Cooling / rad cap

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mike91
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Joined: Wed Mar 01, 2017 8:39 pm

Cooling / rad cap

#1 Post by mike91 » Tue Sep 04, 2018 10:31 pm

We have an 85 that we use for vintage road racing and are having some cooling issues. The engine doesn't get hot but the stock gauge shows it running warmer then I think it should. The engine was rebuilt top to bottom last winter and runs strong. The problem is that it pumps water into the overflow tank. Not sure where to turn but think it is either the rad cap or the head gasket or both. Does anyone use a higher pressure cap if so which one. Help would be appreciated.
Thanks

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OldTZracer
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Location: Alberta Canada

Re: Cooling / rad cap

#2 Post by OldTZracer » Wed Sep 05, 2018 2:06 am

When you say "pumping", I'm leaning towards head gasket. Are you seeing any signs of oil in the coolant?
"...its a 2-stroke ya twit - Its supposed to smoke..."

mike91
Posts: 12
Joined: Wed Mar 01, 2017 8:39 pm

Re: Cooling / rad cap

#3 Post by mike91 » Wed Sep 05, 2018 4:35 pm

OldTZracer wrote:When you say "pumping", I'm leaning towards head gasket. Are you seeing any signs of oil in the coolant?
It doesn't look like oil in coolant but it's not clear either. We use water wetter and distilled water for coolant
.

silverstrom
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Re: Cooling / rad cap

#4 Post by silverstrom » Fri Sep 07, 2018 12:10 am

Definitely appears to be a head gasket. Did you use a genuine Yamaha head gasket? Aftermarket head gaskets have an alarming failure rate.

mike91
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Re: Cooling / rad cap

#5 Post by mike91 » Fri Sep 07, 2018 4:40 pm

Used a Yamaha gasket and re torqued after first ride. Will be changing in tomorrow. I had a KTM 390 with a similar gasket and they recommend cooper coat and the gasket to promote heat transfer from the head. Any thoughts on using it here?

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