Nytro Coolant boiling over

[furg69]

Looking for some help for a friends 2009 Nytro RTX. after just a few minute of riding it runs hot and boils over. we have checked thermostat and replaced it, checked the system for flow and circulation,rads are getting hot and moving coolant (not sure how well) , also did proper system check for trapped air 4 or 5 times. Im stumped. maybe a poor water pump ?

 

[devilnabludress]

take the rad cap off and start it. Does the coolant bubble or nicely circulate? Could also be a bad rad cap, pressure drops in the system lowering the boiling point. Swap it out with another one to try.

 

[mikextx]

Is coolant circulating through all of the heat exchangers? You should be able to tell by feeling them

 

[furg69]

its circulates smoothly then bubbles shortly after, all the rads are getting warm so coolant is doing the full loop, pump turns perfect as well that was checked

 

[Mooseman]

Fan working?

 

[furg69]

Yeah fan is working perfect.

 

[furg69]

as there is no oil in the coolant or coolant in the oil cannister. so its hard to suspect engine damage

 

[furg69]

been doing some reading and found that ALOT of people have head gasket issues but this sled is bone stock no turbo or anything

 

[mikextx]

Seems like it would be loosing coolant if it were a head gasket?

 

[mp5]

Hoist/lift front of sled up off ground a few fewt. Take off rad cap, run engine until fan comes on. If coolant falls well below top of fins, add coolant. You may have air bubbles trapped in system and need to burp them out. This should help release any bubbles up and out.

 

[furg69]

Thanks Mp5 good info. but unfortunately we have did this multiple times

 

[grizztracks]

The majority of the time if it's pushing coolant out the over flow the head gasket is more than likely bad and the head possibly warped. If you replace the head gasket have the head resurfaced just to make sure it's true. I've done several of these head gaskets and the normal failure mode is that the engine compression pushes into the cooling ports and causes it to lose fluid. A head gasket issue on these engines usually is a result of running the engine hot at one point. Also poorly maintained coolant can cause problems. Yamaha recommends changing the coolant yearly which I think is a little excessive so I try to do it every other year.

 

[furg69]

Thanks grizz that's going to be the next step if theres nothing else to check. also I should add that it does run and sound great but still indicates its running hot on the Pod.

 

[grizztracks]

When this happens the engine usually still runs fine. The compression drop is so small that it doesn't affect performance enough to be detected. If you look carefully in the radiator when it's hot you can see very fine bubbles which indicate that the head is leaking. Unfortunately this has been way to common with the Nytro and I believe a result of inadequate cooling capacity.

 

[radianguy]

Furg check my post from a few seasons ago.

https://ty4stroke.com/threads/rad-blowing-off-coolant.144681/