Something's not right. Smells like exhuast in the cabin, and a very slight backfire has developed on the left side...like a very subtle 'pop pop pop' at idle, and a more pronounced, single 'POP' on decel around 2800-3100 RPM. I've got it paired up to a Triad exhaust. What gives?

I swore to my wife that I wouldn't have the car up on ramps for a while since I just pulled it down (after 2.5 months) 2 days ago, so I took it to a custom exhaust place here in town and had them do the install. They said I needed new hoses (parts 21 & 23 here, hope you don't mind George!). The original ones were put back on, but they're pretty deteriorated and have small holes/cuts in them. Could that be it? I wish I understood how heat exchangers worked. I did a search on google hoping to learn just that but came up empty.

Yes, I realize that if there's exhaust pouring into the cabin it could potentially be fatal. I drove the car home with the windows down. I intend to contact the shop today, but was hoping to get some feedback from you all first.

Thanks in advance

Reid

Smelling fumes in the cabin and backfiring/popping both point to leaks. Look it over... if you find holes, they can be patched. Bummer is they can be hidden by the HE tin.

Sounds like an exhaust leak where the h/e's meet the head. Drop the exchangers and get a BIG ass flat file. Take a sharpie and color the end of the flanges. Then take the file and run it across BOTH flanges at the same time until the sharpie is gone. Then file off the same amount of the top of the mounting tabs. Make sure the sealing area on the head is clean and not buggered up. Get new copper gaskest and re-install.

You may also have some residual oil in the tin that is burning off.

The pop-pop-pop at idle sounds like an exhaust leak though.

SSIs are a PAIN IN THE ASS to fit. Every set I've worked with takes a careful eye to make sure they're actually seating on the gaskets and not getting hung up on the heads.

Did the shop even replace the copper gaskets? I always worry about shops that don't specialize on these cars or have some familiarity at least..

Is it exhaust or residual oil burning off the Heat Exchangers...If you have an oil leak, it will blow up onto the exchangers or leak out of the valve cover, or drop down from the push rod tubes, etc...Still not good for you to breath but different that exhaust gases...Soak the HE's and then smolder as the HE's get hot...

How old are the exchangers...

2-OH!

Do you know if they replaced the gaskets? I'm guessing they just threw the exhaust up on there and tightened things down. It takes some time/precision to ensure no exhaust leaks...

old oil in the heat chambers stinks to high heaven when they get hot . run a can or 2 of brake cleaner thru them. rinse with soapy water. they're stainless so they aren't going to rust. do the file thing. LONG, WIDE file, don't grind on them, light passes hitting both pipe tops at the same time. on the install, start all 4 nuts, press the he tight to the head so there's no rocking, torque them in a few stages, in a x pattern, similar to doing lug bolts. left behind o-ring? forget one? be patient, you'll get it.

k

I have a 1.8L engine to put in the 71 and when I first ran the engine while out of the car, the first start-up scared the crap out of me. Smoke was billowing out of the heat exchangers! I shut the engine down and investigated.

The best I could figure out was the inside of the SSHE were coated with old oil from the engine sitting. It took about 10-15 minutes of running the engine before the visible smoke cleared out of the HE's.

I'm sure the smell is still there as the engine hasn't been installed yet.

The intake for the HE's is above the engine right by where the oil breather is. Is the oil breather vented properly? Also, how about the gaskets around the engine tin? Any leak like that will allow engine fumes to enter the cabin.

Spoke

Wow great feedback. As far as I know they did replace the gaskets. I have to assume they did ~ I provided them, and I told them I wanted to keep the old hardware they pulled off (to make sure they didn't reuse what was already on there). When I showed up, my stock HEs were sitting there along with a box of nuts and the old gaskets. I do believe the new ones are on there.

