Leaky Coolant O Rings


6 replies to this topic
  • minnesotajamie

Posted January 03, 2012 - 07:06 PM

#1

I keep having issues with leaky coolant o rings on my 07 YZ450F- the ones that seal the solid coolant pipes near the exhaust header and the water pump. It's worst where the coolant pipe fits into the head near the exhaust header. I use Evans/Zip Ty coolant and it seems to deteriorate the o rings so they get hard and leak. I do mostly woods riding and with the rekluse clutch the evans is the only solution that keeps it from constantly boiling. It's either the coolant or the heat, as the evans coolant allows the engine to run a bit hotter (doesn't boil, though!). I was going to get some viton o rings but I don't know the exact size to order. Anybody have any advice?

  • 2grimjim

Posted January 03, 2012 - 07:43 PM

#2

I keep having issues with leaky coolant o rings on my 07 YZ450F- the ones that seal the solid coolant pipes near the exhaust header and the water pump. It's worst where the coolant pipe fits into the head near the exhaust header. I use Evans/Zip Ty coolant and it seems to deteriorate the o rings so they get hard and leak. I do mostly woods riding and with the rekluse clutch the evans is the only solution that keeps it from constantly boiling. It's either the coolant or the heat, as the evans coolant allows the engine to run a bit hotter (doesn't boil, though!). I was going to get some viton o rings but I don't know the exact size to order. Anybody have any advice?


I do a lot of woods riding with my '06 YZ and I just put an overflow tank on the bike and a 22 psi cap on the radiator. I run plain old 50/50 water ethylene glycol coolant and I never have problems with over heating.

Waterless coolants like the Evans stuff you are using has a very high boiling point (371 degrees) and transfer heat about 20% slower than water/glycol mixes. This means that the radiators need to be about 20% bigger to transfer the same ammount of heat to the surrounding air. Your engine temperatures are probably considerably higher than the 200-220 degres it is designed to work at. Probably closer to 250-270 degrees and maybe higher when you are under full throttle load but because the waterless coolant has such a high boiling point, you will never know that you are overheating your engine. These higher temps can explain why the coolant o-rings are not holding up. You could go to a Viton o-ring for the coolant lines but you are probably going to have problems with the waterpump seals and hoses deteriorating in the future too.

Extended operation at these higher temps will also shorten the life ofthe top end, engine oil, and clutch.

Edited by 2grimjim, January 03, 2012 - 08:14 PM.


  • grayracer513

Posted January 04, 2012 - 08:07 AM

#3

That's one of the major negatives about the Evans solution: the engine runs hotter. And you're right on every detail regarding that. If people who ran the stuff ran a temp gauge, they might decide to switch back to something more normal.

The high temperatures could definitely account for at least some of the hardening and shrinking of O-rings, especially since they weren't selected to be used at temps that high, but I need to mention a couple things:

Running any coolant at 100% like that doubles the concentration of whatever inhibitors and other chemistry there is in the coolant, and this could be attacking the seals.

Also, I have seen a lot of times where the port in the head where that tube goes has become damaged or nicked, etc., so that while it seals OK at first, it doesn't hold up. Worth a look.

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  • 2grimjim

Posted January 04, 2012 - 08:26 AM

#4

Don't get me wrong on the Evans Coolant. There definately applications where this stuff works good. If the cooling system is designed to work with waterless coolant, it is very effective and can be used to increase the HP output in some situations.

There is also a huge benefit in industrial applications where corrosion problems with water based coolants are the cause for most down time. Pure Ethylene/Propylene Glycol will not cause corrosion on most metals.

A dirt bike is one of those applications that I don't think is really appropriate for waterless coolants in most situations. Because if the lack of a thermostat, cooling fan, and necessary increase in cooling capacity, the engine temperatures can spike to very temperatures without the rider ever being aware. 50/50 water-glycol coolant has a built in alarm; it boils and lets the rider know the engine is too hot. In the case of the Evans coolant, it doesn't boil until the temp is at 370 degrees, at that point you have probably caused some engine damage.

  • minnesotajamie

Posted January 08, 2012 - 06:56 AM

#5

I do a lot of woods riding with my '06 YZ and I just put an overflow tank on the bike and a 22 psi cap on the radiator. I run plain old 50/50 water ethylene glycol coolant and I never have problems with over heating.

Waterless coolants like the Evans stuff you are using has a very high boiling point (371 degrees) and transfer heat about 20% slower than water/glycol mixes. This means that the radiators need to be about 20% bigger to transfer the same ammount of heat to the surrounding air. Your engine temperatures are probably considerably higher than the 200-220 degres it is designed to work at. Probably closer to 250-270 degrees and maybe higher when you are under full throttle load but because the waterless coolant has such a high boiling point, you will never know that you are overheating your engine. These higher temps can explain why the coolant o-rings are not holding up. You could go to a Viton o-ring for the coolant lines but you are probably going to have problems with the waterpump seals and hoses deteriorating in the future too.

Extended operation at these higher temps will also shorten the life ofthe top end, engine oil, and clutch.


Thanks 2grimjim. Where did you get the cap and overflow bottle? Did you simply make your own overflow bottle or did you buy one?

  • 2grimjim

Posted January 08, 2012 - 09:14 AM

#6

Thanks 2grimjim. Where did you get the cap and overflow bottle? Did you simply make your own overflow bottle or did you buy one?


The overflow bottle is from '03-'06 WR450. I welded a bracket onto the subframe and mounted in the same place as the WR.

The cap is a Stant Racing 22-24 psi cap, part #10362. They also have a 19-21 psi cap (10361). They are hard to find but they are the best quality cap I have found. I've been buying them from Amazon;
http://www.amazon.co...26042475&sr=1-1

CV4 and a few others sell higher presure caps. If you plan on going with a high pressure cap (or even if you still plan on using the Evans coolant) another good upgrade is silicone hoses.

If you stay with the Evans coolant, you don't need anything but a stock cap. You'll just be wasting money with a HP cap with the Evans coolant.

  • minnesotajamie

Posted January 14, 2012 - 02:01 PM

#7

Thanks Jim. Snowing now in Cleveland so I guess I have no excuses not to take the time to make a few mods!





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