Sounds like induction roar at about 4k revs but dies after?!

[Patrick_g46]

Basically my exhaust backbox has been gone for a while and was quiet loud, the other day I stalled the car after trying to go from reverse to first too quickly, and ever since then when I bring the car up to 4k revs it sounds mental! Really loud, like a roaring noise, this only last for about 6-700revs then car sounds normal again.
It does it even more if the car is under load, like if i have it in a high gear at low speeds and floor it.

I firstly thought it was the exhaust finally given up, but its starting to sound like its coming from the back of the engine bay/exhaust manifold area!

I have had a look and cant see/feel any leaks etc, anyone got any ideas?

Patrick

[diathermy]

Could be the exhaust gasket.

My car made a really loud raspy noise after 4k.
Changed that gasket and it was better.
Got one cheap off ebay for 5 pounds.

On here, some people say could be a cracked manifold. you will have to take it off to examine it thoroughly.

[Patrick_g46]

Could be the exhaust gasket.

My car made a really loud raspy noise after 4k.
Changed that gasket and it was better.
Got one cheap off ebay for 5 pounds.

On here, some people say could be a cracked manifold. you will have to take it off to examine it thoroughly.

Which gasket are you talking about? The fire ring?

[katbloke]

the fire ring is the only gaskey after the manifold before the cat, the downpipe has no gasket between it and the cat afaik

[raviedavie]

Have you still got the cat on it ? if so maybe its crumbled inside ? happened to me with similar symptoms

[Patrick_g46]

Nope I have no cat, i had a pipe welded stagith onto the downpipe just after the lamda and straight through to the U-bend before the backbox, the only box/silencer on the system is the backbox.

I just cant help but think the sound is coming from manifold area, although sometimes sounds can be decieving!