Check Air Box Temperature Control Flap

Post by **MrAl** » 22 Jan 2023, 22:50

Hello there,

I was wondering if there is a way to test the flap that opens the exhaust intake flap inside the air box.
I think that flap opens to allow heat into the engine air stream from the air box when the car first start and until it warms up, then it closes.
I think that's how it works.

I also think somebody may have mentioned something about this but cant remember what they said.

I just want to make sure it closes when it is supposed to close.

Thanks.

Post by **kallekula** » 23 Jan 2023, 01:59

That’s how it’s supposed to work yes. It seems to fail often and does so in the open position. I glued mine shut, lives in CA so it’s really not needed here. Intake air temp dropped and car got better power and ran much better overall. Especially in the summer time.

Post by **MrAl** » 23 Jan 2023, 04:20

Hi,

Oh, you sure thats ok?
Sounds good though.

Post by **scot850** » 23 Jan 2023, 09:39

I tested it worked, not scientifically but blew hot air over the thermostat with a paint stripping gun. It opened up on the cold air intake and then closed back to it's ambient position when the heat was removed.

Neil.

Post by **abscate** » 24 Jan 2023, 01:21

It isn’t a cold start item. It regulates the air box temperature to an unknown set point we should measure and document here because that is what we do. It can only add heat, so the air box will always be at ambient or higher once the car warms up for a minute or two

Post by **volvolugnut** » 24 Jan 2023, 07:39

Popular knowledge from brickboard.com for 240 Volvos says to delete the tube from the exhaust manifold if the air box thermostat fails. I did this to my 240s without problems. However, I live and drive in the South. There may be a different recommendation for newer Volvos and driving in the North.
volvolugnut

Post by **MrAl** » 24 Jan 2023, 18:21

scot850 wrote: ↑23 Jan 2023, 09:39 I tested it worked, not scientifically but blew hot air over the thermostat with a paint stripping gun. It opened up on the cold air intake and then closed back to it's ambient position when the heat was removed.

Neil.

Oh that sounds like a good test. I'll have to try that.
Is there a part number for that thermostat or specific name for it?

Post by **scot850** » 24 Jan 2023, 18:43

It is called a thermostat:

https://parts.volvocars.ca/p/Volvo_1998 ... 42616.html

Part # 9142616

Neil.

Post by **abscate** » 25 Jan 2023, 03:46

On the 1998 the thermostat lives up in the air box with the two vacuum connection hoses. Stock is hard nylon hoses with rubber connectors but often these have been replaced with vacuum line

Post by **MrAl** » 25 Jan 2023, 06:17

scot850 wrote: ↑24 Jan 2023, 18:43 It is called a thermostat:

https://parts.volvocars.ca/p/Volvo_1998 ... 42616.html

Part # 9142616

Neil.

Thanks for the link and the part number. I'll be looking into this and hopefully i can get that part working again.
Have to see what the weather is going to be like today and over the next week. Today isnt supposed to be too good but maybe in a few days better weather. I loosened up the bolts on the spark plug cover (ha ha) yesterday so i can do the rest of the wires quick at the same time as i fool with the air box and ignition coil.