So, my car does leak oil (can you believe that?). The theories posted here about oil being the issue, while possible, don't account for the subtle backfire that accompanies the exhaust smell. Occam's razor ~ I think the two are related. And since an exhuast leak would cause both, that's seeming like the most likely problem. Had I known that they were so difficult to fit, I would have at least warned the guy. Hmm. I think I'll call him and see what he says. Maybe they'll re-fit them for free (yeah right).

Here're a couple pics. See anything interesting/disturbing? Let me know.

Friday!

Reid

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Another. First time I've had my car on a lift, pretty cool to see.

Last one

All I can say is, let me know if you drive over to Portland, I want to hear what your setup sounds like!

Good luck getting it sorted.

Noticed that your muffler bracket is different than mine. Mine goes to the rear of the muffler instead of in front like yours. I went down to see Dave at Triad several months ago and he did some work on my bracket to make it fit closer to the bolts, was almost like it was a little short in width. He seemed to think it was OK the way it was. I guess I got lucky with mine, no leaks and no popping. You might want to call Dave and see if he has some ideas. The number on his web site is still good, at least it was a few weeks ago.
Tom

Warning - possible bad info. Gearheads please flame this down if it is BS.

During safety checks I see the mechanics stop off the exhaust with a bung. If the exhaust is tight the car will almost stall. If there is a leak it because obvious where it is.

I don't like the sounds of that. I would never assume that I had no leaks if the car choked after blocking off a major pipe. Would you expect a car to run through a couple of bad gaskets and pin holes?

But if it was a controlled back pressure that could be dialed down, I suppose it would expose the leaks.

I'm just blabbing though... Sorta fits when I think about it: Kinda like if I was holding my hand over my mouth and you're hearing what was coming out my ears and backside.

My sample space is precisely 1 - that's why I put the warning on. But it did locate a leak on #1 exhaust manifold. And caused me to fail the safety My thinking is that if the leak is substantial enough to cause pocking it is probably big enough that the bunging should help to locate it.

Steve you do have a good idea, but I dont think you said it clearly.

The point here is to try and stifle the noise and force the air out any other direction, if there was a pinhole leak, some preasure from the exaust would make that leak more noticable(audiblely) when looking for it.

I use my shoe.

Start the car, sit down behind.
Put a shoe on each tail pipe.
Push till your foot is holding one completely closed (the exhaust will come out the other one) and then close the other one till you hear the leak...and which side its coming from.

I have never been luck getting the HE's to sit flat on the head on the first try...and I always do it without the muffler.
Then after I KNOW (see sneaker test above) that the head is not leaking, I attach the muffler.

Good luck.
Rich

Lol - with that triad exhaust the shoe trick would be interesting. I have the image of lieing on your back with your legs splayed. Do not be wearing yer kilt laddie!

Update ~ the shop was willing to refit the HEs for free. When I got the car back, same problem. I took the car back again, and was promised that they would find out what was going on for sure this time instead of just attempting to re-fit. What I'm being told now is that the driver's side HE has a leak inside the tin, and that carbon build up in the intake was a further indicator that this is the case. He said they could probably fix it, but that it would (obviously) involve removing the tin, locating, welding, then reattaching the tin. He said it'll never look right after that.

So now I'm trying to figure out what to do. Does this guy's analysis of the situation sound reasonable? Like I said, he's a very good guy, and the shop is a very reputable place. He's done all of these re-fits and examinations for free.

I'm tempted to have him fix it because if I don't, the HE will continue to look nice but will be useless to me. I still have my stock HEs, my other option is to put those back on and try to sell my one good SS one. Or I guess try to find one for sale (yeah right).

What would you do?

If it's not too much you may as well have it fixed. If he has been doing other stuff for free and has a good rep I think you can trust him on this.

very unlikely ...

the tin is not welded to the pipes, just clamped around them. the pipes are stainless steel. how would you get a leak in there?
Andy

I would think you could find out rather easily for yourself if you pour a fluid down the exhaust pipes and if some comes out of the tin there is a leak.... no?

