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Farkle Purchasing System
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Discussion Starter #1 (Edited)
After a cold winter morning's ride yesterday I found myself in exactly the same situation as OP in this old thread:

https://www.stromtrooper.com/dl1000-2002-2012/88714-coolant-leak-help.html#post977082

Right down to the appearance of the coolant drip.

All the hoses going to the thermostat housing are fairly new because I replaced them in the last year or so, except the small one going downward in the photo (described as "Hose, Water Bypass" in the parts diagram). I don't think that's the source of the leak though.

Might this point to a need for a new thermostat? Since that housing has no gasket or seal aside from the thermostat itself, I can't think of what else it could be allowing the leak.

Also, I'm really sick and tired of taking stuff out of the way to replace cooling system hoses. Partly because I just did it a few weeks ago to replace the short hoses that go to the cylinder heads from the thermostat housing.

Would it be so wrong to paint a bit of exhaust gasket maker on that joint? Might stop the drips until I feel like doing the job "properly," at least.
 

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If you just did work on the cooling system that is probably where your problem lies. A clamp may need a tighten or be moved an bit. Even new hoses can be defective. First thing is to locate the leak. Then if gasket maker will stanch the drip for a while go for it. At least you are still riding. Up here in the great white north most bikes are snuggled in their beds.
 

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I too have had drips on both my 1000's. I found that moving the coolant reservoir plug up about3/8" to leave the overflow hose to vent solved the problem on both. Worth a try.
 

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Farkle Purchasing System
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Discussion Starter #4
I think the coolant reservoir plug thing was the key. Moved it up so the overflow tube was uncovered and got the bike good and warmed up. No more drips so far.

Seems like the coolant system gets too pressurized, and springs a leak at the thermostat if you have the reservoir plug in all the way. You'd think the owner's manual or at least the shop manual would mention this.
 

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Farkle Purchasing System
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Discussion Starter #6 (Edited)
It's the big round rubber bung in the top of the whimsically-decorated coolant tank inside the fairing on the right. Part #12 in the corresponding parts fiche:

https://www.partzilla.com/catalog/suzuki/motorcycle/2007/v-strom-dl1000/radiator-hose

FWIW, I still haven't fully resolved this issue. It seems totally random as to when it does or doesn't happen. A few weeks ago I got a few drops of coolant on my left boot, and could see that coolant had been leaking out of the thermostat, dripping on to the cylinder head and then down the left side of the engine.

Found a little bit of coolant in my skid plate when I took it off to clean some stuff last weekend, too. First time I'd had the plate off in months, so it was recent. It is an Enduro Guardian plate so there is one corner where coolant can pool to an extent. Not more than several drops' worth but still Not Good.

But over the last few weeks, I've been unable to actually observe the coolant dripping out of the thermostat housing.

I finally had enough and ordered a replacement thermostat. Don't know how else to permanently fix this. The thermostat itself is the only rubber component in the area that's leaking. Haven't installed it yet though.
 

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Mine is also completely random. Not sure if I should worry about it? Yesterday took it out for about a 30 mile ride, got home, no leaks. Again, mine appears to be coming out the overflow tube, about where my right foot would be if at a stop and foot was on the ground.
 

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Mine is also completely random. Not sure if I should worry about it? Yesterday took it out for about a 30 mile ride, got home, no leaks. Again, mine appears to be coming out the overflow tube, about where my right foot would be if at a stop and foot was on the ground.
Out the overflow tube is no biggie. Don't worry about it. That's why the tube is there. In my experience, temperature swings while parked can cause a drip.

If it becomes excessive, then you probably need to overhaul the waterpump.

FWIW: Mine did that for a while after rebuilding the waterpump and then stopped. I haven't seen a drip in several years.

To the OP: Is it possible the new hoses you installed are not oriented properly? They have a bend to them and different diameters at each end. It is also possible the O-rings on the unions are not seated correctly. Or, as you suspect, the thermostat could be your source. I haven't dug into the thermostat, but did the hoses and unions last year.
 

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Farkle Purchasing System
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Discussion Starter #9
Out the overflow tube is no biggie. Don't worry about it. That's why the tube is there. In my experience, temperature swings while parked can cause a drip.

If it becomes excessive, then you probably need to overhaul the waterpump.

