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Thread: water pump replacement + overheat

  1. #21
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    got my truck back, time will tell if the issue is reoccurring.

    Link to photo of the worn housing:
    https://plus.google.com/103645652808...ts/VQEHwLchqcm

    Also replaced the various rad hoses and the actual pump was bleeding at the weep hole.

    I couldn't find any play in the actual water pump, the bearings are fine... All that... The pump and the gear appear to be solid...

    G
    GMC Sierra 2500hd 2004.5 now with ARP studs

  2. #22
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    That looks more like corrosion/erosion/cavitation from coolant being peeled off the impeller by the volute. I doubt any actual contact occurred.

    You did replace the two thermostats, right? That cavitation could be caused by low/no coolant flow at high rpm/temp, and that could also overpressurize the system and pop otherwise good pump seals.

    Edit: Good hi resolution pic! You can really zoom in and see that there's no sign of scuffing, but it looks like it's been sandblasted. My bet is cavitation at the point in the pump that sees the greatest difference between pressure and vacuum. Literally, tiny steam implosions that will pit the metal they occur on. If you're interested: http://en.wikipedia.org/wiki/Cavitation

    Edit again:
    The relevant entry from the article:
    Discharge cavitation[edit]
    Discharge cavitation occurs when the pump discharge pressure is extremely high, normally occurring in a pump that is running at less than 10% of its best efficiency point. The high discharge pressure causes the majority of the fluid to circulate inside the pump instead of being allowed to flow out the discharge. As the liquid flows around the impeller, it must pass through the small clearance between the impeller and the pump housing at extremely high flow velocity. This flow velocity causes a vacuum to develop at the housing wall (similar to what occurs in a venturi), which turns the liquid into a vapor. A pump that has been operating under these conditions shows premature wear of the impeller vane tips and the pump housing. In addition, due to the high pressure conditions, premature failure of the pump's mechanical seal and bearings can be expected. Under extreme conditions, this can break the impeller shaft.
    Last edited by rapidoxidationman; 02-26-2015 at 20:01.

  3. #23
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    Quote Originally Posted by rapidoxidationman View Post
    That looks more like corrosion/erosion/cavitation from coolant being peeled off the impeller by the volute. I doubt any actual contact occurred.

    You did replace the two thermostats, right? That cavitation could be caused by low/no coolant flow at high rpm/temp, and that could also overpressurize the system and pop otherwise good pump seals.

    Edit: Good hi resolution pic! You can really zoom in and see that there's no sign of scuffing, but it looks like it's been sandblasted. My bet is cavitation at the point in the pump that sees the greatest difference between pressure and vacuum. Literally, tiny steam implosions that will pit the metal they occur on. If you're interested: http://en.wikipedia.org/wiki/Cavitation

    Edit again:
    The relevant entry from the article:
    The thermostats got replaced first thing, also I don't get pressure on my coolant tank anymore. Used to get allot of steam and pressure when I opened it up hot.

    I'll be loading it up with the 5th wheel sometime in the next 5 weeks and i'll find out pretty fast if this was the problem.

    G
    GMC Sierra 2500hd 2004.5 now with ARP studs

  4. #24
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    So finally got it out on a real hill.. Still overheats. I was climbing sisikyou pass today and I had to pull over 4-5 times to let it cool down. 15-30 mph in 1st or 2nd and the ect was still cresting 240 and the tranny was hitting 235.

    Had to pull off let it run for 30-45 minutes with the hood up. Rinse repeat.

    The thermostats both got replaced last year. The ****ty kn filter box gives no isolation so when the engine heats up the filter sucks in hot air. I verified by watching on the edge insight. When I pop the hood the intake trmp drops by 20degrees instantly.

    I'm in San Fran tomorrow.

    Can anyone recommend a good diesel tech nearby.

    That airbox has to go and I need someone to check the cooling system and possibly make some tweaks.

