daman
New member
A stat from a '96 vm may work thos where the shorter style..
Mac
Member
Overheating
Last weekend I had overheating problems as well. Never had trouble before with bleeding the system. Over the years I've bled Viper systems 10-12 times so I'm sure on how to do it correctly. I've tried two thermostats and even put one in 150 degree water on the stove and it worked perfect. It won't open in the machine. The water in the overflow is completly still. Today I pulled the thermostat and reassembled after blocking the bypass. The water swirls around like a torrent in the overflow. Anyone have reasons as to why I cannot run without the thermostat please chime in. My 780 runs hot anyway and I'm gonna see how long it takes to warm up on a 20 degree morning.
Last weekend I had overheating problems as well. Never had trouble before with bleeding the system. Over the years I've bled Viper systems 10-12 times so I'm sure on how to do it correctly. I've tried two thermostats and even put one in 150 degree water on the stove and it worked perfect. It won't open in the machine. The water in the overflow is completly still. Today I pulled the thermostat and reassembled after blocking the bypass. The water swirls around like a torrent in the overflow. Anyone have reasons as to why I cannot run without the thermostat please chime in. My 780 runs hot anyway and I'm gonna see how long it takes to warm up on a 20 degree morning.
SNOWRULES
New member
well broke down today and picked up all the parts to redo the impeller shaft and seals. this included new shaft (and on the new shaft it is all one piece the gear is not pressed on), new oil seal, new mechanical seal and both end bearings. i figure with 12500 kms on the sled it is due anyways. plus this will eliminate one more thing that could be causing my overheating problem. also picked up a brand new thrmostat. so after all this if it overheats and cooks another thermostat i'm gonna be really pissed. can i put the new parts in minus the stat bleed it and test it first? cause someone told me that everytime it overheats the stat will go, that this is how it is designed.
I dont see why not, I would at least leave the old broken stat in there for some type of restriction, as if you run none, it might overheat as the fluid moves too fast thru exchangers to dissapate the heat, just like what happens in a car.
SNOWRULES
New member
thanks mrviper that's what i figured too. that's why i couldn't figure out why it kept overheating before when i just put the broken stat housing in. but i guess it was because i had bigger problems than that. hopefully it'll all be good after these new parts go in. only thing left i can think of.
Mac
Member
Cooling capacity
So if I understand correctly the speed of the circulation won't add to the cooling capacity. We have several piped Vipers in our group and when I look into the reservoir the water is never moving fast in fact hardly moving at all. Don your thinking nothing can be gained by increasing water velocity.
So if I understand correctly the speed of the circulation won't add to the cooling capacity. We have several piped Vipers in our group and when I look into the reservoir the water is never moving fast in fact hardly moving at all. Don your thinking nothing can be gained by increasing water velocity.
usually not, by removing the thermostat in a car the coolant will flow so fast it doesnt have time to transfer heat efficiently, thats why alot of car will overheat worse without a thermostat then a stuck open one, at least with the stuck open one it restricts the flow somewhat and slows down the coolant.
There was gains in cars with high flow thermostat housings, they basicly had a couple extra holes on the outside edge to let a little coolant pass all the time, this helps eliminate the cold surge the engine sees when the thermostat opens. There is a limit to which the coolant speed must be controlled at in which to disapate heat/heat transfer to the coolant exchangers.
As we talked about before, I believe the addition of a small dirt bike radiator would yield positive results in your big bore engine.
There was gains in cars with high flow thermostat housings, they basicly had a couple extra holes on the outside edge to let a little coolant pass all the time, this helps eliminate the cold surge the engine sees when the thermostat opens. There is a limit to which the coolant speed must be controlled at in which to disapate heat/heat transfer to the coolant exchangers.
As we talked about before, I believe the addition of a small dirt bike radiator would yield positive results in your big bore engine.
Last edited:
Mac
Member
Air cooled Viper
Here is a radiator purchased on ebay for $60.00 week ago. It was previously used on a racing go cart cooling a CR250 motor. It will fit near the chaincase and I plan to cut the belly pan and use louvers like a dirtbike to pull in the air. So Don you think reinstall the thermostat and drill small holes in the outer edge to flow more coolant? I need to fabricate a frame to hold the radiator and make it rubber mounted. I'm shooting for 135-140 degrees
Here is a radiator purchased on ebay for $60.00 week ago. It was previously used on a racing go cart cooling a CR250 motor. It will fit near the chaincase and I plan to cut the belly pan and use louvers like a dirtbike to pull in the air. So Don you think reinstall the thermostat and drill small holes in the outer edge to flow more coolant? I need to fabricate a frame to hold the radiator and make it rubber mounted. I'm shooting for 135-140 degrees
Attachments
Wow, thats a whopper, it should work GREAT!!
you can drill 3 holes like a 1/8" diameter in outer ring,this will move some coolant even at idle thru the stat and it also makes it much simpler to bleed the system of air this way.
you can drill 3 holes like a 1/8" diameter in outer ring,this will move some coolant even at idle thru the stat and it also makes it much simpler to bleed the system of air this way.
daman
New member
Here's a couple pics of my drilled 'stat outa my supercharged Bonneville
that i did,it would be the same principle for a sled stat.
drilling the 'stat allows bypass flow during early stages of the warm up and extra cooling and also helps to keep from trapping air in the system after a coolant change.
the only thing i'd be worried about on a sled is warm up time and cold
seizure...because that small amount of coolant circulating would delay
warm up i think..
a 1/16 hole(drill) is about all you need..1 or 2 holes no more
Pic #1
Pic #2
that i did,it would be the same principle for a sled stat.
drilling the 'stat allows bypass flow during early stages of the warm up and extra cooling and also helps to keep from trapping air in the system after a coolant change.
the only thing i'd be worried about on a sled is warm up time and cold
seizure...because that small amount of coolant circulating would delay
warm up i think..
a 1/16 hole(drill) is about all you need..1 or 2 holes no more
Pic #1
Pic #2
SNOWRULES
New member
well guys i finally found the problem on my sled. you guys were right the gear on the crank itself was spinning. all i did was put a little bit of heat to it with a propane torch and it spun like butter. i couldn't beleive how easy it spun with about 5 seconds of heat just on one side of the gear even. this is why when i warmed it up from cold in the basement i had flow because i guess it wasn't warm yet then when i took it out it got hot and would spin. thanks for all your guys help and input. too bad now i have to find a new crank or get it rebuilt. does anyone know if i can use my same shaft and just get a new brass gear pressed on? or would the spinning have taken enough material off that a new one will be prone to spinning again? is there a fix for this? like a steel gear instead of brass seems to me a brass gear would heat up quicker and spin easier. if anyone knows if theres an update for this let me know. thanks
daman
New member
what holds that grear on,just pressed?
SNOWRULES
New member
ya just pressed. dunno why they didn't design it with a keyway, would solve the issue i'm having right now.
trapow33
New member
Did your sled shut off at all? I had temp light problems as well this weekend and it actually shut off my machine (several times) but it was not overheating. How do you know what temp it's reading? I have a post on temp sensor, if you can read it and let me know if yours was behaving the same way. thanks!