Strong exhaust smell

[Falcon_LS]

After driving my Montero around, and allowing to reach operating temperature, there's a strong scent coming from the exhaust. You can smell it the moment you step out of the truck.

Strangely enough, I can also smell it in the engine compartment. If I was to describe it, I would say it smells like very, very strong carbon monoxide. Obviously this is a byproduct of combustion, and is expected - just not this strong. Anybody who's with me in the truck notices it when they step out.

There's no difference in performance, and there isn't a big difference in fuel economy (although it is slightly lower). But the engine idles rough in gear or in park/neutral. Could this be an EGR valve problem? Having said that, I do mix TC-W3 (150 ml to 92 litres/5.1 oz. to 24.3 gal.) with fuel (98 RON/93 AKI) - could that possibly be causing this smell?

 

[ctc]

Carbon Monoxide is odorless.

Yes on the TC-W3...

Does it smell like unburned fuel? Could be a bad catalytic converter.

 

[Deltona_Dave]

Sounds like a manifold or exhaust pipe leak. I would check to see if there is any "scorching or black soot" around the manifolds or connectors in the exhaust pipe. Carbon Monoxide (CO) has no smell, although other compounds in gas do have an odor.

I had a cracked headpipe/collector on an old Datsun 310, it left a noticeable carbon/soot/black streak near the crack.

FWIW,
Dave

 

[Falcon_LS]

Thanks for the input!

Just found a fine crack (about 3 inches) on my passenger side exhaust manifold. This is going to be a pain to replace!

Might as well replace the driver's side manifold as well, I doubt it's too far behind.

 

[Deltona_Dave]

Some manifolds are made from Iron or Stainless. Many a good independent muffler shop may be able to weld the crack. Worth a try and cheaper than replacing...

Dave

 

[Falcon_LS]

Thanks! This one's made of iron, so I'll check out a few shops and see what they say.

 

[PandaBear]

very hard to weld a cast iron manifold. You are probably better off buying one on the internet and install it yourself.

That's what I did.

 

[XS650]

Originally Posted By: PandaBear
very hard to weld a cast iron manifold. You are probably better off buying one on the internet and install it yourself.

That's what I did.


There are special electrode made for stick welding cast iron. You can do it a bit at a time without needing to preheat the part. It need to be peened (a small peeing hammer wil do) to relieve stresses.

I'm a lousy welder and had no problems making major mods to a cast iron exhaust manifold and repairing another.

The special electrode is some kind of nickel, IIRC.

 

[labman]

I have a couple of cast jobs I need to do, but my HF 100 amp welder isn't up to them.

 

[JT1]

I've welded cast iron manifolds before. Not as big of a deal as some make of it.

Give it a try, worst thing that happens is that you need to replace the manifold anyway.

 

[XS650]

Originally Posted By: Falcon_LS
Thanks for the input!

Just found a fine crack (about 3 inches) on my passenger side exhaust manifold. This is going to be a pain to replace!

Might as well replace the driver's side manifold as well, I doubt it's too far behind.


It's not uncommon for one manifold to crack on a V engine and have the other side never crack.

Can you or someone else get at it to weld it in place with nickel electrode. My experience was that very little skill was required, you just need to be able to follow directions as far as using the right electrode and welding at the right speed in small sections, then peening it if that's what is called for.

If you weld it in place, v-groove it a little bit so the weld gets some penetration.

 

[mechtech2]

Welding manifolds is tricky, no doubt about it.

 

[USA1]

Originally Posted By: XS650
Originally Posted By: PandaBear
very hard to weld a cast iron manifold. You are probably better off buying one on the internet and install it yourself.

That's what I did.


There are special electrode made for stick welding cast iron. You can do it a bit at a time without needing to preheat the part. It need to be peened (a small peeing hammer wil do) to relieve stresses.

I'm a lousy welder and had no problems making major mods to a cast iron exhaust manifold and repairing another.

The special electrode is some kind of nickel, IIRC.


Another option is to braze the crack; simple and little welding skill involved, if it is, in fact, a cast iron manifold. Shouldn't cost too much for any welding outfit to do.

 

[Falcon_LS]

Thanks a lot for all the input! Found a reputable shop that welds exhaust manifolds, and I'll be taking the truck in on Saturday.

The guy said he'd inspect it first, so we'll see how it goes.