Capped off pipe

[deejay1272]

Does anyone know about what this pipe is used for (see red arrow below)? I was thinking that perhaps it's meant for the electric fan (my Terc doesn't have a fan any more), but I thought I'd ask here for advice. Any thoughts?

[Typrus]

If I'm seeing right, thats coming off the manifold. If so, it could be that a carb was changed out. One version has a passage from the exhaust mani up to the cleaner housing. The other doesn't.

[deejay1272]

I read through the FSM and discovered that it's possible that this hose once connected to here (see yellow arrow).



It seems that this would only complicate matters to me. I'm planning on capping this off unless there's some good reason to connect back to the air intake system.

[tercel4wdrules]

That looks to me like the AS (air suction) pipe that the California emissions cars have. On these models the air cleaner has an AS valve, perhaps the exhaust manifold was changed out at some point, since it seems to have the HAC system that Federal emissions cars have.

Here is a pic of the AS valve:



Hope this helps.

[tercel4wdrules]

I read through the FSM and discovered that it's possible that this hose once connected to here (see yellow arrow).



It seems that this would only complicate matters to me. I'm planning on capping this off unless there's some good reason to connect back to the air intake system.

The part you are pointing to actually connects to the exhaust manifold, where the red arrow is pointing:



Here in CA it is required to pass the visual part of the smog check inspection. In very cold weather it will help avoid carburetor icing, but only operates when the flap in the air cleaner opens, which is part of the HAI (hot air intake) system. According to the FSM, the flap in the air cleaner opens in temperatures below 72°F, allowing hot air from the exhaust manifold to enter the air intake.

[skyerunner]

You're right about that - it connects between the red and yellow arrows. That hose was gone on mine too, and I replaced it mostly for shits & giggles as it seems to disintegrate and fall off every 6 mos anyway...

hose.jpg

I don't see that copper pipe you have capped off on mine. I can't see clearly in your pictures, but it almost looks like some kind of shoddy welding job that attached that pipe...

[Typrus]

My vote is on the manifold to air cleaner connection, as in the air suction. Not the heat riser deal. Which it seems most of the ones I see have that sucker missing. But it really does help cold warmup, so long as its working.

[deejay1272]

Oh man, this post is uncovering more missing tubes than I expected!

My vote is on the manifold to air cleaner connection, as in the air suction. Not the heat riser deal. Which it seems most of the ones I see have that sucker missing. But it really does help cold warmup, so long as its working.

It certainly looks like you are correct - I'll need to find a tube to re-connect the manifold to the bottom of the air intake. I may also need to refurbish or lubricate some components to make this work better if it's as problematic as you suggest. I'm sure the FSM can guide me through this process.

Now, back to the plugged pipe that the first photo references - when I remove the temporary "cap" that's on it right now, I get exhaust coming out of it. Now that the HAC theory is put to rest, I'm still not sure what this pipe is for. Before I return to the FSM for more searching, are there any other theories out there?

[Typrus]

Your air cleaner is wrong for your exhaust manifold.

It is supposed to hook up to the air cleaner, as shown in the pic that tercel4wdrules posted.

Exhaust is supposed to come out of it.

Its the emissions setup we talked about.

[ARCHINSTL]

Typrus and tercel4wdrules are correct.
At first glance, I thought you had a CA or Canadian-spec car, as they used this manifold whereas Fed cars did not, and at some point someone stuck on a Federal air cleaner.
Then I noticed the HAC valve is still present and hooked up. This is the reddish-topped device just to the right of the shock tower; it has three tubes on its top, one of which is capped. Only Fed cars have this.
So it would seem that:
1. You have a Fed car with a CA/CD manifold, substituted at some point (the head was replaced with manifolds?);
2. You have a CA/CD car converted to Fed specs, which seems unlikely given the cost/complexity (it ain't a 300SL);
3. You have a Fed car with a Toy factory-error manifold, which again seems unlikely.
Mr. Spock would go with scenario #1...