    G
    GMC Sierra 2500hd 2004.5 now with ARP studs

  5. #25
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    Which brings us back to head gaskets

    When you turn the truck off for the evening, is there still any pressure in the upper radiator hose in the morning?

  6. #26
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    Is your fan clutch engaging?
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  7. #27
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    Have you verified that your truck is actually overheating?
    The guage or the sending unit could be lying to you...

  8. #28
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    Sorry for not responding sooner. Been busy getting stuff sorted. Working in SF for a few days and needed to get my ducks in order while helping to get the little girls ducks in order with the wife too...

    In order:
    1) The upper rad hose is soft in the morning. We've had 2 gm techs and an experienced mechanic say that there's no problems with head gaskets so far... Of course that doesn't mean it's true... Just that there's no indication of that issue yet.
    2) The fan is definitely running, but I've never been able to hear it engage, the truck is quite loud, modified exhaust, no muffler just 2 tips. So if the fan is fully engaging i may not be able to hear it. When I open the hood it's definitely running, but doesn't seem to be making much noise. so that could be an issue.

    3) Both the stock indicators we're looking very hot (not quite overheat, but it's a 9500lb trailer and I shouldn't see significant heat issues under these situations). I was seeing 240+ on insight ECT (confirmed on the dash as well as can be). I've seen the Insight and the dash working together previously when the truck went into limp mode. And I was seeing some very hot transmission temperatures. Another 5 minutes would have definitely put me into limp mode and I had to pick a safe place to pull over before that happened.

    In any case I left it at Left Coast Diesel in Livermore for a more thorough diagnosis, I'm working here and won't have time to really investigate it + I'm not anythign approaching an expert. There was a dealership but it wasn't appreciably closer than the diesel specialist. I'm going to have hte air box replaced with something more effective at cold air intake no matter what. The mechanics opinion was a bunk fan clutch or thermostat, but he also said the air filter mechanism was not suitable for my purposes as well (KN airbox + filter).

    Thoughts, suggestions? Anyone know Left Coast Diesel? They had no BBB complaints which I'm taking as a good thing.

    G
    GMC Sierra 2500hd 2004.5 now with ARP studs

  9. #29
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    If you're running under load above 2,000 RPM's, you should hear the fan when it's engaged. If you're running next to a locomotive, you'll hear it, if it's working properly. Loud exhaust won't hide it. You should also hear it for a few minutes after a cold start, especially when it's really cold (winter). The cold start noise is for comparison, as it is no indication of health when the engine is hot. If you don't hear it after a cold start, the clutch is bad. If you're getting up to 240 and don't notice it, it isn't working properly. If the thermostats are not working properly, neither is the fan clutch. Radiator heat is what causes the clutch to engage, NOT direct engine heat. So if the stats aren't opening (enough), the clutch isn't seeing the heat and won't engage.
    1985 Blazer 6.2
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  10. #30
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    Kennedy Diesel-owner
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    2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
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  11. #31
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    Hi Kennedy, that's the fan clutch currently installed.

    G
    GMC Sierra 2500hd 2004.5 now with ARP studs

  12. #32
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    If that is the case then you will have to look at air flow characteristics, cleanliness of the cooling stack etc. That or you are missing the fact that it is engaged.

    The LLY overheat can be a chronic issue for some. There has only been one sure fix that I have ever seen for the really bad ones. The second radiator addition. I don't recall ever hearing from anybody with a LLY overheating after doing this mod.
    Kennedy Diesel-owner
    More than just a salesman-I use and test the products that I sell on a daily basis!
    Superflow Lie Detector in house
    2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
    2005 Chev K3500SRW D/A CC Long LT(SOLD)
    2007 Chev K2500 Classic EC Short LT (Sold)
    2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
    2016 GMC K3500SRW D/A CC short LTZ

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  13. #33
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    A week or so ago we had several days of higher than normal temperatures here in Montana - above 100 degrees F. The engine driven fan could be heard a lot more of the time, while motoring around town.

