95 Es 300 Has Exhaust Smell Through Vents Under Heavy Load

[SAMATSAAB]

I own a 95 es 300 with 176,000 miles on it. It drives great and no mechanical problems. Under heavy load i get exhaust fumes coming through the ac vents. The recirc motor is functioning properly and it comes through the vents under any setting. The exhaust smell only comes through the vents under hard acceleration on the highway or when passing someone. When cruising it's fine, and there is no exhaust smell. I have replaced both exhaust manifolds with good used ones along with the doughnut gaskets. With the car in the air, and the car running, i have not been able to find an exhaust leak by running my hands across the exhaust tube, and there are no black areas along the under carriage or pipes that would lead me to think of an exhaust leak. I love the car and this one problem is annoying. Just wanted to see if anyone else has experienced this problem or may know where prone exhaust leaks may develop on these vehicles. I forgot to mention that I have replaced all 4 engine and transmission mounts so i know there is no flexing of the exhaust pipes. Any helpful advice is greatlt appreciated.

[blk_on_blk]

All I can say is if you're smelling exhaust, then you've got a leak somewhere in your exhaust. Can a muffler shop back pressurize your exhaust system with indicator smoke so you can see where the leak is? It's got to be there somewhere.

[Loyal_Lexinator]

I own a 95 es 300 with 176,000 miles on it. It drives great and no mechanical problems. Under heavy load i get exhaust fumes coming through the ac vents. The recirc motor is functioning properly and it comes through the vents under any setting. The exhaust smell only comes through the vents under hard acceleration on the highway or when passing someone. When cruising it's fine, and there is no exhaust smell. I have replaced both exhaust manifolds with good used ones along with the doughnut gaskets. With the car in the air, and the car running, i have not been able to find an exhaust leak by running my hands across the exhaust tube, and there are no black areas along the under carriage or pipes that would lead me to think of an exhaust leak. I love the car and this one problem is annoying. Just wanted to see if anyone else has experienced this problem or may know where prone exhaust leaks may develop on these vehicles. I forgot to mention that I have replaced all 4 engine and transmission mounts so i know there is no flexing of the exhaust pipes. Any helpful advice is greatlt appreciated.

I have a 92 that has a rear valve cover gasket leaking. Its loosing about a quart after 4K miles... so, by the time its time to change oil, it is almost a quart low. The car has 209K miles on it now, and runs great. The really annoying thing about the leak is that it makes its way down to the exhaust system, and causes a noticeable oder in the car when stopped after it gets hot. It will also cause a slight oily film on the inside of the windows that becomes noticeable after about 6 or 8 months. I wonder if what you are thinking smells like exhaust, is actually oil dripping on the exhaust system. When driving down the road mine is not noticeable at all.

[wwest]

I own a 95 es 300 with 176,000 miles on it. It drives great and no mechanical problems. Under heavy load i get exhaust fumes coming through the ac vents. The recirc motor is functioning properly and it comes through the vents under any setting. The exhaust smell only comes through the vents under hard acceleration on the highway or when passing someone. When cruising it's fine, and there is no exhaust smell. I have replaced both exhaust manifolds with good used ones along with the doughnut gaskets. With the car in the air, and the car running, i have not been able to find an exhaust leak by running my hands across the exhaust tube, and there are no black areas along the under carriage or pipes that would lead me to think of an exhaust leak. I love the car and this one problem is annoying. Just wanted to see if anyone else has experienced this problem or may know where prone exhaust leaks may develop on these vehicles. I forgot to mention that I have replaced all 4 engine and transmission mounts so i know there is no flexing of the exhaust pipes. Any helpful advice is greatlt appreciated.

My '92 LS400, even when new, would end up with exhaust fumes in the cabin with just applying enough extra power for a small incline. I finally discovered that using recirc mode was the culprit. If you switch to FRESH mode you will end up FORCING airflow out of the outlet flow ducts, cabin airflow exhauster ducts, in the trunk at the bottom of the rear quarter panels. For some reason, I suspect aerodynamics, you can get reverse exhaust flow through these ducts in the circumstances you describe.

My LS has a exhauster duct in each side and each has a lightweight rubber "flap" valve to prevent, mostly prevent reverse airflow. At 176,000 miles yours may have lost that ability.