Running warm?

[xp8103]

I think I brought this up last year but I don't remember. But it seems to be getting worse, not better. While my AF reservoir is at its proper level, my bike will run warmer than I think it should. Even on cool mornings (like last Saturday before the heatwave took hold) after a cruise I hear the cooling fan come on. And when it really warms up outside, I can't let the bike idle for any length of time as the temp light will flicker and come on. Once I start moving again, the light will go out.

Water pump not?

[PGlaves]

Thermostat maybe.

Water pump - possible but unlikely.

The first thing I would do would be to thoroughly clean and debug the exterior of the radiator. Soap or simple green - then water - repeat. You want all the radiator passages to be clear - and you want to get all of the layers of bug guts off the radiator fins - down to the aluminum.

If that doesn't cure the problem then check the thermostat.

I have never seen internal clogging of a K bike radiator but I suppose it can happen.

Good luck.

[xp8103]

Thermostat maybe.

Water pump - possible but unlikely.

The first thing I would do would be to thoroughly clean and debug the exterior of the radiator. Soap or simple green - then water - repeat. You want all the radiator passages to be clear - and you want to get all of the layers of bug guts off the radiator fins - down to the aluminum.

If that doesn't cure the problem then check the thermostat.

I have never seen internal clogging of a K bike radiator but I suppose it can happen.

Good luck.

Paul,
Will do that this afternoon. Have a pressure washer that I can regulate pressure with so perhaps with that and some elbow grease I can clean it out.

[tvguy]

K-bikes run hot so the fan coming on is not that unusual. But the overheat light should not be on. Are you sure the coolant level is right? Sometimes the overflow hose (that goes to the external coolant tank) can get a hole or disconnected fooling you into thinking the radiator level is right. The first thing I would do is check, pull off the body work, check that little hose then open the radiator cap and take a look too (do this when the bike is cold:doh )

Could the radiator be plugged? These bikes are getting old enough that it is a possibility. Lax or deferred maintenance of the cooling system could be a problem. Coolant needs to get dumped and replaced about every two years.

In my experience the water pump gives you a nice little puddle under it as reminder that it is starting to go bad, but I'll let the experts chime in on that.

Good luck!

[xp8103]

K-bikes run hot so the fan coming on is not that unusual. But the overheat light should not be on. Are you sure the coolant level is right? Sometimes the overflow hose (that goes to the external coolant tank) can get a hole or disconnected fooling you into thinking the radiator level is right. The first thing I would do is check, pull off the body work, check that little hose then open the radiator cap and take a look too (do this when the bike is cold:doh )

Could the radiator be plugged? These bikes are getting old enough that it is a possibility. Lax or deferred maintenance of the cooling system could be a problem. Coolant needs to get dumped and replaced about every two years.

In my experience the water pump gives you a nice little puddle under it as reminder that it is starting to go bad, but I'll let the experts chime in on that.

Good luck!

Eyeballed the overflow hose over the weekend when I had the gas tank off and it looks to be correctly attached and hole free. I would assume a hole in the overflow would create AF leaks. The sight tube in the reservoir shows the correct level.

[deilenberger]

Eyeballed the overflow hose over the weekend when I had the gas tank off and it looks to be correctly attached and hole free. I would assume a hole in the overflow would create AF leaks. The sight tube in the reservoir shows the correct level.Bad assumption. The tube isn't under pressure when it is dribbling excess coolant down to the coolant reservoir.. so no leaks. But - it is under a vacuum when it tries to pull the coolant back into the system - and then the tiny hole/crack prevents it from pulling the vacuum. That makes it a one way system - fluid goes down, and never goes back up to the radiator.

If you've never replaced the hose - do so. It owes you absolutely nothing, and the cracks form at the radiator connection where you can't see them. When you removed the tank, did you check if hose is cracked or not? It often cracks on the bottom where it isn't immediately visible. Since you have removed the tank, can we assume you also checked the level in the radiator by removing the radiator cap?