  14. #34
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    Quote Originally Posted by DmaxMaverick View Post
    If you're running under load above 2,000 RPM's, you should hear the fan when it's engaged. If you're running next to a locomotive, you'll hear it, if it's working properly. Loud exhaust won't hide it. You should also hear it for a few minutes after a cold start, especially when it's really cold (winter). The cold start noise is for comparison, as it is no indication of health when the engine is hot. If you don't hear it after a cold start, the clutch is bad. If you're getting up to 240 and don't notice it, it isn't working properly. If the thermostats are not working properly, neither is the fan clutch. Radiator heat is what causes the clutch to engage, NOT direct engine heat. So if the stats aren't opening (enough), the clutch isn't seeing the heat and won't engage.

    That's really interesting. I would have assumed the fan clutch would work independently of the thermostats.

    The diesel guy also suggested an SB cold air intake + a scoop below the bumper as a cheaper alternative to buying a lbz air intake kit.
    GMC Sierra 2500hd 2004.5 now with ARP studs

  15. #35
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    Quote Originally Posted by gary_lucas View Post
    That's really interesting. I would have assumed the fan clutch would work independently of the thermostats.
    Common misconception. The fan clutch is air-heat-engaged. With little or no (hot) coolant flowing through the radiator, the air passing to the clutch isn't hot enough to engage the clutch. Once the thermostats open enough, it will heat the air passing to the clutch to engage it, progressively depending on the air temperature. At 240, the stats should be full open, and the air passing to the clutch should be hot enough to cause full engagement. This isn't happening if you don't hear the fan when it's that hot.

    The diesel guy also suggested an SB cold air intake + a scoop below the bumper as a cheaper alternative to buying a lbz air intake kit.
    Cheaper? That's a relative term. How much cheaper is it, if it doesn't work, or doesn't work well enough? It's only a small piece of the puzzle, anyhow. You should be able to source a 2006+ intake system from a wreck for near or below that of an aftermarket kit. The 2006+ OEM system works very well, with little to no improvement from aftermarkets. An added benefit is the filter element required will be for your truck (although for a different M/Y) and commonly available, even if someone replacing it doesn't know of the upgrade. Many of them were upgraded by GM under warranty, so all or most dealerships would be familiar. If you upgrade, you can have the GM vehicle history reflect that, which may add to the trade/sell value.
    1985 Blazer 6.2
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  16. #36
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    Quote Originally Posted by DmaxMaverick View Post
    Common misconception. The fan clutch is air-heat-engaged. With little or no (hot) coolant flowing through the radiator, the air passing to the clutch isn't hot enough to engage the clutch. Once the thermostats open enough, it will heat the air passing to the clutch to engage it, progressively depending on the air temperature. At 240, the stats should be full open, and the air passing to the clutch should be hot enough to cause full engagement. This isn't happening if you don't hear the fan when it's that hot.



    Cheaper? That's a relative term. How much cheaper is it, if it doesn't work, or doesn't work well enough? It's only a small piece of the puzzle, anyhow. You should be able to source a 2006+ intake system from a wreck for near or below that of an aftermarket kit. The 2006+ OEM system works very well, with little to no improvement from aftermarkets. An added benefit is the filter element required will be for your truck (although for a different M/Y) and commonly available, even if someone replacing it doesn't know of the upgrade. Many of them were upgraded by GM under warranty, so all or most dealerships would be familiar. If you upgrade, you can have the GM vehicle history reflect that, which may add to the trade/sell value.
    Fair points, I'm going to try shopping around to find a stock LBZ airbox, but my initial searches we're not looking good.

    WHen I looked in Vancouver, BC I never found anything at the junkyards, not too many of these vehicles end up in junk yards, or at least not quite yet out here.

    I just found the price on a full replacement for the LBZ airbox and it's quite expensive... But on the same general price point of the S and B + scoop (withing a couple hundred). Generally speaking I Don't trust aftermarket so I'd prefer to have OEM stuff.

