I was recently driving on the highway when I smelled rotten eggs. I pulled over only to hear loud metallic knocking coming from an unknown source. The knocking noise does not sound like its the engine itself as it is very random but constant knocking. My oil level was fine as well as all of the other fluids. Car drives and shifts fine with no problems. car was recently rebuilt with every new engine part possible.

any ideas?

 

Something was left unbolted after the motor was replaced? It's really anyone's guess, so I'd suggest trying to at least determined what area the sound is coming from.

 

Does it feel like its suspension related? Do you mean knocking like detonation, or a ******* jehovahs witness with brass knuckles kinda sound?

John ny

 

When i put my ear to the shifter i can def hear a metallic knocking of sorts.
I doubt its suspension cause the car turned fine even from a dead stop.
I'm guessing i might have knocked something out of the cat hence the egg smell but i'm not too sure I was in second giving it pretty good throttle next to an ISF when i smelled the eggs

 

Smell of rotten eggs can mean a bad Cat.

 

Here, I found this thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/rotten-egg-odor-exhaust-234144/

It looks like the rotten egg (sulfur) smell is associated with buildup in the cat. If the cat is damaged as well, you could have pieces of the metal honeycomb bouncing around inside making noise. You can easily check it by jacking up the car, starting it, and listening near the main cat. You can even ubolt the cat and let the engine run with just a downpipe (or headers) to see if the noise goes away. Though this will be very loud, and you'll be able to inspect the cat for damage while it's off.

 

I'm really hoping its cat related the tranny clutch and fly wheel are all brand new. but the noise does seem to occur less maybe about very 3 seconds or so with the clutch depressed

 

Has anyone Checked the transmission fluid?..

 

no i havent checked the tranny fluid although i assume it was replaced when i put the new s5 tranny in

 

I had this. Its your alternator or alternator belt. Tighten it. I have an FD alt in and the belt was slapping one of the bolts on the water pump when loose.

 

Eh, might be a rod knock.

Just kidding.

 

so i just finished pulling the whole exhaust and it turned out not to be anything cat related. After listening to where the noise is coming from it sounds like it could be the throw out bearing. the thing i'm confused about is I just put an act 6 puck clutch with all the new bearings in. Anyway i could fix this with out pulling the whole tranny?

 

Anything in the transmission area means you have to take out the trans.

That said however, some throw out bearings are just noisy and its not a problem. I have never heard of a 'knocking' throw out bearing though.

 

yeah its a pretty loud noise. to be honest at first i thought it was coming from the housings it was so loud. The clutch that was just put in is an act 6 puck so i'm not really too sure why a bearing would go after just 3k miles

 

the engine is a rebuild or a j-spec? If it was a used Auto engine it could be someone didnt install a rear needle bearing in the E-shaft.

I was surprised to read that it was not the cat. Check the tranny mounts maybe or see if any of your mounts look like they have been burned as maybe that is what caused the smell. The smell may have also just been the clutch as it was new I presume. Tuff call on issues like this. If you can get a video someone may be able to help out.

Good luck!

 

Double check all the trans bolts to engine, trans mount bolts etc. Also did you check the u joints on the DS?

 

I'm bringing the car to a friends garage which has a lift so i'll inspect further tommorow.

thanks for all the suggestions on what could be wrong. hopefully it's just the throwout bearing