Coolant loss?

[1vanvan1]

So, went for a ride out at woodhill today. Bike seems to be running well but I noticed a bit of coolant coming from the overflow drain pipe when I got home I checked the coolant level to see where it was at. It is just below where the top of the fins are.

I topped it up and am going to monitor it very closely but does anybody know the cause of this?

Any help would be fantastic.

[green machine]

So, went for a ride out at woodhill today. Bike seems to be running well but I noticed a bit of coolant coming from the overflow drain pipe when I got home I checked the coolant level to see where it was at. It is just below where the top of the fins are.

I topped it up and am going to monitor it very closely but does anybody know the cause of this?

Any help would be fantastic.

Were you stopped or going really slow,mx bikes need the air flowing through the radiators otherwise they are prone to a bit of overheating......quite normal as long as it is pouring out......

[unstuck]

Were you stopped or going really slow,mx bikes need the air flowing through the radiators otherwise they are prone to a bit of overheating......quite normal as long as it is pouring out......

Think he means NOT pouring out.Check for mud and crap in the radiator cooling fins too,could be causeing it to overheat a bit.:yes:

[1vanvan1]

I would say I probably lost about 200-300Mls over the period of 1 1/2 hrs. Wouldn't call it pouring out.


Were you stopped or going really slow,mx bikes need the air flowing through the radiators otherwise they are prone to a bit of overheating......quite normal as long as it is pouring out......

[green machine]

I would say I probably lost about 200-300Mls over the period of 1 1/2 hrs. Wouldn't call it pouring out.

200-300 mls is quite a bit(don't know if i'd call that normal).....i'm no expert but a few of my bikes have boiled over but never lost that much.....mmmm wait and see what a few of the other guys say

[1vanvan1]

Yeah, definately more than normal. Thanks for your input though.


200-300 mls is quite a bit(don't know if i'd call that normal).....i'm now expert but a few of my bikes have boiled over but never lost that much.....mmmm wait and see what a few of the other guys say

[noobi]

Dont worry about it, all 4 stroke mx bikes do that, they dont do well with minimal air flow, they will boil over slightly just sitting still idling for to long. Get an overflow catch tank, it works in a vacuum and sucks the coolant back in when the bike cools down some http://www.mrmotorcycles.co.nz/product_info.php?products_id=1458

[CRF119]

Noobi is onto it, the bikes used in slow trail riding have the over flow catch can so when the water heats and expans is goes into the over flow tank. When it cools again the water in the radiator shinks back down causing a vacuum and sucking all the water that is in the catch can back into the radiator the same setup as a car.

Mx race bikes don't have this they just push out the water they don't need so after a race or a ride your water level when cooled should still be above the fins inside the radiator. My water level is at about 5mm above the fins (10mm below top of cap) in the radiator and has been like that for about 40 hours of riding Of course at running temp the radiator is full because of the water expansion.

[green machine]

Noobi is onto it, the bikes used in slow trail riding have the over flow catch can so when the water heats and expans is goes into the over flow tank. When it cools again the water in the radiator shinks back down causing a vacuum and sucking all the water that is in the catch can back into the radiator the same setup as a car.

Mx race bikes don't have this they just push out the water they don't need so after a race or a ride your water level when cooled should still be above the fins inside the radiator. My water level is at about 5mm above the fins (10mm below top of cap) in the radiator and has been like that for about 40 hours of riding Of course at running temp the radiator is full because of the water expansion.

It's true what you and Noobi say but the fact he lost 200-300mls?,my radiators hold i litre so that nearly a third of the fluid gone....as i said some of my bikes have boiled but never lost that much....

[CRF119]

I guess what he needs to do is fill the radiator do a ride and see where the standard level should be id say you would need to add 100mls to mine to make it full again. In fact ill go try it back in a sec.

[Blackbuell]

Yamaha's dont normally have this problem !!!!!!!

[1vanvan1]

Yamaha's dont normally have this problem !!!!!!!

Shhhhhh, you.

[1vanvan1]

It's true what you and Noobi say but the fact he lost 200-300mls?,my radiators hold i litre so that nearly a third of the fluid gone....as i said some of my bikes have boiled but never lost that much....

Yeah, The book i have says 20-60 cubic cm loss is normal, and it only holds a litre.

