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Hey gang, with my '06 Switchback 600 and the weather in the mid 30's on Sunday, fairly loose snow conditions, I was still running between 170-190 degrees water temperature. Radiator was removed last year and I used a coupling to bypass the removed radiator, pretty straight forward. This sled should have plenty of cooling capacity with the tunnel cooler, running board coolers and rear heat exchanger.

After examing the plumbing and microfiche, I'm thinking that what is happening is that it is short-circuiting the cooling loop. Even with the thermostat open, the path of least resistance is to just keep on looping throug the bypass loop instead of pushing out through the boards and coolers.

I bought a new thermostat as well as some more nylon barb fittings, thinking that when I swap the t-stat, I'll remove the 1" coupling in the bypass loop and replace it with reducing fittings to creat a 3/4" orifice coupling. Am I nuts, or am I missing something here?? Thanks a lot!!
 
most of the bypass kits available use a restricted fitting for the radiator bypass for this very reason.
 
That's exactly what is happening. Your coolant is flowing through the bypass due to the path of least resistance.

AKRMK, there is no way the 600 should need more heat exchangers. The SLP kit on it probably doesn't have a restrictor of any type. Just install a reducer and see what happens.
 
Well, I just got the word back from a contact at Polaris Factory...

The 163 thermostat has a small bypass hole to allow some engine coolant to circulate on engine warmup. Using this part would be the best plan for removing the production bypass on the 600

Looks like the different thermostat is the best bet to do the radiator/cooler delete on the 600's and the 700's in 2006 thru 2008 small blocks.

Plug off the bypass line on the head under the thermostat housing and install the 2008 163" thermostat # 7052452, for the coolest running of these sleds without damage to the pump or seals. This will also eliminate quite a bit of heavy plumbing with coolant in it and clean up the underhood appearance a bit. Probably leave the "inspection" hatch off of the radiator accesss to allow any of the air that might make it thru into the engine bay where it might do some good.

As a note to those who dont speak "bypass"... This is the line that lets enough coolant flow thru the motor to keep the pump and other seals from blowing out and allow a bit of circulation inside of the motor once the thermostat closes.
 
my wifes 06 600rmk 144 has always ran at 170-190 deg, when the temps are mid 30's and it's 100% stock
 
I took out the bypass hose completely and ran a straight barbed fitting,how does is it damage the pump& seals? is it because of lack of coolant during warm up? thanks
 
I took out the bypass hose completely and ran a straight barbed fitting,how does is it damage the pump& seals? is it because of lack of coolant during warm up? thanks

It will damage it because theres nowhere for the coolant to flow thru when the T stat is closed and it will cavitate and build too much pressure.

I did a inline flow restictor out of delrin for a buddy of mine, just a rod rod with a 1/4 hole in it about 1.25" long.
 
Take out the bypass hose completely and pull the thermostat also. This will increase your flow rate, just make sure the coolers are all warm before taking off though in the morning. Your temps will go down, and run more consistantly. Thermostats are for those that don't know how to properly warm up their engines in the morning before riding.
 
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