Cooling Hose Connector Corrosion

Hi all, I am tearing into my 1998 VFR since I had to replace the stuck thermostat and am currently putting the cooling system back together with new silicone cooling hoses. I noticed that the thermostat housing and all the cylinder block/head water joints have pitting on the hose mating surfaces. The two pictures are from the thermostat housing and cover because those were the worst. Is this something I should worry about? None of the pictures of water joints online had this kind of pitting (or corrosion), and I couldn't find any threads on here (or VFRD) about corrosion either.

Also some tips on cleaning these things would be helpful. I already blasted all them with brake cleaner and a wire brush, but they still don't look clean enough to my eye, especially the o-ring mating surfaces.

 

I have found that vapor blasting is the only thing that can actually restore the finish. It won't fill the corrosion pits, but it will stop any further corrosion, as long as the hoses and clamps are properly installed and tightened. If you are really concerned, there are a lot of industrial filler applications that can be used to "bondo" the pits.

 

I had some severe corrosion on the spigot where the coolant expansion tank hose connects at the radiator filler neck on my ST1100, and I used a cold-weld two-part epoxy to fill that, then I drilled out and reshaped with a hand file back to close to original. This gave me no grief over 3 years and 40,000km.

 

Do you think it is worth the time to try to fill them though? I've never taken apart a cooling system before, so I'm not sure if these kinds of defects in the hose mating surface will cause leaks. This isn't a show bike so I'm not too worried about things not looking great, but I want it to be mechanically sound as I plan on keeping this bike for a long time.

 

I didn't bother with filling them in, just wanted to make sure the corrosion was mitigated. I would have done more, but there was still more than enough material left and it didn't warrant the effort, I too did the silicone hoses, and just to make sure, I lubed the inside of the hoses with silicone based o-ring grease. the grease makes it easier to install the hoses and also provides a little barrier from coolant getting between the hose and the aluminum fitting . If you locate the clamps in the proper location on the fitting, keep the clamps snugged up and every now and then pull the hoses off and see what's happening, it should be fine, imo.

 

that kind of corrosion is caused by using tap (not distilled) water and too infrequent coolant changes.

 

That would make sense given the condition of the rest of the bike. Lots of stuck fasteners that should be removed semi-often for maintenance, and the coolant may well have already hit puberty by the time I flushed it. There's still a significant amount of stuff (minerals from tap water?) stuck on the reserve bottle that won't rinse out, so that makes sense too.

Thanks for all the info guys. I'll finish re-assembling the cooling system this weekend and try to pressure test it. I think I'm going to rig up a bike pump into a rubber stopper that plugs the radiator filler. Just got the email that the injectors are in the mail back to me, so I'm going to do everything I can the next week to get this bike rideable.

 

It could be that they used the wrong coolant that had a bunch of silicates and phosphate in it that aren't good for motos, or they tried to control temps by using water wetter and tap water for coolant, then never changed it and ended up having a bunch of galvanic corrosion due to the corrosion inhibitors breaking down. Might wanna pop the cover on the water pump and take a gander.