Puking coolant

[Metalefty]

On my '05 450, I'm having a problem with losing most of my coolant out the overflow within the first few minutes of riding. Everything seems normal, the rads are clean,new rad cap, checked impeller and when cold I took the rad cap off and started the bike to see if there was any blow by from a bad head gasket...no coolant spitting out, now I'm stumped. When I start the bike cold, within a minute I can see the catch tank filling up and then I'll take off down the driveway and back for maybe 45 seconds and a lot coolant is running out of the overflow tube. It's as if the engine isn't being cooled at all. Any ideas are greatly appreciated, Thanks.

 

[Nick]

Does it keep blowing it out forever ? How high do you fill it ? The coolant should just cover the tubes inside. Anymore and it'll just blow it out.

 

[Qui-gon]

Make sure the new rad cap seal actually reaches and seats on the place it is supposed to on the radiator neck. Assuming it is the correct length cap it may be getting hung up on something and not sealing the hole properly. As Nick said it will find its own level but once done no more should come out.

 

[Metalefty]

Does it keep blowing it out forever ? How high do you fill it ? The coolant should just cover the tubes inside. Anymore and it'll just blow it out.

My rough guess would be that it blows about 1/3 of the coolant out in less than 10 minutes, then it's runs hot as hell and the gas in the tank is boiling.
I fill it just below the lower hole.

 

[Metalefty]

Make sure the new rad cap seal actually reaches and seats on the place it is supposed to on the radiator neck. Assuming it is the correct length cap it may be getting hung up on something and not sealing the hole properly. As Nick said it will find its own level but once done no more should come out.

The old cap has been on there for over 4 years with no problems, I just bought this new cap to help cover all angles.


What do you guys think about a very small leak in the head gasket. I had a 2 stroke once that blew a head gasket and when you kicked it over cold with the cap off the coolant shot out like a fountain. Is it possible to have a small enough leak to slowly build pressure? The only thing that keeps me from thinking this is how fast it heats up.
Thanks for the replies.

 

[Metalefty]

New update, I just got done putting a new impeller gasket on and started the bike. I now notice little black particles floating in the old coolant I drained, not sure what it is, maybe rubber from the hoses from overheating, idk. So I top off with fresh coolant, rad cap off, start engine, coolant looks like it's swirling possibly, I put the palm of my hand over the hole and put my finger on the end of the overflow tube for about 30 seconds, no pressure build up, did it again 3 more times and no pressure build up. For the next 2 minutes I watch the coolant very slowly raise about a half inch to the top of the rad, the bike has been sitting idle for about 4 minutes total and the top of the rad is to hot to touch. I put the rad cap on and almost immediately coolant starts drooling from the overflow tube, this time it didn't even go into the catch tank, I watch it drool for another 30 seconds and shut it off. Still stumped...

 

[Nick]

Try another cap. As Ian stated it might not be sealing.

 

[goose202]

Can you see any bubbles in the coolant? Perhaps a blown head gasket.
EDIT: Sorry, just re-read and saw that you checked that. Still seems like the most logical explanation to me though. Strange.

 

[Qui-gon]

Next step looks like you should do a radiator pressure test to see if it looses any pressure when left standing for a while..any quick drop will point to a head gasket failure but it is not always conclusive.

 

[bergerhag]

Also, check that the cap seal seat is not warped or something.

 

[Metalefty]

My dealer has one cap left, he's letting me borrow it, I'll see what happens after that. He's stumped too but is leaning towards a head gasket. I just want to be sure before I get into it.
Thanks again guys.

 

[GMP]

You know a KTM cap works fine right? My '03 250 would drool a little coolant with the stock cap, and that ran no where near hot. A KTM 1.4 bar cap cured that.

 

[Nick]

Yes dont use OEM cap, get one from KTM dealer. Its less money too.

 

[Qui-gon]

How much is the KTM one then? The OEM part is less than $20.

 

[Nick]

I wanna say its $14 but its been awhile. I stocked the KTM part as i could retail it for what the OEM cost me and there was a better margin in it and thats buying from a KTM dealer.

 

[Metalefty]

Sorry it's been awhile, been very busy, I just rode the other day for the first time since I last posted. I ended up buying a 1.8 KTM cap, so it's holding coolant fine during a 2 minute warm up, 10 minutes later it's nice and hot and the catch tank is partially full and I see a drop or two under the bike but no constant dripping, I ride for another hour and a half. When I got home I pop off the cap and yet again, about a 1/3 of the coolant is gone. So instead of losing my coolant in the first 10 minutes, I think I'm losing it slowly through the ride. Yes, it's now time for a pressure test.

 

[Qui-gon]

When you say 1/3 of the coolant gone is that from the total amout or 1/3 of what was in the top tank part of the rad below the cap? If it is the latter then it is just finding its level and another ride should result in no further loss.

 

[Metalefty]

When you say 1/3 of the coolant gone is that from the total amout or 1/3 of what was in the top tank part of the rad below the cap? If it is the latter then it is just finding its level and another ride should result in no further loss.

It's just a basic guess as to how much I'm filling it back up to. I hope your right about it needing filled one last time but my riding buddy following me said he could smell it every so often. Besides, in the past when I've flushed and refilled the system, it never needed this much coolant to top off the radiator.