Radiator overflowing

[Jarhead28]

The other day I was coming down off a high speed run on I 40 with my '99 Valkyrie and got some coolant splash when I got off the exit.
Thought it was just a normal hot summer overheat but now it's starting to splash from the radiator cap.
Deadlined the Valk until the new radiator cap comes in but, since it happens too much now during normal driving I was wondering if it might be a head gasket or something else that someone may have had similar experience with.
I'll keep close to the notes and will get back when the new cap is installed.
Semper Fi
Mike

[Steel cowboy]

The radiator cap has a locking Allen screw on the side to stop it from loosing up. If it's not tighten down you could experience leaking from the area of the cap.

[longrider]

Since our valks are getting older it may be wise to check proper operation of the fan.  Also I remove the radiator every couple of years.  Lay it on a white cloth.  I set my pressure washer down to a very low pressure and gently wash straight on the fins BACKWARDS through the rad.  Lots of stuff will show up. 

[pancho]

Check the overflow hose leading to tank to make sure it is clear. Mine had become kinked where it goes behind the radiator.

[Jarhead28]

Thanks for all of the suggestions. The cap has the required screw and was tightened during normal operation. The two rubber seals inside the cap appear to be in good condition but "appear" and "actual" may not be the same.
The amount of coolant that was exiting during normal riding conditions was excessive and of concern. I will check the overflow tube for blockage and will also wait for the new cap to arrive to see if that was the problem.
I appreciate the suggestions and will attempt to radiator fin cleaning. What is the difficulty level of removing the radiator? I'm fairly mechanically adept and have a very complete shop in my 2400 sq. ft. garage.
I'm located between Hickory and Statesville, NC off I-40 in case anyone wants to drop in for a session. The fridge is stocked with adult beverages.
Semper Fi
Mike

[Bighead]

One question. Did you recently put a chrome cover over the radiator cap? Reason I ask is I have one on my ‘97 Bee that is billet and has a set screw to hold it to the radiator cap. No problems in 22 years. A couple of years ago I wanted one on my IS. But that one is waaaaayyyy out of production, so I find one that says it fits. So I get it and put it on ,looks good. But after about 6/7 miles I start smelling hot antifreeze, look down and the whole side of the engine is covered and all over my boot. Anyway it didn’t quite fit easy. So while forcing it on I broke the seal on the gasket on cap. Just removed it and loosened the cap tightened it back never leaked another drop.

[pancho]

The radiator removal is not hard at all. If you need a service manual, one can be downloaded here.

http://www.valkyrienorway.com/download.html

[klb]

Mine started leaking a couple years ago. Everything looked good so all I did was tighten the tabs a bit on the cap and no leaks since. Hope your new cap  will solve the problem. You are close I live in Hickory off I-40 near exit 125.

[gordonv]

Any guaranty that the leak is coming from the cap, and not the top radiator hose?

[RWhitehouse]

I was getting little dribbles of coolant from the cap now and then, I'd generally notice dried streaks of coolant on the side of the tank or the hose after most rides in warmer weather.

I just replaced the 21 year old cap and the issue vanished. a OEM honda one was less than $20 online. There is a Mr Gasket aftermarket cap with a little temp gauge built in, but I read too many reports of these leaking as well, so stuck with OEM.

[MarkT]

After you get this leak solved, you might want to look into replacing the coolant with Evans waterless permanent coolant.  It prevents corrosion, hot spots around the cylinders and heads eliminating cavitation, eliminates the coolking system running under pressure with it's very high boiling point so never a boil over, and eliminates maintenance on your cooling system.  Yes it's expensive but once done, never change the coolant again.  I've put it in all of my Valks, Gold Wing, Kubota and 4Runner.
Watch this:  https://www.youtube.com/watch?v=t7PykrgzWPQ

[WintrSol]

After you get this leak solved, you might want to look into replacing the coolant with Evans waterless permanent coolant.  It prevents corrosion, hot spots around the cylinders and heads eliminating cavitation, eliminates the coolking system running under pressure with it's very high boiling point so never a boil over, and eliminates maintenance on your cooling system.  Yes it's expensive but once done, never change the coolant again.  I've put it in all of my Valks, Gold Wing, Kubota and 4Runner.
Watch this:  https://www.youtube.com/watch?v=t7PykrgzWPQ

Not sure I like some of the cons with that stuff: https://greengarageblog.org/17-waterless-coolant-pros-and-cons

[MarkT]

After you get this leak solved, you might want to look into replacing the coolant with Evans waterless permanent coolant.  It prevents corrosion, hot spots around the cylinders and heads eliminating cavitation, eliminates the coolking system running under pressure with it's very high boiling point so never a boil over, and eliminates maintenance on your cooling system.  Yes it's expensive but once done, never change the coolant again.  I've put it in all of my Valks, Gold Wing, Kubota and 4Runner.
Watch this:  https://www.youtube.com/watch?v=t7PykrgzWPQ

Not sure I like some of the cons with that stuff: https://greengarageblog.org/17-waterless-coolant-pros-and-cons

None of the cons listed apply to my installs except the price. I can discuss them one by one but won't bother unless this thread continues about that.  I've been using it for years and I'm completely happy with it - no complaints except the price and now I have no cooling maintenance and no chance of aluminum corrosion.  Works for me - based on years of experience with multiple vehicles.

[Valk737]

My fluid was transferring into the reservoir and then out of the reservoir on to the ground.  A new radiator cap fixed it

[F6Dave]

When I bought my Interstate used in 2005 a bit of coolant leaked around the cap.  Since it still had the Honda extended warranty, the dealer ordered me a new cap.  I swapped it myself in the parking lot and thought all would be good.  It wasn't.

It rode home and it still leaked.  So, I did what was suggested in another reply:  I bent the tangs on the radiator opening ever so slightly so the cap would tighten up a bit tighter.  Problem solved.  It hasn't leaked in over 90,000 miles.