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jafo
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Post by jafo »

I did'nt read every reply on this topic, just a few and did'nt see anyone mention the water pump. Is it leaking possibly? Maybe not out wards but inwards? If your getting air sucked into the impellers, one it will not flow correctly and two it'll introduce air into the system causing steam pockets flow problems. I don't know about bike engines & how they would react toa small leak, I only had mine apart once, but also another thing that can cause overheating that alot of people don't think about is small holes in the head gaskets. It only takes a pin hole leak into the cooling system to introduce hot exhuast gasses into the coolent there by heating the coolent up quicker than it the radiator can cool it down. It would cause constent excessive heat once it builds up. Plus if it gets to hot, it will form steam pockets in the coolent passages and that would also cause flow problems. I had a head gasket do this to me on a car engine one time. The head gasket was'nt blown out enough to cause it to noticeably burn coolent, it was just large enough to push the hot exhaust gasses into the coolent system and make the engine run much hotter than normal. I also would notice a loss of coolent from the system, at a slow rate. Again Bike engines may be somewhat different or may react in a different way than car engines do. So take all this into account when reading this stuff. It's just a few ideas off the top of my head.

What type of mix do you run in your coolent system? I run pure coolent in mine, not additives. I don't run ata the elevation you run, but mine has never overheated...... yet.

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Post by Colorado Mike »

Thanks for the ideas. I'd like to replace all my gaskets, just to eliminate the possibilities you mention. Since that involves a lot of work, I'm gonna try another cap first. I'd really rather save the tear-down for the off season when I plan to send my head of to RB. The black particles I see in the recovery tank have me re-thinking that though. As for the coolant, I was using Maxxima premixed coolant, I think it's 50/50. Then I tried Engine Ice, which didn't make much if any difference. after that was gone, I went back to regular Prestone 50/50 since it's cheaper. I'm sure bike engines aren't that different from cars when it comes to cooling. I've seen vacuum leaks on cars cause this too. Maybe I'll invest in one of those vacuum/pressure testers, or take the bike to a radiator shop.

Thanks again
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Post by KDXGarage »

Just to refresh my memory, as I assume you have already mentioned this. It is just doing it when you are going slow at super high altitude, right?
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Post by m0rie »

The black specks that your seeing might be the oil seal between the water pump impeller and the clutch case. Thats easy to check and would be worth it just to verify the impeller looks and functions like it should.

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Post by Colorado Mike »

Well, it used to be that if I was at 9000' and was going under 5 mph and the temp was over 80°, it would boil. Yesterday I was at much higher altitude, going faster to where I think a good amount of air was going through the rads, it was cooler, maybe 65-70°, and it boiled bad. I think it's getting worse and something is broke, rather than a design that's not good for high altitude. I'll read up on how the impeller comes out and check that too.

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Post by KDXGarage »

Have you tried different ratios of distilled water to coolant/anti-freeze?
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Post by Colorado Mike »

I just changed the oil and didn't see any coolant in it. Drained the coolant and it looks clean as always. When I took the pressure cap off I noticed the gasket on the pressure release plunger had little bumps of rubber on it. They wipe off pretty easy, but I'm gonna get a new cap. My current theory is these little bumps cause the plunger to not seat well and not allow enough pressure to build up in the system. This would allow the coolant to boil off rapidly at high altitude (at least in my tiny little mind). And allow lots of vapor next to the hot spots in the head, causing them to get hotter, causing more vapor, etc. etc.

I popped the cover off the water pump. The impeller looks all clean and shiny, and it spins when the motor does. I didn't pop it off and look at the O-ring yet, I want to have a new one in hand before I do that.

Oh, and I haven't tried different coolant ratios. Mostly cuz nobody I ride with has any problems, and they just use 50/50. The other reason is I'm pretty lazy and would like the convenience of just pouring it out of the pre-mixed jug.

I'll keep you posted as the saga continues.
Last edited by Colorado Mike on 11:40 pm Aug 07 2005, edited 1 time in total.
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Post by KDXGarage »

Thanks for the info. Keep us posted.
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Post by canyncarvr »

This is the first time you replaced the cap? That's a good idea on GP if you have heating problems.

I've had a couple of problems with cooling systems...the caps LOOKED ok...but replacing'em took care of the particular issue.

Yeah..ANY bumps or ANY sign of wear/abrasion on the first seal means replace it.

Your rad vanes (plastic pieces in front) don't happen to be backwards? I'm not sure they even fit both ways..but I'm just wondering..........

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Post by Colorado Mike »

Nope they're frontwards. I put a new cap on that's a 1.6 whatever, up from the stock 1.1 whatever ( I used to think the whatevers were atmospheres, but they're not according to the radiator dude I talked to). I only got to ride yesterday at about 9,000'. It didn't spew. The coolant stayed pretty much at the level I filled it to, a few drops made their way out the overflow tube, I'm thinking just from the bouncing I was doing.

So far it looks good, but it was very cool yesterday, so I'm not counting any chickens. (For Kay Dee, that means I'm not convinced yet). If this works I still won't know if I had to go to the stronger cap or if the 1.1 was just bad, but I bet putting on a fresh 1.1 would have worked too. My bike felt like it was running cooler too, didn't notice any significant heat on my legs, which was not the case before. If it runs well in heat, then I'll put the right rad brace back on, and change the jetting back leaner (to where it runs strong :supz: ) and see how it goes.

Thanks everybody for all the ideas,
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Post by KDXer »

Actually Mike I thought that was only an aussie saying. Just like keeping all your eggs in one basket. Hey why did the chicken cross the road ?? :rolleyes:


Glad to hear your possibly on your way to a resolution.
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Post by IdahoCharley »

COmike - you are correct in thinking that the cap is rated in atmospheres. I do not know what the mechanic told you - but rating radiator caps in atmospheres is the norm. The rated pressure that the cap will hold changes based upon barometric pressure.

Example: Sea level 29.92 Bar Pressure equals ~ 14.7 Lbs of absolute pressure therefore a cap rated at 1.5 will be good for holding in about 1.5 x 14.7 = 22 psig: The same cap is only good for 18 psig at 5000 ft elevation (24.60 Bar) and about 15 psig at 9000 feet elevation.

This one of the reasons that bikes boil over easier at higher elevations combined with less dense air to draw heat away from the radiators. Also normally working the bikes harder since there is less oxygen molecules to combine with the fuel: less compression in the cylinder, etc, etc.
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Post by Indawoods »

Charley... sometime you can make me feel really stupid! :rolleyes: :lol:
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Post by m0rie »

>|<>QBB<
Indawoods wrote:Charley... sometime you can make me feel really stupid! :rolleyes: :lol:
Some people just have a God given talent for that sort of thing... :supz:

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