bubbles in expansion tank

[houndog]

Hi guys, the other day I started my '04 ec 300 and while it was warming up I noticed that the expansion tank had filled up about half way and the hose was bubbling inside. the coolant level was normal before starting it. I warmed it up , no extra smoke but I do run it at 28:1 with synthetic oil so it always smokes a little more than when I was at 40:1. She's got 5K miles and never had a bit of trouble. I change oil frequently and have an alloy impeller on her. I rode about 10 miles.....no smell of coolant and it did not use any. When she cooled off it sucked the coolant back in the radiator. Started her again today and the same thing, tank filled up about half way and the hose was emitting bubbles. Bike seems to run fine.

What do you fellows think? Time for head o'rings? The bike runs excellent and starts easily but I sure do not want to take a chance that I've got a small problem that might get bigger!

Thanks for any help or suggestions!
Ed

 

[Jakobi]

The bubbles are simply caused by the flow of the water through the system. Its not extra air being pulled into the coolant otherwise it would either pop the expansion tank, or more likely cause the pressure to push the cap open and spill coolant out the overflow.

Thats the whole purpose of the expansion tank; to give the excess water somewhere to go as it heats and expands. My guess is that if you take the cap off the rad the level will be almost to the top. If you take some out and have it just across the fins you'll see much less action in the expansion tank.

 

[houndog]

Thanks Jakobi, my concern is that it seems to have changed. Both the 450 and 300 have the same amount of fluid, to the top of the neck but the 450 does not ever fill the tank more than just a little. they both have the same alloy impeller. I agree, in that I thought it would pop the cap if it were really pressure. This has not happened and I see no evidence of coolant loss. With 5k on her and never been touched, I'm just getting a little paranoid, I like to fix things before they really go south! OTOH, why screw with something and potentially risk causing an issue!

May very well have been like this all along but it worries me that I did not notice this before. I've owned the bike since new. I changed the coolant last year and have not added any since. Plan on changing it today.

When I took the cap off with it running it was kind of "bubbly and frothing".

Do you still feel the same with this additional info?
Thanks for the reply!
Ed
edit++++ darn it, Jakobi, i was just about to hit send and realized that I think I did in fact top the thing off when I changed the fluid in the 450!!! It seems the fluid was covering the fins and not in the neck, so I added a couple ounces to get it "like the level in the 450"!!!!! I'm kind of dumb like this and sometimes forget stuff! I will take your suggestion and remove just a little! Thanks again, but still please share any thoughts!

 

[Jakobi]

See how you go. Personally I'd be pulling it down for a fresh top end if it was my bike at 5,000kms.. But thats just me. Cheap insurance and you'll be amazed how much more go it'll have with a fresh slug in it

My 2010 has 6,000kms and is on its 3rd top end. I aim for around every 75-80hrs

 

[houndog]

Hey Jakobi, 5k km...ha ha....I meant 5K miles!

I changed coolant and put level just above fins. Level in tank seems "normal", but still fills up a little within a minute or so, but there is lots of foam and bubbles in radiator if running with cap off. So I cranked the 450 with cap off....after a few minutes it too was foamy, but not as much. When I put the cap on, it never filled the expansion tank even with the level to the top of the neck.

They are not acting the same but nothing seems to indicate combustion gas in the coolant except the filling of the tank and the extra foaminess.

This engine is in very good running condition, very smooth, as much compression as when new and is as fast as it ever was, no way I'll touch it as long as it is running, sounding and feeling like it does.

I'm thinking those o'rings are going to get replaced even if just for my peace of mind. I assume the head can come of easily with the engine in the frame?

I don't "race' this bike, I trail ride and dirt road stuff only. Occasionally go to the State Forest and thrash it. I always use the clutch and keep my oil changed enough it's always clear. I'm a decent rider but I strive for "smooth" rather than "fast".

