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1985 VN-700
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418 Posts
Discussion Starter #1
After the other day I have decided to flush my cooling system. I bought some prestone stuff good for aluminum engines and ran straight water through first. Now, my bleed screw is almost stripped, so rather than take the chance I just ran the bike with the radiator cap off. I got quite a few bubbles and when I revved the bike the water would shoot right out the cap hole. Is this normal, or I am thinking I know why I have a hot running bike as I am suspecting a head gasket leak now.:mad:
 

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Registered
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273 Posts
:beerchug:
You may have a stuck thermostat. The water shooting out is the result of the increased RPM at the water pump when you rev the motor.

Questions:
1)is your cooling fan running when warm? Check the fuses and wiring.

2)does it overheat at speed, or when idling? (reverts to the t-stat and the fan).

I would change the thermostat first, and let the bike completly warm up.

A head gasket would show white smoke out the pipes and would drop the coolant level.
:beerchug:
 

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1985 VN-700
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418 Posts
Discussion Starter #3
Ive changed the thermostat. The fan works. In fact now the bike is running cooler and the fan turns on sooner. Im thinking the cleaner stuff really may have worked. The. Ike would run all the way to red. Now its running halfway like it used to. I can see the needle drop when the thermostat opens. So i will run a couple more days then replace the coolant. Hopefully i got it.
 

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Heading to the DARKSIDE!
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177 Posts
I have drained my coolant from my cooling system and refilled it many times.....and I have never once used my bleeder screw. I just fill my coolant overflow up to a little over the full mark and add coolant to the cooling system at the radiator/system cap till it's full then squeeze the fat "L" shaped radiator hose at the bottom of the radiator to get some of the air out of the system. Then top off again. After I warm the engine up to running temp and the thermostat opens and I let the system cool back to ambient temp I take off the coolant system cap and add coolant to top off again.....then check overflow tank level. This is "my" procedure and I have never had one issue with air in the system. I also only use distilled water and water wetter with about 15 to 25% green antifreeze added in.
 

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1985 VN-700
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418 Posts
Discussion Starter #5
Thanks for the tip Brett. My 12 mile ride home in 88 degree weather wasnt so good. It got to about a eighth of an inch from the red. Drats. I will run the cleaner a couple more days. I had a few traffic lights on the way home so that didnt help. Still a little better than last week.
 

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Heading to the DARKSIDE!
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177 Posts
If you keep having trouble and rule out the thermostat being the problem.....Take the radiator off the bike and put a garden hose in the radiator top hose port and the water should flow out the bottom hose port without water backing up at the top port and overflowing back out.....If this does happen......your radiator is seriously clogged.
 

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Wareagle1970
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409 Posts
Not sure if this will help any, but when I flush my radiator I put a gallon of vinegar in the radiator, crank the bike and let it run for about 10 minutes, drain the vinegar, refill the radiator with straight water, crank the bike up for about 10 minutes, drain the water then run water through the radiator to remove any residual vinegar. I then put in a gallon of Engine Ice.
 

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Wareagle1970
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409 Posts
Vinegar flush and Engine Ice is a very good tip.
Saw where I left off first draining the radiator before filling with the vinegar:doh::doh::doh:
 

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1985 VN-700
Joined
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418 Posts
Discussion Starter #10
Thanks. I am suspect of the radiator which is why I tried the flush / cleaner solution. I may take the radiator off and bring it to a local radiator shop to see if it can be dipped. Other wise i'm gonna look for another used one. The bike is a 1985 so its probably due.
 
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