So lately we've started noticing that when we turn on our blower, we get a very strong exhaust smell coming through the vents. We turn off the blower and the smell stops. I know the car is running rich just by looking at the new plugs I put in, so going to be replacing the O2 sensor. But any idea on where the leak could be coming from that the blower motor is sucking it up. Not seeing any exhaust in the engine bay when I fire up the car.

 

Unless your car is smoking YOU WON'T see any exhaust gasses in the engine bay. Unless it's an obvious crack a visual inspection is a poor way to detect exhaust leaks. Get something into a spray bottle to spray onto all the exhaust joints in the system and look for bubbling. Pay attention to the header/manifold area.

 

If it's cold enough in the mornings that you have visible exhaust when the car is cold start the car and have someone put their foot over the tailpipe and look under the vehicle to see where the exhaust is leaking.

 

^^Good one. Didn't think about the cold.

 

yeah I live in Utah, so know all about the cold mornings. I'll try both tips this weekend. I'm thinking it's gotta be by the header/manifold area.

 

I small amount of seafoam into the line off the intake manifold for the brake booster will show you every single leak the exhaust system has.

First time I every used seafoam, I was shocked how many leaks there actually was. There were 4 IIRC.

 

yeah I've used it in the past on a few of my vehicles. Honestly, when I seafomed the civic.. hardly any smoke came out. I was actually surprised with it being a 19yr old car

 

found the leak. The exhaust manifold is cracked. Going to order a replacement. Any recommendations?

Guess it's a good thing I need to replace it. While I was trying to get the O2 sensor out, the nut stripped. ugh.
Did find out that there is a Viper 500 ESP alarm system installed. Just missing the remote and the chirp speaker. Everything is still hooked up including the shock sensor.

 

What car? Unless it's got a D16Y7/D16Y5 with the integrated catalytic converter I'd just buy a used OEM manifold. Other than what I mentioned most of the rest of them don't crack very often and they're pretty expensive new.

 

And the o2 sensor probably did not need replacement until it got boogered up.
The ECU was adding fuel to compensate for the excess air from atmosphere being introduced into your exhaust tract through the leak before o2S1 (your primary o2 sensor)

Fix the leak first,
reset ECU,
And go from there.

 

only code the ecu is throwing is the vtec spool.
It's a 94 EX z6 engine.
Here's the crack


replacing the o2 due to not sure when it was replaced. for all I know it's stock.

 

Yeah, just buy a used OEM replacement. I have one here that's cracked like that on my scrap pile, but it's the first one I've personally come across like that in 5+ years of working on this stuff.

 

thanks. Are they difficult to swap out? Haven't replaced one of these yet.

 

No, just unbolt it and bolt the new one up. Those 3 nuts that hold the top half to the downpipe can be kind of miserable if they use salt on the roads in your area though.

 

Don't fix it if it hasn't broken yet.

Try to refrain from wastefull spending if possible.

I do agree with 94eg8, that is a gnarly crack in that manifold, maybe it can be split in two now.

 

replaced the manifold with 4-2-1 headers and a new downpipe. Getting the spring bolts onto the downpipe was a PITA!!!. The crappy part is one of the bolts for the headers snapped off the block when I went to torque it to spec. Good news is; no more exhaust leak.
You can see the missing bolt on the bottom left.


Next step is to paint the valve cover, replace the valve cover gasket, drop the oil pain and replace that gasket (small oil drips, and the pan is coated in oil), also have a leak that is some type of clear fluid o.0 which I need to track down. Replace the PS Pump..it wines at me when I start the engine and it's cold. Replace the weather stripping on both d/p doors. (I just love getting a $10 shower on the side of my head when running through the car wash.)
Longest part of this project is going to be fixing all the dents on the fenders/rear quarter panels and getting it prepped for a paint refresh.

Interior I plan to get the JDM center console arm rest and install that; as well as a new sunroof motor.

Thanks for the help everyone.

 

put a rag in the tailpipe, and then it will make the exhaust go out where its leaking..

 

exhaust leak is fixed. My manifold was cracked.