Not to start the "great oil debate" because I don't care what folks believe or do but I run between 20:1 and 28:1 with full synthetic, Red Line, Amsoil, Quicksliver TC....... some call that crazy.....they rebuild their bikes, I don't.
I realize the power valves may not like such a rich mixture but so far I've not had an issue. I've used 3 plugs in 5,000 miles!

For background, I'm an old guy, been riding smokers since the late 60's. That said, I don't think for a minute I "know it all". Which is why I asked for opinions on this coolant thing!

So assuming I'm not about to mess with the rings/piston.....from your experience, is changing the o'rings, just for peace of mind, easy and can be done without removing engine?

Thanks!
Ed

 

[andoman]

Yes, the head comes off with the engine in the frame.
I'm with those that suggest that you should just do a top end while you are at it.

 

[robicon]

What kind of shape are your rads in? Are the finns starting to bend or are they plugged. maybe it's just not cool like it should, or did.

 

[houndog]

Hey guys, thanks for the replies and suggestions! The radiator is "as new", has no dinged fins! The bubbles start before it warms up and the foam soon after.

At this point I'm sure the o'rings will be replaced. There is no evidence that coolant is getting into the combustion chamber but I do believe that a small amount of pressure is getting into the water jacket. I would have thought it would consume coolant but have been told by "real mechanics' (like some of you) that it is possible to leak pressure into jacket but be so slight that coolant might not get into chamber. I think that's where I'm at.

Guys, the engine is tight, no piston noise at all, compression is "as I remember it new", it is fast as Hell, no excessive smoking, starts the first or second kick. Very smooth.
If someone said it was a new motor you'd not doubt them. I know it's hard to believe given the miles but please trust me I know what a fast dirt bike is. No, it's not like my bad ass CR250, "The Bunny", but she was a serious race bike. Ported, head work, carb mods, suspension work, blah, blah, blah.....

I'd do a top end if I had an inkling that it "needed" it. Of course I'll inspect the bore and if I see something odd, well, you know what will happen!

Guys, I put a 100hp (actually I run it from 75 to 125 but usually leave the 100hp jets in) nitrous kit on my Probe GT "sleeper" ( no badges, ac, power anything, it was specially ordered with just the engine and suspension of the GT) at 185K miles.....I was told this was crazy and would kill it with those high miles and should rebuild it first. Well, 180lbs of nitrous later.....and now with 248K miles she's still kicking ass...and getting 25 MPG. I seem to have very good "luck" with engines. I wonder if synthetic oil and changing it often matters?

Thanks again for the replies and suggestions!

Ed

 

[pscook]

What pressure rad cap do you have? My 1.2 started weeping, so I swapped in a 1.4 and no problems. It might be that your cap is just worn out and needs to be replaced. Just a thought.

 

[houndog]

Hey Phil, my cap is weeping! I did not think that could cause a problem as it is slight, but it does "weep" a little! It's a 1.2 the 450 has a 1.4. I'll swap them (if they fit each other) and see what happens. The shop is closed today so if they won't exchange, I'll snag one tomorrow to try. The owner has a 300 also and I'm sure he'll let me try his.

Sure would be sweet if it's the problem.
Thanks again to you and everyone posting with suggestions!
Ed

 

[GMP]

I doubt you have a problem with head orings. All I have seen like this will pressurize the system fast and blow the cap. Change the cap to a new 1.4, and make sure the sealing surface in the rad neck is smooth and clean. A few seconds with a scotchbrite pad is all it needs. best thing to do with that expansion tank is dump it. You don't need it, and its just another thing to fail.

Nothing wrong with alot of oil as long as your jetted right, its been proven to make more HP from better ring seal. I think 32:1 would be more than adequate for a 250 though. I run 36:1 Amsoil and have a 100 hr piston in my '07 with 190+ PSI compression and most of the coating still on it.

 

[(F5)]

ohh lets start an oil debate. . .

Probably more rad caps have been unnecessarily changed on vehicles than any other part in the vain hope it will be the leaking head gasket (ok o-ring) fix.

