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  1. #1
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    Heads up re: stage 2 with no cooling upgrades

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    When installing further upgrades on my car today, the shop found a significantly leaking water pump as well as badly leaking coolant crossover pipe seals. This was perplexing because my Q5 3.0t was built in spring 2016 and has only 37k miles, immaculate and maintained by the book. Findings were from top rated APR shop that has done many dual pulley setups etc. These were not small leaks but more of an impending failure and/or overheat soon type scenario.

    Only explanation I can think of is car ran single pulley Stage 2 with stock cooling system, and must have been running a bit too hot that way... even though only for 5 months or so. L.A. traffic I'm sure didn't help with heat soak.

    For those of you with stock cooling, please be careful. I got lucky and had them change the water pump and crossover seals with new OEM ones for relatively low cost because the car was already apart. This could otherwise be a costly repair. FYI

  2. #2
    Established Member Two Rings
    Join Date
    Dec 11 2014
    AZ Member #
    301892
    Location
    Texas

    Quote Originally Posted by stapan View Post
    When installing further upgrades on my car today, the shop found a significantly leaking water pump as well as badly leaking coolant crossover pipe seals. This was perplexing because my Q5 3.0t was built in spring 2016 and has only 37k miles, immaculate and maintained by the book. Findings were from top rated APR shop that has done many dual pulley setups etc. These were not small leaks but more of an impending failure and/or overheat soon type scenario.

    Only explanation I can think of is car ran single pulley Stage 2 with stock cooling system, and must have been running a bit too hot that way... even though only for 5 months or so. L.A. traffic I'm sure didn't help with heat soak.

    For those of you with stock cooling, please be careful. I got lucky and had them change the water pump and crossover seals with new OEM ones for relatively low cost because the car was already apart. This could otherwise be a costly repair. FYI
    Our SQ5 had a coolant leak as well. It was pulled with an APR tune but the dealer fixed it under warranty as the root cause was a mechanical failure unrelated to the minor mods. I don't recall what happened but a broken crossover or burst control valve sounds familiar. I'll see if I can find the paperwork at home later.

    I think this might be a known issue...whether it's common enough for a TSB I don't know.

    Note: Ours was bad enough to trigger a dash light or alert (wife drives it so I didn't see it) and there was coolant all over the driver's side of the engine bay. Leak was towards the front/top of that side.

  3. #3
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    So I just got stuck in terrible traffic that had me mostly idling for 30 minutes and did some observations using Torque.

    First of all, my temps got way higher just idling than they did doing WOT runs. Hit 149f IAT and 228F coolant temp. This is in 77F ambient conditions in mostly shade.

    The first interesting thing about this to me is it implies the primary heat risk for our cars isnt going fast but rather extended standstill. Now this is with the Merc Racing hx installed so keep that in mind.

    The second thing I noticed is when I turned on the AC after a long time having it off, my IAT dropped by 10+F and coolant temp dropped by 20+F over a 5 min period. So the learning is turn on AC if idling a long time! Goes against conventional wisdom but I guess its forcing fans and/or pump to run that weren't doing so even at the high temps.

  4. #4
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    After 15 min with AC on, IAT is now 132 and coolant is 200. So total drop of 15+F IAT and 25+F coolant just from turning AC on.

  5. #5
    Veteran Member Four Rings SQive's Avatar
    Join Date
    Apr 26 2014
    AZ Member #
    197039
    My Garage
    2012 R8 GT; 2016 SQ5; 2017 Q7
    Location
    DFW

    Quote Originally Posted by stapan View Post
    After 15 min with AC on, IAT is now 132 and coolant is 200. So total drop of 15+F IAT and 25+F coolant just from turning AC on.
    Shut the front door!

    Anyone care to 'splain dis shit?

    I mean, I know the Demon runs AC coolant through it's intercoolers, but not Audi, right?
    2012 R8 GT, Suzuka with carbon fiber (#298 of 333)
    2017 Q7 P+, Ink Blue, Pistachio Beige, Warm, Vision, Bose, Towing (wife's ride)
    2016 SQ5, Sepang, Black Optic, Technology, BBS CH-R Gold 20x10.5 with 295's
    -2014 SQ5, Monsoon, Sans pano, totaled by a Xanexed-out broad in a Denali XL

  6. #6
    Stage 2 Banner Advertiser One Ring Damon@IE's Avatar
    Join Date
    May 30 2018
    AZ Member #
    419719
    Location
    Salt Lake City, Utah

    Quote Originally Posted by SQive View Post
    Shut the front door!

    Anyone care to 'splain dis shit?

    I mean, I know the Demon runs AC coolant through it's intercoolers, but not Audi, right?
    AC turns on the electric fans, causing more air to move over the radiators.

    Audi shares the engine coolant with the heat exchangers on the 3.0t, there are aftermarket kits to adapt the AC to the coolant lines and you separate the cooling system for the supercharger from the engine coolant.
    Software Engineer
    Live Fast, Buy Fun
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  7. #7
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    It comes down to this IMO (hypothesis): the Audi software thresholds on our cars are set too high for turning the electric fan and coolant pump to a high duty cycle, especially for vehicles with higher pulley ratio than stock. I.e. they are probably calibrated for the heat generated at stock pulley ratio levels, rather than dynamic enough to adapt to the altered conditions. Turning AC on overrides the fan and coolant pump duty cycle in those situations bringing temps back to normal levels.

    I often tried to keep AC off thinking it would generate more heat. I suspect this contributed to my coolant leak issues.

  8. #8
    Stage 2 Banner Advertiser One Ring Damon@IE's Avatar
    Join Date
    May 30 2018
    AZ Member #
    419719
    Location
    Salt Lake City, Utah

    Quote Originally Posted by stapan View Post
    It comes down to this IMO (hypothesis): the Audi software thresholds on our cars are set too high for turning the electric fan and coolant pump to a high duty cycle, especially for vehicles with higher pulley ratio than stock. I.e. they are probably calibrated for the heat generated at stock pulley ratio levels, rather than dynamic enough to adapt to the altered conditions. Turning AC on overrides the fan and coolant pump duty cycle in those situations bringing temps back to normal levels.

    I often tried to keep AC off thinking it would generate more heat. I suspect this contributed to my coolant leak issues.
    Any tuner that doesn't turn up the coolant pump duty cycle is doing something wrong. ;)
    Software Engineer
    Live Fast, Buy Fun
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  9. #9
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    They must not be, because look how popular the coolant pump constant on mod is (across all tubers including APR)

  10. #10
    Established Member Three Rings MSq5's Avatar
    Join Date
    Feb 14 2017
    AZ Member #
    393251
    Location
    Gulfport, MS

    I'm staying with my conservative 179mm crank pulley until I address upgraded cooling to try to avoid undue stress and coolant leaks. I live in a climate that rarely freezes, so I've upped the water to coolant ratio to 80/20 and also adding RP water wetter to the mix. Ok so far.

    Good to know that a/c helps by running the fans and pump more. Just about necessary to run a/c all year here anyway due to high temps.
    2017 Q5 3.0T S-Line | Brilliant Black | EPL Stage 2 93 octane tune | JHM 179mm crank pulley | aFe Pro 5R (part#10-10121) filter in "modified" stock air box | 034 silicone throttle body hose

  11. #11
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    Be careful out there.. 187mm crank is actually higher ratio than I was running with just an EPL SC pulley when I had these issues.

  12. #12
    Active Member Two Rings
    Join Date
    Nov 27 2017
    AZ Member #
    410432
    Location
    Los Angeles, CA

    I mean 179mm.



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