[xp8103]

Bad assumption. The tube isn't under pressure when it is dribbling excess coolant down to the coolant reservoir.. so no leaks. But - it is under a vacuum when it tries to pull the coolant back into the system - and then the tiny hole/crack prevents it from pulling the vacuum. That makes it a one way system - fluid goes down, and never goes back up to the radiator.

If you've never replaced the hose - do so. It owes you absolutely nothing, and the cracks form at the radiator connection where you can't see them. When you removed the tank, did you check if hose is cracked or not? It often cracks on the bottom where it isn't immediately visible. Since you have removed the tank, can we assume you also checked the level in the radiator by removing the radiator cap?

I did remove the cap but since the bike was cold didn't think that I should see much in there. Will do that this afternoon as well. You guys are the best.

[xp8103]

Well....... We pulled the tank and checked the overflow tube by pressurizing it. No problem here. Pulled the cap off the radiator. Ok, there was nothing there but it's a short hose to the top of the radiator. So we pulled the short tube off. Still didn't see anything. Replace the short tube and decide to start pouring in AF and see what happens. It took more than it should have. Really. We could hear it gurgling in the radiator. Eventually it filled and was slightly below the cap. Put the tank back on and fired the bike up. Let it run at idle for at least a half an hour. The cooling fan came on eventually and would start and stop with regularity, but the high temp light never came on.

We took that as a good sign. We'll see.... Thanks for all the helps guys!

[JPK1100]

Thanks for asking... My K1100 behave a little bit like yours, although no warning lamp yet.

I know they run warm, but I am also sure this one has been warmer for a year or two.

It gets warmer earlier; the fan starts earlier too and stays on longer.

I changed the coolant last year, with no results.

So I will follow the checking procedure prescribed by Don and Paul

JPK1100
Somewhere in Canada (and not very far from Maine)

[deilenberger]

The fluid did go somewhere. If I had to guess - my WAG would be your cap may be crudded up (tech-term).. they do that. Deposits plug the valves in it and they hang up open.. which allows the coolant to pump itself down to the reservior.

If that is the case - a new cap is about $20 or so. Worth doing every 5 years or so, just to get new rubber gaskets on it. If that isn't the case, I'd be looking for where the coolant went to. It doesn't evaporate, it's a sealed system. Check the bottom of the water/oil pump for drips. Coolant drips aren't good. There is a weep hole on the bottom of the pump - swipe your finger across it and see if it comes off with antifreeze on it.

Glad the mystery is semi-solved..

[xp8103]

Don,
Agreed. But I have not seen any of the tell-tale signs in any of the tell-tale spots. The water pump is dry. The oil was changed last fall shortly before winter storage after about 4000 miles and showed no sign of AF.

I'd be willing to guess that perhaps the thermostat (or water pump?) was changed before I got the bike? It was at the dealership for almost a year and could have been changed even before that and the radiator improperly filled to begin with. The first time I noticed something was amiss was on the way home from the first significant tour I took with it after only owning it about a month. It was a cold rainy wet late April morning and we stopped on the side of the road to chat with a fellow we hooked up with who was in the last leg of his Florida to Maine ride on his new bike. I left my K idling while we talked. When I walked back to it, the temp light was on.

Let's hope it's fixed.

[deilenberger]

Nik,

Hope so. I would suggest (which I'm sure you're doing anyway) - just keep an eye on the coolant level in the radiator.

I have had the caps go bad.. the seals shrink and the caps no longer seal the system under pressure, and the little valves inside the caps crud up and no longer seal. This can cause pumping of the fluid down to the reservoir - where it weeps out unnoticed. BTDT. I tried cleaning the cap and replacing the seals - then I realized a new one is really a cheap part (for a BMW) - and just replaced it. End of problem.

Just a thought. And good luck!

[xp8103]

Thanks Don. I think a new cap might be good insurance. The more I get into the bike the more I realize that there are a lot of likely 21 year old parts still on it and I would'nt be surprised if the cap is one of them.