Author Topic: Coolant drop after first runs post engine rebuild?  (Read 177 times)

tzar250

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Coolant drop after first runs post engine rebuild?
« on: March 17, 2018, 09:44:41 AM »
Hi

After a protracted full engine rebuild, I've run the engine for about 30 minutes so far.

I've just removed the fuel tank, as I wanted to replace the carb float valves and have noticed that the coolant level in the tank has dropped by about 8mm compared to when it was filled.

There are no signs of any external leaks at all and so I'm fearful that it may be leaking internally?

My only hope is that perhaps there was a pocket of air trapped in the system that escaped once it was running.  Does this seem possible - or am I clutching at straws?  I could do without taking the engine out and apart again!

Thanks in advance for any thoughts.

kva882p

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Re: Coolant drop after first runs post engine rebuild?
« Reply #1 on: March 17, 2018, 11:19:35 AM »
just top it up,and run it again. if it keeps losing there may be a problem but youre worrying too soon.could be air

teezer250

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Re: Coolant drop after first runs post engine rebuild?
« Reply #2 on: March 17, 2018, 06:57:32 PM »
More than likely it was air trapped and when run it has been forced out.
I usually run my bikes engines with the radiator cap off and let them warm up and blipping the throttle while watching the coolant in the radiator circulate and then slightly drop from the filler neck.
I then put the cap on and top up the expansion tank to just above the lower mark.

tzar250

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Re: Coolant drop after first runs post engine rebuild?
« Reply #3 on: April 06, 2018, 08:44:43 PM »
Hi

Thanks for the suggestions.  Sorry for delay in replying but I had to take the clutch cover off anyway to investigate cross contamination of the transmission and 2 stroke oil - so had to drain all the coolant out again anyway.

However, having put it all back together again after hopefully sorting the oil problem, the new coolant seems to be holding its level after a couple of half hour runs - so it did seem to be a trapped air problem causing the original drop in level - fingers crossed!

Thanks again.