Projects Exhaust Smell Inside Car - Seal Firewall?

Oh ok thanks for the advice!

 

I couldn't agree more. The reason it smells like exhaust is because it IS exhaust. Except that instead of being p***ed through your exhaust system and out the tail pipes, it's p***ing by the rings, chillin in your crankcase, and being forced through the valve cover breather or road-draft tube.

I have a similar issue as of late. Been planning on installing a bung in the exhaust pipe with a sealed line from the valve cover to redirect blow-by through the exhaust. If the rings aren't toast on your engine, a proper PCV system should ventilate your crank case

 

Thanks! I already know there is an exhaust leak in the pipes under the p***enger floor. I'm going to start there.

I am planning to seal the cab up with grommets and sheetmetal from the inside and might eliminate the fresh air ducting into the firewall and seal it up (still not sure).

It has a PCV valve on one valve cover, and the breather on the other. Should I buy a breather that has an outlet, and then run a hose back and T into the PCV line?

Thanks,

 

It has a PCV valve on one valve cover, and the breather on the other. Should I buy a breather that has an outlet, and then run a hose back and T into the PCV line?

NO! the way it works, is that the breather side lets in filtered outside air, and the it travels through the crancase, and then exits by the PCV pulling it into the carb to be burned.
BUT, if you engine is putting out more crankcase pressure than the PCV system can handle, (usually worn rings) then the excess pressure that doesn't get pulled in by the PCV, can also blow out the "inlet" side of the engine, or out the breather. This can also happen if the oil return p***ages are blocked, and fresh air can't run from one valve cover to the other, due to sludge.

 

Like my old man used to say... sometimes you have to jack up the radiator cap and slide a new car in under it...

 

Oh ok I understand. So in my case, I should seal the firewall really well and leave it as is? Maybe replace the PCV valve. I'm not looking to replace any major engine parts any time soon so my guess is leave the breather there.

Supposedly the 350 was rebuilt in 2009 and had only 250 miles when I bought it late last year but I'm skeptical that's true.

 

Best I can offer, if after you replace any bad hardware (PCV, PCV hose, clear any clogs) is if you do like the factory does, and instead of a separate breather, run a large diameter tube up to your air cleaner, you won't have any excess blowby getting on your engine, or fumes in the engine compartment..at least from THAT source!

 

Got it, so replace the PCV valve, check the PCV hoses and replace if necessary.. then remove the breather completely and replace with a valve cover adaptor that can accept a hose, then route that hose to the air cleaner?

 

I didnt see it mentioned. Home Depot sells Peel n Seal for roof repair. Its similar to name brand sound deadening stuff but way cheaper. (there will be many groans here) I used it on my entire floor/firewall/doors/roof with no issues for a couple of years (sitting outside in sun and cold all year long) Not only does it help with sound, but it would help to seal up smaller holes in stuff too.

 

Bottom line: You have several issues that fall into two categories.
1. Your body could/should be air tight enough that if there was a fire outside you would not smell it inside. Work on that one leak at a time.
2. Whatever is creating the smell, other than at the end of the tail pipes, could/should be remedied.

 

My kid and I have been chasing the same problem on his O/T 260Z, they are notorious for exhaust fumes.
Most of the problem was coming from the back end of the car, had to seal up the tail lights, redo the trunk seal, extended the tail pipe a little bit past the bumper.
We stopped quite a bit, but not all, so we started taping off suspect areas on the hatch and different holes around the back of the car.
We found a hidden area that was causing the problem, no more smell now.
Do some taping and go for a test drive, if you think you found it remove some tape and see if it comes back.

 

That's actually a wonderful suggestion. Not only does that stuff seal up holes, it provides a heat barrier. It's amazing how similar it is to Dynamat, despite the fact that it's like 1/4 of the price. I've used that as a first layer for heat resistance, then a second layer of carpet padding for sound deadening. The sticky surface will close up some air intrusions for sure.

 

Thanks I'm going to use this. In another post I made a reference to something like stick and seal but I meant the peel n seal stuff. Did you use sheet metal from Home Depot as well for larger holes?

