Hello all, I have a 1999 F4 and it has been overheating to the point where the coolant is boiling over (the overflow tank), have already replaced the thermostat, and still have the same problem, am thinking the problem is the water pump, a friend gave sketchy details on testing the water pump and am not sure, my clymer manual isn't much help either, I am somewhat mechanically inclined and do most of my work myself, just need some pointers if anyone has any, thanks alot.

 

Does the fan kick on? Does it only do this when your sittin?

 

Yes the fan does kick on, and yes as a general rule the overheating/coolant boiling over occurs while sitting still however i'm not sitting in extended traffic its not normal in other words, also it didn't do this before while sitting still. Also I have noticed that after I begin rolling once reaching the boiling point it continues to boil once rolling and leaves a trail of antifreeze/coolant, very odd to me, considering previous repairs, is there anything I can do short of replacing water pump? Is there a way to service the water pump?

 

How many miles are on this thing? Just get a new water pump. I'd at least take it out and look at it. Did you replace the thermostat with an oem one?

 

My machine has 36000 miles on it! It runs great and haven't had any real problems to date knock on wood. As with all of these Honda F series bikes I expect it will run forever since i take care of it. I have kicked around the idea of putting in a new water pump but wanted some other peoples' (you) opinion before I go order the part typically 150 bucks, if you know any cheaper places let me know I would appreciate it, and install the thing and have the same problem. So in your opinion you think the water pump is gone also? One last question, a friend of mine who is pretty sharp with bikes, said I can test the water pump by figuring out which hose is the inlet and which one is the outlet and disconnect the inlet, fire up the bike and feel for suction, if that is good then disconnect the outlet, fire up the bike and watch for coolant to spray out with force, if coolant only comes out slow then my water pump is bad, what do you think of all this, I'm a little skeptical about this method of diagnosis.

 

yes the T stat is an oem honda one

 

I had a Kawi 250R with this problem and it ended up being a non-visible crack in the radiator that didn't allow the pressure buildup, so the coolant wouldn't cycle properly. My guess is that the pump is easier to test for. You can take the bike to a shop and have them hook their vacuum to the cap to see if it's a pressure problem.

 

Hey one of my buddies had this happening to his bike. We were thinking head gasket but I said for the heck of it lets pull the radiator cap off my bike and see if it still does it.. . .Guess what has not happened since so give that a try

 

Have a look at the bottom of your water pump (left hand side, hasthe 2 hoses comming into it), there is an inspection hole there, if there's any coolant comming out of it, you have a damaged seal in your water pump internally, it cannot be fixed. The water pump has to be replaced as a complete unit, there are no servicable parts available for the water pump. ust a thought.

 

i had a similar problem with my 99 f4, a "mechanic" told me i need a new radiator. it ended up being some hoses were switched around going in the engine and air cleaner under the gas tank, i'd check those out. the manual doesnt help out too much here just kinda look for ones that might get mixed up and try swapping them.