CRF's Only Forums

I am working on my 450 and I have already made some modifications to make it run cooler for trail use. I added a radiator fan and put in Engine Ice. I rode on a day that was in the 80s and it seemed to do really well, didn't get too hot. I just rode a couple weeks ago and it was much much cooler weather, infact there was ice/snow in the area we rode, temps between 40-50 degrees. We also rode about 5 miles on the street. I noticed that the temps were always much higher than my last ride, even when riding higher speeds on the road or in very cold areas. It was driving me crazy trying to figure it out. Well, I bought some larger radiators (along with some other goodies). I went to install the rads and drained the coolant and to my surprise, there was BARELY any coolant in there.

I know I checked it after my last ride, so I am not sure what happened. I also don't think it "boiled" out as I have an overflow bottle and don't remember seeing it fill up and I don't remember any boiling of steaming (I am always paying attention to the bike). I also know that it didn't leak any coolant before the ride, because it is in my clean garage and there is nothing on the floor or anywhere.

I had always thought that you would see fluid coming out the weep hole if there was a leak. After doing some research, it sounds like when the seals first start to go bad, it ONLY leaks out the hole when it is warm. In other words, it would leak as I am riding but as it is sitting in my garage there is no leaking.

Since I am already installing new radiators and hoses, after those are installed and I double check and make sure everything is sealed, would my next course of action be to install a water pump seal kit? Honestly, if I run the bike just to see if it leaks coolant again, I don't think I want to risk damage to my bike. I am kind of leaning towards just replacing all the seals/gasket and the bearing just to be safe. Is this most likely the best course of action?

The trouble with waterpump seals they can leak either out the weep hole or into the transmission.

Check there first.

You really need to do a pressure test on the cooling system both hot and cold states.

Did you note the volume you put in as you may have had an airlock which means the fluid wasn't there in the first place even if you saw it at the cap.

As Ray stated. You can have either the inner or outer seal fail on the water pump. The inner lets the coolant into the transmission, the outer out the weep hole. I would certainly start there for a fluid level and condition check of the transmission. Otherwise you may have a leak you are not seeing as it may be only leaking under pressure. None of those prove to be true and it's time suspect the head gasket.

The trouble with waterpump seals they can leak either out the weep hole or into the transmission.

Check there first.

You really need to do a pressure test on the cooling system both hot and cold states.

Did you note the volume you put in as you may have had an airlock which means the fluid wasn't there in the first place even if you saw it at the cap.

Was topped off, now virtually nothing.

I’m going to replace all of the seals (gasket between the water pump/clutch and the case, seal between water pump cover and the small 2 round seals for the pump bearing) as well as the bearing and shaft. I’d just rather do all of it at the same time and be done with it. The kits are fairly easy to acquire.

Did you find coolant in the transmission oil?

Did you find coolant in the transmission oil?

Just got done with the install. No coolant in transmission fluid that I could tell. Looked all red and oily. Maybe I went overboard but I’d rather be safe than sorry. Only took around 90 min taking my time.

Normally a better process is to find the problem that needs to be fixed before starting to try and fix things that a problem might be.
If you found no coolant in the transmission the inner seal is fine. If you have no coolant coming out of the weep hole the seal was fine. You probably have coolant leaking elsewhere that needs to be found.

Lets get back to basics.
I think a pressure test of the cooling system is needed before riding to be sure.
If for no other reason than piece of mind.
I would do a cold test first then warm up bike and do another test.
The cap should still be checked even if nothing appeared to go into the overflow.