88894035?

Discussion in 'GM 6.5 Diesel Engines' started by TurboTahoe, Jun 2, 2009.

  1. TurboTahoe

    TurboTahoe Recruit

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    In the current MaxxTORQUE issue, Heath mentions that his testing shows that the 97+ "high volume" water pump was not that great, and that the "factory service replacement water pump" (#88894035) was the preferred replacement, giving 48 GPM performance, whereas the 97+ only gave 22 GPM! Wow.

    I have a 97+ water pump, AC Delco Model 251-590. It appears that the recommended pump is also called an AC Delco 251-603.

    After all these years of reading, I never knew there was a difference. Any comments from the troops?

    -Rob :)
     
  2. toddlnrd

    toddlnrd My first diesel!

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    I believe Heath was saying that the 48 gpm and 22 gpm was the flow to the passenger side of the engine, not the total flow of the water pump.

    As to the model numbers, I don't have a clue.

    Todd
     
  3. DieselSlug

    DieselSlug Rust.....What rust....

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    The stock older pump flows 85 gpm, and the newer 97 plus stock jobs put out 130gpm. I am in the ssame boat as you but i bought a dmax fan with the four bolt setup and want to stick with it, you can go to a parts store and request the one for a 97 year truck and it iwll be a 130 gpm pump, the one he talks about i think is a newer model yet with the screw on fan..... A/C DELCO 251-603
     
  4. TurboTahoe

    TurboTahoe Recruit

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    Yes, I understood that. It is simply that in the discussions all these years, we've only talked about 2 pumps - one pre-97, and one 97+. I didn't realize that there was a third option, that 'factory service replacement' option, which apparently is even higher flow. I was wondering if anyone had first-hand experience with it.

    -Rob :)
     
  5. DieselSlug

    DieselSlug Rust.....What rust....

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    If i didnt spend the money on the fan i would have bought it by now......
     
  6. TurboTahoe

    TurboTahoe Recruit

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    Local stealer says that the 251-603 = $405.70! Wow.

    -Rob :)
     
  7. Matt Bachand

    Matt Bachand Depends on the 6.5

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    Bailing GM outta bankruptcy, one water pump at a time!

    I think they should make new light duty tahoe's and pickups with the military 6.5 and updated DB-4's. That should bail em out:) Since they ditched the 4.5l diesel, why not use the military proven 6.5's and keep em in circulation :):thumbsup:
     
  8. TurboTahoe

    TurboTahoe Recruit

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    Ha ha Matt, well-put!

    Well, we gave 'em $50B (I wonder if it was illegal, actually), and MORE TO COME, with no proof that anything was being run differently. (Where's MY bailout?)

    I love my two 6.5s, and plan to keep them, God willing, for a long time, but that seems pretty excessive for a water pump.

    -Rob :)
     
  9. schiker

    schiker Active Member

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    I was thinking of posting something on another thread then didn't. Not sure I wanted to post here but as long as for discussion.

    I'd like to see the test procedure and equipment they used to gather that data. I don't claim to be an expert just playing devils advocate here.

    These water pumps are not positive displacement and true flow rate is unknown and variable depending on RPM and most importantly how open the thermostat is.

    I believe I have a decent understanding of the radiator cap and increase in pressure is good for increasing boiling point. I had never heard the waterpump increases the pressure in the block. Its a closed loop system and yes there is a pressure differential top to bottom hose for flow but not sure how much pressure differential is from head to top hose radiator inlet (which is high pressure and lower hose would be low pressure thus causing flow.


    What controls localized boiling is....
    System pressure, turbulation, flow, temp control, casting thickness of metals, and coolant surface tension.

    Flow is going to take the path of least resistance and I am not sure how the water pump can really change that. I think its due to different turbulation but not sure how its different or why. I would have like more discussion in the article along those lines and explain the mechanics of it. Not sure about any differences in the pums inlet or outlets that equalize the flow????

    Yes, I believe one pump can out perform another if you measured temps and compared several probes in different areas but is it really a flowrate difference or turbulation and/or flow combined. ? In any event one seems to perform better for Heath but I would like to know the exact and real reasons why.
     
  10. TurboTahoe

    TurboTahoe Recruit

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    Some excellent points, Schiker.

    I also realize that thermodynamically, you can have TOO MUCH flow, where the coolant doesn't pick up enough heat as it passes by the heated surface. It's a matter of balancing the flow. The description in the article is pretty basic, but my main point is that I didn't realize there was yet another option for HO water pump, and wanted to know if anyone has installed one and/or physically compared the 97+ versus the 88894035 variant.

    -Rob :)
     
  11. DieselSlug

    DieselSlug Rust.....What rust....

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    Yeah, gm should give us all new trucks or parts to offset our tax dollars given. Customer loyalty. Try calling your local a/c delco warehouse, this will eliminate the dealer, or the middleman, go right to the warehouse. There are a few warehouses around here. However if you dont have an account with them they cant give you prices over the phone, you have to physically walk in. Dumb rule....
     