However the GG ones seem to fail for some reason. KTM run same size as they are essentially KTM rads. Maybe because GGs had softer springs in the caps than the orange bikes for many years?

 

[GMP]

Yes, 1.2 is too light. The 1.8 on the '12s is excessive IMO. The 1.4 KTM cap is good, and the bike shouldn't boil as long as the seal is good.

 

[robicon]

Sorry for the hijack but what is the problem with having coolant in the tank?? I always have coolant in mine, I like been able to have a quick look and know I am full. I run a lot of harh single track and when the ktm's are boiling over I never have and never have to add any. When others are over heating I have a quick look and if I see some in the tank it gives me piece of mind.

 

[GMP]

You don't resist boil over from the tank, its from the good GG cooling jackets and large rads. The tank and connection lines can (and have) been abraded and damaged from contact with the fork, cables, wiring etc. behind the headlight. Dump it and use a short crossover line, and fill the system to about 10mm over the tubes in the rad to leave an air gap. '12s have no tank, either did our older US spec XCs from '00 - '02.

 

[houndog]

Hey guys, again, thanks for the suggestions and help. My issue is not with the level in the tank, but the bubbles. I swapped the 450 1.4 for it's 1.2 and no change, bubbles almost instantly. The "problem" is that there were never bubbles before. I ordered the o'rings. The bike runs "as new".....and I'm not about to take a chance that it is in fact leaking into the water jacket, it does have 5K miles. At this point I've done all the "wish it away" fixes! So I'll change the o'rings. Should have them and have it done by the first of next week. In the mean time I guess I'll have to ride the 450 It sucks being down to only one GG
Ed

 

[Jakobi]

Now that you've mentioned this mine seems to be bubbling more than I remember too. Today it had a little layer of foam sitting above the coolant in the expansion tank. Its always bubbled through a fair bit (even after new orings and top end). Maybe I'm just paying more attention to it now you mentioned it.

Did you change the o-rings out and see if it made any difference? I have a spare set of o-rings on the ready if thats the case. In the mean time I'm keeping an eye on everything and going to ride it.

 

[GMP]

Remove the rad cap, if you have a leaking head oring the combustion deposits, oil, etc. will be evident floating in the coolant. That tank was put on the bikes years ago, they are streetable in Europe but have no fan. No need on a race bike, they figured this out on the '12.

 

[houndog]

Hey guys, will try and put them on tomorrow.....I'll report back.

Again, I never noticed this before and my 450 does not bubble at all.

GMP, there is nothing in the radiator and I did change the coolant. What came out was kind of nasty looking but I did not see any deposits or trash.

This bike is tagged and I ride it on the street, dirt roads and forest, in other words anywhere I want. I don't "race it" but some of my buddies might say otherwise when we hit the woods. I take extremely good care of it other than washing it . I actually use the clutch, every single time!

I am hoping that I caught a leaking o'ring right at the start......if bubbles/foam come after replacing them I'll still be worried but will ride her.

At 5005 miles I don't mind replacing them "just in case", plus I'll get to look at the cylinder walls....if anything looks "wrong" she'll get a new top end. There is nothing to indicate it has problems in that area. It's just so smooth, quiet and too fast for me to think it needs even rings.

Maybe if I ran my oil at 50:1 instead of 20 or 28:1 it would be time for a piston. The chance of me running 50 or 40:1 with any oil is about the same as the sun not coming up! And no, I don't care what the manufacturer says nor do I want to start a "great oil debate". It's jetted for the rich oil mixture. I do have concern for gumming the power valve but this has not been an issue in 5k miles. I run synthetic only, Amsoil, Redline, or Mercury PWC (the TC one, not the TCW3!). I don't mix fuel/oil types either.

I'll report back and thanks again for all the replies and advice!
Ed

 

[Jakobi]

No layer of anything floating on my water. Was a little tiny bit of something on the bottom of the rad cap though. Maybe a little emulsified oil. I'll be keeping a close eye on it.