Overheated engine

[jefgil123]

Can you remember about how many miles you went between seals the other times? Is it about 12 hours? also.
What kind of coolant are you using?

Jeff in CA.

-EDIT - P.S. - What radiator cap are you using - a higher pressure one ??

Maybe when the engine gets hot the overpressure blows thru the seal instead of out the cap ????
(But I wouldn't expect anything to blow with the Evans Coolant......hmmmm.
I am working on a cooling system "sight glass" that goes on the hose coming out of the head.
Will keep you posted. -EDIT-

[GMP]

Very odd. The GG motor uses a high speed ceramic/graphite pump seal, common in industry but not in the MC world. A much better design than the common seal on shaft that most bikes use. I have found it to be exceptionaly reliable. Hundreds of hours on three bikes with no failures. What has been the failure mode? The ceramic will not wear so its either the graphite ring, spring failure, fit in side case, or the boot is leaking on the shaft.

[Eric K]

Here is the history of waterpump seals...

'01 XC300
Original seal failed at 82 hours [stock coolant]
1st replacement seal failed at 4 hours [Prestone/water 50/50 mix]
2nd replacement seal failed at 51 hours [49 hours Prestone/water 50/50 mix, 2 hours w/Evans coolant]
3rd replacement seal still holding at 280 hours [48 hours Prestone/water 50/50 mix, 232 hours w/Evans coolant]

'06 EC300
Original seal failed 90 hours [Evans coolant]
1st replacement seal failed at 12 hours [Evans coolant]
2nd replacement seal just put in [Evans coolant]

I also helped a friend replace a waterpump seal on a ’01 XC300. I estimate it had between 100 and 200 hours of total use.

I have not seen any visible seal failure mode on any of the failed seals.
The waterpump shafts have not been grooved and bearings are solid.

Years ago, my local GG dealer told me that the waterpump seal had to be shimmed to avoid failure. Since I had just put in my 3rd seal on the '01 XC300, I was going to wait until it failed again before any shimming. However, it has fortunately held up. I don't recall any specifics of the shimming recommendation and the shop is no longer in business.

[blitz11]

My old Honda cx 500 had the ceramic water pump seal, as did yamaha 500 visions of the early 1980s. very reliable seal. I bought a spare, but haven't had to use it yet (at about 100 hours of use to date).

The theory of too high a pressure radiator cap is a good call, too. A definite possibility.

[GMP]

The shaft grooving is a non-issue as it does not spin withen the boot, boot fits tight to the shaft (or should). Was the fit(s) still tight?

The Prestone mix I could see POSSIBLY having a wear effect on the graphite ring as there are silicates in that coolant.

As system pressure builds, the sealing surfaces are pushed together even harder. With EVANS, there is very little system pressure, but I do not think the seal design needs a certain pressure, thats what the spring is for. Also the pressure is low with all coolants at startup. What I do beleive is that a certain amount of preload is required in the design of the fit and this is what the shimming would change. We have to get the exact size and preferably mfg. of the seal and look up the data sheet. I'm sure its also important that the ceramic half that presses into the case over the bearing be in square.

FWIW, I have only used Engine Ice in all three of my bikes with 1.4 bar caps. I have a gallon of EVANS NPGR on the shelf I was going to use after I do the top end (soon).

[Eric K]

The seal fit over the shaft snugly. I could not see an obvious failure on the seals.

On installation, I verify the seals are aligned squarely to the hole/shaft.

With the Evans coolant I run the radiator cap backed off just a bit to reduce the system pressure.

When I look at the failure data, there is no clear signal to me other than they have a short expected life.

On the bright side they are easy to change.

[wence]

Had the exact problems you were having on a 98 Rmx 250.
Turns out the head gasket was leaking into the barrel.
Had to reface head and barrel to eliminate warp and replace gasket.This happened on two occasions until doing the head and barrel work.
Good luck.

[Eric K]

The head o-rings were not leaking. I replaced them anyway.

Since replacing the waterpump seal, the engine has not even come close to overheating.

I stuck a temperature tab on the outside of the cylinder just below the head. On high elevation, warm day, tight singletrack, climbing steep hills with many tight 1st and 2nd gear switchbacks the warmest temperature reading was 203 deg F.

The waterpump seal is currently holding up. As long as the seal holds, it works great.