Exhaust smell - if the wastegate dump doesn't seal....
#1
Burning Brakes
Thread Starter
Exhaust smell - if the wastegate dump doesn't seal....
Hi, been chasing an exhaust leak that's getting smells in the cabin. Have a 'creaky' fitting where the wastegate dumps back into the main exhaust pipe - was wondering home much exhaust that can get into the car..... I think everything else is pretty tight.
Symptoms are:
- only smells under boost
- cabin has to have negative pressure. IE: window open or something
- not really any real smell when the blower is running
- seal between the hood and the firewall is good
- shifter boot to the cabin is pretty good but has one small tear in it, I cover it with a little tape.
I really don't think it's coming in from the back of the car but can't 100% rule it out. Any thoughts?
Symptoms are:
- only smells under boost
- cabin has to have negative pressure. IE: window open or something
- not really any real smell when the blower is running
- seal between the hood and the firewall is good
- shifter boot to the cabin is pretty good but has one small tear in it, I cover it with a little tape.
I really don't think it's coming in from the back of the car but can't 100% rule it out. Any thoughts?
#4
Drifting
Check your hatch seal. Seems to be the most common exhaust entry point.
#5
Burning Brakes
Thread Starter
Thanks Jerome - helpful data point.
All the ususal suspects have been checked - headers, x over pipe, joints in that area, rear hatch seal, hood/firewall seal and nothing seems to clearly at fault.
Really unsure how to track it further...frustrating.
All the ususal suspects have been checked - headers, x over pipe, joints in that area, rear hatch seal, hood/firewall seal and nothing seems to clearly at fault.
Really unsure how to track it further...frustrating.
#6
Hi, been chasing an exhaust leak that's getting smells in the cabin. Have a 'creaky' fitting where the wastegate dumps back into the main exhaust pipe - was wondering home much exhaust that can get into the car..... I think everything else is pretty tight.
Symptoms are:
- only smells under boost
- cabin has to have negative pressure. IE: window open or something
- not really any real smell when the blower is running
- seal between the hood and the firewall is good
- shifter boot to the cabin is pretty good but has one small tear in it, I cover it with a little tape.
I really don't think it's coming in from the back of the car but can't 100% rule it out. Any thoughts?
Symptoms are:
- only smells under boost
- cabin has to have negative pressure. IE: window open or something
- not really any real smell when the blower is running
- seal between the hood and the firewall is good
- shifter boot to the cabin is pretty good but has one small tear in it, I cover it with a little tape.
I really don't think it's coming in from the back of the car but can't 100% rule it out. Any thoughts?
Kent
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#9
Rennlist Member
You have a cracked 2-3 pipe in the header. The crack is where the short pipe joins the long pipe. The crack opens under the high heat of boost. I chased the same problem for a couple of months. You have to open the exterior metal jacket to see the crack.
I installed the replacement headers, but I think I will repair the original. Thinking about a flex section in the 2 pipe.
You could have leaking gaskets if not turbo type. My bet on cracked pipe.
I installed the replacement headers, but I think I will repair the original. Thinking about a flex section in the 2 pipe.
You could have leaking gaskets if not turbo type. My bet on cracked pipe.
#10
Burning Brakes
Thread Starter
Thanks for the suggestion but that may not be it. The headers were recently swapped out and I pressure tested the new units to check for leaks.
Still, if it was a cracked header, explain why it only fumes the car with the windows down and not with the cabin blower on. It can be the just the drivers window
Still, if it was a cracked header, explain why it only fumes the car with the windows down and not with the cabin blower on. It can be the just the drivers window
#11
Rennlist Member
The way the heat crack operates is closed at room temp, barely a hair line. (I could barely see the faint line along the crack at room temp) And the crack opens at boost exhaust temps.
A pressure test at room temp might not reveal the crack. Unless you were using 100PSI in a water bath and looking for bubbles. And even then, you would have very small flow. The outer metal heat jacket makes discovery difficult.
A pressure test at room temp might not reveal the crack. Unless you were using 100PSI in a water bath and looking for bubbles. And even then, you would have very small flow. The outer metal heat jacket makes discovery difficult.
#12
Jeff
After tracking down some boosts leaks and installing a new hood seal, more of the smell is gone. I did notice quite a bit of oil in the intake track so I am thinking I might try the LR Catch Can as that might be the issue and not exhaust at this point.
Kent
After tracking down some boosts leaks and installing a new hood seal, more of the smell is gone. I did notice quite a bit of oil in the intake track so I am thinking I might try the LR Catch Can as that might be the issue and not exhaust at this point.
Kent
#13
Burning Brakes
Thread Starter
Hi Kent, good to hear you have some progress. Where were your leaks?
Not sure how oil would lead to exhaust in the cabin - most cars will recirculate crankcase gasses into the intake so they get burned again.
My leak remains elusive - I'm pretty fine with the windows up but put the windows down and hit the boost and it's not pretty. Clearly the low pressure in the cabin is sucking fumes in...from somewhere.
Alan - I did a pressure test @ 20psi and things seemed good. Your point on heat is well taken but I would expect to see soot around the heat jacket and I don't. Would you expect to see this
Not sure how oil would lead to exhaust in the cabin - most cars will recirculate crankcase gasses into the intake so they get burned again.
My leak remains elusive - I'm pretty fine with the windows up but put the windows down and hit the boost and it's not pretty. Clearly the low pressure in the cabin is sucking fumes in...from somewhere.
Alan - I did a pressure test @ 20psi and things seemed good. Your point on heat is well taken but I would expect to see soot around the heat jacket and I don't. Would you expect to see this
#14
Burning Brakes
Thread Starter
BTW, I think my next test will be to put some tape around the hatch, tail lights and see if that doesn't stop the smell. I'm sort of wondering if negative cabin pressure isn't working together with the exhaust pipe to suck it in thru the back. I need exhaust tracer dye!!
#15
Yes, I replaced the rear hatch seal and duct taped the trunk holes, that made a bid impact.
My theory is now based on other threads that our cars have a lot of blow by from the head in to the intake track. If you have a boost leak, you may well be smelling crank case vapor and not exhaust.
My top hose to the intake was misaligned.
My theory is now based on other threads that our cars have a lot of blow by from the head in to the intake track. If you have a boost leak, you may well be smelling crank case vapor and not exhaust.
My top hose to the intake was misaligned.