Cold coolant leak saga...
- Elmobile
- Posts: 256
- Joined: Sat Aug 22, 2015 8:35 pm
- Location: Bridgewater, Nova Scotia, Canada
- Motorcycle: 1990 GL1500SE
Cold coolant leak saga...
I have had a cold coolant leak for quite a while now.
Recently I decided to tackle it. I purchased all the O rings for the water pipes and the seals for the intake manifolds with the best intention to replace them. I removed both radiators and fans to see better down under... When I realized how much work I was getting into and more importantly no traces what so ever of any leaks, I decided to back out of it...
Put every thing back together with new clamps. No leaks for about 10 days BUT now it is back...
When I start the engine, first time in the morning, I get a small puddle under the front cowl. I measure it, it is about 15 cc (5 oz), not much. then as soon as the engine barely warm up, it does stop and will NOT do it again, regardless how many time I start/stop for the rest of the day.
So I decide to go deeper and find the source.
I removed the front lower fairing, the radiator grille and the left fan. Because it stops so quickly, I could not trace it visually completely but I believe that it is coming from the thermostat cover, next to the screw on the side of the left fan. Long story short, I have a couple of questions:
According to the service manual, I only need to remove the radiators to gain access to the 3 bolts holding this cover. Is that correct? Next question:
Do I really need to do this now? As far as I can see the clamp for the water hose on the top of the cover is pointing the wrong way. I am not sure I can get it loose from the front, meaning I may have to get at it from the top?
I am not planing any long trip this summer, just day trip within the province. Would monitoring the coolant level be safe enough so I can keep riding until the season is over? Any thoughts?!
Recently I decided to tackle it. I purchased all the O rings for the water pipes and the seals for the intake manifolds with the best intention to replace them. I removed both radiators and fans to see better down under... When I realized how much work I was getting into and more importantly no traces what so ever of any leaks, I decided to back out of it...
Put every thing back together with new clamps. No leaks for about 10 days BUT now it is back...
When I start the engine, first time in the morning, I get a small puddle under the front cowl. I measure it, it is about 15 cc (5 oz), not much. then as soon as the engine barely warm up, it does stop and will NOT do it again, regardless how many time I start/stop for the rest of the day.
So I decide to go deeper and find the source.
I removed the front lower fairing, the radiator grille and the left fan. Because it stops so quickly, I could not trace it visually completely but I believe that it is coming from the thermostat cover, next to the screw on the side of the left fan. Long story short, I have a couple of questions:
According to the service manual, I only need to remove the radiators to gain access to the 3 bolts holding this cover. Is that correct? Next question:
Do I really need to do this now? As far as I can see the clamp for the water hose on the top of the cover is pointing the wrong way. I am not sure I can get it loose from the front, meaning I may have to get at it from the top?
I am not planing any long trip this summer, just day trip within the province. Would monitoring the coolant level be safe enough so I can keep riding until the season is over? Any thoughts?!
- golden highway
- Posts: 401
- Joined: Mon Dec 31, 2012 9:23 am
- Location: Louisville, Kentucky
- Motorcycle: 1987 Interstate
1998 Aspencade
Re: Cold coolant leak saga...
I think a lot of 1500’s do this. Mine did this only when the temperature dropped close to freezing but only small amount and doesn’t continue. Seems like after you see the small drip you don’t see anymore until the weather warms up for awhile and drops again. In the warm weather there are no issues. I never really found where it comes from. I did a search and it seemed to be a common issue. Mine stopped on it’s own years ago. I would make sure your antifreeze is full which it probably is and forget about it unless it drips all the time. I forgot about mine and 8 years and no issues.
- AZgl1800
- Posts: 2932
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'02 GL1800 lives in Dawsonville, GA now.
My son is going to enjoy it for many years to come.
Re: Cold coolant leak saga...
my '94SE had a seep...
I just ignored it rode on.
I just ignored it rode on.
- minimac
- Posts: 929
- Joined: Mon Aug 06, 2012 9:25 am
- Location: Oswego, NY, Leesburg, Fl
- Motorcycle: 1993 GL1500 Aspencade
2006 Yamaha Morphous
2011 Silverwing
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Re: Cold coolant leak saga...
On mine, I can sometimes smell a coolant leak-but it is only occasionally. I couldn't find a source, or even evidence, of a leak. I made sure all of the hoses were visually good, and made sure the clamps were all tight. I got in the habit of checking the fluid level weekly. Sometimes it's good, sometimes I need to add a little. It's NOT going into the oil, so it's a minor PITA, but a lot less aggravating and easier than pulling every thing apart.
- bigsteveswing
- Posts: 161
- Joined: Mon Jun 11, 2018 4:40 pm
- Location: Erie, PA
- Motorcycle: 1992 GL1500I
Motorvation Formula II sidecar
Re: Cold coolant leak saga...
Last winter mine sat in the garage under cover next to wifey's car. No leaks or puddles for a couple months, then the temp dropped to below zero in February and all of a sudden I had a small (about 3 inches round) puddle of coolant. Cleaned it up and have never seen another one, checked coolant level and changed oil in spring and all was good. I think the metal contracted in the extreme cold.
I'm keeping my eyes open but not losing sleep over it.
I'm keeping my eyes open but not losing sleep over it.
Big Steve
Keep America Strong: Weld It
Keep America Strong: Weld It

