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Electric Airpump Fix 850 1997

posted by  someone claiming to be Chaz on  Tue Sep 17 16:19 CST 2002 [RELATED]

My air pump experience may save you some money. The dreaded “check engine light” came on. I used the OBDII plug/software to determine it was the secondary air system. My friend had just spent $600 at the dealer having this pump replaced. A quick check & sure enough the $230 air pump seemed dead, it was metering almost 200 ohms. Bay13 has good instructions for pump removal from the top of the car. Once I got the pump out & on the bench I thought I’d try the disassembly & repair option first before I ordered a new one. The first thing I did was to remove the snap cover on the end of the motor, this cover contains the wire lead-outs (BTW the end cap does not contain the brushes so it is not tricky to remove or reassemble). Water poured out but there didn’t appear to be any rust. I pulled the spade connectors that attach the led out wires to the brush assembly and found the ground connector to be loose and corroded. Resistance measured directly in the spade terminal was less than 1 ohm, which is about right. I connected a battery directly to the spade terminals and the motor sprang to life. I cleaned the terminals, re-crimped the ground clip to make a good connection, pushed the spade connectors back on, sprayed in some moisture displacer made for electric motors, pushed the end cap of the motor housing back on and reinstalled the pump. The control valve and relay check out OK and now the pump works fine. It took about an hour & a half, start to finish. Now that I’ve done it once I think you can get the end cap of the motor off without removing it from the car by pulling off the air dam and going in from the bottom. Good luck to all you fellow cheapskates out there….

Charlie







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    Electric Airpump Fix 850 1997

    uid 47's pic
    posted by  Paul S. on  Wed Sep 18 03:23 CST 2002
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    last visit: Mon Sep 11 09:50 CST 2000
    [RELATED]

    Ken is correct. get a new valve.

    You got lucky on the pump - my thought process was exactly like yours as to getting the pump on the bench and making it work - alas mine was siezed for life - I even drilled the rivets out - but it was d-e-d dead. One solid mass of rust and crud. To make matters worse the hot gases and water were blowing out the side seam and took the large simple relay out (that was never properly sealed and what a stupid location for the relay)
    --
    www.fidalgo.net/~brook4








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    Electric Airpump Fix 850 1997

    posted by  Ken Temkin on  Wed Sep 18 02:14 CST 2002
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    last visit: Wed Oct 22 12:06 CST 2014
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    Charlie,

    I don't think you fixed your problem.

    Yes you repaired the electric air pump, and I commend you on that. And it sounds like you got to it just in time.

    But the point is, how did it get that way? This air pump design is not unique to Volvo--it is used on many cars. The problem is that Volvo did a lousy job in locating the pump at such a low elevation and in procuring defective air valves.

    This air pump was never designed to operate in the presence of water. So where did the water come from?

    First, what does this pump do? It injects fresh air into the exhaust manifold in order to assist the catalytic converter in doing its job (a simplified explaination). When the pump is not operating, the air valve is supposed to close and seal off the airpump from the exhaust stream. Why? Because the exhaust stream is laden with warm, moist air, which, when it hits the cool pump, or it's associated tubing, condenses into water.

    The point is that that water came from somewhere. Where it came from is your improperly functioning air valve.

    You said you tested your air valve. I suspect you tested your air valve for basic functioning. I suspect that you did not test to see if the exhaust side of the air valve was sealing 100%. In fact, testing for this is very difficult.

    Bottom line, replace your air valve with a new unit (I believe they have been improved) and you shouldn't have to repair your pump again.

    Ken








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      Electric Airpump Fix 850 1997

      posted by  someone claiming to be Chaz on  Fri Sep 20 13:31 CST 2002 [RELATED]

      Ken,

      Thanks for the info. I bought the car used and the valve appears to be new, probably replaced in an attempt to correct the check engine light with a cheaper component than the pump. But I’m still looking for the best way to test the unit. Do know of a better way to test the valve?

      I pulled the inlet hose and felt for escaping exhaust gas when the valve was energized and when it was off. It seems to seal completely when it is shut off. My original thoughts were to use an old style fuel pump/vacuum gage to check for minor leakage but with the success of placing my finger over the inlet I skipped the instrumentation. BTW with the engine at idle and the valve open I was surprised to find a slight vacuum on the inlet. I assume this is due to the placement of the air injection jets in the exhaust ports that a venturi action occurres at low exhaust pressures.

      Charlie







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    Electric Airpump Fix 850 1997

    posted by  jon alias jon on  Wed Sep 18 02:12 CST 2002
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    Excellent advice. Thank you for the idea.
    Last year I had similar problem but the pump would still run. It was just water inside that was freezing (winter) and preventing it from spinning. I talked to Volvo tech and he suggested drilling a small hole (1/8" - 3/16") at the bottom of the pump to drain any water that may collect there if my check valve were to fail again.
    Cheers.







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