Noise, Knock, Tap, Heck I dont know...

[sho_shane]

I have a noise coming from under the hood. I say under the hood cus I dont know for sure where its coming from. Motor or Trans is what im trying to find out.

I have a 1991 SHO with 183K on it. It had the Rod Bearings done at 171K and the last 60K was done at 94K so I know its time for that.

I have a tap/knock that only happens between 2000 and 3500RPM, It only does it when the car is moving. If you rev the motor sitting still in gear with the clutch in or out of gear with the clutch out its smooth as glass and not a wierd sound at all. But if your raising in speed you can hear it from 2000-3500RPM. Sometimes you will not hear it at all and sometimes you will. To me it sounds like its coming from the drivers side of the car but I know sound can traval in metal so im not sure.

I would really like to know what yall think and any help would really be great.

 

[sperold]

You have to come up with a way to get the sound to happen so that a reading can be taken by a stethascope. I think I understood that it doesn't happen with the car sitting still (clutch in, and clutch out in neutral).
Worst case scenario is your differential pin moving out into a hard surface.
Less worrysome would be cam chain noise.
Shouldn't be a rod bearing if everything was done correctly.
The drivers side has the transmission / differential (where the pin is).
Take the hood off and come up with something innovative.... soon.

 

[sho_shane]

Well thats another think to, You cant really hear it on the outside of the car, or at least I cant when im going with the window down.

 

[sho_shane]

Come on guys i need yalls help..

 

[JRA2000TL]

I just did bearings on my 95 and sometimes when it's cool outside I can hear this light tapping/knocking upon accel. If it sounds like mine, I'm thinking it's a cam chain because it smooths out or drowns out when you get up to higher speeds or rpms. You also can't hear it all the time either. I only hear it when I'm moving and accelerating. It's not an alarming horrible noise but more like a rapid tapping.

I'm thinking we have the same deal and since our bearings were recently replaced w/ no issues....could be our cam chains but it's hard to tell. You can put a stethoscope on that side of the valve cover and rev the motor while it's parked....what you may not be able to hear normally when the car isn't moving, you might be able to hear a slight amplified noise w/ the "ears" on."k

I can tell the diff. between this and an engine "knock"....and it's definitely not down in the bottom of the engine, so it's probably just cam chain slap.

 

[Enzo731]

I posted a few videos, maybe it`s something similar to what I have? check my posts, or my youtube ID which is the same as my username. It might be helpful.

 

[sho_shane]

Guys still no clue what it could be. Im really thinking its a tranny issue since the motor is perfect no mater how you rev it when its not moving...

But I cant really think of anything in the tranny that would knock only in between 2-3rpm?

 

[Eric VerValin]

Jack it up.... block the wheels, and put it in gear... let it get up to 2-3k in first where you can hear the noise, then shut the car off, and get out there and listen..

I had my differential bearing's go out in mine... sounded more like a wheel bearing than anything... pretty sure there is a video of it on my photobucket account.. I'll have to double check..

 

[SeanMc]

Accessory side? Probably the timing belt tensioner. Driver side? Probably a cam chain tensioner. Bottom? Rod bearing. Top? Meh, just a noisy valve train.

 

[sho_shane]

To me inside the car sounds like the driver side. I dont really hear it outside of the car. And if you are heavy on the gas I dont hear it at all, Past 3000rpm and bellow 2000rpm I dont hear it, It does not do it at all when you just sit still and rev the motor.

I do not the tranny has that repair sleve on it but I dout that means anything...

 

[Eric VerValin]

You can hear it a lot louder in the second one... but those were my diff bearings...

 

[thegovernor9912]

I have the same noise, and no solution for you.

i can tell you that I have driven the car for 15K+ miles without incident with this going on.

 

[sho_shane]

Same here, I can tell you that after really messing with the car lastnight I can barley here it when im just sitting still. I think now that it might be a rod knock only showing up after the oil thins and under a load.

I never here it at all for the first few after I fire up the car and head down the road. I dont understand though, the RB's were done 20k ago unless it was just not done right?

From what I know of SHO's, if you hear the knock at all though its to late so I guess ill just keep driving it and looking for another motor or doner car.

 

[pitaSHO]

Does your oil pressure light come on? Are you handy with a wrench? Pull the intake and the valve covers and check the cam chains to see if there is any slack. If there is, replace the tensioners. I had that happen on my 93 last week. I replaced the tensioner and that fixed that problem. If it's coming from the bottom and is a rod bearing then the oil pressure light will come on. If the rod bearings were recently done and you exhaust every other option you might want to drop the pan and check to make sure that all the rod caps were put on in the correct direction; they are directional and have to be oriented correctly or they will wear the bearings FAST. I know a guy who did that and caught it before it hurt anything; all he had to do was replace the worn rod bearing; no other damage was done. :angelnot:

Chris K.

 

[sho_shane]

Does your oil pressure light come on? Are you handy with a wrench? Pull the intake and the valve covers and check the cam chains to see if there is any slack. If there is, replace the tensioners. I had that happen on my 93 last week. I replaced the tensioner and that fixed that problem. If it's coming from the bottom and is a rod bearing then the oil pressure light will come on. If the rod bearings were recently done and you exhaust every other option you might want to drop the pan and check to make sure that all the rod caps were put on in the correct direction; they are directional and have to be oriented correctly or they will wear the bearings FAST. I know a guy who did that and caught it before it hurt anything; all he had to do was replace the worn rod bearing; no other damage was done. :angelnot:

Chris K.

No Oil Pressure Light But pulling the Intake and Valve Cover and looking at the Tensioner over this weekend sounds like a fun project. I assume I can still get all the gaskets and the Tensioner at vato zone if I need to right?

 

[pitaSHO]

The intake and valve covers are fairly simple. The rear one can be a pain in the ass, but should take less than an hour to get it all apart. The cam chain tensioners are unobtainium; you'll need to scout a set of used ones from somebody on the forum if you need them. The valve cover gaskets you can get at shosource. They have tensioners, too, if I remember.

Chris K.