- DenverWinger
- Posts: 2318
- Joined: Thu Jun 23, 2011 2:20 pm
- Location: Denver, CO
- Motorcycle: (s)
'80 GL1100 STD Vetter (2005-)
'93 GL1500 Aspencade (2017-)
'83 Trav-Lite Camper (2010-)
Past rides
'72 CL350 (1980-1988) sold
'78 Suzuki GS550 (1985-2005) sold
'77 GL1000 (2002-2006) sold
Re: Cold coolant leak saga...
Mine will drip maybe a half-cup of coolant on first start after a long sleep or if it's been particularly cold.
Never a drip after that, though. If someday carburetors or something else causes me need to tear into the guts of her I might see if I can find where the drip comes from... but unless that happens I'm just not gonna worry about it.
Never a drip after that, though. If someday carburetors or something else causes me need to tear into the guts of her I might see if I can find where the drip comes from... but unless that happens I'm just not gonna worry about it.

A local inventor has figured a way to turn a sausage grinder backward to manufacture pigs.
♫ 99 Little Bugs in the Code, ♪
♪ 99 Bugs in the Code. ♫
♫ Take one down, Patch it around, ♪
♫ 127 Little Bugs in the Code. ♫ ♪
~Mark

♫ 99 Little Bugs in the Code, ♪
♪ 99 Bugs in the Code. ♫

♫ Take one down, Patch it around, ♪
♫ 127 Little Bugs in the Code. ♫ ♪

~Mark
- Elmobile
- Posts: 256
- Joined: Sat Aug 22, 2015 8:35 pm
- Location: Bridgewater, Nova Scotia, Canada
- Motorcycle: 1990 GL1500SE
Re: Cold coolant leak saga...
Some comfort knowing I am not alone with this issue...
Joke aside, I have been riding it while keeping a close eye to what's happening and fluid level. It only leaks when I crank the engine, not much and not for very long. It is coming from the front of the thermostat cover. I had to remove the left fan to have a better look but it is there!
The 1500 is my primary ride for this summer. I want to make sure that I do not have any other underlying reliability issue(s). I did get the seal for the thermostat and hopefully will not have to use it until next winter. It is with my stash of parts for upcoming project!
Now if only I could get to improve my mileage. Only got 26.7 and 26.8 on my last 2 tanks. I know I am dragging a sidecar but still think I should do better. Wondering how synchronizing the carbs could affect the mileage performance?
On the other hand, riding a sidecar is too much fun!
Cheers.

Joke aside, I have been riding it while keeping a close eye to what's happening and fluid level. It only leaks when I crank the engine, not much and not for very long. It is coming from the front of the thermostat cover. I had to remove the left fan to have a better look but it is there!
The 1500 is my primary ride for this summer. I want to make sure that I do not have any other underlying reliability issue(s). I did get the seal for the thermostat and hopefully will not have to use it until next winter. It is with my stash of parts for upcoming project!
Now if only I could get to improve my mileage. Only got 26.7 and 26.8 on my last 2 tanks. I know I am dragging a sidecar but still think I should do better. Wondering how synchronizing the carbs could affect the mileage performance?
On the other hand, riding a sidecar is too much fun!

