Exhaust smell when using heater

[maclaren65]

Ever since I added the Steve Wong chip and cat bypass pipe (which I love!) to my 87 3.2 Carrera, I've noticed that when I use heat in my car I get some exhaust fumes. Enough that I usually crack my windows open regularly when I use heat. I didn't notice this situation when my cat was connected to my exhaust system, which makes me wonder why this is happening now and if it is related to the cat bypass. Do you think my factory heat exchangers might be leaking?

Thanks,

Richard

[Reiver]

Exhaust fumes or an oil smell. I always get a slight whiff of carbon products when the heat is on (no cat with bypass).
The extra heat generated by the cat may have eliminated the oil smell somewhat along with residual CO.

[aj88cab]

The heat exchangers have a positive pressure, so it is unlikely that exhaust would be drawn into them even if they are showing gaps around the exhaust pipes. More likely scenerio is you have a exhaust leak at one end of the cat by-pass pipe and that is being drawn into the engine cooling fan. Check your exhaust gaskets.

[88911coupe]

Andrew, just to clarify, are you saying the pressure inside the HE is higher than the pressure inside the exhaust tubing? If so that's good to know since if you had a rusted through exhaust pipe it would still tend to push the fumes out the exhaust...correct?

[aj88cab]

No, I was assuming you were talking about the heat exchangers leaking around the seams around the exhaust pipe with external exhaust gases getting into the HEs. Leaking from the actual exhaust piping inside the HE would be a very bad condition and would be more pressure than the air flow in the HEs.

Sorry for the confusion...

[Dublinoh]

Did you use anti-seize grease? That could be creating a smell as it reacts to the heat. Also check that everything is tight.

[rick-l]

Is this hose dripping into the heat exchanger intake below the fan into the heater?

Pelican Parts - Product Information: 930-110-595-05-M260

[JohnJL]

CO is odorless, so smelling something else off is probabably a helpful tell-tale. Check for holes in the heat exchanger-to-heater box hose. Timing with your chip swap could be coincidental. In any case chase own that smell.

[rick-l]

Are you smelling exhaust or gas vapors?

[RSBob]

Do you still have the rubber seal between the engine lid and the rear valence? If it is missing, you will be sucking exhaust into your fan, through the HEs, and into the cabin. Ask my missing brain cells how they knew.

[maclaren65]

Thanks for the input guys. I'm planning to look at under my car this weekend. I'll post back in a few days.

Richard

[maclaren65]

I didn't refresh the page before posting my comment. I only installed the cat bypass and related gaskets, no anti-seize grease. Before I swapped the cat for the cat bypass I didn't notice any exhaust smell in the cabin. Now I smell it. I'll try to check all the points mentioned and get back to you guys after Saturday. Thanks! -- Richard

[Horch]

I have the same problem: installed a premuffler instead of the cat and now the car "smells" more, especially if heat is permitted in the interior. Checked the hoses and heat exchangers, but they 'look' OK. Can't really determine if it is burned oil, exhaust fumes or burned copperpaste (on the bolts).

[maclaren65]

Tonight, I looked briefly looked under my Carrera in the garage with a flash light. The rubber boot/cover on the driver's side heat exchanger has a failed strap on the end closest the muffler. At a minium, I need to replace the strap and maybe the rubber sleeve/cover for good measure. Anyone know which parts I need on Pelican?

I attached two photos of this issue. Pardon the messy underside engine grime. The car had a leak from the driver's side valve cover when I bought it and I have not figured out an east way to clean up the underside since I fixed the small leak. Suggestions?

I also notice the oxygen sensor wire was disconnected in the engine compartment ton ight. I reconnected it to the male recepticle on the left side of the engine bay. Not sure if what this would have affected by being separated. Ideas?

Thanks for the input. Cheers,

Richard

[Tidybuoy]

Originally Posted by maclaren65

Pardon the messy underside engine grime. The car had a leak from the driver's side valve cover when I bought it and I have not figured out an east way to clean up the underside since I fixed the small leak. Suggestions?

Could you be smelling burning oil? I have a similar problem. I have a couple of engine leaks and the burning oil gets into the fan which is then blowing into the heat exchangers. I didn't notice a smell before but it was summer and I wasn't using heat.

When I cleaned my engine with degreaser, the heat exchanges started pumping a smell (like a burning candle) into the car. This eventually burned off but was very annoying.

[JJ 911SC]

Originally Posted by maclaren65

... Pardon the messy underside engine grime. The car had a leak from the driver's side valve cover when I bought it and I have not figured out an east way to clean up the underside since I fixed the small leak. Suggestions?

Couple of products at Post 1 & 2 of http://forums.pelicanparts.com/cleaning-detailing-polishing/550748-best-cleaner-bar-none.html

[maclaren65]

Tidybuoy: I think it's an exhaust smell. Maybe I should get a second opinion. Seriously, I'll ask my buddy, who is a three Porsche owner too, what he thinks the smell is.

JJ: I like Seventh Generation products, but I don't have a lift. :/ Thanks for the suggestion. Where did you buy your lift?

[JJ 911SC]

Originally Posted by maclaren65

JJ: I like Seventh Generation products, but I don't have a lift. :/ Thanks for the suggestion. Where did you buy your lift?

In Canada, check link at post 20 of Is a Superlift a good one for 911's?

In the US, the link at post 1 seem to be the same one (same price as well).

These 2 are assemble/made with North American part, ie my motor is a Baldor Industrial and the pump is from Monarch. Don't think you'll find these on the one from China...

Lots of threads on lifts with lots of opinions of which one you should get ; scissor, 2 posts, 4 posts, Max Jack and so on. No matter which one you get, it will be best buy after the car

[mnez]

Removing the cat will make the exhaust more "smelly", which is maybe why you notice it now. After removing the cat, I can smell exhaust through the heat when stopped at traffic light, but not when moving. I presume it is exhaust whafting up from the dual tailpipes in still air and getting sucked up by the fan. It likely always did that, but wasn't that noticable with the cat on. So I just turn off the heat if stopped for long.

[Dublinoh]

Do some searches on replacement hose for that area. Original is 60mm and difficult to place. Use an aircraft 2.5 inch hose rated for a high heat area and it is an easy install. You only need a couple feet to replace both sides.