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  1. #1

    Default Why do I have two thermostats?

    I replaced all the hoses on my starboard engine and in the process discovered two thermostats. I'd like to know why, and try to figure out if I might have installed one backwards(I reused the old thermostat). After I replaced all the hoses I refilled the antifreeze and now it seems I'm running hot, even though the temp gauge shows normal. All the coolant hoses were very warm and a couple were so hot I could only touch them for a second or two. The sea water side was ice cold. The bottom of the heat exchanger was cold, the top very hot. The manifolds and risers were hot. So I'm wondering if I installed the forward thermostat backwards or something. The forward thermostat housing didn't really have a "groove" or seat for the thermostat, it just kinda sits there over a hole, you have to be careful installing the top of the housing or you'll disturb the placement of the thermostat. I understand that I can have air in the system, but I know I'm pumping sea water. I have a receipt in the boat showing a FWC exchanger being fabricated and installed about ten years ago. I'm not sure if it used to be RWC and was coverted to FWC or what. Perhaps the forward thermostat was left over from the RWC system... The aft thermostat is one of those big ones and I never removed it. The forward stat is small like the standard automotive size. The engine is about(not sure what year, perhaps as old as 1968) a 1974 International Palmer Ford 351. It's very hard to find info on these engines. There are a couple pics of the same engine in some early 70's correct craft or slick crafts or something like that. All those pics show RWC systems. This motor runs great.. My portside engine is a 2001 Crusader 350, it's and interesting setup to say the least.



    Forward housing



    What are those "caps" on the bottom of the housing? Think I should replace them? Is there something better I can use? Would that be a good place to plumb in a red dot heater?





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  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,765

    Default Re: Why do I have two thermostats?

    Definitely a novel setup...in many aspects....

    Regarding the front housing - based on its appearance, I'd venture a guess that it a RWC thermostat housing.....and the "caps" you inquired about aren't needed with the replumbed system.....Regarding the 'rear housing', man - I'd have to ponder that for a while as it doesn't make a lot of sense to me....especially the smaller hose connected to the 90 deg elbow out the back of the 'rear housing'.....

  3. #3
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,765

    Default Re: Why do I have two thermostats?

    As far as the orientation of the stat in the front housing, the 'spring' of the stat should go down, into the block.....and there should be some concentric locator (mechanical) to locate the stat in the housing....

  4. #4
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Why do I have two thermostats?

    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  5. #5
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Why do I have two thermostats?

    It takes a nickle to go first class!
    If it aint broke dont fix it!!

  6. #6
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    3,470

    Default Re: Why do I have two thermostats?

    Do you have coolant circulating through the exhaust manifolds? Follow the path of the raw water it looks like it dumps out the risers and the coolant circulates through the exhaust manifolds into the top of the heat exchanger then comes out the bottom to the circ pump on the engine? I would say the thermostat in the rear housing does not need to be there. According to that flow chart if you have 160 degree thermostat the coolant coming out is 160 degrees and circulates thru the manifolds so yea it would quite alot hotter going into the heat exchanger especially if your working the engine hard. Definately a odd duck.
    It takes a nickle to go first class!
    If it aint broke dont fix it!!

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