Where can I find an explanation of my air cleaner?

I took the air cleaner off so I could make a close comparison of my carburetor with pictures of a potential replacement.

It had more stuff attached to it than I knew about. When I looked it up in Chilton and Haynes I found descriptions of various parts in different places, no unified explanation.

There’s a hot air intake system, which has a switch mounted inside the AC, connected to 2 thin hoses, 1 of which goes to the HAI diaphragm.

A large hose connected to the bottom of the AC goes to a rubber or plastic canister under the AC - some kind of vapor recovery system?

Another thin hose on the bottom goes somewhere; another thick hose goes somewhere.

Is there a single place I can find a description of all this stuff? I looked at a couple of auto parts places in hopes of finding a manual for a replacement AC, but they don’t sell them.

87 toyota pickup dlx 4-cylinder 5-speed manual carbureted 22R engine

Open the hood, and look for an emission sticker under the hood.

That should reflect the routing of the vacuum hoses.


That’s the kind of thing that is seldom explained well in the repair manuals. They’ll tell you just to inspect the hoses and make sure they are routed properly. Which is usually all that’s needed actually.

But good idea to try to understand how it all works. I can’t speak to your engine configuration, but on my carb’d Ford truck the air cleaner ass’y is configured more or less like this. I expect the same functions are used on your truck, but probably done a slightly different way.

  • There’s a hose from the clean air side of the ass’y that goes to the charcoal canister. That is so gas fumes that are stored in the canister have a path to be drawn into the engine when it is running. I think that’s also to allow gas fumes in the carb bowl to have a path to the charcoal canister when the engine is off, but now sure how well that works in practice.

  • There’s a hose from the engine exhaust manifold area to the air cleaner ass’y. That’s to allow engine-heated air into the engine when the engine is cold. There’s a corresponding door in the air cleaner ass’y that opens to allow the heated air in, and blocks off the cold air when the engine is cold. That’s all done to make the engine run smoother when it hasn’t yet warmed up.

  • There’s a vacuum line from the intake manifold to a vacuum control gadget riveted inside the air cleaner ass’y , and another vacuum line from that to a vacuum motor that controls the door I mention above. That gadget is what controls how much the door opens, corresponding to the temperature.

  • Finally, I think this is the last one, there’s a hose from the clean-air section that goes to the valve cover. That’s to allow clean air to be drawn into the crankcase, part of the pcv system. That air eventually goes down one side of the insides of the engine, into the crankcase, and up the other side and exits the engine at the other valve cover via the pcv valve, then into the base of the carb where it gets burned up inside the engine.

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Hmmmm… do you really think it would last 30 years? I bought 1 from the local dealer 13 years ago . It has no air cleaner in it; 1 unnamed hose routes to the air cleaner. And it’s all acronyms. I forgot to mention it’s California. Is this it?

You can see one of the hoses I mentioned, from the canister to the air cleaner. On your truck it appears to go through a vsv (vacuum switching valve) first. And then through another valve of some kind just to the left of the carb, before eventually going to the air cleaner off the top of the diagram. That diagram doesn’t show all the connections to the air cleaner ass’y from what I’d guess, mainly to show the vacuum line routing. For exaple the hoses to the distributor don’t generally involve the air cleaner ass’y. Those come from ports on the carb.

The clean air side? Do you mean inside the filter rather than outside it?

Is this a thick hose connected directly to a large rubber canister? I have 1 of those. It looks like a fume-scavenger.

Is this the hot air intake (HAI) system? A thick hose from the manifold inputs into a switch controlled by smaller hoses, one to the HAI diaphragm, another to… don’t know where.

Eventually connecting to the PCV valve?

I would also recommend taking photos of the entire process and how everything is hooked up as you unattach the old carb. I’ve found photos of my work as I proceed to often be an invaluable tool.

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This is a great product


using it can save a lot of time especially when there is a long wait from tear down to reassembly.

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My parents once owned a 1983 Buick Century. They took the car to the dealer for a tune-up. It ran worse when they got it back. Another trip to the dealer didn’t help. I was at their house for Sunday dinner when my mother mentioned the problems with the car. After dinner, I took a look at the car. When we started the car, I heard a vacuum leak. The hose to the thermostatic control on the air cleaner had been left disconnected. I connected it.and.the car immediately ran better. With the hose disconnected, it continually drew hot air off the exhaust manifold. However, the car didn’t have any pep. The dealer’s service department had retarded the timing to try to compensate for the disconnected hose. My dad went back to the dealer and they tried to charge him for resetting the timing and adjusting the carburetor. Fortunately, I was there to intervene. I tried to explain the problem to the service manager. He said that a tune-up didn’t include setting the timing and adjusting the carburetor. When the service manager asked me if I was a mechanic, I replied, “Go get a car with a problem. I’ll bet a month’s pay I can diagnose the problem faster than any of your mechanics”. The service manager backed down and my Dad didn’t have to pay an additional charge. I am just glad that the agency didn’t employ any mechanics that post on this board or I would have been out a month’s pay.

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Thanks for your concern, but I didn’t need help getting everything re-attached properly. I hadn’t thought about my air cleaner. I’m pretty sure that 50 years ago they didn’t have so much stuff in them. I realized I hadn’t thought about everything that was in mine until now. When I tried to figure it out with my reference books, I found the various parts scattered, no unified discussion.

Yes. I think the designers didn’t want gas fumes to have to go through the air filter element, as the element could be degraded by the fumes.

Yes, directly from the air cleaner to the canister. It’s about 1/2-3/4 inch diameter, a flexible-metallic hose on my truck. It works in both directions I think. With the engine running it pulls fumes from the canister into the engine, and with the engine off it scavenges fumes evaporating from the carb fuel bowl into the canister. I doubt the latter works very well at removing evaporating gas fumes from getting into the outside air, which would explain why yours is configured in a more complicated manner. i.e. so that it works better.

Yes, about 3 inches in diameter, a flexible-alumnimum hose, similar to used for venting clothes driers. There’s a sort of chamber next to the exhaust manifold that is the source of the hot air. I call that the Washington DC part of the engine … :wink: . The cold air intake (which has a similarly thick hose connected from the front grill area) is adjacent to where that hot air intake hose connects to the air cleaner ass’y.

Yes, clean air comes out of the air cleaner ass’y through hose from there to the valve cover, and gets sucked into the valve cover on that side, down the engine then through the crankcase, pulling fumes with it up the other side of the engine to the valve cover on the other side (v8 engine) then through the pcv valve then into the engine at a hose connection near the base of the carb.