My van sounds like a go-kart

I drive a 2005 toyota mini-van. Lately the engine has started sounding strange. it has been sounding like a tiny diesel engine or like a go-kart. There are no lights on on the dash, I have not noticed any changes in fuel consumption, acceleration etc. and the temperature is normal.
Is this a timing issue? is my car about to die? what are the repair costs?
Thanks a million

Does it sound like an exhaust leak?

I left the car Idling and walked around it and the sound seems like it is coming from the front. It may sound like an exhaust leak. If it is a leak can I still drive it for a couple days?

Leave the widows open and you will probably be OK but don’t put this off. Carbon Monoxide poisoning is nothing to fool with. Get to a service shop soon.

Take it to a shop that does exhausts, not the dealer. It sounds like the front flex pipe is leaking. This is a common point of failure on these vans, especially if the exhaust is still original. You can fix it using an aftermarket piece for $200 to $300. The dealer will want close to $500.

I wouldn’t drive it with a leak too long for safety reasons. You will also get a “check engine light” soon if the leak continues to grow and it might adversely affect your catalytic converter since it won’t be able to get up to temperature. If you kill the cat your repair bill will be steep indeed.

If you develop an exhaust leak up near the engine, like at the exhaust manifold, that can sound like firecrackers going off in the engine compartment. You hear a definite bang bang bang sound. How loud it is depends on how bad the leak is. If it has that bang bang bang quality to the sound, my guess is either the exhaust manifold gasket is leaking or it has a crack in the manifold. Not sure about minivans but Corollas used to be well known for developing cracks in the exhaust manifold.