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coolant coming out of compression release lever

28 posts in this topic

I washed my 98 YZ400f today and started it up. everything was fine. But when I reved it up coolant came out of the compression release lever. And then when I took off the radiator cap there was white foam in the radiator. how can coolant come out of the lever and what caused the foam? The clymer manual doesn't help at all. Some help would be greatly appreciated. :thumbsup:

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Sounds like you may have blown a head gasket. I don't know if it works on a bike or not, but I do know that if you take the rad cap off and turn over the engine with a blown head gasket it will spit coolant out of the filler hole. This is caused by the compression leaking into the water jackets. Hope this helps.

Josh

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Thanks for getting back to me. The worry I have is how can water come out of the lever chamber and not oil as well? What are the signs of a cracked head? The bike has great compression. Also, the bike did not overheat...

thanks, Dan

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Where, in a little more detail, did the water/coolant come from?

How do you know it's coolant?

Was the foam in the radiator oily?

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The coolant came from the compression release on the front of the cylinder head. I thaught it was coolant because it was so watery, but it was brownish in color But not straight oil. And the foam was white with no traces of oil.... I just check my radiator and there is no oil in there.

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Sounds like a head gasket to me, it could be a cracked head, but common things being common. I'd bet on the head gasket.

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yah, drain your oil out to see if its liek a brown color, or a creamy color. if its a creamy color, i know what your problem is, becuz i had almost the same problem on my 250F

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I just checked the oil in the frame and in the tranny and both are black in color with no trace of water that I could see

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Can crap get sucked into the engine through the exhaust pipe like a vacume? Decause right before this happened I just finished washing thick mud off my bike with a pressure washer.

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Your cylinder is the lowest point in your exhaust system. If you got water down the pipe, it flooded into the cylinder when the exhaust valve opened.

Hydrolocking can cause BIG problems... everything from a bent rod to blown head gasket or even stretched head studs/bolts.

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Does it run now? Is the water level low? Is there still water coming out of the decomp lever? How did you notice this? Could it have been something splashed on there and just looked like it was coming out of the decomp?

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I noticed the water because my Dad was on the bike it happened twice when he reved her up, and when I noticed it it freaked me out so I shut it down. I will try to start it this afternoon after work. I'll let you all know what happens. Thanks again for helping me out

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The coolant came from the compression release on the front of the cylinder head. I thaught it was coolant because it was so watery, but it was brownish in color But not straight oil. And the foam was white with no traces of oil.... I just check my radiator and there is no oil in there.

There may not be oil in the radiator (not surprising) but before you go starting it up, I'd drain the oil and see if there is water in the oil. If so then you'll know for sure that you've got a serious problem.

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Pressure washers have to be used carefully. They are quite capable of pushing water past a gasket, never mind a seal. Also consider that most of the exposed oil seals on the engine are designed with the most emphasis on keeping things in the engine, not on keeping it out.

One of the possibilities that occurs to me is that you pushed water in past the outer lip of the decomp shaft seal while blasting the mud off the front of the engine. You may even have managed to push a bit of dirt under the inner lip of the seal as well, but either way, there may be water trapped in the void between the inner and outer lips of the seal. When you rev it up, the rise in crankcase pressure pushes on the inner lip, compressing anything caught between, and squirts some of the water out.

If the foam in the radiator is not oily, it's probably just an indication that the coolant is "tired", and needs to be replaced. Since the bike was running fine when you shut it off and none of this water spitting behavior was happening before you washed it, my guess is that it's a wash problem. Change the oil as a precaution. Sounds like it's time anyway. Then see how it goes.

Some things you should avoid with pressure washers:

> Blowing water at gasket seams at close range (less than 14") at an angle that would encourage water to be forced through the joint.

> Spraying seals at close range at an angle of closer than 60 degrees from the shaft centerline.

> Spraying the chain at closer than 18" and at anything other than straight from the sides. This is very important in the case of O-ring or other sealed chains, but it doesn't help a non-sealed chain to shove a bunch of dirt into it, either.

> Spraying in such a way as to force water into the control cables.

In general, think about what you're doing at all times, take it easy on the carb, and like the man said, keep the water out of your exhaust. And no matter how you wash the bike, remember that the air filter will not stop water. If you get it wet, any water on the element will be pulled in through the intake when you start it. Small amounts are harmless, but if there's enough, it could get into some of the air jets in the carb and cause trouble, so try not to flood the air box.

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Other thoughts here, check the vent out of the top of the cylinder head. Make sure that hose is not plugged up. If it is, the pressure has to go somewhere and that seal will be the next easiest place for it to vent. The foamy stuff could just be the condensation pushing past the seal.

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Thanks for all of your help, I think grayracer is right I should get a chance to start her up tomarrow.... I bet everything will be back to normal.

thanks again, Dan

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Other thoughts here, check the vent out of the top of the cylinder head. Make sure that hose is not plugged up. If it is, the pressure has to go somewhere and that seal will be the next easiest place for it to vent. The foamy stuff could just be the condensation pushing past the seal.

... by the way, I was checking the bike out and I noticed that the breather tube was being cooked by the exhaust pipe.... maybe it's plugged. I think I might reroute it to the airbox.

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Take the spark plug out and kick it through, if you got water down the exhaust it will kick out the spark plug hole.

Good luck, next time wash with house or use a nozzle and stuff a rag down the exhaust and tape it off.

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stuff a rag down the exhaust and tape it off.

Or stretch a latex glove over the end.... that works better if you have a silent insert that has multiple holes or a pipe with stacked plate baffling on the end.

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