    Based on what you've described I'm thinking the fan clutch (newish though it is) or the t-stats are bunk... And I'm fairly sure that the crappy K+N air box is exasperating the problem. Engine gets hot, then feeds itself hot air stays hot... etc. Fix the t-stat / fan clutch and get some cold air and it's probably ok. Possibly even cheaper to just replace all 3 and see what happens.

    Does anyone know of method for testing for restrictions in the cooling system? Some way to test total flow?

    Gary
    GMC Sierra 2500hd 2004.5 now with ARP studs

  17. #37
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    I know of no simple or inexpensive way to test coolant system flow. If the components are healthy, then the system should operate as designed. Unfortunately, the design didn't take a turn for the worst until the LLY. The LB7's are generally cooler than they should be, but I think that was overkill from the start. Not that I mind, but it takes a LOT to get it close to hot. I've flogged it, pedal to the metal, for 7 miles of 6%+ grade at 122 degrees ambient with 14K+ in tow, and it got "hot". Hot, at that time, was 230-ish, with the A/C on. Turned off the A/C and it settled down to 220 and stayed there. The drawback is, it's not a barn-burner in the winter, which means less heat in the cab. As with previous discussions on the matter, it isn't the heat that's the problem. The problem is the heat you can't manage. The LLY's have a issue the LB7 and LBZ's don't. We'll work the problem as best we can. I have installed a "cold air intake" system that's not really improved over OEM, but it overcomes an issue that was an issue with the original OEM system. The "Swiss cheese airbox" and snorkel removal was a solution to one problem that led to another, which I think is, at least, part of the issue with the LLY.
    1985 Blazer 6.2
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  18. #38
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    Quote Originally Posted by gary_lucas View Post
    That's really interesting. I would have assumed the fan clutch would work independently of the thermostats.

    The diesel guy also suggested an SB cold air intake + a scoop below the bumper as a cheaper alternative to buying a lbz air intake kit.
    Not a fan of the gauze type intakes be it dry, oiled, or whatever. Even more I really HATE the street sweeper design of those scoops. Just watch the dust curls off shoulder from the vehicle in front of you. Your intake will be in or near this flow ready to suck it up.

    I think what I might suggest is the LBZ mouthpiece and then use the Volant intake kit (without the snorkel)with the Donaldson Power core filter:

    http://www.kennedydiesel.com/detail.cfm?ID=690

    If you feel the need to snorkel I would add a nylon prefilter.

    As for used air boxes they are so commonly destroyed in a wreck that you will seldom find one in salvage. Unfortunately, many LBZ owners throw theirs away after throwing away their money on a fancy aftermarket intake kit.
    Kennedy Diesel-owner
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    2005 Chev K3500SRW D/A CC Long LT(SOLD)
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    2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
    2016 GMC K3500SRW D/A CC short LTZ

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  19. #39
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    Hrm, I'm restricted to whatever they have in stock at this point need to head back on Friday or Monday. Will give them a call today and see where there at.

    WHat a massive pain in the ass, the crazy part is I did pull all those hills before the water pump started to fail. So something has gone south since then or the t-stats / fan clutch that got replaced we're defective.

    I don't think it's possible to screw up a water pump install in a way that's not obvious.
    GMC Sierra 2500hd 2004.5 now with ARP studs

  20. #40
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    Refresh my memory has the cooling stack been removed and cleaned?

    Thermostats replaced? and if so GM or aftermarket?
    Kennedy Diesel-owner
    More than just a salesman-I use and test the products that I sell on a daily basis!
    Superflow Lie Detector in house
    2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
    2005 Chev K3500SRW D/A CC Long LT(SOLD)
    2007 Chev K2500 Classic EC Short LT (Sold)
    2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
    2016 GMC K3500SRW D/A CC short LTZ

    Custom tuning in house using EFI Live tuning software!

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