 

I was able to weld the vast majority of my firewall and floor shut. Shaved everything from engine bay that wasnt needed.
Peel n Seal I mostly used for heat/noise but figured in your case it might be a good air stopper too. If you want to stop heat, keep shopping at the Depot, I found Reflectix (bubble wrap with tin foil on each side) there and have used it as a heat barrier, works really well on ceiling, floor and firewall.

if you're going to caulk and screw sheet metal from there would work. I'd look to see if you have a local HVAC or metal supply place around. HVAC would sell you s****s dirt cheap. I buy all my metal as "drops" from a local place. half sheets of sheet metal, lots of various sizes of other metal by the pound. for small jobs I can almost always find what I need in the drop bins

 

Awesome thanks for the advice!

 

I dropped by and had a look the other night. The floor pan is missing from the rear seat base to trunk/gas tank. You need to seal it as this open area is catching the exhaust from the crushed exhaust pipes under the front seats and allowing the exhaust straight into the cabin. I think these two things are your main items to address.


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Thanks, Roger that.

 

The floor pan is missing from the rear seat base to trunk/gas tank.

Here I'm thinking we are talking about half dollar size holes and smaller.
Geeze oh Pete! Not stop sign size holes

Sealing holes and missing a section of floor pan are quite different , you'll not likely find a rubber plug at Home Depot to fit in there and seal it, nor will peel-n-seal fix this

 

as soon as I saw air ride and the "quality" of the trunk /gas tank area I knew the trunk floor was open to the outside world. all these idiots do air ride and rip out half the trunk and just go, the only thing that matters is to be low so your friends think you are cool, meanwhile every time you drive you are killing yourself a little bit.

I don't know what would make a person think you don't need a complete trunk floor in a car. saw a 50 a while back for $65,000 on ebay, all done up, painted and chromed and when the trunk was open you could see the tires and frame sitting there. people are ****ing idiots.

the two firewall vents with no seal don't help either.

 

Yea I agree, It's the quality I expect for the price I paid. I bought the car as is for less than the cost of the paintjob that was done to it in 2009! In either case I will be getting sheet metal and covering stuff up with screws and caulking. They are big holes but enough support that most sheet metal will work fine. I'm sure I can find a friend with a welder if I need to add any structural support but I don't see why I would in the areas that are open.

 

If you have a freind with a welder,by all means make a pan and weld it in properly or move on to another car.cauking and sheet metal patches dont cut it when your gonna be hauling your family around in it.you get hit from the rear ,your screwed.

 

Oh, come on. It sounds like you left out a pretty major detail when describing the problem. Did you really not think that HOLE had anything to do with the problem? Sounds like your girlfriend has better sense than we gave her credit for. At least someone who has minor leaks, like all of us, learned something. Thanks to the HAMBers who did visitations.

 

Yes I learned something but I only recently (as in 3 days ago) found/heard what we suspect is a leak in one of the pipes.

 

As far as sealing up all the holes you have on your firewall, why not get some 3M Strip Calk. It comes in a package of several 12 inch strips that can be used to fill as large or small of an area as needed. You use it just as you would modeling clay or Play-Doh. Just be sure the area is clean and free of grease. It will create an air & water ***e seal that can easily be removed at anytime. As mentioned earlier those fresh air ducts need to be sealed as well. It's nice to see that some of the locals are willing to help you out by coming over to ***ist you in any way that they can.

 

Oh cool, that is good advice. Thanks so much.

 

Your welcome, and we are all still waiting to see a picture of you car!

 

Quick silly question. I'm going to buy grommets for the firewall to properly p*** some of the wiring through. Is there anything wrong with using the grommets that have a split end so I can avoid having to disconnect the wiring that's already there?

 

Nope no problem at all. You may want to glue the ends on final ***embly but that it not normally necessary. GM used that type of grommet in the '60s.

 

Great thanks!

 

Are you clear that you should be fixing the missing floor area first??