Smell of exhaust with cabin heat on

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Noticed a smell of exhaust making it into the cabin, seemingly only with the heater on. This doesn't appear to happen if the temperature dial is at or turned to the left (cool side) of the 12 o'clock position.

Any ideas? I'm wondering if there's possibly an exhaust or turbo leak and having the heat blend flap in certain positions redirects it into the cabin.

papaindigo · **Posted:** Tue Nov 07, 2017 12:38 am

I wouldn't think so. There are only to air "intake" modes on the HVAC unit - 1) recirculate which means no external air comes in vs. 2) all other settings. In condition #2 all external air comes in via an intake under the right, viewed from inside the cabin, side of the plastic cowl under the wiper blades. As a result I'd think any exhaust smell should come into the cabin, if at all, in any vent or temp mode other than vent set to recirculate.

Not saying you don't smell exhaust just saying that smell shouldn't have anything to do with HVAC temp setting.

GordnadoCRD · **Posted:** Tue Nov 07, 2017 12:39 am

I had the same thing, and noticed I had a small exhaust leak at the turbo / exhaust pipe clamp connection. I tried tightening the clamp and it helped but it was still there.
I took the pipe off, cleaned the inside of the pipe & clamp, and the whole turbo outlet flange.
Applied Nevr-seize all over the turbo outlet flange (both front and back sides of the raised flange), all around the inside and outside of the exhaust pipe flare, and around the inside of the v-band clamp.
When I put it back together this way, it tightened up much tighter, and other than a bit of chemical smell when the nevr-seize heated up and gassed off, the exhaust smell is gone. I probably should replace the gasket seal there that separates the engine compartment from the air inlet vents.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

papaindigo wrote:

I wouldn't think so. There are only to air "intake" modes on the HVAC unit - 1) recirculate which means no external air comes in vs. 2) all other settings. In condition #2 all external air comes in via an intake under the right, viewed from inside the cabin, side of the plastic cowl under the wiper blades. As a result I'd think any exhaust smell should come into the cabin, if at all, in any vent or temp mode other than vent set to recirculate.

Not saying you don't smell exhaust just saying that smell shouldn't have anything to do with HVAC temp setting.

Makes sense, and I agree with what you're saying. But I'm at a loss to explain why it only seems to happen (or be noticeable enough to pick up on) with the heat running. Cool air (A/C on or off, ditto the recirculation setting) seems to have no impact.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

GordnadoCRD wrote:

I had the same thing, and noticed I had a small exhaust leak at the turbo / exhaust pipe clamp connection. I tried tightening the clamp and it helped but it was still there.
I took the pipe off, cleaned the inside of the pipe & clamp, and the whole turbo outlet flange.
Applied Nevr-seize all over the turbo outlet flange (both front and back sides of the raised flange), all around the inside and outside of the exhaust pipe flare, and around the inside of the v-band clamp.
When I put it back together this way, it tightened up much tighter, and other than a bit of chemical smell when the nevr-seize heated up and gassed off, the exhaust smell is gone. I probably should replace the gasket seal there that separates the engine compartment from the air inlet vents.

Interesting, and thanks for the suggestion. If it gets a bit warmer here in the next day or two I'll crawl under and check on it.

Living with the smell of Nevr-Seez would be far preferable to how it is now. Any recommendations on which Nevr-Seez would be best to use?

GordnadoCRD · **Posted:** Tue Nov 07, 2017 12:50 am

casm wrote:

papaindigo wrote:

I wouldn't think so. There are only to air "intake" modes on the HVAC unit - 1) recirculate which means no external air comes in vs. 2) all other settings. In condition #2 all external air comes in via an intake under the right, viewed from inside the cabin, side of the plastic cowl under the wiper blades. As a result I'd think any exhaust smell should come into the cabin, if at all, in any vent or temp mode other than vent set to recirculate.

Not saying you don't smell exhaust just saying that smell shouldn't have anything to do with HVAC temp setting.

