1998 V70: Whirring noise after engine shuts off

allenavery · Post by **allenavery** » 04 Jul 2007, 06:40

Hi, everybody:

My first post. I've got a 1998 Volvo V70, with about 130,000 miles on it. Has anybody out there had a similar problem? After I shut the car off, it continues to make a clunky whirring sound for a few seconds, particularly after a drive longer than 20 minutes, and after being on the highway. It doesn't make the sound while the car is running. The problem appears to be intermittent in that it doesn't appear to do it in the parking garage after I get to work, but does to it sometimes when I get home later in the day. Other than the car preferring that I be at work, instead of at home, does anyone have any thoughts on what might cause this?

At best, I'm hoping its just the fan, or at worst the alternator or a pulley. However, the spindly, chunky sound, which is not too high-pitched, has me worried that it might be something bigger, and more expensive...

Let me know what you think.

Allen

Post by **JRL** » 04 Jul 2007, 07:05

There is clunky and whirring, usually not together.
Could be the secondary air pump, try to isolate where the noises are coming from

volvox · Post by **volvox** » 04 Jul 2007, 10:28

Could it be that you A/C or fan is turned to Auto?
Often times if that's the case and you don't turn it off before you turned off
the engine - the fan will still spin for a minute or two after the engine is shut off.

Post by **pfeener** » 04 Jul 2007, 18:37

JRL is probably correct. It's most likely the air pump to your secondary air system. It only runs occasionally when the ECU decides to turn it on. The secondary air system is an emissions control system that blows fresh air into the exhaust system to burn up some of the unburned gasoline in the exhaust stream. These things get really ratty sounding when they start to fail. The pump runs at different times, but it will usually run for about 2-3 minutes about 15 seconds after the car is first started in the morning and it will usually turn on right after you pull off the highway.

You can test run the air pump easily by removing the pump relay and shorting out the pump wires. The relay is in the kidney shaped fuse box up near the firewall on the drivers side. Remove the air pump relay and you'll see 4 spade connectors that the relay plugs into. They'll be two small connectors and two larger connectors. With the car not running and the key turned off, short out the larger two spade connectors with a large gauge wire and the pump will run. If it makes the sound then that's your problem.

90% probability this is your problem. It'll run you $700 - 800 at a dealer for a pump and a SAS valve or you can do it yourself and save a few bucks. The SAS valve is the root cause of the pump failure. If it doesn't close all the way it will leak exhaust gas into the pump chamber where the gas condenses and fills the pump with water. Let us know and we can help you through it if you decide to do it yourself.

Here's a pic of the system. Number 7 in the illustration is the SAS valve. A new pump is around $300, but you can also get a used VW pump and modify it for a lot less $$$.

Post by **pfeener** » 04 Jul 2007, 18:39

Sorry I forgot the link to the pic.

http://www.fcpgroton.com/csv70/csv70airpump.htm

zenmervolt · Post by **zenmervolt** » 04 Jul 2007, 20:48

You've probably already checked this, but just in case: Are you sure that it's not just the electric radiator fan? Most modern cars will run the radiator fan for a few minutes after shutting the car off to prevent heat-soaking of the engine and radiator (and thereby keep the coolant moving slowly through the system due to thermo-siphon). Maybe all you're hearing is the radiator fan? It doesn't happen all the time, but only when the coolant is at certain temperatures.

allenavery · Post by **allenavery** » 05 Jul 2007, 11:23

Wow. thanks for all the suggestions! I'll try to poke around, and see if I can hear what's making the noise, and if it's related to the a/c or fan. Thanks for the tip on the VW pump, too. My attention has been diverted by another project, 9 months in the making, which finished up earlier this week. I'll crack open the hood on the car next week, if I sleep enough...

Post by **pfeener** » 05 Jul 2007, 11:41

No big deal. If it's the pump, the noise won't hurt anything and when the noise stops it means the pump has frozen up and you'll get a CEL with a PO410 code. In either case it won't do any harm to anything. You can drive it with a bad air pump for as long as you want, you just won't be able to pass inspection.

john200981 · Post by **john200981** » 06 Jul 2007, 20:03

allenavery wrote:Hi, everybody:

My first post. I've got a 1998 Volvo V70, with about 130,000 miles on it. Has anybody out there had a similar problem? After I shut the car off, it continues to make a clunky whirring sound for a few seconds, particularly after a drive longer than 20 minutes, and after being on the highway. It doesn't make the sound while the car is running. The problem appears to be intermittent in that it doesn't appear to do it in the parking garage after I get to work, but does to it sometimes when I get home later in the day. Other than the car preferring that I be at work, instead of at home, does anyone have any thoughts on what might cause this?

At best, I'm hoping its just the fan, or at worst the alternator or a pulley. However, the spindly, chunky sound, which is not too high-pitched, has me worried that it might be something bigger, and more expensive...

Let me know what you think.

Allen

Does this sound last about 10 seconds and have a small "clunk or click" that happens about 3 or 4 times during the noise?