I had a similar problem when I had my 2.0.

I know a lot of people probably don't do this, or think it would work, but FAT Performance said they use a little bit of red high temp RTV on both sides of the exhaust gasket/washer. I tried it, and it solved the problem. Went for many, many years and miles with no problem.

I doubt the pipe is leaking inside the tin but maybe the tube seam did split. After the HE is removed it can be tested to see if it holds pressure. I am sure there are a number of ways this could be done. The first thought I have is the tabs that the studs go through are too close to the ends of the pipes and hitting the head. Thus preventing the HE's from being fully seated on the copper gasket.

See Andy, that's exactly what I'm thinking. It just seems very unlikely. Aside from one little ding in the tin, the HEs are in great shape (see pics). I can't imagine a hole forming. Beyond that, I bought them from a member here who told me they worked perfectly, and I feel he was telling me the truth.


Hmm. Seems like it would have to be a pretty big hole for that to work if there were no pressure to force the liquid through a hole. Beyond that I don't have them here, my car's still at the shop.


Good idea Mark. I think I'll pursue that first.

Maybe the member that sold me the HEs will chime in with his take on the likelihood that there's a hole...

Not really... Take a piece oftin and block off one end of the pipes. then fil it up with water and plug the other end.

It could very well be the pipe inside the tin has a crack. The last time I was at Brad Mayeurs shop he showed me a SSI exchanger that had what sounds like the same issue you are having.

When the outer skin was removed you could see that both pipes had cracks in them about 2 -3 inches long. One of them was split open enough that you could stick a pencil in it.

For me, before I would start cutting open a SSI exchanger I would try the red high temp RTV that 914-8 mentioned and see if that does it. I will talk with Brad and see if he can give me more details on what he found. I have a friend that is a helicopter mechanic and he gave me some of those CO detectors that is used in small aircraft. This might not be a bad thing for everyone to keep in their cars?

what did they do to pinpoint the leak in the piping? they did this with the he attached? i was not aware of any seams in the piping. something new every day.

Turns out it really is leaking inside the shield. They blocked off all but one tube and put applied pressurized air at 15 lbs. and could hear it "leaking like crazy" inside the shield. Guess that answers that. He said that if it's a fracture it's quite easy to weld up and fix, but that once it's all put back together it will be obvious when looking at it that it's been repaired.

This sucks. Time to put the stock exchangers back on I guess and try to sell these with a full disclaimer on the damage. Wish the same had been done for me when I bought them.

I agree with the following... MUST be done! A run of the mill exhaust shop will not do this and hopefully they installed the gaskets at the HE/Muffler flanges.

Final torque-down is after they're warm to ensure no leaks.

I'm glad you've got a go ahead plan.
Personally, I'd and
I don't think there's much of a market for broken SSIs.

You could always inject some LA air, then just sit back and see where it leaks out.

To me it definatly sounds like a leak at the heads. My .02

I must not have been clear. With the HE off of the car, they blocked off one end and put 15 lbs. of pressurized air to the other end and could hear it "leaking like crazy" underneath the heat shield. It has a leak, that much is certain at this point.

After further consideration though, I'm going to have them fix it.

just fix the leak.

It wont take much to cut the tin open, weld the pipe and re-weld the tin back.

Besides, how often do you look under the car at the H/E's?

Bummer about the SSI's. It is hard to believe that would fail but apparently they have. Do they look like they had been damaged in any way like in a rear end crash? My guess is this is probably a failure of the pipe from the pipe manufacture. Inside the tins the pipes are not bent much. Hard to blame SSI.

Yep, bummer. They look fine, just one very small dent in one of the heat shields, but otherwise they look great. I'll see if I can get the guy who's working on them to snap a picture or two of the damage once he pulls it apart.

Probably cheaper than buying a replacement.

When this type of pipe is manufactured, it is rolled from flat material and seam welded. It would be interesting to see if the break was along this seam. Please post a picture when you can.

