Just for clarity, the LS thermostat housing is at the far left side of the circulation pump casting:

It is very common around here for mud daubers to block small holes like the "pee tube" on a wide variety of boat engines.  It might be worth the trouble to find the transom outlet that @csleaver mentioned and inspect it for mud or other evidence of bugs.  A wire is the tool of choice to break up the mud to get a path for the water to flow again.  Another option might be to find the other end at the intake manifold and pulse it with a bit of compressed air to make sure it is clear.

Item 149 Is the PCV breather hose. No thermostat hose in your pic.

On 4/26/2024 at 5:02 PM, Powerstroked said:

Getting a late start on my winter project...

Overall dimension 44mm.

Length is 39+153+43 mm= 235mm long (Inside hook to coil to Inside hook)
Coil is 5mm thick.

29 coils.

Using a luggage weight tool, I can start to spread the first coils with 45 lbs of pull and get decent deflection with 70-80 pounds.

My two racks are ~15lbs/each (30lbs )+ Two 8 inch tower speakers ~7lbs/ea (15lbs) + bimini, lights, (~15lbs) and tower itself. 

 

Using your numbers and assuming the coils touch each other at rest, 153/29 gives a maximum coil thickness of 5.28mm.

Springs are measured with force per deflection, so grab your tools and measure again.  Put some weight (I'll call it W1) on the spring as a preload to make sure the coils are separated, then (accurately) measure the overall length (I'll call it D1).  Now add enough weight (D2) to get to "decent deflection" and measure the length (W2) again.  The spring constant K is then:

K = (W2-W1) / (D2-D1)

You mixed unit systems in your original post (mm and pounds), but those are easy to convert to N/mm or pounds/inch.  A stiffer spring will have a higher K value.

I'm curious to see the placement of the springs in the tower.  Please post a photo that shows the general arrangement.  I'm picturing a cantilever arm forward of the hinge, with the springs pulling down toward the tower base.

Csleaver, I know this is the wrong motor, it's an Indmar 350 but would this be the hose I am looking for?  Item 149 in this picture https://www.indmar.com.au/engineschematics/chevy/pre-2014/monsoon-5-7-assault-340hp-345hp-350hp/upper-intake-assembly.html

A 2020 25LSV would fit the bill for your use case as well. Not sure about the low 100s but you get the updated hull from 2019 (surfs great) and the 2020 updated helm and operating system.