Vacuum lines to air box

George Dawson · Post by **George Dawson** » 18 Jun 2012, 18:55

I found a black hose down between the air filter box and the engine and unconnected to anything. It is about 10 inches long. On the backside of the air filter box are two rubber elbows. The top one is white. The hose will fit into the elbow and I assume that is where it belongs. Do you have any idea where the other end goes? I have spent a good deal of time trying to locate where the other end goes. I have not looked under the battery as recent shoulder surgery prevents me from trying. Any help will be appreciated.

I hope this is not a second post. I made the mistake of not saving what I first posted and lost it. That hope that doesn't happen again but being 76 years old I won't bet on it.

Post by **misha** » 18 Jun 2012, 19:25

If it's a plastic vacuum line(hose) it connects in this area...in the picture it's circled in red:

: v 70 engine bay.jpg (48.46 KiB) Viewed 14588 times

George Dawson · Post by **George Dawson** » 20 Jun 2012, 09:04

Thanks for your help and photo, I am going to pull the battery and the battery box out this afternoon and if I find the connecter I will photo it and send it back to you for you collection of images. From the looks of this photo I should clean the engine to concours condition but I won't.

Post by **taxi** » 20 Jun 2012, 15:15

Hi! I dont have a picture, but my (-97 850) little black hose goes from one side of the airfilter box to the other (picture above, the other end to the side not seen in the picture), I think it controls the cold air flap-regulator-thing.
I also have a longer hose from the backside of the airbox to something over the radiator, something that looks more important.
The only danger for you (if I understood correctly) is a little un-filtered air going in.
Cold air flap is of course good to have working, but it wont ruin the engine if its not.
Good luck!

George Dawson · Post by **George Dawson** » 20 Jun 2012, 22:01

This is about my 1998 S70 Volvo, basic engine. Here is a photo of the white connector. There is a 25 cm or so, (I am assuming that this has not been broken or cut off) 3 mm OD black hose, that goes in the end of this connector. I am trying to find where the other end goes. Note the black connector and it's white hose that is mounted under the white connector is goes up to the area of the radiator. Thanks for those that have given me some ideas. I have removed the battery and battery tray and looked inside the airfilter. I have looked extensively in the reach of the hose when connected to the white connecter and beyond. There is nothing that looks like a place for the other end to go. I appreciate any ideas that you might have.

DoItMySelfGirl · Post by **DoItMySelfGirl** » 26 Mar 2018, 09:30

A moment ago I found a post that mirrored my issue but had to stop and register (all said and done) now I can't find it. I have a Volvo 2000 V70 SE 2.4L 5cyl. A friend of mine noticed a dry rotted rubber connection tip that was connected to my AIR FILTER HOUSING UNIT, problem is as I didn't remove it(he did) I can not for the life of me figure out where from that point of connection that it needs to be connected on the other end. The hose is about 10in long and is on the smaller size of a coffee straw. Everyone that has had head under my hood, always comments how quiet and smooth my motor sound in general, much less given ago of car. Point being now it sounds a bit chunky or rattles when idling. I believe this hose is the culprit. I have 2 codes coming up, one is (front speed sensor) the other is some air intake code. I didn't hear a difference in car immediately after it was removed (was highway all the home, not much idle time) but next day was neighborhood driving and it was apparently clear that little hose does a big job, or at least a job that is very Audibly apparent if not attached. Sorry so long winded, long winter surrounded by children, not adult stimuli

Georgeandkira · Post by **Georgeandkira** » 26 Mar 2018, 10:10

These small, hard hoses are part of the intake air temperature control system (NOT the official name).
Vacuum is tapped from the intake manifold's left side (right as you look at it) via a single tube to the rear of the air filter's box.
It goes into a thermostatic valve and this vacuum is routed to the air blend actuation door (valve?).
The vacuum to and from said thermostat have little rubber elbows to connect to their respective nipples.
Similarly, the source of the vacuum at the manifold has such an elbow.

Those elbows break with time.
The one on the intake manifold has enough room so a 3'-4' length of vacuum hose (I use silicone) can take a bend without kinking. The connections behind the air filter box have little clearance so replacement elbows are likely the best way to go.

Post by **abscate** » 26 Mar 2018, 11:12

DoItMySelfGirl wrote: ↑26 Mar 2018, 09:30 A moment ago I found a post that mirrored my issue but had to stop and register (all said and done) now I can't find it. I have a Volvo 2000 V70 SE 2.4L 5cyl. A friend of mine noticed a dry rotted rubber connection tip that was connected to my AIR FILTER HOUSING UNIT, problem is as I didn't remove it(he did) I can not for the life of me figure out where from that point of connection that it needs to be connected on the other end. The hose is about 10in long and is on the smaller size of a coffee straw. Everyone that has had head under my hood, always comments how quiet and smooth my motor sound in general, much less given ago of car. Point being now it sounds a bit chunky or rattles when idling. I believe this hose is the culprit. I have 2 codes coming up, one is (front speed sensor) the other is some air intake code. I didn't hear a difference in car immediately after it was removed (was highway all the home, not much idle time) but next day was neighborhood driving and it was apparently clear that little hose does a big job, or at least a job that is very Audibly apparent if not attached. Sorry so long winded, long winter surrounded by children, not adult stimuli

An MVS welcome and a salute to those we handle the house, kids, and car !!

The hoses here are controlling a flap which controls the temperature of the air going to the air cleaner as George says. There is a big fat elephant hose of Aluminum that goes back to the rear of the engine and picks up warm air from over the exhaust system, cold air comes in the front. The hoses route vacuum to a motor door which balances the cold/hot air, and the balance is handled by a little thermostat gadget up in the air box - where the two hoses go onto those nipples.

They arent critical, they won't damage your engine, but, just as you noticed, idle can get lumpy while normal driving is fine.

You can just pull off the rubber parts, go to a store like Advance or Pep Boys and match the inside diameter of the rubber elbows with hose and then just replace the elbow plus hard line with hose - for under $10

The connections behind the air filter box have little clearance so replacement elbows are likely the best way to go.

You can also roll them up into a nice little loop to get them to slide on with a kink.

Post by **scot850** » 26 Mar 2018, 11:15

Assuming you have a non-turbo, these are the pictures for a 00 V70 base (non-turbo) airbox:

: Black pipe from intake thermostat housing

: Pipe ends at the upper air box cover

You can see from here the connections for both ends of the black hose. This hose as stated previously works the vacuum to help open the thermostat flap fully when engine is warm.

Check the thermostat is actually working. At around 25C it should be fully open even without the engine running.

Neil.

DoItMySelfGirl · Post by **DoItMySelfGirl** » 26 Mar 2018, 12:43

Thank you guys so much for the quick replies. I have two nipples per-say next to each other on the air intake house/box (so does it loop back to the one under the first?) and I see a white one like yours Neil one going to where it seems it should go and the end of that one is stuck on a bolt! Not sure that is its home