Wierd noise about 2k RPM

[mkiiSupraMan18]

OK, Rebuilt engine, all stock. Maybe 2500-3000 miles on it. 7mgte, 7psi, been hitting FCO like a mother since it's been together (hole in IC and 15 other leaks that Jason and I found). Been running basically a turbo elbow the entire time, yeah... No oil leaking problems, never been low. it's on it's 3rd oil change currently.

It was really wierd. We took the car out after fixing the boost leaks and we were still hitting FCO after shifts, and it's ALWAYS hit FCO just before or after the shifts. We did a 4th gear pull and it ran perfect until it went to shift into OD, shifted smooth and BAM... fco. No surprise really. So we turn around on a side road, go to head back, just normal cruising and we start hearing the noise I described earlier. We weren't boosting, well, we weren't ripping on it anyway, thats for sure. so we just cruised on back to see what was up. It's not a super loud noise, but it was kind of hard to hear over the "exhaust".

Anyway... It kinda sounds like a metal shield vibrating back and forth up against something but thats not what it is I am 100% possitive. Anyway, I jacked the car up, had my dad rev it to 2k and listened around w/ a stethoscope... Oil pan, it was very faint in some areas, but I don't believe its coming fromt here (It deff doesn't sound like RK). Listened on the Auto Trans pan, got noticeable louder, but still wasn't super loud. So then I put it on the bellhousing... I had to take the stethoscope off.

My questions now are:
1) Is the bellhousing just making the sound more audible since it's aluminum or some other wierd phenom like that?
2) It's the torque converter, right?
3) Loose bolts, something all up in it?


This piece shoulda been a 5sp a LONG time ago anyway. I just hope that it isn't engine related. Somebody give me some good news. :icon_conf

 

[jdub]

I have an auto tranny and mine made a sound similar to what you described...a sort of "buzzing" sound that was louder at low rpm.

Turned out it was the downpipe...there is a bracket that secures the downpipe on the passenger side of the tranny that attaches to the bellhousing. It fits right against the downpipe...needs to have a clamp around it holding the pipe securely.

Also check the heat shield above the downpipe mounted on the chassis. Mine was a little loose and was causing noise as well.

 

[mkiiSupraMan18]

^ Not possible. I was running the turbo elbow only. But I guess it could have been the engine/trans supports. But it doesn't really sound like that through the stethoscope. Kind of a high-ish pitched hollow sound. Like a lifter actually. But it's deffinitely a lot louder under the car than above it.

I'll check the heat shield above where the cat would normally be.

 

[JSHeinrich]

I have a similar problem (atleast it sounds like the same thing). When mmy rpm's are in 1000 to 1300 or 1400 i get a crazy rattle sound...haven't quite figured it out yet...

 

[jdub]

Sorry - didn't realize you were running with no exhaust.

Are you sure the flex plate bolts were torqued properly?

Is your tranny fluid at the correct level warm...there's a specific way to check it in the TRSM for an auto.

 

[mkiiSupraMan18]

Yes, flex plate was torqued correctly. The torque converter was also.

Last time I checked the trans fluid was at the correct level as well. If it was low wouldnt it be shifting like crapp as well?

 

[jdub]

Yes, flex plate was torqued correctly. The torque converter was also.

Last time I checked the trans fluid was at the correct level as well. If it was low wouldnt it be shifting like crapp as well?

Could affect shift, but it might be a slightly low/high...something you may not notice. Also can affect converter stall speed. Checking the fluid for an overfill is as important as checking it for being low...it needs to be in the warm operating range with it warmed up (obviously).

Might want to put your stethoscope on the starter to see if that it the source...it should be disengaged after start...just throwing out a couple of thoughts.

 

[mkiiSupraMan18]

^ It's a brand new starter, but I will deffinitely take a look at it after school today.

 

[mkiiSupraMan18]

Could I also get a list of every possible reason I would be hitting FCO @ stock boost with a stock wastegate (unshimmed).

Also, Boost creep. It'll boost to 7 psi and will gradually just keep working it's way up. We shimmed the wastegate way out and it was running 10-12 psi and would still hit FCO at about the same time and under the same circumstances. We have swpped out AFMs, so that is not the case.

*edit*
And there are 0 (zero) boost leeaks from the turbo to the TB. Oh, and it's just a code 34. :icon_conf

 

[dbsupra90]

matt-

pull a plug wire one at a time from the coil pack and see if the noise goes away. if it does, you know its a motor prob and what cyl. if not, you know it is elsewhere.

 

[Adjuster]

What does it sound like?

If your getting a tick tick tick or clack clack clack noise from there, it's a cracked flex plate.

I have seen this in a GM auto trans, and one Supra. (A 91 turbo/auto.)

Sounded pretty much the same. The Supra was broken way more than the Camaro however. (I changed mine out on the Camaro when it first started to make noise, but he drove around for a long time, and it was about broken completely away from the starter ring where the tourqe converter attaches, to the center where you bolt it up to the crank.)

 

[mkiiSupraMan18]

I will check all three things that have been suggested so far. I would call the noise more of the "clack clack clack" as opposed to the "click click click" .

Will taking the plug off make the noise dissapear even if it's in the valvetrain? My first thought was a floater when it started....

+1s for all.

 

[mkiiSupraMan18]

^ Adjuster was ftw.

Time for that 5 speed swap. :icon_bigg

*edit*
t'was the broken flexplate... the noise was the holes hitting the edge of the block/oil pan. doesnt appeared to have messed either up though.

 

[jdub]

If you need a flex plate, I'm pretty sure I've got one...you can have it for the cost of shipping

 

[mkiiSupraMan18]

Oh, I have another... its just that if I pull it. I'm going 5 speed. :icon_bigg

What a great exscuse, eh?

 

[jdub]

Yeah...that's a good one

 

[rumptis]

Matt and I pull his trans last night and it for sure was the flex plate hitting oil pan and making the nose but not sure why it started all the sudden...nothing was broken.

I do have one question though...there is a spacer that goes alone with the flex plate...does that go between the flex plate and the crack or does it go on the outside of the flex plate?