In any event, you really need to have a SECURE cap on that pipe to keep exhaust fumes from percolating into the cabin; CO can be pretty insidious, obviously.
Tom M.

[Petros]

it appears to me it is pointing at the flap valve on the heat riser off cold air inlet, this is to keep the intake air at a constant (relatively high) temp for emissions reasons. The valve is temp controled and vacuum actuated.

If that is all the tube goes to it will not have much effect on drivablity. On cold start-up the exhaust manifold is not warm enough to make any difference, that is why the electric heat pad is under the carb in the primary venturi.

I have my heat riser disabled and the valve rigged to always take the cold air from the inlet duct off the grill area (next to the head light). Cold air will be more efficient (better fuel economy) and more hp at full throttle. I have no trouble with drivablity, even in freezing weather, it only takes about 30-60 sec of low revs on a sub freezing moring for mine to drive just fine.

Always taking warm air into the carb will reduce the peak pressures in the combustion chambers and reduce some of the emissions formed, especially at full throttle. Since both more power and peak economy are high on my priorities, I would rather always have cold air going into my carb.

[deejay1272]

You're right about that - it connects between the red and yellow arrows. That hose was gone on mine too, and I replaced it mostly for shits & giggles as it seems to disintegrate and fall off every 6 mos anyway...

Hey Skyrunner - any chance you know the outer diameter of that hose or the part number by chance?

[Typrus]

You can get replacement lengths at Autozone on the cheap. Find the diameter as I don't remember off-hand. Or you can bring the cleaner in.

The manifold gets hot alot quicker than the rest of the engine. Now, while I agree it'd be nice to disable it once coolant temps are say, 100 degrees, but it all depends. At this point, some carbs work a whole heck of a lot better than others, re-built or no.

As for your nice issue with the hose, if you follow back to the manifold, you'll find its a big banjo-fitting. If you have the interest, you can PB the thing, remove it, then find a shallow plug that'll fit the threads. Amphasis on shallow as the deeper it is, the more it interferes with exhaust flow.

And don't take CO lightly..... Dad was cooking last year and didn't think much of the smoke in the kitchen- he ended up passing out. Turns out it was CO poisoning. 7 Hyperbaric chamber treatments later and he still has some short term memory issues. Kinda messed up.

[ARCHINSTL]

As for your nice issue with the hose, if you follow back to the manifold, you'll find its a big banjo-fitting. If you have the interest, you can PB the thing, remove it, then find a shallow plug that'll fit the threads. Amphasis on shallow as the deeper it is, the more it interferes with exhaust flow.

I believe you are talking about the pipe leading from the manifold to the EGR valve. For those who plug it when the EGR pipe is removed, the bolt size is 20x1.50mm - and also use some shallow washers.
I think deejay 1272 is talking about the pipe on the top of the mani which, in CA/CD cars, would be connected to the air cleaner front.
You are correct on the AZ/ADV sourcing for the mani to heat inlet on the cleaner horn; it is a standard fit - actually, I just measured mine, since it is redundant with the Weber; it requires an ID of 1.5" (or about 39mm),
Tom M.

[deejay1272]

Typrus, thanks for the carbon monoxide warning. I'll take this much more seriously.

Regarding the exhaust manifold port shown by the red arrow below, there doesn't seem to be much of anything coming out of this port when the engine is running (just after starting). Is it possible that exhaust is coming out of this port when the car warms up? Since it's part of the HAI system, then I'd expect exhaust to be coming out of this immediately upon start-up. I still plan on purchasing that tube to keep things as stock as possible (and avoid CO poisoning), but I'm just curious at this point and I want to get to the bottom of this



Update on the port with the weird temporary cap on it - I purchased a 5/8" cap and a good hose clamp to cover that port permanently (for now). No clue as to what this was being used for....I'll report back if I ever do figure this out.