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    Thread: Secondary water pump issues.

    1. Member
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      01-21-2012 07:37 PM #1
      I have a new Bosch secondary water pump that I tested before installing. The pump works on the bench but I'm not getting any current to it after shutting down the engine. I tested it at normal operating temp as well.

      I wanted to test the relay and I found it in Bentley but not in the van.
      Where is the relay?

      I doubt that the relay is the problem but I don't know where else to look.

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      01-22-2012 10:51 AM #2
      Temp gauge low when engine is at normal temp. Aux pump does not run with the rad fans after shut down of the engine.

      I'm considering changing coolant temp sensor that feeds the temp gauge and the aux pump.
      Please advise.

      Also, I have done the temp/fuel gauge fix in the dash cluster board and I have good continuity at the 3 solders to the socket of the voltage regulator. Temp gauge still runs low when the engine is normal temp.

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      01-22-2012 06:32 PM #3
      Bentley says to test the temp sensor below 103C and above 104C.
      <103C open and >104C continuity.
      If continuity happens above 104C then is that how hot the coolant must be before the aux pump runs?

    4. 01-22-2012 11:24 PM #4
      I forget exactly which one it is but the relay is one of the ones in the "add on" row in the fuse/relay panel. The bottom two rows of the panel are part of the main panel and then there are some ones above that that are clipped onto the main panel. It's one of the ones up there.

      The relay outputs 12V+ when the ignition is off and never when it's on. When off, the 12V+ output is then switched on/off to the pump via the thermoswitch. The thermoswitch is rather inexpensive and you may want to consider just replacing it blindly since it's so cheap. It's in the fitting that comes out of the head between cylinders 1 and 2 and it's the 4-pin sensor (the 2-pin one is for the ECU).

      I have found that this time of year it's not that uncommon for the pump to not-run. I live in SoCal and on typical days even in our "warm" climate at freeway speeds I'm sometimes lucky if the dash gauge reads much past 160F anyway and this often doesn't make the pump kick in when I park the van.

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      01-23-2012 08:29 AM #5
      The thermoswitch is rather inexpensive and you may want to consider just replacing it blindly since it's so cheap.
      Are you referring to the sensors in the t-stat housing?

      I have found that this time of year it's not that uncommon for the pump to not-run.
      Thanks Matt, that makes more sense now.

    6. 01-23-2012 11:12 AM #6
      Quote Originally Posted by grubyuppie View Post
      Are you referring to the sensors in the t-stat housing?
      The thermostat housing has no sensors; the thermostat on these vans is actually in the lower radiator hose connection where it goes into the block waaaaay down low.

      The housing coming out of the head though (which looks like a thermostat housing on most cars but on this one houses nothing but two sensors) are where the ECU temperature sensor is (2-wire) and the dash gauge/coolant after-run pump sensor (4-wire IIRC) are.

      VW is strange that way

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      01-23-2012 12:29 PM #7
      Thanks Matt, that helps very much. I took a look at it again after reading your post. What is the best way to remove the t-stat housing bolt that is behind the AC comp?

    8. 01-23-2012 03:52 PM #8
      Hmmm you should be looking at this part to remove:
      http://store.europarts-sd.com/thermo...1992-1996.aspx

      I don't remember the specifics of removing it other than I don't have any recollection of it being unusually difficult or needing anything special even though the space is a bit tight. I must have gotten it out with typical hand tools. Maybe I did it with a closed-end wrench if depth was a problem for a rachet-socket combo.

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      01-23-2012 08:56 PM #9
      The trichotomy of low coolant temp, poor cabin heat, and no aux pump after run was fixed with another new thermostat. I pulled out the new 80C and replaced with a Behr 87C t-stat. Now the temp gauge goes 1/3 up the dial, the heater is blazing hot in 15 minutes, and the aux pump kicks on after shut down with the coolant >170F.

      I used a 10mm box on the t-stat housing bolt that is behind the AC compressor. That was a little tedious but other than that the r&r was a slam dunk.

      And thanks again for the help gti matt!

    10. 01-26-2012 03:49 PM #10
      Quote Originally Posted by grubyuppie View Post
      The trichotomy of low coolant temp, poor cabin heat, and no aux pump after run was fixed with another new thermostat. I pulled out the new 80C and replaced with a Behr 87C t-stat. Now the temp gauge goes 1/3 up the dial, the heater is blazing hot in 15 minutes, and the aux pump kicks on after shut down with the coolant >170F.

      I used a 10mm box on the t-stat housing bolt that is behind the AC compressor. That was a little tedious but other than that the r&r was a slam dunk.

      And thanks again for the help gti matt!
      For such a small underhood space it leads one to believe these vans can run hot since the engine bay is crowded but the reality is their cooling systems are actually quite aggressive. The other thing that might be a factor is the plastic fins that cover the fans. They're supposed to be closed below a certain temperature to restrict airflow across the radiator for faster warmup. Mine are stuck open all the time (not sure why; I never cared to investigate because I'm not in a very cold climate so it doesn't bug me) so on cool-ish days my van takes forever to warm up (yes my t-stat is good...I replaced it not long ago with no change in warm up time).

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      01-27-2012 09:15 AM #11
      My fan covers are open while cold so I assume that they are stuck open all the time.
      Last edited by grubyuppie; 01-27-2012 at 03:47 PM.