FWIW: Mine did that for a while after rebuilding the waterpump and then stopped. I haven't seen a drip in several years.
That was going to be my suggestion, but as you say - sometimes the overflow will drip a little for no obvious reason. It's only if it's all the time that you need to think about a water pump rebuild, IMO.
To the OP: Is it possible the new hoses you installed are not oriented properly?
No. Suzi did us a solid here - it's almost impossible to install them wrong.

They have a bend to them and different diameters at each end. It is also possible the O-rings on the unions are not seated correctly. Or, as you suspect, the thermostat could be your source. I haven't dug into the thermostat, but did the hoses and unions last year.
O-rings (#9 in the Radiator Hose parts fiche) are original AFAIK. I have new ones, but decided not to attempt replacement when I put on new connector hoses. Too much work, and the leak wasn't coming from there anyway. Well enough alone and all that.

Haven't had any more leaks from those hoses or their fittings, so I suppose that was a good call.

Reason I think it's the thermostat that needs R&R is that the only coolant drips I can see are coming from there.

I'm replacing the thermostat today, but it's tough going. Even with the fuel tank removed, there is almost no room to work. Removing the airbox will allow a smidge more room to swing a (stubby) wrench. I really don't want to remove the throttle bodies.
 

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Farkle Purchasing System
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Discussion Starter #11
Since the O-rings are down near the cylinder heads but I was seeing drips from the thermostat housing, I'm guessing it was the thermostat that was leaking.

Got the T-stat swapped yesterday. The old thermostat looked fine. Its rubber gasket was still pliable, and looked just as good as the new one. Dunno how it was leaking.

Went for a half-hour or so test ride yesterday, and to work today, with no coolant drips so far. But that doesn't mean much - it was an intermittent leak anyway.
 

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Farkle Purchasing System
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Discussion Starter #12
Nearly bi-weekly update: Looks like a new thermostat fixed the drip. Have been on long rides, lots of short rides, several in between rides, no more drips.

I still don't understand it. Old thermostat looked fine; the rubber was in great shape. But there you are.
 

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Farkle Purchasing System
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Discussion Starter #14
Nevermind, damned thing STILL drips occasionally.

It took a while to work out that it was happening at all. Until last weekend, I never caught it dripping. I'd just find a few white streaks (what evaporated coolant leaves behind) along the top front surface of the stator side of the engine, exactly where you'd expect drips from the thermostat housing to go.

I've tightened the thermostat housing bolts as much as I dare. I really really really do not want to crack the housing. The bolts have blue thread locker on them so they should stay put.

This is so incredibly frustrating. I don't want to have to top off coolant every month, & feel obligated to take extra coolant along on trips. At this point I've replaced all the cooling system rubber, save for the cylinder head O-rings and water pump area (and I'm not getting any leaks from there).

If I still get drips would it be pointless to place a bead of RTV gasket maker along the bottom seam of the thermostat housing? I suppose that might simply redirect the leaking to the top of the housing, but I'm out of answers at this point.
 

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Farkle Purchasing System
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Discussion Starter #16
Before, it looked like I wasn't getting any leaks, but the working theory now is that I get a drippy thermostat housing until the engine warms up sufficiently.

I went for a long-ish ride over the weekend & got home with no evidence of leakage.

T-stat housing bolt torque checked. Service manual calls for only 7.0 lb-ft which is basically "hand-tight."

If the T-stat housing only seals properly once the engine is hot and stays there, that would account for the dripping I've been seeing on more recent, very short rides, and the lack of evidence of leakage after longer rides.

I'm sick of dealing with this, so I've put a bead of RTV (Permatex Optimum Grey) on the seam of the thermostat housing. Giving it a full 24 hours to cure before I ride again. We'll see whether it does anything.
 

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Farkle Purchasing System
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Discussion Starter #18
No dripping seen after two short rides (<5 miles each). I think the RTV gasket maker did the trick. Have not been riding much the last week, but will be going on a long-ish ride this afternoon.
 

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Farkle Purchasing System
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Discussion Starter #20
I'm reluctant to say "it's fixed" given the prior experience, but it hasn't dripped again so far. Did not smell any hot coolant during today's ~4 hours of riding, nor did I observe any dripping from the usual location.
 
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