I have a 1984 Firebird with the 305 with about 162,000 miles on it. The previous owner had messed so much with the stock computer controlled stuff that I finally gave up and went with a regular carb and distributor and the car runs MUCH better. It also has a new Dynomax cat-back system on it.

I've had a problem with a strange smell from the car both before and after this conversion to a non-computerized setup, so I know it's not the revised ignition and carb. After shutting the car off, there is a strange, strong smell (very hard to describe) that hangs around for a couple of hours and slowly fades away. This is not a fuel smell.

The car has the stock cat converter (I am not sure if it's been hollowed out or not, never checked it). The car has plenty of power and starts right up and no problems running at all. Is it possible for a catalytic converter to produce a strange smell like this after shutdown? I am at a loss as the engine and everything else seems to be in great shape for the mileage. The cat is the last thing that I can think of. Anyone want to hazard a guess on this one? Thanks for any input.

Brad

 

Does it smell like phosphorus(rotten eggs?)

 

Not really. I've smelled the rotten egg smell from converters before and this is actually different and stronger than what I've smelled before. I've checked the engine bay and undercarriage. Can't seem to detect exactly where it's coming from. Nothing around the exhaust pipes that are burning from the heat or anything. It's really weird and very hard to discribe. Sorry I can't be more specific. If the internet had a "smell-a-vision" feature, I'd see if I could send some your way!

Likely, the only way to be sure is to replace the cat and see if it goes away. I'm at a total loss to explain this one!

Brad

 

If I were a betting man.....


take your radiator cap off, and check the color of your antifreeze. Also take a nice big whiff of the inside of your radiator while you're at it.

 

I just put a Dynomax on today myself and noticed a strange smell. Nothing was wrong except for that smell. I figure it may be some type of paint of coating they apply to the muffler.

However I like the new exhaust !!

 

Well, the antifreeze is nice and clear and clean, normal green color as it's been all along. It smells like antifreeze and nothing more. I've had this antifreeze in there for about a year now with no change in color or smell.

I too noticed a bit of a smell after the Dynomax cat-back install, but that's been over a year ago and it went away fairly quickly.

This is a huge puzzle that seems to have no solution. I will start saving for a new cat, Y-pipe and headers and see if the old cat might just be the culprit. The car is great and with it's new paint and interior, looks terriffic. I love it, I just don't want to smell it anymore!

Thanks for the replies. I'll keep looking.

Brad

 

there are oils that are placed in the pipes for install. I forget the reasons it's there, but I know all of the catbacks have it. If you look up the thread "Why does my hooker stink" you'll find more info on it

 

That oil is there so the parts dont start to rust untill after they are installed.

 

Ok, here's an update on this very strange situation. I just finished installing new Hedman coated shorty headers and matching Y-pipe.

I noticed after removal that the old stock cat had been hollowed out, so it's not likely the smell was from that. It did have some kind of junk coating the inside of the cat that I couldn't figure out though.

I replaced the old hollowed out cat with a new cat and connected it up to my Dynomax cat-back. It runs great and the sound is essentially like stock.

I have also noticed that almost all of the smell is gone. It is still slightly there, but NOTHING like I had before. My guess is that the engine, being high mileage is burning some oil (but very little really, if you can believe the dipstick) and may be producing the smell because it's worn. The new cat is killing much of this off before it's released out the tail pipe. This is a good thing unless this will plug up the new cat down the road! Good thing I'm going with a new engine next summer! Can't wait to put the 350 in there. Likely this will kill the weird smell entirely... I hope!
Brad