DIY: 1998 V70 S.A.S Pierburg Air Pump Rebuild (for $20)

[pkc303]

Very nice write up.

[europetech]

Hi,
Excellent tutorial which helped me rebuild the air pump in my 1997 V40.
I preferred to replace both bearings and all went well.
However, when you mentioned the air valve could not be repaired, I read that as a challenge. I repaired my valve using an aluminium tube from an old bicycle pump and used a 2 part epoxy metal glue to hold and seal it in place. The inside had "rotted" out and the tube was a tiny bit larger than the original which meant the valve base had to have a channel cut into it. But as the center of the base part was also friable, I had no problem with cutting the channel.
After reassembly I tested it using a syringe to pull a vacuum that opened the valve nicely.
Tricky to get the valve seat square and to the correct height for the diaphragm to seal against.
Having said that, I have no idea how badly your valve was damaged.

Air Valve.JPG (51.49 KiB) Viewed 1433 times

If there is an interest, I could post more detailed instructions.
Cheers from down under,

[MrAl]

Hi,

That's interesting too. I had a missing air pump and bad check valve when i purchased my car. I had to replace both.
There is a diode bypass trick but i never tried it yet. Other people have had success with that. I was a little leery of trying it because it involves modifying the computer electrically, and if the computer gets messed up it could be very expensive i would imagine. Well, that and i already bought an air pump by the time i found that information out

[enotslim]

Just saw cn90's method above to bypass a dysfunctional sas air pump simply by removing the hose leading to the air valve and protecting the open end to prevent debris from entering. Very simple. How has this worked out and are there any significant problems, other than noise (presumably from air entering the open ended hose) until the valve closes? At least it seems like a way to verify the pump or relay as the most likely source of failure. Seems like the pump could remain in place and this fix would still work.

Background - 1998 V70 T5: I verified the relay works and that current is getting to the relay. Jumping the relay didn't start the motor or produce any response - not even an aborted start, lurch, noise, etc. Could the motor have a strictly electrical problem rather than water damage to the bearing?

[erikv11]

Absolutely. When the pumps fill with water they don't just fail due to bearing damage, that's just most common. You can also apply 12V directly to the pump to be sure the wiring is OK.

Pretty much the same time this DIY was written, the community put the finishing touches on how to safely and robustly delete the SAS. So much easier, unless you live in CA or are an absolute purist, is to just get rid of the air pump and all the plumbing: http://volvospeed.com/vs_forum/topic/14 ... with-pics/
Or, if you want to keep the air pump system here's another option: viewtopic.php?f=7&t=75710

Remember, for context, some P80 cars shipped with air pumps, some did not, even in 1998. SAS no doubt has some value for controlling emissions but you're probably doing 100x more good by staying out of the disposable economy and not throwing away the car.

[enotslim]

When doing the diode deletion can you also totally remove the sas plumbing? I didn't realize that from my previous reading. This must require dealing with the outlet from the air box and inlet to the exhaust, right?. Can you also leave it all in place?

Regarding the trick of simply removing the air pump from the system, does the fact that air making its way to the exhaust during cold starts would not pass through the standard air filter affect anything else, like the cat converter, or anything else? Come to think of it, *does* air make it to the exhaust during cold start without the air pump? This would require a pressure gradient from the supply hose (high) to the exhaust (low). If the P0410 code is not set then this must be the case, i guess.

[erikv11]

With the diode trick you remove the pump, the rubber hose from the pump, and all vacuum lines. You leave the air pump relay and the solenoid in place. Passing through the air filter (or not) doesn't matter, it is not metered air. No issues reported (certainly no codes when done as prescribed) from now many hundreds of instances of this modification out there.

I also like to remove the SAS valve and plug and cap off the hole, but you will need to fab up a little plate to do that. With a turbo back there it is a PITA to remove the SAS valve attachment pipe from the exhaust and plug the pipe with a bolt, but that is the way to go.

You can also swap in a non-SAS, T5 ECU (or program one) and remove even the relay and the solenoid, but that takes more time and $.

[enotslim]

Removed the hose from pump to sas valve and saw standing water in the pump. No surprise, I guess. Capped the hose with window screen and reassembled with everything else as is. There may be an additional noise on cold start but doesn't sound like air flowing into an open hose. Much lower pitch. Anyway, I'll monitor the cel and codes. I cleared the codes within the past month and P0410 was re-triggered within a day or two. Does resetting the readiness status (by disconnecting the battery, which I did not do previously) mean it might take longer to trigger P0410 if it is still faulty? I'm approaching this step-wise just to learn a little about what I'm doing before deciding on a permanent fix. Thanks for your help!

[erikv11]

Resetting the CEL by a code reader or by disconnecting the battery does the same thing. The code is set because the pump is not turning on, so yes it will come back. Unhooking the hose won't change anything. If you get rid of SAS, you can cap the hole in the air cleaner with a large rubber plug, or glue something over it, etc.