Metal Accordion Pipe To Air Box 1998 v70 946841, 9438274

[MrAl]

14. Install the air cleaner housing and hoses if removed.
15. Start the engine and ensure that it starts and runs normally.
16. Replace the negative battery cable.

HA HA. I never knew you could start the engine with the negative battery cable removed HA HA i just had to laugh when i saw that one.
Maybe the guy who wrote this had a supernatural Volvo, or EXTREME dyslexia

You have to use the hand crank, but watch out for the kick back

Oh so that's the trick. I thought i would have to push start it (ha ha).

[MrAl]

Little, very little, update...

Today i went out and charged the battery because i did run it down a little trying to start the other day and failing to start after several attempts. It was no where near dead, but i figured if it has to sit another few days it would be good to keep the battery level up.

After i charged it i figured maybe i should try to start it again just for kicks.
To my amazement, it started right up first try. Is that nuts or what.

The only explanation i can think of is that the other day it had been very rainy out and i always had a problem with this car in the rain or very damp weather. One day it stalled right in the middle of an intersection and i was lucky to get it started again so i could pull onto a side road. I had to keep the rpm up a little hoping it would stay running as it was running really really rough almost stalling out again. After maybe 20 seconds it started to run normally again.

One of the things i think might be happening is when the battery gets low the car wants to stall out. The battery gets low when driving in rainy weather because i have to keep the headlights on, that's law here. I wonder if something is very sensitive to the battery voltage level in these cars, or just mine. Any ideas?

[scot850]

No, there is a thermostatic controlled flap inside the air-box. Where the silver corrugated pipe attaches to it and the black rectangular cold air intake meet there is a double flap. there is a thermostatic unit that controls how far the flaps should be for cold/hot air based on whatever Volvo engineers decided should be temperatures.

What happens with age (just like coolant thermostats) the thermostat fails, and depending where in it's cycle it fails it may stick at the cold side which is ok. But if it fails on the fully open warm side with the metal silver pipe it is feeding hot air constantly into your air-box which tends to reduce power.

In warm areas or even to maybe an arbitrary 0C/32C many just glue or jam the cold air flap fully open all the time as they get little value add from it operating v's cost to replace the whole lower air-box. Not even sure if it is still available.

Actually I am totally wrong. Just looked up the air-box and you can now buy that thermostat again for around $35 US in Canada. You didn't used to be able to buy it separately, although I may be wrong on that.

https://www.volvovancouverparts.ca/a/Vo ... 68258.html

On the parts drawing about the air-box is #5 and the thermostat #6a

Neil.

[454cid]

When they work, they work great to the point where it would have been good to have a similar arrangement for the turbos for cold climates. Helps the engine heat up much quicker and therefore the cabin as well. The thermostat is the only downside unfortunately, and unlike the 240 is not replaceable. I think I read a thread somewhere on someone who modified a P80 NA flap to use a 240 one.

Neil.

Hi,

What thermostat? There is one inside the pipe?

It's in the bottom of the air box. The fresh air duct from the front of the car connects on one side, and the aluminum duct connects from the back. I think the thermostat is down there on some cars, but on mine it was a little square deal in the lid with vacuum lines. It controls vacuum to the door actuator where the two ducts connect, selecting one or the other based on the temperature.

[MrAl]

Part numbers 946841, 9438274 for reference. It’s 2inch / 5 cm corrugated aluminum pipe, available as “heat riser pipe” at yourvFLAPS LIKE Advance or Autozone.

Hi Steve,

Thanks for the suggestion and wouldnt you know it the hose was cracked when i did the distributor cap.

It seems Advance and Autozone didnt have one though so i moseyed on over to FCP Euro and found one for about $17 USD, plus shipping.
Do you think it can be taped up or fixed until the new pipe gets here?

[volvolugnut]

Some duct tape may work until it gets too hot.
volvolugnut

[scot850]

+1 on the Duct tape should be fine for a few days until the new pipe gets to you. They get brittle with age and can split as you found out.

Neil.

[MrAl]

Some duct tape may work until it gets too hot.
volvolugnut

Yeah i wonder how hot that pipe gets, it's on the air box end not on the exhaust manifold end. About 2 inches from the very end that connects to the air box.

[MrAl]

+1 on the Duct tape should be fine for a few days until the new pipe gets to you. They get brittle with age and can split as you found out.

Neil.

Yes it was even cracked before i got to it, and it started to crack a little more also after i handled it a little.
The new one has been verified to fit this car so i hope it does.

[MrAl]

+1 on the Duct tape should be fine for a few days until the new pipe gets to you. They get brittle with age and can split as you found out.

Neil.

Yes it was even cracked before i got to it, and it started to crack a little more also after i handled it a little.
The new one has been verified to fit this car so i hope it does.

Now that i think about it, what happens if the pipe leaks excessively or is missing entirely?
i dont care that much if it take longer to "warm up" the engine if that's all it is.