08 m8 overheating. what direction does coolant flow?

[bartonls]

Hey guys,
So I have an 08 m8 and the previous owner took the thermostat out for some reason... So I put one in. I burped the system properly (so i think) by using a engine hoist to lift the front of the sled up in the air so it was above the heat exchangers, then filled the coolant bottle slowly (while shaking the sled a little). After letting it sit and shaking and filling until it was full i pulled the sled a few times and made sure the coolant was totally full. I lowered the sled and started it up, let it get warm, then turned it off and checked coolant level. I didn't need to add any.

Then I started it up and it didn't seem like the coolant was flowing. The heat exchangers didn't get too warm. So not wanting to hurt anything I drained the coolant and re-burped it using the same method as above. Once it was full I started it up again and still didn't think the coolant was flowing. So I took it for a spin around the house because we got about 12 inches of snow.

The heat exchanger got a little warm... but not hot.. but an infrared reading of the head got up to 220 and while idleing it boiled over and spewed antifreeze out the overflow.

So I figured it must be something else like the water pump or thermostat is bad. I pulled the whole engine out again and tested the thermostat and it is good. Then checked the impeller in the water pump and it is also good and the shaft is good since it spins when i slowly turn the engine.

The question I have is what way does the water pump supposed to turn and what side of the engine does the coolant flow out of? the impeller spins counter clockwise which seems opposite to me as the fins hook to the right (look at picture below). Does it pump water from reservoir through thermostat into water pump, up to head, and down through the engine and out the right side? If so the impeller sort of makes sense but it seems like an inefficient method to pump water.

If that is correct, and nothing is wrong with the pump, what else could it be? the small hose on the back of the water pump was a little bent, i'm not sure the purpose of it since it goes from water pump back to water pump, so maybe that?

I also read that if the head is warped air can enter the cooling system and cause the engine to overheat and boil over, but why then is the heat exchangers still not warm?

It seems like there is just air in the system but I burped it many times to make sure and I don't know how else to test it.

Engine is currently out of the sled. sorry for the novel I am just trying to give everyone a complete description so I eliminate suggestions I have already tried.

Thanks in advance,
Landon

 

[Daltech]

You are correct. Water flows from pump, up to the cylinder head, and then down true the cylinders crank case and out. Called "reverse" flow cooling system. It works really good.
I would take of cylinder head and check head O-rings. Seems like you have a compression leak from combustion to cooling system.
There should be cooling lines going under the engine to the trottlebodies. Maybe that whats looped?

 

[bartonls]

Thanks Daltech for the reply!
So that does make sense it would flow that way. But to me it seems like that is going to pump coolant very inefficient because the fins are just 'flinging' coolant up to the head and not using the fins to grab and pull the water through the engine like if the impeller spun clockwise not counter-clockwise. But thats just me.

So I took the head off, O-rings look fine but I might as well order some in (too bad it takes a couple weeks to get them). If this was the cause, would coolant not flow to the heat exchangers? because they were not hot and were barely even warm if you could call it warm (felt cold) but not freezing like all the other metal on the sled. That is why I thought it may not be circulating.

Also the small tubes from the water pump do not go to the throttle bodies like they should on my set up (it is just looped back on itself). So since the circuit is still being connected it shouldn't make a difference to water pumping correct? even if the line was pinched?

Thanks for anyone that helps! I really appreciate it!

 

[strong]

They can be a pain in the butt to get all the air out of the system. boiling over is normal, just try not to run them hot for very long, the sled will pretty much take care of its self, warning light, safe mode and what not will kick in, but about the easiest way to get the air out is to run it. check it often. the faster you run the engine the faster the air comes out, once the thermostat opens.

if the motor is out, and you have a hoist fill the lines before you put the motor back in, may help.

 

[oldcrow]

Centrifugal pump impeller 'flings' the liquid away to the outlet. It does not 'cup' or scoop the liquid.
Water is always circulating inside the engine till the engine comes up to temp the thermostat opens allowing cooled water from the exchangers to enter the engine.
Something to check, I see water is no longer run to the throttle bodies. They could have had an orifice restricting the amount of flow thru them. I would look into blocking off that loop if your not going to run coolant thru the throttle bodies.
The pump will only pump so much and it's going to take the path of least resistance.

 

[bartonls]

thanks strong and oldcrow!
Strong, I do not have any gauges hooked up and the ecu was programmed by the arctic cat race team so I am not sure it would shut itself down if it go too hot.. but I agree that there may have been some air in the lines despite my best efforts.
Oldcrow that is a good idea, I should cap off both ends and see if it improves circulation. After I get it all together it will be impossible to determine what the real cause was but oh well as long as it works I am happy.
Thanks a lot!

speedwerx built the engine so I was thinking maybe they did something so it runs without a thermostat. Maybe not, but I'll give them a call and see what they say.

 

[bartonls]

Lesson learned. Should have called speedwerx from the start. Apparently back in behind the thermostat they tap and plug a hole where coolant flows from the bottom end to the thermostat so the coolant warms the thermostat so it opens. Well if you remove the thermostat there is nothing to block this hole so coolant can backflow. So they tap the hole and plug it off. So me not being familiar with thermostats put a thermostat in without removing the small plug. So apparently the thermostat was never opening in the first pace, and that is why coolant was barely circulating, hence that is why the heat exchangers never got hot and why it overheated...

Thanks everyone for there help. And if anyone has an engine built by speedwerx and they took the thermostat out and you want one back in, remove the plug before installing the thermostat and having to install and pull your engine out 3 times!

I won't be able to test it out to see if it works until the 16th but I will post when I figure it out. But it should work

 

[bartonls]

darn

So the sled worked awesome this weekend, water temp was normal, good flow etc. until... I noticed that the coolant level was down a little, so I refilled it. about 10 miles later of boondocking, I noticed my water temp gauge was up to 150 degrees so I shut her down. Coolant was leaking out of the bottom like crazy. Had my dad pull me back with his supercharged apex. SO I HAD TO PULL MY ENGINE AGAIN!!! found out it was the mechanical seal on the water pump shaft, the coolant was leaking out of the weep hole.

IF YOU HAVE TO PULL YOUR ENGINE, ALWAYS REPLACE EVERYTHING THAT COULD WEAR OUT! Do not be cheap like me and just replace things that you need at the time, I should have replaced the mechanical seal when I had the water pump cover off the first time! I just didn't want to spend the $25. Now I am stuck waiting another week until the parts come in. Lesson learned.

I also have to replace the lower gusset... so that is a big PITA