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oh no, not another Vee coolant drip thread!

16K views 119 replies 9 participants last post by  larolco 
#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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#2 ·
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.
 
#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.
 
#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.
 
#8 ·
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.
 
#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.
 
#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.
 
#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.
 
#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.
 
#21 ·
Desertbike, was that you who posted elsewhere about exhaust dents, or am I misremembering?

I happened to be under mine this weekend swapping out chain and sprockets and had a look. There is a factory dent on the kickstand side to allow for the OEM center stand, but there is no indentation on the other side. So, I do believe you have dented your pipe.

I also think you should not worry about it since there is an almost identical one, factory-installed, just a few inches away.
 
#22 ·
Yep that was me. I'm just going to leave it be. No impact to fuel economy seems apparent. I got 44 mpg on my last tank (it helps to stay off the interstate!).

The most likely culprit for the extra dent would have to be a rock. Before the skid plate, I did a fair amount of riding on rocky dirt roads. Can't remember bottoming out the suspension hard enough to do something like that but who knows?

If the extra dent were caused by a rock though, I would expect it to not be so gently curved. You'd think a sharp rock would have almost punched a hole in the metal or at least creased or scratched it. Go figure.
 
#26 ·
Inevitably, some evidence of leakage, but it's so slight that I couldn't figure out where it was coming from.

Happened after a very short (<5 minutes total engine run time) ride.

At least I'm pretty sure it was coolant. Felt greasy like coolant does, but there wasn't enough to get a good look and I certainly wasn't going to taste it.

I guess I'll call that a win? Previously I would get enough drippage to pool between the cylinder heads. Now I'm just getting one or two drops.

Still nothing on longer rides, so I guess there's that.

I give up. I'm not tearing the bike halfway apart to replace the coolant union O-rings (especially given I can't even trace the leakage there), but maybe I'll do them when I have the airbox off for something else, later this year.
 
#29 ·
At least I'm pretty sure it was coolant. Felt greasy like coolant does, but there wasn't enough to get a good look and I certainly wasn't going to taste it...
How is your (clutch) slave cylinder doing?

..Tom
 
#28 ·
update to the update: I slathered on some more RTV, double-coating the area that was visibly dripping & extending the "gasket" a bit. Gave it a full 24 hours to cure.

Fingers crossed, no more drips so far.

If I can't 100% eliminate the drips I guess I can live with it. Leakage is greatly reduced vs. before applying the RTV gasket maker, and doesn't seem to happen at all as long as I ride more than ~5 minutes.
 
#31 ·
Yeah forgetting the sleave/spacer was why I broke my first one. :)

You seemed unsure if the coolant drip was actually coolant. With it coming from the left side I wondered if it might be fluid from a leaky slave cylinder.

..Tom
 
#33 ·
Ugh, I was STILL getting some drips despite the RTV.

I applied more RTV. Seems to have stopped the drips again, at least temporarily.

It's possible that while I've stopped leakage through the bottom seam of the thermostat housing, the coolant is just leaking out of the top seam instead. I couldn't get RTV up there without smearing it all over lots of other stuff & making a huge mess, so I didn't try.

I now have some different RTV, designed specifically for coolant system sealing. The next time I have the tank and airbox off, I'll clean off the gray RTV & put a bead of the "water pump" RTV between the thermostat housing halves.
 
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