Corrosion Inside Water Pump Housing - Rev3 270

[subanator]

Have anyone come across a solution to fixing the corrosion to the magnesium casing on a Rev3?

Mine is a '03 Rev3 270, and have replaced this casing before for the same reason.

A mate said his chewed out again also, and was shocked to find mine had done the same a year and a bit later.

I found the old coolant to be gycol based organic type, ok in alloy engines, but changed to the recommended synthetic based type after the last casing change.

This has made no difference. Apart rom buying an alloy casing, what have other owners done or found?

A mate had a similar experience with a Husky, and they epoxy coated the inside.

[barrybaines]

Change your coolant at least 6 monthly that should help

[totalshell]

the 03 rev 3 certainly 'seem' to have issues with corrosion of the water pump housing and a t least two threads have covered this in the last year. My personal solution was to fill the corroded areas with araldite and only use water without additives. during the following 12 months certainlt the corrosion did not become any worse , although just shy after a year of using the epoxy it started to 'peel' from the surface of the corrosion. I have now used a petrol tank sealent epoxy to try to gain a more permanent solution.

Of course the permannet solution would be to spend the 46 quid on a new casing which Im told will not corrode.

the following link take you to the last time this was discussed and links in there will take you further

http://www.trialscentral.com/forums/index....p;hl=water+pump

Edited April 2, 2007 by totalshell

[subanator]

Thanks for the reply, sorry I did not search first but was in a hurry to post. Since doing that and talking to the local dealer, and have read the linked post provided.

It seems that Beta is choosing to ignore this problem (do they read these forums?), as it occurs through the following years models with magnesium alloy casing of twin pipe water pump design. I am not sure why this occurs, electrolysis seems to be the culprite, but is this cavitation, as it only is around pump impeller? I have noticed it picks away under the paint layer internally on exposed edges, so it must be sacrificial as in anode by current flow. Maybe it needs a sacrificial anode, so where does it deposit to?

I am not sure why coolant would deteriate over 6 months, as it should be inert, but may contaminate and aid the electrical path.

I know of the sealant trick inside the cover, but as commented in the linked post, it will get under that if not applied properly. I think this would be ok to do if not too bad or from new.

I have tried adding a piece of wire bonding the casing to the frame, with hope this will change the electrical path. Electrolysis is not that simple however.

Mine is weeping at the o-ring seal now after inspection, used sealant goo to get another ride out of it for the weekend, but have decided to buy the slightly heavier aluminium casing from the earlier 2002 model.

I believe the Honda CRF250 engines are problematic in this area too with magnesium alloy waterpump casings, dont know if the Montesa engine varient is similar?

[bony toe]

I have a 03 rev 3 that corroded through the casing. When I mentioned it to the local importer here in South Africa he offered to replace the casing without charge, no questions asked. The new casing was flown out from Italy so the beta factory probably knew why it was being replaced. I certainly got the impression that the official policy is to replace the casings so it may be worthwhile to lean on your importer for a free replacement.

[shercrazy]

is the impeller fan tight? i know sometimes they get wobbly and chew a groove leading you to believe the liner is eroding, happened to me, replaced the fan and it was fine? hope this helps..................................john