I think I ruined my bike. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 22 (permalink) Old 07-24-2017, 09:41 AM Thread Starter
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I think I ruined my bike.

Well maybe not RUINED,

if you guys have seen my other post about the cooling issues I'v been having, you would know that iv tried a ton of things to get my cooling situation in order. Today I thought I had it all fixed, completely flushed the coolant and refilled it with 50/50 mix. And yes I did it properly, the radiator and reservoir were both full and free of air in the system (i bled the air). So today I took it for a spin to a wawa thats about a mile from my house. when I got to wawa, it seemed to be working perfectly, no coolant dumping out everywhere and the temp was reading about 1/2 way between cool and hot. However on the ride home everything seemed normal until i turned onto my road. Im about 1 minute from my house at this point, as I drive down my road, the temp guage is reading about 3/4 the way to the hot zone. then when I was literally 15 seconds from my house the guage was on the boundry of the red zone. when I pulled in my driveway I immediately turned off the engine and I was still just on border of the normal / hot zone. The gauge needle was splitting the white line from the red line basically. But then after the engine was off for about 5 seconds, I heard this loud hissing sound, and then a loud POP sound and next thing I know im in a cloud of steam (smelled of coolant) that was coming from the front portion of the engine. So i feel like I blew a head gasket and I have no clue what to think. The engine is now tinted orange from the coolant and im just praying that I didnt completely f**k my bike that I literally just got 3 days ago. Im hoping it wasnt from the cylinder but I am doubtful that it was something else.

EDIT: I also forgot to mention that the radiator fan was not running at all during this whole thing, even though I know it works because I saw it on yesterday?

EDIT2: Welp I found out what happened. After letting the bike cool down for a bit I went out to inspect the damage. Turns out the upper coolant/radiator hose burst. Figuring its 27 years old, it doesnt surprise me. But still with this issue now solved, I still just dont understand why it keeps overheating in the first place. I completely refilled all the coolant and bled the air, what could be the issue? maybe the thermostat?


Last edited by hayflana; 07-24-2017 at 10:27 AM.
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post #2 of 22 (permalink) Old 07-24-2017, 10:53 AM
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thank goodness! I was hoping it was just a coolant hose.

As for the issue, yeah it could be the t-stat, could be the radiator clogging, could be the coolant you used. You said it was orange, did you use dexcool? If so, why? I believe these bikes specify green coolant, which I run with no problems.

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post #3 of 22 (permalink) Old 07-24-2017, 10:55 AM
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Sounds like the fan isn't working right. At speeds below a constant 35-40mph, that's a problem. Could be the fan switch, or the blue wire at the Junction Box is loose on the spades, as mine was. The fan should have been running the whole time temp gauge was above halfway.

I would put a complete set of hoses on my parts list. You don't want hoses popping while riding, antifreeze is as slick as ice or oil.

Orange antifreeze, Dexcool, is not the hot ticket, go green. But the orange needs flushed out first. Just say no to Deathcool.
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post #4 of 22 (permalink) Old 07-24-2017, 12:31 PM Thread Starter
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Huh I read somewhere before i did a coolant flush that dexcool is the best to use on a 750? I guess ill switch to green than.
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post #5 of 22 (permalink) Old 07-24-2017, 02:37 PM
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Originally Posted by hayflana View Post
Huh I read somewhere before i did a coolant flush that dexcool is the best to use on a 750? I guess ill switch to green than.
I don't think it was here as most of us like the green ****.

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post #6 of 22 (permalink) Old 07-25-2017, 06:05 PM
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Originally Posted by hayflana View Post
Huh I read somewhere before i did a coolant flush that dexcool is the best to use on a 750? I guess ill switch to green than.
I remember a few years back reading the same on this forum and almost fell into the Dexcool trap myself.

If someone finds that post...DELETE IT!!

Use any green coolant that is safe for ALUMINUM. Pick wisely grasshopper
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post #7 of 22 (permalink) Old 07-25-2017, 06:28 PM
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Originally Posted by kc2dgq View Post
Use any green coolant that is safe for ALUMINUM. Pick wisely grasshopper
This is probably going to be contradictory on the surface, but one should probably avoid any coolant that mentions silica / silicate as an ingredient, as in "Prestone's Silicone/Silicate Formula". (Not meaning to malign the Prestone brand, as they have several formulations *without* silica.)

Here's where the contradictory part comes in: most green coolants (so-called Gen 1 or Type 1) have silicates. There are green coolants (Honda Type 2, for example) that are silicate-free and therefore long-life: silicate formulations last at most two years before needing replacement, and you don't want silica in your motorcycle cooling system -- chews up water pump seals.

Avoid Dexcool like the plague unless you want to take a chance on being one of the people where the coolant has turned to sludge in your engine.
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post #8 of 22 (permalink) Old 07-25-2017, 09:29 PM
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My bike had the same issue, the fan relay in the junction box was bad. Didn't want to replace junction box so I now have the fan on a toggle switch; you can try the solo relay method; which worked for me awhile but stopped and I had to go back to the manual switch.
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post #9 of 22 (permalink) Old 07-26-2017, 07:40 AM
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My 85 was getting to the point where it would always run 3/4 to just below. I changed the thermostat, flushed it, no change. Well then I got to thinking that the radiator tubes are extremely small and would not take much to block off at the ends. So I removed it and soaked it in radiator cleaner, then back flushed both directions with hose pressure water. This made a huge difference. Not 100 percent but at least 80 percent. So on that note I may remove it this winter and soak it for a longer period.
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post #10 of 22 (permalink) Old 07-26-2017, 11:21 AM
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It's true your T-Stat might be bad or that your radiator needs a flush, but if your fan isn't coming on (or just working intermittently) then you've got an electrical problem on top of those other issues and that needs to be addressed first.

There are three relays in the junction box that are known failure points with established workarounds. One of those relays controls the fan based on the temperature sensor input. You can test this by shorting across the fan switch found at the bottom left side of the radiator. It should have a black wire with a yellow stripe. (different than the temperature sensor). Short that wire to ground and the fan should come on even with the key removed. You may have to short the wire at the junction box, since the electrical connection might be sealed to protect against water damage at the sensor.

If the fan doesn't come on, then you're looking at a bad relay or a bad fan. If the fan is bad, the relay should make a 'click' when you short the sensor wire. If there's no click, install a manual switch for the fan. If the relay does click, check that the fan motor does work by shunting 12v to the positive lead of the fan.

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