Cheers.
- ct1500
- Posts: 1562
- Joined: Wed Nov 10, 2010 8:09 pm
- Location: Glastonbury,CT
- Motorcycle: 1988 GL1500
- Contact:
Re: Cold coolant leak saga...
The plastic thermostat outlet cover gets warped with age, I would have that on hand also.
Local and need repair help with your 1500, Valkyrie or ST please click contact
Nothing leaves my shop till its' perfect
This is what I do
Nothing leaves my shop till its' perfect
This is what I do
- bigsteveswing
- Posts: 161
- Joined: Mon Jun 11, 2018 4:40 pm
- Location: Erie, PA
- Motorcycle: 1992 GL1500I
Motorvation Formula II sidecar
Re: Cold coolant leak saga...
That's about what I average on in town runs, never really ridden long distance yet. I am also putting "substantial" load on the bike seat in addition to the sidecarElmobile wrote: ↑Mon May 25, 2020 5:40 am Now if only I could get to improve my mileage. Only got 26.7 and 26.8 on my last 2 tanks. I know I am dragging a sidecar but still think I should do better. Wondering how synchronizing the carbs could affect the mileage performance?
On the other hand, riding a sidecar is too much fun!![]()
Cheers.

+1 on the fun factor though

Big Steve
Keep America Strong: Weld It
Keep America Strong: Weld It

- Elmobile
- Posts: 256
- Joined: Sat Aug 22, 2015 8:35 pm
- Location: Bridgewater, Nova Scotia, Canada
- Motorcycle: 1990 GL1500SE
Re: Cold coolant leak saga...
Looks like I better get use to this mileage! Was hoping for a little better but it is what it is...
CT1500: I know I probably should but that would be another $60.00/$65.00 here in Canada. So I'll try the seal first and if needs be It will another redo with the cover. Looks like you can get to it from the front once the radiators are out. Doesn't look too bad if the screws come loose that is...
And thanks again for your help with the carbs rebuilt. The bike is now behaving like I think it should...
CT1500: I know I probably should but that would be another $60.00/$65.00 here in Canada. So I'll try the seal first and if needs be It will another redo with the cover. Looks like you can get to it from the front once the radiators are out. Doesn't look too bad if the screws come loose that is...
And thanks again for your help with the carbs rebuilt. The bike is now behaving like I think it should...

- Elmobile
- Posts: 256
- Joined: Sat Aug 22, 2015 8:35 pm
- Location: Bridgewater, Nova Scotia, Canada
- Motorcycle: 1990 GL1500SE
Re: Cold coolant leak saga...
Well as I said before I did not replace it... I took a piece of glass with 220 emery cloth on it to "resurface" the cover. Looked real good once I was done. It took quite a bit to have a flat surface again. Ran all summer (7500kms) without any trace of a leak.
About a month ago we had a cold front. Temperature dive down to -10C (14F). Next morning I had a small green puddle under. I thought I was in trouble again... BUT we are now in cold weather again and no sign of trouble so go figure!
I will not redo it again if it stays as is. However, long story short, my advise would be to replace the cover. It is not an easy job. Lots of stuff in the way to get at the screw behind the cover...
Hope this help!
About a month ago we had a cold front. Temperature dive down to -10C (14F). Next morning I had a small green puddle under. I thought I was in trouble again... BUT we are now in cold weather again and no sign of trouble so go figure!
I will not redo it again if it stays as is. However, long story short, my advise would be to replace the cover. It is not an easy job. Lots of stuff in the way to get at the screw behind the cover...
Hope this help!
- jek7galo
- Posts: 37
- Joined: Wed Jan 03, 2018 9:55 am
- Location: Porto Alegre - Brazil
- Motorcycle: 1998 - GL 1500 SE
2000 - ZX 12R
1995 - ZG 1200
1986 - CBX 750 F
Re: Cold coolant leak saga...
thanks for your answer, I did the same process with the sandpaper, but now a crack has appeared in it, I will have to replace it.
not to mention the broken screw that I had to remove the first time I removed it
not to mention the broken screw that I had to remove the first time I removed it

- Elmobile
- Posts: 256
- Joined: Sat Aug 22, 2015 8:35 pm
- Location: Bridgewater, Nova Scotia, Canada
- Motorcycle: 1990 GL1500SE
Re: Cold coolant leak saga...
A crack!... I did not consider that possibility
I am going to remove the carbs as part of my winter list to have them ultrasonic cleaned. While everything is opened, I am now thinking to replace that part as well as replacing the O ring in the cooling tube. I bought them when I was looking for my coolant leak not knowing where it was coming from.
Looks like it is going to be a long winter list
Cheers

I am going to remove the carbs as part of my winter list to have them ultrasonic cleaned. While everything is opened, I am now thinking to replace that part as well as replacing the O ring in the cooling tube. I bought them when I was looking for my coolant leak not knowing where it was coming from.
Looks like it is going to be a long winter list

Cheers