Metal Accordion Pipe To Air Box 1998 v70 946841, 9438274

[MrAl]

You need a cone shaped mandrel to expand that, fingers won’t work well. Take the time to do it right.

Worst case, use aluminum heater duct tape to tape it on to the heater box.

Hi,

You mean the air box? That should fit ok it's just at the manifold where it has to be wider or a sleeve over it like the old one.
I dont have the tools to expand it i dont think. It's also very stiff, doesnt even bend easy, although it does bend.
Let me see how it goes first, hopefully it works ok as is.

[scot850]

I will try to find the one I somehow have in my spares. I do recall they had the 2 step version at one point but it may have been on 850's. I think the one I have is all the same diameter. It will fit with some force. Try spraying the manifold end with some lube first and then try to rotate it on to fit it. One it is on it will expand with the heat but it should be a snug fit.

Neil.

[MrAl]

Hi,

Ok thanks.
Crummy weather have to wait for a better day.

[MrAl]

You need a cone shaped mandrel to expand that, fingers won’t work well. Take the time to do it right.

Worst case, use aluminum heater duct tape to tape it on to the heater box.

I ran into a bit of luck this time.
I took the air box out for the other repairs and found that the diameter of the hose actually fits not only the air box but also the exhaust manifold pipe without any flaring or even the so-called 'sleeve'.
The only reason i can think of now for the sleeve is to reinforce the strength of the metal pipe at the exhaust manifold end. The old pipe broke right off at both joints this time and i did not tug very hard, so it must have been a very old pipe. Good thing i got another one rather than the tape, no regrets on that purchase now. The old pipe almost crumbles in your hands like a old, stale, saltine cracker.

I cant see exactly how the flap mechanism in the air box works yet i think this one may be different. So far it looks like a purely mechanical thermostat that has a shaft that connects to the flap, and it looks like the flap will close if the thermostat gets hot because the arm must be pulled in by the thermostat. So no motor in this one just that thermostat.
That might mean that if i do test this for temperature it may only be applicable to this model air box, whatever that part number is.

BTW the thermostat looks nothing like the links given in this thread or another thread previously. It looks more like an engine coolant thermostat but smaller diameter and looks longer. I'll take a pic at some point, gonna rest up a little right now.
The air filter was a little dirty but i am not sure how clean they have to be, or if they can be cleaned.

[scot850]

Ye it has no motor, it is just a thermostat pushing and pulling and I think there is a return spring in there. Been a while!

Neil.

[MrAl]

Ye it has no motor, it is just a thermostat pushing and pulling and I think there is a return spring in there. Been a while!

Neil.

Hi,

Yeah on a more close examination, i found it is not even a thermostat it is a vacuum actuator that opens/closes the flap(s).
There are two flaps, one opens the front air intake tube (going to the very front grill) and closes the exhaust intake (into the air box) port.
As it stands not running, the front cool air port is closed and the exhaust port is open. That means it gets all of it's air from the exhaust manifold. Maybe once it starts up the vacuum line pulls it so the front port is open and exhaust closed but i havent looked into that yet as i have the box in the house right now for inspection.
Funny i went to put the heat gun on it and saw that there was a vacuum line right underneath it and that led to a enclosure that looks like a diaphragm housing which would be vacuum sucked in order to open the front port and close the back (exhaust) port, or partially open/close each port.
I would expect that to cause some problems if it no longer worked right. The vacuum line connecting that comes from the other side of the air box and it looks kind of poor using a tie wrap to hold a stiff vacuum line into a soft rubber like vacuum line. Probably leaks a lot. Should replace that line i guess, and it's only about 18 inches long.

Is there any recommended type of vacuum line for these things?

I'll try to get a picture of this mechanism and post in a few minutes or so.

[abscate]

Thanks for adding to the knowledge bank on this. It looks like the default state for the vacuum actuator, which I called a vacuum motor above, is sprung closed, which admits heated exhaust air only. On startup, engine vacuum goes to the air box, but that only gets back to the vacuum actuator if the air box thermostat has warmed to the ….

Set point?

….at which point it regulates intake air by mixing cold/hot air. We could guesstimate this by looking at the IAT temperature in a scanner on a warmed up car, I’ll guess it’s 5-10C above ambient or so in normal climates. It can never be below ambient of course

[454cid]

That's the system I have/had. Mine was always 1/2 way in between so air was open/partially-blocked from both sources. I'm not driving the car in the winter, so I removed the lines, and capped all the ports. I also replaced the lower half of the air box with one from a turbo that's not encumbered with the air doors.

[MrAl]

Thanks for adding to the knowledge bank on this. It looks like the default state for the vacuum actuator, which I called a vacuum motor above, is sprung closed, which admits heated exhaust air only. On startup, engine vacuum goes to the air box, but that only gets back to the vacuum actuator if the air box thermostat has warmed to the ….

Set point?

….at which point it regulates intake air by mixing cold/hot air. We could guesstimate this by looking at the IAT temperature in a scanner on a warmed up car, I’ll guess it’s 5-10C above ambient or so in normal climates. It can never be below ambient of course

Hi,

Oh no problem as long as i can do this stuff i like to contribute when possible.

I tested the vacuum actuator and it appears to work, but i didnt check the 'thermostat' because i didnt know what that was or where it was, but i think i do know now. Apparently it looks like a vaccum line runs to the air box from the engine somewhere, goes to what must be the thermostat, then a line runs from that to the vacuum actuator. The actuator works i tested it with a vacuum pump, but i dont know what level of vacuum it works at because i dont have a gauge for that. I also dont know if my car produces enough vacuum to operate it properly yet.

I also ran into another little problem. The metal hose i purchased is too long, way too long, to fit the car. It has to be cut down by at least 12 inches probably more. I guess this is cut with a hacksaw? It appears to be made of aluminum. The metal is rather thin, but it seems to be sturdy unlike the old piece of junk that was on there before. It did fit on the exhaust manifold pipe nice tight fit.

[454cid]

Apparently it looks like a vaccum line runs to the air box from the engine somewhere

The source is the vacuum tree on the the intake manifold. I think all ports are the same.

I also dont know if my car produces enough vacuum to operate it properly yet.

I put a gauge on my car, and it was in the teens (psi) at idle. I just googled for a generic spec for any/all engines and it was in the ball park.

I also ran into another little problem. The metal hose i purchased is too long, way too long, to fit the car. It has to be cut down by at least 12 inches probably more. I guess this is cut with a hacksaw? It appears to be made of aluminum. The metal is rather thin, but it seems to be sturdy unlike the old piece of junk that was on there before. It did fit on the exhaust manifold pipe nice tight fit.

It might work. If the hose is too flexible (and it doesn't sound like it) I'd go with some sort of tin snips. Maybe even a utility knife would work. Maybe try a couple of cuts in the area you know you'll need to be cut off, and see what works best?