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AQ 260 Thermostat???-gctid406057

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    AQ 260 Thermostat???-gctid406057

    During an extremly low tide the other day, I touched the muddy bottom just past my dock and not long after the engine ran hot. I wasn't far so I turned around and went back to the dock to check things over. Pretty sure I sucked up some mud or kelp but eventually blew it out because she's cooling fine now.

    I decided it was worth my while to check the thermostat anyway since its basically the only thing on my engine that hasn't been replaced in the past 2 years. SO.....I pull the thermostat housing to have a look....but no thermostat. WTF? It's a 350 chev engine basically....isn't it supposed to have one!?

    IT's an AQ260 with a fresh water cooling package installed. Is it possible the thermostat completly corroded and disappeared? Or did the PO remove it and not put one back in? Or, does this setup not need one?

    Ran for about 8 hours since and ran at temp just fine.

    #2
    tedstrophy wrote:
    During an extremly low tide the other day, I touched the muddy bottom just past my dock and not long after the engine ran hot. I wasn't far so I turned around and went back to the dock to check things over. Pretty sure I sucked up some mud or kelp but eventually blew it out because she's cooling fine now.

    I decided it was worth my while to check the thermostat anyway since its basically the only thing on my engine that hasn't been replaced in the past 2 years. SO.....I pull the thermostat housing to have a look....but no thermostat. WTF? It's a 350 chev engine basically....isn't it supposed to have one!?

    IT's an AQ260 with a fresh water cooling package installed. Is it possible the thermostat completly corroded and disappeared? Or did the PO remove it and not put one back in? Or, does this setup not need one? Ran for about 8 hours since and ran at temp just fine.
    I'd say no..... the thermostat did not corrode away in a PH correct E/G solution. Hard to say why the stat was removed.

    All marine engines are designed to operate with a thermostat installed regardless of what you may find or read here. Our Closed Cooling systems can become un-balanced when the stat has been omitted. This will also affect WH and Cabin Heater function.

    Since you may have pulled in mud or weeds, I'd suggest that you take the entire sea water side apart, and examine each area.

    This would mean all suction hoses, the ends caps of the H/E, etc.

    It would also be a good idea to pull your risers and look at the manifold-to-riser sea water transfer ports.

    I'd also check the scalloped areas of the risers where the rubber couplers are clamped. All too often these OEM couplers are too short, and one of the band clamps eventually compresses the rubber into the scalloped areas.

    When/if this happens, the spent sea water becomes restricted.



    These rubber couplers (actually 95mm soft wall Marine Exhaust hose), whether OEM or OEM replacements, are always too short! If you replace them, purchase your new 95mm hose by the foot and make each one about 2" longer so that the band clamps can be moved further up the riser neck, and away from the scallops.

    As for the stat temp rating..... a 160* will likely maintain a 170/180* engine temp.

    Your sea water pump is capable of supplying much more sea water than required to remove engine heat, so if you have any salt crystallization concerns, your exhaust should still run cool enough to avoid this.... and especially if you do the above.

    .
    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

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      #3
      There is one heat exchanger manufacturer that incorporates the thermostat into their distribution housing which is attached externally to the H.E. shell.With that particular model, the original thermostat located in the outlet of the intake manifold is removed.I'll see if I can find a pic of it to post, I had one that I sold last year to a guy in Canada............Was it you ??Post a pic of yours, odds are it is not the one I mention, the above info is more of a FYI for whoever wants it.Here is one, the T-stat is in the housing attached with 2) SHCS

      [img]/media/kunena/attachments/vb/709863=30386-exchanger.jpg[/img]
      " WET EVER "
      1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
      mmsi 338108404
      mmsi 338124956
      "I started with nothing and still have most of it left"

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