Exhaust fumes smell inside the cabin

Hi all,

My Prius V cabin smells of exhaust fumes. In the beginning, it seemed like I could just close the vent, but it has gotten worse that eventually closing the vent didn't help. Realizing this is not safe I stopped driving it immediately and I took it to my mechanic who duly changed the exhaust manifold gasket thinking that was the issue. This didn't help, the problem remained.

We did a second try at finding the source of leak, this time with some spray under the car, but with the heat rising and tight spaces around exhaust manifold, it's hard to be certain where the leak comes from. So we decided to change the exhaust manifold, the manifold gasket again (engine side), the round gasket connecting the manifold to the muffler assembly, and of course the spring bolts.

Looking at the old exhaust manifold, my mechanic thinks there were some leaks with the manifold warping in certain locations and burnt marks around the holes (see pics). I drove the car again today, it has definitely improved in terms of smell, but it's hard for me to tell that the smell is gone for good if I leave the vent open (i.e. not recirculated inside). It could just be my fear of inhaling carbon monoxide. But I am not 100% confident that this issue is solved.

The other concern I have is that why would the manifold look like it is in the pictures where certain locations look like it has experienced more heat and even the newly installed gasket that was not even ran for 100 km since installation is already busted on one of the sides. What could be causing this issue? Or is this to be expected given the engine runs at a very high temperature?

I will be driving this car tomorrow to work, to make some more observations, and if it does get worse again. I will definitely open the windows if I realize it still is a problem.

Any help and suggestions much appreciated.

 

Which part under the hood is the timing chain cover located? I will have that checked also. Thanks.

 

I bought this car last summer. The owner mentioned about cylinder head gasket was redone, but the exhaust manifold is further down, isn't it? So this might be the original manifold still.

 

Ok passenger side, if I'm not mistaken, the oil filter is on that side also. Will ask my mechanic to check it on the next oil change. Thanks a lot RJ. Appreciate your suggestions on this one.