterior purpose, being that it's a bracket with an additional 2 anchor nuts on it, indicates to me that it used to have some sort of heat shield that bolted to it from the factory.
It's been a long time since I had a T25 installed and even longer since I got my motor off the pallet so I don't remember what all used to be there... but you shouldn't remove it for the sake of removing it, because it Is helping to keep the compressor housing together. There should be 2 other areas on the back of the housing that have similar measures in place.
It's probably not the source of your noise. It wouldn't be hitting your motor mount there because as the engine rocks back and forth the mount compresses along with it, so the bracket and the shield on the mount are always the same distance from one another. (edit: i just re-read that you had just bent that shield out of the way. I'm guessing it didn't help?)
If you originally suspected an exhaust leak, I'd continue along that route. Get a small telescoping mirror and a light and make sure the 4 nuts on the turbo flange aren't vibrating loose. They're supposed to be held in place with lock-tabs so they don't rotate loose from vibration and heat expansion. Were the lock-tabs installed when changing to the Megan manifold? They are very important to retain. If reused a few times they can break, but you can order a new pair for a 300zx turbo from the dealership.
Also, did you use the tin/paper turbo flange and header gaskets that came with the manifold, or are you using new Nissan gaskets? The tin/paper gaskets can blow out from heat alone, especially at the T2 flange where the turbo bolts to the header.
Have you bottomed out and crushed the bottom of your downpipe? That force can deform your header and/or turbo gaskets and cause a leak, too. I finally realized that recently after trying to fix an exhaust leak that I was sure was my forward downpipe gasket.
Finally, don't rule out that your exhaust manifold may have a hair line crack in it somewhere, most likely to occur along a weld seam. Lots of people use Megan manifolds without any issues but there can't possibly be a 100% success rate.