I put 150MLs back into it to fill it to the top level. But then i figured it wouldnt run through to the other side so I doubled that firgure to get an approximate of 300MLs

[CRF119]

Ok so this is on a 2008 CRF450 bike temp last time i raced i think got to 80 before the start because we had to wait for something at the gate. Typical temp is 60-80 degrees.

So just went and filled my radiator back up which i never do because it will just spit it back out and i put 160mls of water back in. First i measured from the lower seat of the radiator cap which is what you fill it up to and i measured 23mm down to the water level at room temp.

So i guess you need to do the same to your CRF250 (Probably the same radiators). Don't guess what comes out that over flow because it looks like heaps but really you can lose quite a bit from it and think its lots but it not. If it boils you wont see water just lots of steam ive done this 3 times.

Let us know how you are getting on. If it is anything more then 160mls then id say you may have a rooted radiator cap. Or it might be coming out the water pump seal a mates bike has rooted 2 of those (08 YZF450) or you might just have a serious over heating issue which would be strange but i wouldn't rule it out yet

[CRF119]

Don't double it, it has a balancer pipe and its just water level it will level it self out. I rocked my bike to the left to make sure the other side was full when i did my calculation so if you do the same the we are on the same page.

[1vanvan1]

Sweet, that better knowing it was only 100-150mls low.

I am going to get one of those race temp sticker things you can stick on the side of your bike to check the temp. Just to give me a bit more piece of mind.


Don't double it, it has a balancer pipe and its just water level it will level it self out. I rocked my bike to the left to make sure the other side was full when i did my calculation so if you do the same the we are on the same page.

[CRF119]

Just double check it next time. You can also buy Thermocaps. I use one very handy. Motor bike shops sell them. You can view the temp as you ride. (Providing you can see your radiator cap

http://www.jegs.com/webapp/wcs/stores/servlet/ProductDisplayPopup?storeId=10001&catalogId=10002&productId=874786&itemId=870880&langId=-1&showValue=1

[cambocambo]

are you sure that you didnt have any air bubbles in the radiator when you filled it originally and riding the bike has shaken them out? small possibility but worth a check.

[ktm84mxc]

Yep its a common problem with MX bikes in the forest, MR Motorcycles does a catch tank to trap the coolant to help cure this problem.
KTM also do an electric Fan system also, You may look at a higher rated radiator cap also.

[socialites]

Yep its a common problem with MX bikes in the forest, MR Motorcycles does a catch tank to trap the coolant to help cure this problem.
KTM also do an electric Fan system also, You may look at a higher rated radiator cap also.

All of the above is true, however, although the catch tank at MRMOTORCYCLES is a good piece of work, it only holds 60ml and the pressure that the radiator blows out at normally blows those 60ml straight out of the overflow thus leaving very little to recycle. I tried it on my crf450r but did not work, I have since fitted an overflow bottle that I sourced from a scrap yard and it looks and fits factory.

[Jay GTI]

Don't double it, it has a balancer pipe and its just water level it will level it self out. I rocked my bike to the left to make sure the other side was full when i did my calculation so if you do the same the we are on the same page.

Yeah they will even out, so what goes in is what is required. To be double sure, just start the bike after topping up, run it for a couple of seconds and check the coolant level again to make sure no air was trapped in the system.

[CRF119]

Catch can idea is great but on a CRF you have a hollow frame if you are cleaver you could use one frame spar for a catch can and run a clear tube up the side for level indicator :) In the states ive seen guys using there spars for extra fuel.

[Edbear]

Don't lose your cool! Makes your bike hot stuff! :yes:

[1vanvan1]

Just double check it next time. You can also buy Thermocaps. I use one very handy. Motor bike shops sell them. You can view the temp as you ride. (Providing you can see your radiator cap

http://www.jegs.com/webapp/wcs/stores/servlet/ProductDisplayPopup?storeId=10001&catalogId=10002&productId=874786&itemId=870880&langId=-1&showValue=1


Borrowed a radiator cap from another bike for the day today. Didn't lose any coolant. So I presume it it the radiator cap. So going to buy a new one :D

[KCOW]

I wldn't be to concerned as my CRF looses abit after I fill the radiator. Good anti freeze is the go and my old man nakes sure dat he uses a anti freeze dat is gd for ali radiators.
Not da same as a car anti freeze.