Do not remove your thermostat ....

Mac

Mac

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News breaker report!!! About a month or so ago we had a discussion about removing the thermostat to reduce the engine temperature. http://www.totallyamaha.net/forums/showthread.php?t=56193&page=2&pp=10
I tested this theory and removed my thermostat plugged the bypass and lost a piston in about 5 minutes. It stuffed a ring on the exhaust side but the cylinder was ok. When I opened the motor all three pistons were overheated. My digital temp gauge did not even read high temp. The coolant flows so fast the coolant does not remove any heat. I took one for the team here guys so do not remove your thermostat. ---Mac---
 
didn't some of the mid 90s Vmax's have coolant running continuously? I seem to remember they fouled plugs because they took longer to warm up.
 
Red head tripples or the '97-'01 twins didn't have a stat factory.wonder why they don't have problems.

just the big mills(viper,SRX,v-4)had them.
 
Daman - Some of the engines that don't have thermostats may have another limiting factor to slow down the coolant like smaller hoses or fittings. I should have known better and in the previous thread I questioned the speed of the coolant as a potential cause for a problem. In the article's Buffalo Bob referenced they make for a good argument that this could be successful. I had a piston on the shelf and put everything back together with the thermostat reinstalled without doing anything else. Sleds runs great.
 
its not about the thermostat being in it, its about what it does. in these two motors and in all the four strokes, the stat controls a fast warm up cycle when closed, rerouting the fluid through the motor only, when it warms up, it opens up the heat exchangers to the flow of the coolant. if it is removed, coolant will take the path of least resistance and just go around the warm up loop. sorry i didnt see this post before to warn anyone. the vmax sleds do not have this warm up feature and dont run a stat, that is why they take for ever to warm up and can cold seize easier.
 
right you would want a fast warm up IMO,yamaha should have kep the thermos in all if ya ask me..there's nothing different looking to me from the
red head WO to the vipe/srx with,if one needs to warm up all should need.
unless..the bigger coolers(more coolant)is what comes into play.with
the srx and vip/v-4.but then the older sleds'96 down had them,dunno..
 
BETHEVIPER - I plugged the bypass and still overheated. The speed of the coolant must be controlled to remove heat.
 
Yeah, some have and some don't. Point is the sled was designed around it being there or not. Back in my stock car days when a guy blew a stat (stuck closed) track side we'd pull the stat and cut it so we could get the plunger out, but we'd put as much of the housing back in as possible to restrict the coolant flow.

And Tony, if you are doing 660 and shutting down you probably don't even need coolant in it technically. It's basically a drag car in that distance.
 
i have a few muscle cars with radical engines and if you try to run em with a low temp stat or no stat the fluid never stays in the radiator long enough to cool down and runs hotter than a high temp stat, this is why when you do chip mods to fuel injected car you get a higher temp stat
 
Did you totally block off the bypass loop?? I was specifically warned not to do that as the water pump would tend to cavitate... I have removed the t-stat and restricted the bypass flow line leaving a 3/16 hole in the bypass loop.. Temps dropped and no problems.. Warm up time has increased but that is minor..
 
ottawaair said:
sleds w/o stat must have in-line restrictors built in & possibly a lower volume water pump.
Click to expand...
one thing i do notice on model's WO is that the coolant out put flow (thermostat)hose is smaller(1/2 reduced) on the other side of the fill hole(rad cap)VS the front side that clamps onto the thermo housing neck,that there would be a good restriction.

scan0001-8-1.png
 
Removing the thermostat does not speed up the coolant flow in any way. The thermostat is only there to help build water temperature quickly. When closed, it is a closed loop that only flows coolant through the motor, to the coolant bottle, and back to the motor. When opened, it allows coolant to flow to the heat exhangers, but also allows coolant to get back to the bottle. The coolant hoses that run from the thermostat to the bottle are smaller so that more of the coolant is forced to travel through the heat exhangers to cool down. However, there is too much coolant travelling through this smaller hose, which results in warm coolant right out of the motor to travel to the bottle, and back to the motor, causing higher water temperatures. You can help to force more coolant through the heat exhangers by installing a plug into that smaller line that goes to the bottle, but that plug must be drilled out to allow some coolant flow. Jabber is right by stating that if you block off the return line (line from the thermostat to the coolant bottle), you will likely cavitate the water pump. The problem with doing this is that is takes quite a bit longer for the coolant to heat up to sufficient operating temperatures since it has to travel through the heat exhangers at all times. You must be more patient in letting the snowmobile warm up, or it will result in cold seizures. I do not run a thermostat in my trail 780, and without it and limiting the coolant flow to the bottle, it runs approx. 20-30 degrees colder at all times.

So, removing the thermostat does not increase temperature whatsoever. Simply removing it and doing nothing additionally will only slow down the temperature buildup, but will not change the overall operationg temperature. Removing the thremostat, and restricting (not blocking) the return line to the bottle will force coolant through the exhangers, and the end result will be a colder running motor.
 
valin said:
Jabber is right by stating that if you block off the return line (line from the thermostat to the coolant bottle), you will likely cavitate the water pump.
Click to expand...

But the redheads only have two big hoses going to the tank. What's different so the pump don't cavitate?
 
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