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      01-28-2012 10:25 AM #12
      The other thing that might be a factor is the plastic fins that cover the fans. They're supposed to be closed below a certain temperature to restrict airflow across the radiator for faster warmup.
      Do you know at what temperature the fins close? Have you tried to repair yours?

    13. 01-28-2012 02:18 PM #13
      Quote Originally Posted by grubyuppie View Post
      Do you know at what temperature the fins close? Have you tried to repair yours?
      Not sure at what temperature but I haven't tried to repair mine or investigate it much. Since I'm in a warmer climate for the most part (SoCal) it's not that important/urgent to me. But when I have the fans out to work on the engine later this month maybe I'll take a look at it.

    14. 03-21-2012 02:12 PM #14
      I thought I would post a reply to this thread as well since my issue is similar. My van temp gauge has always run at half way or a tad above. One day my coolant after run pump decided to explode ( at the top of a ski mountain no less). So temporarily we by passed it, but since the pump wasn't connected my temp gauge didn't work. So my brother ( who is a mechanic) jumped the wires together and it got my gauge working again. Except now it always reads just below 3/4 mark. The fans turn on to start cooling at 3/4 mark, going down the road on the highway it is 3/4 mark. So I thought the gauge was just reading high ( the fans are coming on at 3/4). So then I got a new pump, put it in but i don't think it's working when the van turns off. Haven't 100% confirmed this yet. But I thought this would have got my temp gauge to read back at half way again ( I thought maybe there was some kind of resister on the pump) But it's still showing 3/4. I guess I will check the relay for the pump first but I'm also curious about why my gauge reads high.

    15. 03-21-2012 03:52 PM #15
      Not sure about the gauge but assuming your pump is new and not defective, you might need a new thermoswitch or check the relay. The thermoswitch is pretty inexpensive. It's been my experience that on cooler days that the pump might not really turn on.

    16. 03-21-2012 04:57 PM #16
      Ok thanks. It has been cooler days even though the van temp was right up there. I will check the relay first. Any idea which one it is?

    17. 03-22-2012 11:30 AM #17
      Wiring and relay locations may vary from year to year and possibly even within years, but on my '93 it was up high on the fuse/relay panel in one of the locations that looks like it's added on after the fact to the top of the panel.

      In looking back at one of my earlier threads on this, I guesstimated it was the one with a '38' on it.

      http://forums.vwvortex.com/showthrea...1#post71648013

      And a description of what I found:
      http://forums.vwvortex.com/showthrea...1#post71651181

    18. 03-22-2012 12:26 PM #18
      Thanks so much for the info! My searches didn't come up with this thread but I guess people call it the secondary pump as well. Thanks again

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      05-01-2012 12:49 AM #19
      Update:

      Now that the weather is warmer my new secondary pump kicks on after shutting off the engine. It's good to hear that Bosch purring away on warm afternoons!

    20. 05-01-2012 01:19 AM #20
      Yep, it's reassuring that all is well.

    21. 05-01-2012 11:08 PM #21
      According to the Bentley, the thermoswitch (F165 on the ACU, and something like F45 on the AAF) which feeds the aux pump, comes on at 234F and turns back off at 226F.

      So things need to be pretty toasty for it to turn the aux pump on.

    22. 05-01-2012 11:13 PM #22
      Here's the part that operates the fan shutters:

      http://store.europarts-sd.com/thermo...1992-1996.aspx

      If you reach in there and wiggle the connection to the shutters and this part, you can see the shutters move a little.

      Looks simple to replace.

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      06-04-2012 09:47 PM #23
      Quote Originally Posted by tds3pete View Post
      Here's the part that operates the fan shutters:

      http://store.europarts-sd.com/thermo...1992-1996.aspx

      If you reach in there and wiggle the connection to the shutters and this part, you can see the shutters move a little.

      Looks simple to replace.

      I can't find that part on my van. Where is it located? And I assume that the fans open when it's hot.

    24. 06-05-2012 12:08 PM #24
      Quote Originally Posted by grubyuppie View Post
      I can't find that part on my van. Where is it located? And I assume that the fans open when it's hot.
      Looks like it's in between the fans:

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      06-05-2012 12:14 PM #25
      Thank Matt,
      I don't have that part but I do see where it mounts on the fan housing. Where does the wiring connect into harness?. Without it the fins are always open which explains why the fans seem to be running often.

    26. 06-05-2012 12:18 PM #26
      Quote Originally Posted by grubyuppie View Post
      Thank Matt,
      I don't have that part but I do see where it mounts on the fan housing. Where does the wiring connect into harness?. Without it the fins are always open which explains why the fans seem to be running often.
      Mine appears to be missing as well, as my fins are always open. I bought mine from the PO in Tucson, AZ and the van had spent its entire life prior to that in southern NM and AZ and I wonder if someone removed it as an attempt to allow maximum airflow at all times to the radiator in all temperatures. I make a few trips to Palm Springs and the Coachella Valley in CA so I'm kinda fine with that.

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      06-05-2012 12:22 PM #27
      That makes sense that the fins open will improve air flow when it's hot. I think I'll leave it off with the fins open for the summer.

    28. 06-05-2012 12:50 PM #28
      Check out this brief thread on the subject:
      http://forums.vwvortex.com/showthrea...t=fan+shutters

      Apparently they only should close below 77F so I guess you can look at that and compare to your local climate and determine how much you are or aren't missing out on.

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