Coolent overflow

[studwand]

I just changed oil in my 2005 yz250f. I was running yamalube 15w-50 and just put some 10w-30 in it. I noticed while riding today that antifreeze was coming from the overflow hose. Is this caused from the lighter weight oil? (temperature was around 75 degrees F today)

 

[rmc_olderthandirt]

The oil would not have a direct effect on the cooling system.

If your cooling system is puking water then you have a significant problem.

Best case is that the radiator cap has failed and is not holding pressure. Make sure you have it on tight, and that it isn't damaged. Perhaps you can borrow one from someone else to see if it is the cap or something else.

If the cap holds pressure then it means that something is causing the pressure in the cooling system to go up above the release point of the cap. The two likely scenarios for this are:
1) Head gasket leak that is allowing cylinder pressure to leak into the cooling system.
2) Something is causing the bike to overheat.

Lots of reasons why it might be simply overheating. Radiator could be damaged, pinching off enough of the tubes such that you just weren't getting enough cooling.

Dirt or other debris blocking the radiator

Water pump has failed

Engine failure of some sort that makes it run really hot (too lean, timing off, valves badly adjusted, etc.)

You are simply riding it too slow and lugging the engine.


Rod

 

[studwand]

Well i was riding it up and down my street really slow so hopefully thats all that was wrong. It was just a few drops coming from the overflow.

 

[rmc_olderthandirt]

Well i was riding it up and down my street really slow so hopefully thats all that was wrong. It was just a few drops coming from the overflow.

that doesn't sound right.

What I meant by riding slow would be like riding slowly in soft dirt or sand. The engine has to work hard but you aren't moving fast enough to keep the air flow through the radiator.

You would have to be seriously lugging the engine to overheat it on a paved road. If you were stuck in rush hour traffic you might over heat it but just taking it for a slow ride up and down the street shouldn't.

Try this: take the radiator cap off and start the pike. Look down into the radiator. When the engine is still reasonably cool, do you see bubbles coming out of the coolant? Bubbles would indicate a head gasket leak.

Rod

 

[youngnbald]

you can "overheat" for just idle on the driveway. I had this happen also and didn't know. I now have an overflow system on my crf450R. If anything comes out now, its captured and sucked back into the system when it cools again. I do trail riding and temp rises from going slow.
I have a Trail Tech Vapor on my bike and highly recommend it.
http://trailtech.net/vapor.html
look at post or search for coolant overflow or turkey baster. To prove what I am saying, start your bike and let it idle on and heat up on the concrete. If you had your radiators all the way full when you shut it down the bike will spew a small amount.

 

[youngnbald]

Coolant Overflow Turkey baster trick

Ok, here are pictures. On the left side of bike is my overflow.
Walmart in automotive section look for "The Mixmizer". It was to be used as a syringe to mix different levels of oil/gas.
At Lowes I walked around the plumbing department and bought (I think) a 1/2" PVC cap and something with the 90 degree elbow that a hose will slip on. Also bought clear hose, can't remember the diameter.
Route the new hose from the radiator overflow hole to the bottom of the "Mixmizer". I cut the tip of the Miximizer until the hole is larger and the hose will slip on it. On the top, I threaded the 90 elbow in the PVC cap and insert the cap into the Mixmizer. The red in the pictures is the RTV sealant I used to seal the cap and hose together. I think I did superglue also on top to be sure it stays. All you're doing is creating a capture for the spew. A hole in the top gives a vent. When the engine cools down, it sucks back into the system. Same thing done your car or truck. This is what I invented and cost MAYBE $12.

 

[youngnbald]

I can't get the pictures to work due to file size. Email youngnbald@hotmail.com if you want more. Be sure in subject line you state coolant overflow so I find you in the spam folder.

 

[jb_dallas]

I had an overheating issue with my YZ400F. The radiator cap spring seemed weak to me, so I bought a high pressure cap ($20, label says "outlaw") and filled it with water wetter and distilled water. The only time it will overheat is riding in 100 degree weather or slow trail riding (which it really isnt designed for)...I would say that is normal. I also have a Trailtech Vapor and it is the best piece of mind you can own...it displays digital temperature.

 

[youngnbald]

Just ran the weekend with 95 degree weather. Even on the track and not a high temp issue I came back to the vehicle to rest and the overflow caught anti-freeze. After my rest, I looked at it again and the level was gone and pulled back into the system. My temp held 160-170 on the track.
The Vapor is a perfect, feel better add on!!!!! So much information and knowledge gained.