Horrible exhaust smell in the car, usual fixes already done

[Guest bastaad525]

One thing I have had a major problem with from day one of putting this turbo motor in my 240, is horrible exhaust smell in the car sometimes. It happens the worst when it's cold out, late night/early morning, if I drive with the windows down at all. It's also much worse after any hard driving at all. I've already gone over the car and replaced all the seals and weather stripping in the back that normally would keep this smell out, and they were all working and doing a good job when I had my N/A motor in the car very rarely ANY exhaust smell and even when there was it was always very faint and went away very rapidly. The entire exhaust system minus the downpipe is new with the turbo motor, so I dont think there are any leaks (gonna have to check and be sure though.... I did watch the guy do the work and he was taking his time and seemed to be doing a thourough job of it.) Sucky thing is, in SoCal the weather sucks ass right now and driving with the windows up would really really be unpleasant... I can't figure out why so much would be getting in the car all the sudden, as soon as I so much as crack the windows. Any ideas?

[fastzcars]

Hi Bastadd525, I had a similar problem, and couldn't find the problem either. Then when I replaced the seals I had the rear hatch glass removed to replace the rubber, I could see through the window opening that the lower passenger corner part of the seal was not touching the hatch . The frame of the opening was ever so lightly lower, causing the new seal not to work. I had to pry it up gently with a hydrolic bottle jack, I hope I'm not confusing you? , The second thing could be that the new exaust tip maybe too short, and not extending far enough away from the lower valance. Try clamping an extension to se if that helps. good luck. 8)

[Guest bastaad525]

hmmm I hadnt considered the new tip, it IS definately much shorter than the one that was on there before, it only extends past the valance about two inches... I wanted to keep it as short as possible to make it look nicer. Before it extended out a good 6" or so... no smell in the car but damn i hated the way it looked. I'll also take a close look at the frame of the car where the hatch sits, and see if indeed it is not touching somewhere. Thanks for the tips.

[j260z]

one of the reasons the coefficient of drag is so bad on the early z is because of the design of the rear of the car. it allows the air to swirl around the back of the car and more than one person has noticed the exhaust smell. other than trying to lengthen the exhaust tip, the other option would be to install a fin on the car to help clean up the air flow out the back and add some downforce at the same time.

[spotfitz]

I had replaced all the vent lines and weatherstripping in the rear of my '74 and nolonger had the exhaust smell. I then put a 3 piece rear spoiler on it and got the exhaust smell again. The '74 is now down and getting ready for paint, but I'm hoping that once I get it back from paint jail and go turbo that the new exhaust system will take care of the problem. I'll be running 3" to the dynomax turbo muffler, which is 3" in and 3" out. I'm HOPING I won't have to put a tip on it, but if I do it will point down to help rid the exhaust smell. Check back in about 2 years. lol

SO, some spoilers can actually be more of a cause then a cure.

[Guest bastaad525]

I had considered adding a spoiler to ease the problem... it makes sense that it should help it (though people seem to be split 50/50, on if it does or not). The weird problem is that after I replaced the rear weather stripping and tail light seals, the smell was 99% gone. That was before though when I had my N/A motor and a different exhaust system, with a tip that extended about 4-5" out from the rear valance of the car (just far enough to extend out past the bumper, which I later removed). Then I switched to the turbo motor, and put a new exhaust system, with a tip that only extends about 1-2" out from the rear valance. The odd thing is, for the month that I drove the car before having to rebuild the head, with this exhaust system and shorter tip in place, I dont remember the smell being this bad, or really being there at all. But... I'm not 100% sure if it was bad or not, to be honest.. I really dont remember, I only drove the car for a short time with the turbo motor before the head went screwy and had to be rebuilt.

 

Okay let me ask this, on a 240, with the rear bumper removed, what length do you guys recommend the tip extend from the the valance? I wanted to keep it short as w/o the bumper in place it didn't look that good when it was like 5" out, but looks take second place over function... this smell is killing me literally I think... giving me headaches and making me feel naseuos and burning my throat. I went to the muffler shop today and he said $30 to extend the pipe out a couple inches, but dont want to spend the money if it wont help... I've already done way more than enough of that with this car. I'm going to take you guys' word here one way or the other, if you think extending the tip will help then I'll do it.

 

I guess I should mention (this is covered much more in depth in my thread in the turbo section) that since rebuilding the head the car has mysteriously begun to burn oil and smoke pretty bad occasionally. BUT, I do remember how the exhaust used to smell before, if you'd stand behind the car, and I can't say if you stand back there now that it smells any stronger/worse.... so why would it smell so much worse inside the car? Just thought I"d mention it though

[Guest bastaad525]

Also, do you guys really think that adding a tip that points down helps? Since I may be cutting the tip off either way I may just switch to one like that.

[Guest bastaad525]

Anyone? Planning on going back to the muffler shop tommorow if you guys thing that lengthening it will help. Mostly I just want to know how long I should have them lengthen it. How far out do you guys' tips extend past the valance?

[Guest 240hybrid]

Don't forget the seals in the fire wall. There are quite a few seals that might be bad and letting fumes in. The hole for the wire harness, holes for heater hoses, throttle linkage, etc. Check those out too.

Also what does the inner shift boot look like? Might be getting a good bit of fumes through the hole there, if the boot is cracked and crumbling.