  12. NVW

    NVW Active Member

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    IIRC Turbine Doc has the updated cooling with the Screw on fan from Heath

    Leo
     
  13. 94K30

    94K30 Diesel nut

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    Hi Rob, That part number, ACDELCO 251-603 is priced $218.04 from
    AC-Direct (seems to be part of amazon.com)
    Marc
     
  14. mitchedo

    mitchedo New Member

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    I bought a screw-on take-off from Peninsular (because I already had the screw-on fan), but the part number is different from the one in the MaxxTorq article. I'm bumfuzzled.

    I bought Bill's new clutch and composite fan, which has helped my cooling situation some. I've ordered a new radiator and AC condenser to eliminate those as a problem area. I'm going to power wash the tranny cooler; the oil cooler is new, as is the rest of my cooling system. We'll see what happens.
     
  15. buddy

    buddy New Member

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    The water pump is the one used on 2000 model 6.5s. Apparantly GM realized it helped too but ended the series of truck the year after.

    The actual flow cant really be too much to some extreme point where pressure causes problems elsewhere. heat transfer is based on temp difference, so moving the fluid faster just means the water the block comes in contact with will be cooler all the time, as it wont soak up as much heat. But that doesnt mean that the thermal transfer stops it just continues. So you get more efficient heat transfer that way, because as heat is soaked (the temperature delta decreases) the efficiency of transfer goes down.

    Its easy enough to test something, but to explain the results is a lot harder, so I am not surprised if its not explained why one would flow more.
     
  16. schiker

    schiker Active Member

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    I wasn't sure if all combinations were tested from one read it seamed the combo of the ACDELCO 251-603, the single stat with the older heads performed best for Heath.

    BUT I think the heads were changed in 97 too weren't they??? Which was to also improve coolant mixture/flowrate and in conjuction with the 130GPM and 2 stats was GM latest and greatest combo that seems to work well. But if you mix and match any components it has different effects.

    Interesting wonder what the rating of this ACDELCO 251-603 pump is? I am guessing its below 130 GPM but more than the first series pump.

    The restriction to the bypass (when 2 stats are used) was interesting but again would like to know more about it. For instance if you used a 130GPM and restriction when the stats are closed is there good coolant mixture and flow to warm the stats? Or would be advisable to use a restriction but maybe put a hole in each stat to encourage flow past them and equalize temps faster.


    Thinking ..... I am just guessing that with the new heads with hi flow 130GPM pump - 2 stats creates the path of least resistance towards the radiator but when the stats are closed you want the big bypass. Would the restricted bypass be too little for the higher flowrate pump and new heads?


    Lastly wasn't the radiator changed during the 90's that might have some influence too.


    Then I forget the article is about upgrading older trucks not necessarily stating its the best for all trucks.
     
  17. Turbine Doc

    Turbine Doc Just Another Diesel Guy

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    Yes I have the Heath spin on for the burb, and yes you can have too much flow which is why the Heath also has a orifice in the bypass. Without going into thermodynamics deeply temp can be impacted by flow, or there would be no need to regulate with a stat or a orifice or different sized pumps.

    IIRC head flow wasn't changed much until latest offerings around 2000, AM Gen has high flow heads, my project egnine has Chinese copies of the latest AMG head, passages are bigger than ones in my 98 heads
     
  18. midniteplowboyy

    midniteplowboyy Recruit

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    I wonder about the restricted bypass also, looks like the coolant would get alot more stagnate through the engine.

    I think the new style aluminum radiator cool worse than the old ones, there just alot cheaper for them to build.

    I have an old copper one to try in the 93(someone replaced it with an aluminum one), still have a factory copper four(IIRC) core in my 92.

    I have a new dual stat setup for the 93 with the 97 HO/pump, but hadn't had time to fab a throttle bracket and I'm not sure there better than a single stat yet. I need to try it though, yesterday I really hammered it getting on the interstate messing with a guy and I looked down at the temp gauge, it was sitting on about 230ºF and the temp at the rear of the head was 150ºF, the water aint getting out of the head fast enough.

    The 93, also has the newer style chinese knock off heads.
     
  19. ghitch75

    ghitch75 livin' in the sticks

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    it you want a HO pump just get 1 for a 97 or up from napa...you can get a reman for for 46 buc's and a new 1 for 98 buc's....had my buddy @ napa pull both pumps (95 and 97) the 97 had HO on the pump and the 95 didn't.....clean your rad and cond. and a robertshaw t-stat and it will run nice and cool....
     
  20. TurboTahoe

    TurboTahoe Recruit

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    GHitch, I think you misunderstand the main point of this post. Heath's MaxxTorque article references a 3rd HO pump which is NOT the same as the 97+ pump. They claim it increases effective GPM flow significantly more than the 97+ pump. I started the thread to see if anyone had experience or details about the new pump, which is AC Delco 251-603

    -Rob :)
     

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