I own a 1966 Valiant, and I just replaced the exhaust manifold with one I salvaged from a 1978 (I think) van. I experienced no problems during installation aside from the 20 minutes getting that pesky washer under the choke pocket in place. When I fired her up, however, there was an exhaust leak filling the engine compartment with smoke. Upon further examination I discovered that a majority of this exhaust was coming out of two holes on either side of the exhaust manifold stack near the counterweight area facing the driver’s side.

I am assuming these were part of the egr system on the van, but I obviously don’t have that system on my Valiant. How should I plug up those holes and will it affect anything if I do plug them? Can I simply tap out threads and insert a bolt?

Any other ideas?

Tapping and plugging them would be the way to go, but I have never ever heard of anything like this on a slant six. Pictures?

I know some exhaust manifolds used an o2 sensor but not 100% positive about what year they started them (those would come already tapped)

As long as they don't interfere with the counterwight or the flap inside I don't see why tapping them and putting a bolt in them would do any harm. Wouldn't hurt to use your favorite high temp goop on the threads as a sealent either.

[quote="Pierre"]I know some exhaust manifolds used an o2 sensor but not 100% positive about what year they started them (those would come already tapped)

huh, O2 sensor? Are you sure you saw an o2 sensor in the exhaust manifold and not 3 inches down the exhaust pipe. I have a motor/trans from a 87 ram sitting around at home and it doesn't have an o2 sensor in the original manifold.

My 86 Dodge van with the factory original slant six has the O2 sensor in the back of the exhaust manifold directly above the flapper shaft. My brother's 83 Dodge slant six van (currently in my driveway) has the fitting (unused) for an O2 sensor in the exhaust pipe about eight inches downstream of the manifold to pipe flange.

my 75 dart motor had that plug in it, its for egr, all i did was take the line on it, cut it and braze it together but i take it u dont have that metal line. tapping and and just installing a bolt would work, or weld a plate over it. that would fix it up the welding part may be somewhat tricky if its installed unless your expenenced in welding

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Cuda Progress
The dart as it sits now

1966_Dart_Wagon, I'm not sure what you remember on your '75, but there is nothing on any-year/any-model slant-6 exhaust manifold for EGR. No hole, no port, no nothin'. The EGR provisions are all in the intake manifold.

The O2 sensor port, on exhaust manifolds so equipped, is indeed at the top rear of the central collector area. But it's a large tapped hole, not a small one, and there's only one, not two.

Is your manifold heat control valve completely intact and in place? I can think of two small holes that are supposed to be there, one on the front of the collector and one on the rear. The front one is plugged with the counterweight stop/thermostatic spring anchor pin. The rear one is plugged with a similar pin to which is attached one end of the antirattle spring (the other end being attached to the heat riser valve shaft itself).

Kinda sounds to me as if those pins might be missing from your manifold, as if somebody did half a job of trying to defeat or remove the heat riser valve.

I agree with Reed that good, clear pictures will help us figure out exactly what you're dealing with, but I don't necessarily agree with him that "tap and plug" is the way to go. We really need to figure out just what these holes are, whether they're supposed to be there, and what's supposed to be in 'em.

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Too many people who were born on third base actually believe they've hit a triple.

Thanks for all of your information.

I will post pictures this wekend. It's really hard to explain without a picture.

Everything is intact as far as the counterweight assembly and it is fully functional. The O2 sensor on the van I took the manifold from was on the driver's side of the intake manifold, but I used only the exhaust manifold and my original intake. There was an odd sheet metal flange of some sort that went around the exhaust manifold stack and went to some sort of pipe fitting at the top by the carb. Whatever was attached to this was missing at the junkyard. I am wondering if there was some slight vaccuum action that sucked that exhaust into the air cleaner to get re-combusted in the carb. The sheet metal fitting was not air tight in the least...just two bolts holding it on.

Please keep checking back and offering your suggestions.

Nope. There is no such a thing as an O2 sensor in the intake manifold. They are always in the exhaust stream (manifold or headpipe).
That will have been the heat stove for the thermostatic air cleaner found on all '70-up Chrysler-built passenger cars
No, that is not how EGR works.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Smog pump? Don't know for that year.
Are you sure the donor vehicle had an original engine?

No, smog pump either dumped in through the head or into the exhaust pipe about 3 inches past the manifold. Speaking of which, is there an advantage of one system over the other?

The air ("smog") pump injects air through the head and/or into the catalytic converter.
See description of why there are two different air injection points Here.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

o crap, yeah after reading your post and actually thinkin about it duh exhaust gasses wouldnt be put back into the exhaust manifold wow my bad got ahead of myself sorry

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Cuda Progress
The dart as it sits now