Coolant loss and running hot

Information and questions on GL1500 Goldwings (1988-2000)
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Joined: Mon Oct 29, 2012 7:59 pm
Location: Campbellville, ON, Canada
Motorcycle: 1992 GL1500SE

Coolant loss and running hot

Postby fnickel » Wed Aug 13, 2014 8:38 pm

Recent 5-day trip around Lake Huron on my '92 SE. I had left the 2 plastic covers off above the rad cap and the overflow tank in order to better monitor coolant levels during the trip, because I had some coolant seeping out over the cold winter during storage. On the second morning of the trip, when checking the level in the coolant overflow bottle, the level was suddenly full, right to the top, not in between the dipstick marks where I had filled it to. Puzzling, right? I didn't check the level in the rad, but decided I would continue and closely monitor the levels. While riding that morning, the engine temperature steadily increased over the next hour and a half until I decided to fill up gas and check out the coolant situation. The temp was not into the danger zone yet, but was at about the 3/4 mark, and there was evidence of coolant loss all over the left side of the bike (on the inside of the left handlebar, all over the left side bodywork, even as far as the left rear bag). After letting things cool down a bit, I added water to the rad. It took about 1.5 quarts of water to fill it to the top. We continued on our way in Bay City, MI to the Honda bike dealer about a mile up the road to get some advice. Checking it out with the service advisor, we found no evidence of leaks at that time, and he recommended to continue on the trip, monitoring the levels. The only thing he had noticed, was that the lid for the coolant recovery bottle was not on tight, which might have led to some loss out of that bottle. There have been no further issues, and I have since replaced the hose inside the coolant recovery bottle on his recommendation, and the hose running from the coolant recovery bottle to just under the rad cap. Still no issues, no obvious coolant loss, or overheating problems.

Now, some questions. Does anyone have any ideas what happened to cause this?
1. Did the thermostat get stuck closed? If it did, what should/would happen? As coolant overheats and boils and expands, is there a relief valve that allows the pressure and coolant to escape? Did this possibly occur in this case?
2. Is the coolant loss all over the left side of the bike explained by the cap not being tight on the coolant recovery bottle? Why would the level in that bottle still be full, and the loss all have occurred from the rad and engine?
I'm just wondering if I should be getting deeper into this issue this winter to solve this (if there is something to solve), and whether I should look into the winter leaking problem during storage (coolant collecting on the right cylinder head, and then dripping onto floor. I am told that is probably the O-rings on the lines running to the carbs and manifolds).
Any and all advice by you experts will be considered, and thanks in advance for any opinions and suggestions.

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Re: Coolant loss and running hot

Postby cbx4evr » Wed Aug 13, 2014 9:16 pm

When a thermostat sticks closed you will overheat the engine. The relief valve is built into the rad cap. When it lifts the coolant will flow into the coolant recovery tank.

I suspect that the loose cap on the recovery tank allowed the tank to overflow and that is what you are seeing. Normally there is a hose on the coolant recovery tank that the coolant would flow out of onto the ground under the bike. Your loose cap negated that.

Not sure why you would have overheated or had too much coolant in the first place but I have a suspicion. Did you refill the system when you noticed it weeping from over the winter? If so you may have just over filled it.

One character about glycol sitting in cold storage over the winter is that it will weep slightly. I have that every spring on both my water cooled bikes. It doesn't amount to too much coolant but it sure gets my mind racing about what could be wrong. I will usually wipe off the area and watch for any leaks after putting the bike into service. So far so good.
"It´s a friggen motorcycle, it´s not supposed to be comfortable, quiet or safe. The wind noise is supposed to hurt your ears, the seat should be hard and riding it should make you s**t your pants every now and then. "

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Re: Coolant loss and running hot

Postby WingAdmin » Wed Aug 20, 2014 10:06 am

I agree that it sounds like it was overfilled over the winter - I also get minor coolant leakage during the winter, and it goes away once it warms up.

You might want to check for cracks in the cap nipple or reservoir nipple, as well as the hose leading from one to the other. A small crack in any of these areas might not be enough to leak coolant when it is being pushed from the radiator cap to the reservoir. However, once things cool down, instead of fighting gravity drawing coolant up from the reservoir, it will suck air through the crack. The end result is the radiator pushing hot coolant out to the reservoir, and replacing it with air when it cools down. You check the radiator, it's low, so you fill it up. It gets hot, pushes coolant out to the reservoir, which now overfills/overflows. Once it cools, the same thing happens, it sucks air back into the radiator instead of coolant.

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Re: Coolant loss and running hot

Postby fnickel » Wed Aug 20, 2014 9:34 pm

Thanks to both of you, cbx4evr and WingAdmin for your replies. Your insight has given me some assurances that things might be OK. I have replaced the hose between the rad and the coolant overflow bottle, and also the pickup hose that goes to the bottom of the coolant overflow bottle. Both of these did have cracks in them. Next spring I will pay proper attention to the first start-up, and adding of coolant to the system, and monitoring it afterward. The bike has been running normally in the last 6 weeks since the episode on the trip; no overheating, no coolant loss, everything good.

Is there a good reason to replace the thermostat over winter, even though it is acting normally now? Do they tend to get erratic with age, or do they stay pretty consistent? Are you aware of anyone bypassing the part of the cooling system that goes to the carbs and intakes? What would this do to the start-up and cold weather running characteristics of the bike? Would some of the sensors need to be disconnected in order to make this happen? If the running characteristics of the bike would not be adversely affected, it might be worth doing this in order to eliminate the seepage and leaking issues in those areas. I think the rest of the cooling system seems to be pretty robust. Thanks again to the forum for your help. Greatly appreciated.

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