Overheating

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keithj

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Jul 19, 2013
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Idaho Falls
Howdy folks,

I've got an overheating problem I hope you can provide some direction on. 2003 VMax, stock engine and carbs. It's always run fairly close to the red line on the temperature gauge when running it hard. The fan turns on like it should, and has a manual switch I kick on when needed.

Coming home on a longish 5hr ride in high temperatures, the temp gauge rose into the red. I babied it home without too much trouble. Coolant fluid was low, which I replaced, but I think that was a symptom of overheating and not the cause.

This weekend I started to diagnose. The fan cycles as expected when temp nears the red line. No cold spots can be felt in the radiator coils. Coolant moves from the overflow tank as expected (pushes coolant top tank at high temp, siphons coolant as the engine cools). This makes me think that both the radiator cap valve and the water pump are moving coolant as they should. The only thing I've done is drain and flush (with vinegar) multiple times and replace the coolant. No leaks can be found.

Any thoughts on where to look for the problem?
 
How about a new thermostat. It might be getting gummed up and not opening fully.
 
I removed mine 25 yrs ago, why? I really don't remember. But she warms up quick and hardly ever get to redline unless I get caught in New Orleans heavy traffic. There are no gaskets, just an Oring on the thermostat housing that is reusable. You might want to remove it and see how it does on temperature. Like JF said, it may be gummed up or just not functioning properly.
 
Before getting too far into looking for a overheating issue it would be prudent to check that the water temperature indicator and associated sender are giving the correct reading.

If possible check the coolant temperature with a calibrated instrument.
 
I had issue on my 90 when I bought it. If parked or in traffice I would hear it start to bubble and send water out over fill or coolent neck. Temp gauge was never over half. I replaced it with a new sending unit I bought off vmaxoutlaw.com. Now I have fan come on before it gets half way, and have never had it overheat. Although it doesn't seem to like to idle too much when the fan is on. It's wasn't a costly replace, and was pretty easy to do also..
 
had to do my 97 that way. it was thermostat. and replaced fluid with yamaha coolant. thermostat not expensive but rad fluid was. no overheat issues since. hope this helps.

Sent from my 5860E using Tapatalk 2
 
Just priced a thermostat now they are 41.58 at the stealership.
Matter fact the parts guy freaked out.
 
Do you like to spend $$$ comparatively-speaking? You should read the links I posted, visit your local auto parts store and save $$$! :ummm:


Just priced a thermostat now they are 41.58 at the stealership.
Matter fact the parts guy freaked out.
 
A good flush, automotive cap, sender, and T-stat. And,Long life antifreeze pre mixed. I never run hot anymore. The fan is on most of the time, but not an issue for me. The sender trips around 170 degrees. My OEM tripped at over 200 degrees. It's difficult for a vmax cooling system to cool down from high temp. Unless you shut down. If I ran a manual fan switch, I'd flip it on early.
 

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