Dark Coolant

The coolant in my 03 WR450's catch bottle is murky brownish. Doesn't necessarily smell like oil though. The bike has 1500 miles on it. I've been doing mainly street riding and its been hot here. If I heat the coolant too high does it change color? There are no signs of forced entry of dirt to the system.

Any thoughts?

two thoughts come to mind - mud or rust....

Mud should settle out to the bottom over time - has to sit though..

Rust - not sure where it would come from......

if it was Oil, it should separate out to the top...

Mud is the most likely - do any riding in mud lately - could get into the overflow bottle if the lid was loose.

Have you checked your color at the rad?

Last 500 miles have been in town. If its oil, where would it be coming from?

old coolant changes color also

The only 2 places oil might come in is:

The water pump area, if your seal on the oil side is gone, and the coolant side seal is wearing...should be getting an oil drip at the weep hole though.

Second place is on the cylinder head gasket - but in most instances - because of the pressure difference, coolant goes into the oil, not vise versa....

Could also be a cracked right side case cover, but doubt it....

I would drain and change the coolant, see if it comes back. At the same time, do your oil and look for signs of coolant in it - if there are no signs, you're likely ok, but keep an eye on it.

It's likely sediment from corrosion of the steel parts in the cooling system. If the coolant has been diluted with water over time the corrosion inhibitors quit working and you will begin to see this.

Do you know what type of coolant it is, and has it been in there since 03'?

It's likely sediment from corrosion of the steel parts in the cooling system. If the coolant has been diluted with water over time the corrosion inhibitors quit working and you will begin to see this.

Do you know what type of coolant it is, and has it been in there since 03'?

Coolant is original. I figured that the miles were low, so changing it wasn't necessary. But I guess its 5 years old, so time to change. Do I get it from Yamaha?

local bike shop.

Engine Ice...

local bike shop.

Engine Ice...

+1, Engine Ice is a good coolant for these bikes, it has a good corrosion inhibitor in it and is environmentally friendly :)

I wonder if it does not make sense to try and flush the system with a product you dump in, circulate for a while and drain:confused:

I wonder if it does not make sense to try and flush the system with a product you dump in, circulate for a while and drain:confused:

If my coolant system was a funny color I would definitely flush it out.

I change mine once a year. But I am a maintenance freak. I re-grease everything just about twice a year.

Nice to catch those odd loose bolts before they fall off. yes I use locktight...

Coolant should be changed (ideally) every two years at least. Same time, change your brake fluid. I do these at least once a year.

LOL, at five years, I would expect it to be datk!

I would flush the system with some boiled water several times before putting in the engine ice.

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