[fastzcars]

You might try a temporary tube extension. Go to pep boys and buy a short piece of exhaust tubing that would fit on the outside diameter of the current tip. Just clamp it with an exhaust clamp. Just to see if it works. I would try the same length as it was before the new system was put in. I think you said it was 6 inch past the bumper? If it works then start cutting down the temporary extension an inch at a time, until the smell comes back. You may only need to extend it 1 inch to make a difference? I know it's a lot of trial and error, but that's the nature of the hybrids. Also I second 240Hybrids suggestions. There are alot of gromets in the back, under the carpet and in the passenger rear side interior panels to leak. Hope that helps. 8) 8) 8)

[Guest bastaad525]

actually the rubber seals in the firewall are all bad I've been aware of that... but what I dont get is they've always been that way, but the smell has only ever been this bad and this constant two other times, and those were when I first put the turbo in and only had the downpipe open right under the drivers seat, and when I first got the 240 and all the rear hatch and tail light rubber was bad. That's the weird thing... nothing has really changed recently except the exhaust system, and even then as I said I"m not sure it even smelled like this with the short tip before rebuilding the head. I guess I can try to clamp an extension on there as you say... I'm thinking it will be hard to find a pipe that fits over the outside diameter of the tip, w/o being incredibly loose over it, loose enough that a clamp wouldn't really do the trick. *shrug* I'll find out today. I'll check the inner shift boot too... my center console isn't even bolted down You know... I have this feeling the boot isn't there because when the mechanic shop did the motor swap and I picked up the car, I saw this inner boot sitting there by my car.... I thought to ask but forgot... that would make sense though.

[Guest Zed Nugent]

check all the rubber seals in thr back of the car , fuel line , fuel vent hoses

, antenna drain grommet tail light seals ect. also if the car was damaged in the past , there may be gaps in the sheet metal underneath, ( dont ask me how I know) fumes can get sucked in any of these.

[BayAreaZT]

Try pointing the exhaust out in an angle. That should help get the fumes away from the turbulent air in the rear of the car.

[Guest bastaad525]

I went to three different auto zones today to try to just find an extension that would fit over my current tip, but couldnt find ANY. So I went to the muffler shop that's done all my exhaust work, and had the guy cut off the tip and weld on another one that was about two inches longer, and also had him bend it so that it points at about a 45 degree angle down/out away from the middle of the car. It's a good thing that he did this for me for free, because it did not help one bit As a matter of fact it seems to have gotten worse.

 

I am so sick of this car...

 

and I mean that figuratively AND literally... I can't even drive it for more than a few minutes w/o getting a headache. I'm out of $$$ and out of patience so fuggit, I'm gettin rid of it.

[Guest 240hybrid]

gettin rid of it heh ?? I wouldn't let it discourage you. I have read alot of your post about problems with a stumble while accelerating and about a bent valve. The thing I always tell myself when modifiying/swapping parts and motors for that matter, is that this isn't a stock setup and may encounter problems with doing these swaps that will have to be worked out.

Think of how much testing and problem solving the engineers go through making any kind of car from scratch... . Dont' let this exhaust problem get the best of you, you've made it this far.

I would just go through them all, the firewall/inner shift boot/seals for vent hoses+vent tank to see which are bad. Then just stuff a piece of rag or something in or around the bad ones to see if they are the problem areas causing this problem. Process of elimination, theres only so many places the fumes can be coming from.

Also, could the exhaust be leaking from somewhere maybe??

[Guest bastaad525]

problem is I dont have any more $$ to keep spending and spending fixing this and that and this and that. Someone once told me to think about how much you THINK this kind of swap will cost then double it. At the rate I'm going it should be more like tripple it. I could be making payments on a brand new 350z for the money I'm putting into this car, $10,000+ in one year, and I"m tired of it. I cant keep spending more and more, so I'm done. And by the way the muffler guy did check the whole exhaust system and didn't find any leaks it's all welded up tight, and I've made sure that there are no leaks where fumes could be coming from the engine and getting into the car. The thing that gets me the most is that the smell was never this bad before, and I dont know what has changed that could make it so bad, unless again, it is simply because the motor is now burning oil, making the smell much worse, in which case no amount of fixing seals would take care of it anyways.

[Guest 240hybrid]

Yeah, it does get old when you have to keep throwing money at a project, but I guess thats why its called a "project". I would think with the motor burning oil, you would smell a lot more fumes than normal and that might be the problem.

 

All I can say at this point is to let it sit for a while and then come back to it in a week or so before you decide to sell it. Give yourself a break to regroup and rethink it.

[Guest bastaad525]

heheh a couple people suggesting that same thing to me... I wish I could take a break from it but the problem is it's my only car and I gotta get to work everyday. I guess now that I've had a chance to sleep on it I'm maybe having second thoughts but I guess I'll wait and see what kind of offers I get for it.

[EvilRufusKay]

I have been having the same problem with my V8 Z. I actually take a spare set of clothes with me to work and douse myself in colonge so I don't reak of exaust. I am heading in the direction of rear seals for my car, extending the tip did not help my problem. I feel for you as I have the same exaust sickness. It grates at you... you love your car but can't remember where you parked it because of the drain bramage!!!

[Guest bastaad525]

Seriously....

 

I swear it was never this bad before though, either before I put the turbo motor in or before it bent a valve and I had the head rebuilt, I'm not sure, but with my n/a motor and su's, after I replaced the rear seals exhaust smell was NEVER an issue, and nothing back there has changed since then. At least it almost non noticeable with the windows up usually, and since I usually work graveyard I drive to and from work in relatively cool weather so keeping them up isn't so bad... going back to work at 6pm today though in expected 90 degree weather... that is gonna suck.