Jeff N.

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?

Paulyy

get the car on a hoist or jack stands.. go under it with a torch and look at every join/gasket there is. If it leaks you'll see some black soot around it.

Jeff N.

Yes, done that.

Question is - 'how much exhaust gets in the car from a leaky wastegate to exhaust pipe joint'.

jerome951

I doubt enough that you'd notice. I run my wastegate to atmosphere (dumps just after the wastegate) and don't really notice much smell even when driving on the track w/ the windows down.

Check your hatch seal. Seems to be the most common exhaust entry point.

Jeff N.

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.

kent426

Funny, is this just a Seattle thing? I have the same exact problem except my waste gate dumps direct to the atmosphere. I found that I had a boost leak that was part of the smell as well as an irratic idle, now there is still a faint smell, enough to make you loopy after a few hrs of driving. I was told by Lindsey Racing that the stock waste gate creeps open at 50% of what the boost level is set at.

Kent

kent426

Has anyone had down pipe leaks?

Jeff N.

Kent - did you locate the problem and resolve it or is it still occuring? I still have my problem.

Alan 91 C2

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.

Jeff N.

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

Alan 91 C2

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.

kent426

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

Jeff N.

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

Jeff N.

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!!

kent426

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.