I'd have to say they ARE bent much.
There's at least half a dozen bends in there.

Much is a relative term. The bends are slight as compared to where they bend up toward the head. I would think that the bends up to the heads would be the first place they would fail. The outer pipes ar bent a little more than I expected. I am curious where and why they failed.

Are those your pipes in the picture? Why were they taken apart?

That's just odd.

I do remember in metallurgy class the professor talking about welding stainless fire extinguishers that tested out great when new, and years later, blowing apart at the weld. I just can't imagine a force great enough to bend the tubing at the crack.

Wait a minute, that piece of shit honda I used to own would misfire and send a big flaming explosion down the exhaust system. You could feel it traveling down the exhaust as it hit each bend and then into the muffler where it exploded the muffler off the car...

It happened 3 times and trashed 3 honda exhausts....

Needless to say, I will never own another honduh....

Ken

No, those aren't mine. I just liberated the photo from an add in the classifieds.
I don't know why the heater boxes were stripped off.

I just thought it would make for an educational moment.

I was thinking it might be of interest to someone who was able to perform the repairs themself.

Latest update for those of you interested ~ I stopped by the shop yesterday and the owner took me back to look at the HE. He hadn't opened it up yet (waiting on my replacement gaskets to arrive), but I was still amazed by what he showed me. There are several tiny stress fractures at the base of the "bolt arms" (where the bolts go through to attach the HE to the head). They've very very small and you'd never see them unless you looked very closely. Beyond that, the mating surface of the HE at the head end wasn't even close to flat. Not even close. Looking at it's profile it looked like someone had ground it down in an attempt to make it look like the surface of a pond on a windy day. It was crazy. So to everyone who suggested the file technique, you were spot on.

He did finally open it up today and found a "huge split" in one of the pipes. He cut out that section and replaced it, filled in the stress fractures and trued the mating surface. Looks like I get to pick up the car this evening. He saved the fractured part of the pipe at my request ~ I'll post a picture of it when I get it back.

Here's hoping the repairs were successful....

That is exactly what I seen at Brad Mayeurs shop. You need to check your SSI exchangers before you install them.

also it seems its inportant to annul(spell?) the copper by getting it red hot first with a torch, then cool. this makes them more malible to seal better

Went and picked up the car today. Check out the pics of the section of pipe removed/replaced that was inside the heat shield. Crazy! This was obviously not a split at the seam formed when the pipe was rolled. I'm having a hard time wrapping my mind around how this could happen. That crack goes 270 degrees around the circumference of the pipe.

Driving the car home from the shop today was an eye opener. First thing I noticed was, well, no exhaust pouring into the cabin. That's a nice feature. Next thing I noticed was the sound...wow. Even with the leak the car sounded great in my opinion (not including the popping on decel). But man now it sounds just that much better. A much nicer resonance, more of a growl and less throaty is how I'd describe it. My wife followed me home from the shop and when she got out of our truck when we got home she said, "damn the car sounds sweet!" (she's a keeper ). But the most rewarding part of this little 10 minute drive was just that...the drive itself. Very simply put, the throttle response was noticeably more precise. I don't fully understand the negative effects an exhaust leak can have on our little cars, but for those of you that do, does it make sense that it would drive better? I swear...and I don't think I'm imagining it...it seems a tad bit quicker as well.

It's funny - I hadn't realized just how much the exahust leak issue had soured me on this car. Always having to drive with the windows down, popping every time I'd downshift or let off the accelerator at high RPM...kind of just sounds like no more than just a small annoyance. But now that it's fixed, well, I realize that it was more than an annoyance. It pretty much made me not want to drive the car at all. I can't believe how much I enjoyed the ride home from the shop today! I guess it was the first time I've ever actually driven my car with a properly functioning Triad/SSI combo...and it now comes HIGHLY recommended by me.

Enough rambling, on to the pics. Thanks all for your input, it helped.

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