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Discussion Starter #1 (Edited)
A 2001 Vn 750 was brought to my attention with an odd coolant leak. It idles just fine and stays at normal temp. Once applying a load (riding) it quickly overheats and pukes coolant out of the coolant res. hose.The coolant levels are good and the thermostat is good. Any ideas for trouble shooting? Thanks in advance!
 

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A 2001 Vn 750 was brought to my attention with an odd coolant leak. It idles just fine and stays at normal temp. Once applying a load (riding) it quickly overheats and pukes coolant out of the coolant res. hose.The coolant levels are good and the thermostat is good. Any ideas for trouble shooting? Thanks in advance!
Do the upper and lower radiator hoses feel equally warm to the touch when the engine is warmed up?
Just wondering if the rad is plugged up, or even partially so.

How many miles on the odometer?
Any chance the coolant pump is worn out?
 

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Discussion Starter #3
We tested the radiator and there is flow, comes out as quick as it enters. Also pressurized to 28 psi and no leaks. Real head scratcher
 

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How quickly did you test the flow? There might be some gunk getting lifted at a higher flow rate and plugging the hole. Happened to a buddies Malibu.
 

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Discussion Starter #5
We've done several flow tests, and flushed the whole system about three times now.Pump tested good I'll have to check the milage, even checked the impeller to ensure it wasnt loose and its not. Even the dealer is stumped lol
 

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Does the temperature gauge confirm overheating?
Or just coolant puking out on the ground.

Couldn`t be something as simple as an overfilled coolant reservoir could it? :confused:
 

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Discussion Starter #7
The temp guage does show its overheating, and no all levels are checked before testing then same deal occurs. I would think if anything it would overheat at idle but it'll sit and idle for 25 minutes and its fine the second you get about a block down the road it begins its overheat and puke routine.
 

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Water flow diverges into each jug in the vee. You may only have one jug overheating. If one of the jugs is clogged, you will still see flow at the cap via the remaining clear jug. I would check for flow coming from the top of each jug (start with the front one).
 

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Discussion Starter #9
we'll give it a whirl
 

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Also, I'm sure you have also checked to see that the radiator fins are not bent or clogged ... right ?
 

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Discussion Starter #11
Well I think theres been some progress. The PO removed the origional thermostat and installed an automotive cap, after replacing the thermostat the cap wasnt changed. It may have not been venting properly and causing the coolant to perculate. After installing a new cap so far so good, more test rides to confirm. Thanks again for all the ideas! Gotta love the Vulcan clan!
 

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Glad to hear you are making progress. Hope you have the steel pony cured. :smiley_th
 

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Went thru same issue last year except it only approached the red zone and needle never went there. Coolant spitting out often. Did all the same plus more. Finally, after pressure tested, new thermo, new temp sensor, etc.. it started tiny leak from one of the fins. Must have been letting air in and causing overheating until the leak was noticeable by drips. Replace radiator and problems solved. No spitting since.
 

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You can check for collapsing hoses. I had a car that would sit and idle all day long, but as soon as you took off and put the engine under load, it would overheat.
Lower hose would collapse shut, cutting off coolant flow, and subsequent overheating would occur.
Changed the hoses, and problem went away.
 
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