Makes sense, and I agree with what you're saying. But I'm at a loss to explain why it only seems to happen (or be noticeable enough to pick up on) with the heat running. Cool air (A/C on or off, ditto the recirculation setting) seems to have no impact.

Maybe our olfactory sense works better with warmer more humid air, than with colder drier air?

GordnadoCRD · **Posted:** Tue Nov 07, 2017 1:02 am

casm wrote:

GordnadoCRD wrote:

I had the same thing, and noticed I had a small exhaust leak at the turbo / exhaust pipe clamp connection. I tried tightening the clamp and it helped but it was still there.
I took the pipe off, cleaned the inside of the pipe & clamp, and the whole turbo outlet flange.
Applied Nevr-seize all over the turbo outlet flange (both front and back sides of the raised flange), all around the inside and outside of the exhaust pipe flare, and around the inside of the v-band clamp.
When I put it back together this way, it tightened up much tighter, and other than a bit of chemical smell when the nevr-seize heated up and gassed off, the exhaust smell is gone. I probably should replace the gasket seal there that separates the engine compartment from the air inlet vents.

Interesting, and thanks for the suggestion. If it gets a bit warmer here in the next day or two I'll crawl under and check on it.

Living with the smell of Nevr-Seez would be far preferable to how it is now. Any recommendations on which Nevr-Seez would be best to use?

I couldn't find my Permatex, so I ended up using this stuff. https://www.amazon.com/dp/B005YSII7U/ref=twister_B009VO2P4A?_encoding=UTF8&psc=1 It's not the best for the job, but it's what I had at the time. Copper-Kote or something like that would probably be better.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

GordnadoCRD wrote:

I couldn't find my Permatex, so I ended up using this stuff. https://www.amazon.com/dp/B005YSII7U/ref=twister_B009VO2P4A?_encoding=UTF8&psc=1 It's not the best for the job, but it's what I had at the time. Copper-Kote or something like that would probably be better.

Got it, and thanks. I should have a can of spray copper exhaust gasket sealant around here somewhere, but have no idea where it is (and it would probably be a pain to apply in the space available). Placing an order tomorrow.

GordnadoCRD · **Posted:** Tue Nov 07, 2017 1:14 am

I would recommend something a little bit goopy.
It would be better for plugging the tiny gas leaks between the turbo flange and the pipe, as well as lubricating the clamp and pieces it's pulling together.
This is working OK so far. It's been on about 6 weeks.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

GordnadoCRD wrote:

I would recommend something a little bit goopy.
It would be better for plugging the tiny gas leaks between the turbo flange and the pipe, as well as lubricating the clamp and pieces it's pulling together.

Good point. Skipping the spray.

Quote:

This is working OK so far. It's been on about 6 weeks.

Hm, interesting. I'll give it a shot as well, but am curious as to longevity. Guess we'll find out

My wife mentioned that she had been hearing something similar to but not as loud as the sound of a blown exhaust gasket under acceleration (which I hadn't noticed), but that it had stopped a few days ago. I'm wondering if this wasn't the clamps loosening up to the point where the exhaust escape was no longer making that sound; the timeline on when she heard it vs. when I started smelling the exhaust seem to coincide.

papaindigo · **Posted:** Tue Nov 07, 2017 3:46 pm

The connection is a marman flange (https://en.wikipedia.org/wiki/Marman_clamp) sometimes called a "V" band flange/clamp. It's possible but somewhat unlikely that the clamp is lose. It's more likely that the exhaust pipe was not correctly centered on the turbo before the clamp was tightened. Either way undo and reclamp with/without "goop" will likely stop any leak.

GordnadoCRD · **Posted:** Wed Nov 08, 2017 2:07 am

I'm sure you are right. The goop I put on basically helped it center it's self, and allowed the clamp to draw up much farther without excessive torque.

GordnadoCRD · **Posted:** Thu Nov 16, 2017 1:33 am

Looks like I've got the opportunity to "ramp it up" and try something better.

All that dyno testing had enough heat and back-pressure to harden and vibrate the pipe dope loose. Gonna find me some bigger guns.

Smell of exhaust with cabin heat on

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