2004 Crf 450 Cooling System Problems!!!!!!!!!!!!!!!

[mc202]

I have a 2004 crf 450 and im running into some cooling system problems. It started by overheating and blowing steam out the vent hose by the rad cap. i checked all the fluids and they were good. It kept steaming. I had to put in a new top end because it was due. the first ride out after the rebuild it started steaming again. I switched the rad cap to a higher pressure kawasaki cap. kept steaming the 2nd trip so when i got home i was pissed and noticed one of my radiators was bent so i went and bought new fluidyne oversized rads. started the bike in my driveway and it pukes coolant out within 30 seconds. usually happens after i crack the throttle. so what the hell?? any help would be awesome thanks much

[MELK-MAN]

likely a head gasket and not a cooling sys issue. There is some info on this same topic.. click "search" then type "overheating"

[Shawn_Mc]

Ya, Id bet head gasket too. The cylinder over pressures the rads and blows past the cap.

It started doing this after you did the top end, no?

[finleyj450]

I would say check the head gasket also, and also you might check all the hoses first to make sure there is no paper in any of them...

I had the exact same problem with my 04 that you are having right after I rebuilt the top end, did the exact same things you did and nothing helped. I was getting ready to pull the motor apart to put in a new head gasket when I pulled off a Rad hose and had a big piece of paper stuck in one of the plastic fittings.. Hopefully it helps

[oakhillbiker]

I had the same problems on a used 03 I bought the head was warped there was a low spot by the exaust

[mc202]

thanks everyone for the help. So it sounds like its probably the head gasket. Im going to pull the hoses off tonight and see if they are clogged if not i guess a head gasket is in order!

[MELK-MAN]

there is nothing that would bostruct the entire flow of coolant.. even if there was something obstructing the coolant flow, it would not boil out of the overflow tube for several minutes. The combustion gasses pass the leaking gasket into the coolant jacket, and very quickly, the intensely hot air displaces coolant (depending on how bad a leak..). get the head off and go from there. ?

[erichshonda]

Before you replace the head gasket you should check the head to see if it is indeed warped . If you dont have a mechanics straight edge you can use a glass table with 600 grit sandpaper laid upon it. Then put head on it

& rotate it around applying equal pressure. Then inspect wear pattern on head to verify if it is warped or not. When done be sure to clean thoroughly to remove particulates

[Rocksalt]

Take a sharpening stone and in a circle pattern stone the head. When done clean it and then put a straight edge across it and use a feeler gauge to see if there are any gaps.

You may have a cracked head if it is straight!

[Shawn_Mc]

One thing to note here...

When scraping any remnant from the head of the old gasket use a plastic scraper. The head is really soft. The head gasket is a thinly coated tin gasket. If you gouge the head with a blade you could end up ruining it at worst, or end up needing to get it machined to remove the hacked portion and restore the surface.

With the gouges and scrape marks in the head that Oakhill put up Id be really surprised if that head ever held a seal again (without some monkey work that is)

[Hondafamily931]

Im having a similar problem with my 04. I tried a high pressure cap, it slowed it down, but didnt stop the overflow completely. The only time it overflows is if i hit the gas, which leads me to believe it is the head gasket. If pressure is getting into the system via the head gasket, would there not be white smoke coming from the exhaust as well? Im on the verge of pulling the head, just wanted to avoid it if possible. Thanks.

[oakhillbiker]

With the gouges and scrape marks in the head that Oakhill put up Id be really surprised if that head ever held a seal again (without some monkey work that is)

yep some monkey work with a very fine hone and fixed it up no problems I ground the intake seats myself too 55 + hours on it now

[oakhillbiker]

Im having a similar problem with my 04. I tried a high pressure cap, it slowed it down, but didnt stop the overflow completely. The only time it overflows is if i hit the gas, which leads me to believe it is the head gasket. If pressure is getting into the system via the head gasket, would there not be white smoke coming from the exhaust as well? Im on the verge of pulling the head, just wanted to avoid it if possible. Thanks.

when you pull the head you will find your problem

[MELK-MAN]

as posted above, you will find out when you pull the head. But no, the head gasket can be leaking one direction from the massive pressure created in the combustion chamber (1200psi i think was posted earlier??), not from the 1.1bar (under 22psi??) water pressure of the cooling system when it is warm.. ?

[erichshonda]

A combustion leak tester is a proven easy test to use. The tester turns the fluid from blue to yellow if carbon dioxide is present (a byproduct of combustion) simply remove a little coolant from the radiator so coolant doesnt contaminate the test fluid in the beaker then insert the end of tester onto filler neck start the engine then squeeze the bulb on the end of tester. If fluid turns yellow, confirmed combustion leak

[orangyktmthing]

Another thing for the o.p., if you installed the head gasket (I believe that you stated that you did a top end on it....) and just immediately torqued the head down to the specified readings, that could be one of your problems. I just did a complete rebuild on my 05, and bypassed the part in the service manual that stated to torque it down in either two or three passes. After I tore the head off it ...again... and followed the instructions, I had no leaks. FYI, I torqued in a sequence starting at 15ft/lb, then 30ft/lb and finally 44ft/lb.

[mc202]

So the ol 4 filthy got tore down this weekend. They reused the stock head gasket when i had it rebuilt. Not sure why that would ever make sense. I had picked up a cometic top end kit so when i had it tore down i decided to put the new base gasket on as well. The new head gasket fixed the problem. ready for this weekend.

Thanks everybody for the help i appreciate the hell out of it

[MELK-MAN]

So the ol 4 filthy got tore down this weekend. They reused the stock head gasket when i had it rebuilt. Not sure why that would ever make sense. I had picked up a cometic top end kit so when i had it tore down i decided to put the new base gasket on as well. The new head gasket fixed the problem. ready for this weekend.

Thanks everybody for the help i appreciate the hell out of it

.. it doesn't make "cents" (LOL) to reuse a head gasket especially when under no time crunch (vs. trackside with no spare just before a race..) and ya put a ton of money into the rebuild.. just plain bad judgement (IMHO). Be glad that is all it was though, and original suspisions were confirmed.

[snakeriverrangerider]

A combustion leak tester is a proven easy test to use. The tester turns the fluid from blue to yellow if carbon dioxide is present (a byproduct of combustion) simply remove a little coolant from the radiator so coolant doesnt contaminate the test fluid in the beaker then insert the end of tester onto filler neck start the engine then squeeze the bulb on the end of tester. If fluid turns yellow, confirmed combustion leak

That's ingenious! So far, that is the top tip of the year. I never knew suck a test existed. Will any combustion leak tester work or do you need a motorcycle specific one?

[Jonathanpace]

I have a crf 450r which i found the head wraped as well, but it was already machined but still they did it wrong and it is still wraped, can i machine it agian ??? and what is the limit for machining the head agian???????