Tri-Z - Radiator / Waterpump / Thermostat - Overheating Problems

[brandonlowe2]

So we went riding yesterday at Rockcrusher farms again for the second time. After about 2 hours of riding... the Tri-Z started overheating again (same place as it did the first time we rode there) My overheat light still doesn't work.. re-wired it, but, guess I need to replace the bulb too... anyway, the coolant starts boiling and pouring out of the overflow tube all over the ground (and I mean pouring alot)

Let it sit for a while and it cranked right back up and we rode for another hour or so... towards the end of the ride it cut off on me.... I knew it was time to put her up for the day.... only problem is I was at the top of the mountain. Got her back on and about half way down she cut off again. Let it sit for a few, then made it back to the truck.

Surely something is wrong and its not that I should just plan to ride only 2 hours at the time? Also, shouldn't that boiling water overflow into the overflow tank under the seat instead of out onto the ground?

What should I be looking for the fix or replace? I have 2 weeks until my next ride and want to make sure I won't run into this problem again.

[jonolanracin]

I would take water pump cover off and check to see if the impellar has come unpinned thats most likely problem.just take cover and see if impellar spins if so its broken

[brandonlowe2]

I would take water pump cover off and check to see if the impellar has come unpinned thats most likely problem.just take cover and see if impellar spins if so its broken

Ok, thank you. I did some looking... looks like the OEM impeller breaks quite often.... found an aftermarket billet one... good grief its expensive.... any chance the Banshee one is the same? Aftermarket billet for it looks identical and is half the price....

http://www.ebay.com/itm/Yamaha-Tri-Z-Sprock-Racing-Billet-Water-Pump-Impeller-/162283281188?hash=item25c8d65b24:g:EeYAAOSwB09YLKQ L&vxp=mtr

[dave ytz250s]

overheat light should turn on when you start the bike for about two seconds then turns off, like jonolanracing said, check the impeller and also check that the thermostat opens full

[El Camexican]

A few random thoughts…

- I wouldn’t think you would overheat an engine with a malfunctioning water pump because you rode it for 2 hours VS only 30 minutes. If there is a mechanical problem it should show itself in no more than 20 minutes of riding all other circumstances being the same.
- If you want to know if your temperature bulb is working park in a dark place and start the trike. The bulb will come on for a few seconds and then go out. If it doesn’t then it’s either burnt out of you have a wiring/sensor issue.
- The higher the elevation you are at the lower the temperature your coolant will boil at. That may be why it happened near the same spot as before.
- If you have coolant coming out of the cap and not going into the bottle you likely have a damaged seal on the cap and it’s allowing coolant to get past the seal rather than routing it into the tube that leads to the overflow tank.
- A weak spring in the cap will allow fluid to escape at a lower pressure level, you may want to go up a couple pounds, but not much more as you start to risk stressing gaskets and seals. Replacing the stocker would be my pick.
- It’s perfectly normal to flow coolant into the overflow bottle, that’s what it’s there for.
- If you want to know if the pump is working just open the rad cap and start the trike cold and let it sit. When it warms up you’ll see the fluid flowing. This indicates the pump and thermostat are working.Look for air bubbles as well, this could mean a head gasket leak which would add to the fluid pushing out issue.
- The plastic water pump impeller is molded to the steel shaft. It can crack and might slip on the shaft when it gets hot. I have seen cracked impeller first hand, but I don’t know if they ever slip because of it. Maybe someone else has seen one behave like that. You can still get a new one for about $30 bucks, or step up to the SS unit offered by Off-Road Innovations for about $100. There is a pin that holds the drive gear in place, I was not aware they also failed like the impellers, but if it did it would be a big problem.


“towards the end of the ride it cut off on me” “Got her back on and about half way down she cut off again. Let it sit for a few, then made it back to the truck.”

I don’t understand these comments. Are you saying it stalled, or seized, or just spit some fluid out? If it is stalling are you able to kick the engine over at that time, or is it locked up?

[jeswinehart]

I believe I have hears that if the pressed on stock impeller comes loose or other wise coming loose folks have drilled thru them and the shaft and pinned them fast.
If the plastic drive gear is shot (there may well be a reason why it is shot since they are made of plastic and made to give up in case something wads up) there are a few available on ebay. I don't think you can get them any longer at Yamaha (hope not or I would not have made the mold for my wife :) )
Lots of darn good suggestions so far ! several I would not have thought of.
http://www.ebay.com/itm/232163015361?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

[El Camexican]

I don't think you can get them any longer at Yamaha (hope not or I would not have made the mold for my wife :) )

http://www.boats.net/parts/search/Yamaha/All%20Terrain%20Vehicle/1985/TRI-Z%20-%20YTZ250N/WATER%20PUMP/parts.html

Yep, drive gear is obsolete, but the impellers are still available. Looks like the price has gone up a bit though.

[brandonlowe2]

I don’t understand these comments. Are you saying it stalled, or seized, or just spit some fluid out? If it is stalling are you able to kick the engine over at that time, or is it locked up?


Well i guess I would say it stalled out. It happened both times when I came almost to a stop, then started to accelerate again and there was no throttle power... started choking... almost like it was out of gas (and yes I checked both times and had well over half a tank left). Engine was not seized would turn over just fine ... took several kicks both times to get it started again however. Both times after it started it ran perfectly normal. The second time it happened was approximately one 10 minutes after the first. The first was approximately an hour after the "2 hour" mark where the coolant start s bubbling and pouring out on the ground (when that happened it did not cut off on me I cut it off to cool down)

The light bulb is definitely burnt out... or not wired correctly one because it does not come on at all when the trike starts

[El Camexican]

Do you recall if there was any white smoke coming out of the pipe when you would get it restarted?

[brandonlowe2]

Do you recall if there was any white smoke coming out of the pipe when you would get it restarted?

To be honest I don't recall. I was mostly worried about getting it going and getting back to the truck... I was 10 minutes down the trail and 16 minutes until park close lol....

What would white smoke mean?

[Scootertrash]

That you're burning antifreeze, possibly a blown head gasket.

[El Camexican]

To be honest I don't recall. I was mostly worried about getting it going and getting back to the truck... I was 10 minutes down the trail and 16 minutes until park close lol....

What would white smoke mean?

Like Scooter said.

My thought being that if the leak increases with heat (distorting the head as the heat builds up) that you could be loosing enough compression that the engine has almost no power and stalls out at some point. A leak like that could be pressurizing your coolant system with air and causing it to blow the rad cap open. If that's the case the stalled and therefore unpressurized cylinder would likely allow some of the pressurized coolant into the cylinder and that would appear as white smoke when you fire it up.

If it was my engine I'd at least remove the water pump and the head and find the problem(s) rather than speculate. If it's gotten so hot that it won't run you could have some internal damage. Assuming it hasn't been fully rebuilt recently your engine could be suffering from any combination of issues. Sounds like you enjoy some pretty long rides, so why take a chance.

[yaegerb]

x3, This sounds like a blown headgasket to me.

[3 Wheel Drive]

Id watch out for white smoke, thats often a sign of antifreeze leaking through the head gasket.

[brandonlowe2]

Sounds like I might need to just order a new head gasket and replace it this weekend to be safe... next weekend I am going to my family's farm and I have been looking forward to this ride since I got the Z. Will also check the impeller while I am in it.... then next weekend hope for the best and that it doesn't have the same problem