Help......Overheating after replacing thermostat, hoses, & cap.... Solved

That's not right and suggests the thermostat is not moving. The thermostat should stay closed and keep the coolant circulating just around the engine and wax unit until it reaches its opening point of 78C. So no coolant should be reaching your radiators until that point and they should be cold to the the touch. When the thermostat opens it will release hot coolant suddenly to the radiators and they should go from cold to ouch in a few seconds.

Given your description I would say your thermostat is jammed part-open but not enough to allow any proper cooling.

 

Sounds like the water pump is working fine. BTW, this is exactly my VFR's temps this week on the way to work, without the eventual overheating.

65 degree morning while on the back roads temps were not going over 181. Jumped on the interstate I saw 210 then came back down to 185 to 195 and settled in there for the remainder of the ride.​

It's an OEM cap, the new AS3 hoses wouldn't be an issue, bike was ok before changing everything so I wouldn't suspect the pump or head gasket. The thermostat tested good out of the bike, a faster opening thermostat isn't going to cause the bike to go to 250F+, a bad cap might. Air in the system, bad cap or the lines may be crossed? My '99 doesn't have the wax idle unit, could crossing those be an issue, is it a one-way flow?

Lets go back to what changed on the system that I created this issue. I changed the hoses, thermostat, cap, and emptied the cooling system. Before I did all that I was not having an issue with overheating.​

 

The fight goes on without definite answers. I think I am crossing more things off the list that are not the problem than I am finding the problem.

As Vfrcapn has suggested, the water pump is not the issue. The pump looks good a little tight to turn but I would think that is normal. The passages look really clean. Which makes me think the passages in the block are clean as well.

OH ERIKA!!! Hold the phone!

While writing this up I was studying the routing in the manual and my pictures and you’re not going to believe what I found in my search…. Well maybe you will. Vfrcapn almost had it nailed.

I swapped the bottom large hoses going into the water pump. I will post pictures to make sure I am correct.

Boy, did I pay the stupid tax on this one. Next huddle is filling the system without air.
This just made my day!

 

From what I can tell you did it right and I F'ed it up. I'm not surprised I messed it up. I paid close attention to the small hoses and the routing, but the bigger ones seems to point to where they needed to go. I ASSUMED, and it got me.
You need to use the "+" symbol next to the video symbol for pictures on this site.

 

Sounds like you may have found the problem. I had the same AS3 hoses on my last bike and routed like Mello.

 

At least you didn't route it like me.

Yes, I hope so. I tried to be as detailed as I could. The only thing lacking was being able to upload a video of the bike running with coolant coming out the radiator fill opening.
If it wasn't for you guys helping me think this through, I'm not sure I would have figured it out.
The Forum is a very valuable tool. Too bad it has too many ads.

 

so, main take away from this thread is something I instinctively did a few years ago when I tackled a full hose replacement. I replaced one hose at a time. I didn't rip the whole system down at once. hopefully this little tip helps the next guy, lol

 

I made this mistake before, that's why I suspected hoses. At least you weren't on the side of the road in the Mohave desert trying to fix it as the daylight was fading!

I couldn't take the ads and ponied up the $25. I used to donate that much annually to vfrd, so it's a wash.

 

Ok, I've got to ask...who is Erika?

 

LOL, I spelled it wrong. I was too excited when I found the issue. it should have been.
EUREKA!!!

For the record I only took off one hose at a time for the hoses that connected to the thermostat. I figured the large bottom ones pointed to where they were suppose to go. That was my assuming mistake. God forbid, I try and do the vacuum hoses on the throttle body. What a nightmare I would make if I got those wrong.

 

"God forbid, I try and do the vacuum hoses on the throttle body. What a nightmare I would make if I got those wrong."

If they are still the stock vacuum lines they are numbered, and the service manual identifies their locations (at least mine are).

 

Oh sweet, that is good to know.

Rode the bike today the temp got as high as 215 but as i was riding it came back down to 185. I pushed it hard to get it to overheat. It seems to like to sit at the 180 to 190 temp while riding around. I'm going to call it good and begin my daily rides.
I really do appreciate all the help. You guys are awesome. thank you!

 

This was the water pump connections on my '99 when I got in 2021. I replaced the hoses but did not check the routing...so...fuck.
Thank-you for posting about your experience & thanks everyone who left comments.

 

Hey, I have a similar issue... The bike is running hot. I have had it for about 14 years and I know it is running way hotter than it used to. I worry that if it gets up to 110 outside, it might overheat even on the freeway. So I figure I need to check the thermostat. But I am having trouble getting the throttle assembly off. I have got it to the point where I have the 4 intake hose clamps loose, but the assembly feels like it is bolted to the motor. I have a paper Honda shop manual, and it has been spot on for 12 years. But now it feels like I am missing something. My neighbor says that sometime the original sealant acts like epoxy. So I tried to pull it off with a come-along. But it just lifts the bike up. Has anyone run into this before, or have any ideas how to get it off the engine? It would not surprise me if this is as deep as anyone has gotten into the bike in 100,000 miles and 26 years.

 

I don’t believe Honda uses any sealant on the throttle body boots/insulators (could be wrong tho). It’s more likely that the rubber on the boots have hardened after so many years and so many miles of heat cycles. That would probably explain why it feels really hard to take off. I would try spraying WD40 around the boots where it meets with the throttle body and slowly prying with a wooden board of some kind (so you don’t scuff or damage anything). I know some people also use either a heat gun or a small flame of some kind to heat up the rubber. Which would make them more pliable and easier to take off. Although I would be very careful if you try using a flame. This method works well for old carbureted bikes but with fuel injected bikes with all the wires, hoses, and sensors around, I would use the flame idea as a last resort. Not the mention you have to be 100% sure there is no gas residue anywhere around the bike.

Buy these. They’re just as high quality as OEM but for cheaper and they’re even made in Japan.

https://ebay.io/m/Qk5psG