RZ/RD 350 & Misc. 2-Stroke Tech BBS

Took a ride to test my bike as the weather wasnt scorching. Coming from a stop and go traffic and getting a free flow highway for 20 minutes stop in front of my garage to put the bike inside, I noticed coolant dripping from the left side of the bike. Took the left side side cover on the overflow tank, bottle was full and pop the top of the bottle. I got an aluminum Radiator 4 years ago, a new thermostat and a new metal impeller from Economycycle. Could my thermostat gone bad in 4 years? Rad cap is the original Yamaha. Any ideas guys? Bike was hard to shift when really hot, never had a problem before the rebuild from Wicked. Hope he didnt take my impeller and toss it out, and replaced with some crappy one.

Mine did the same thing last year, Head gasket failed, I wasn't using an OEM head gasket, Cleaned up the head, bought an OEM gasket and it fixed my problem

Really? Head gasket failure? Better go to the Yamaha dealer see if I can buy one and replace it.

Hi:
If the temperature gauge was OK during the ride, it could be that you just stop the thing from everything super hot to no cooling at all, and the thermal inertia of the whole system expanded the refrigerant beyond the ability of the tank to contain. However, concerning is that the cap of the tank was popped; it could be the head gasket leaking combustion gas into the coolant chambers; not unusual. Way to be sure is to have a gas analyzer sniffing the radiator cap, as it should detect hydrocarbons right away. Another way is to observe if there are small bubbles reaching the top of the radiator at the cap location.

AlexG

Been there done that. Genuine Yamaha head gasket in your future.

redman412 wrote:Really? Head gasket failure? Better go to the Yamaha dealer see if I can buy one and replace it.

I would check a few items before plunging into the head gasket, Proper rated rad cap is a biggie, thermostat, impeller. Make sure it actually is circulating the coolant.
Mine went into the red before it puked the coolant.

im ordering a new thermostat and rad cap. Ill check the impeller as is brand new metal one from economy. What a PITA!!!

It's unlikely your impeller has failed.

The first thing I'd do is pull the clutch cover and make sure the plastic drive gear is still good and properly attached to the impeller shaft.

I have seen an impeller separate from the shaft on one of my old Banshees, I was using an aftermarket one, Id check it as well as the gear on the back as John recommends..

You're right Paul. Nothing is impossible. I've seen some bizarre things fail over the years.