Rear Head Coolant Pipe Leak - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 5 (permalink) Old 03-27-2020, 08:36 PM Thread Starter
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Rear Head Coolant Pipe Leak

I just recently put my engine back into the frame, and after doing so have developed a leak where the rear cylinder coolant pipe goes into the head. Coolant dribbles out and down my engine block once it starts running and pressurizing the system. I do have an o-ring installed, but I can't be sure that it is the proper size. Does anyone have any ideas on what diameter o-ring is supposed to seal this pipe?

I read the other thread which suggested that there might be corrosion, but I have wire brushed that away. Would double o-rings work? Could I use some RTV in addition to o-rings?

Thanks in advance.
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post #2 of 5 (permalink) Old 03-28-2020, 08:55 AM
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I used 5/8" because the auto store didn't have metric. I used two o-rings on each pipe and coated them with grease.

RTV will push the o-rings out as it cures.

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post #3 of 5 (permalink) Old 03-28-2020, 09:38 AM Thread Starter
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Cool, thanks. Hope that works for me!

Quote:
Originally Posted by Spockster View Post
I used 5/8" because the auto store didn't have metric. I used two o-rings on each pipe and coated them with grease.

RTV will push the o-rings out as it cures.
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post #4 of 5 (permalink) Old 03-31-2020, 07:31 PM
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I ordered the original from the local dealer. Costs a little more but no leaks.
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post #5 of 5 (permalink) Old 04-02-2020, 01:19 AM
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I almost always recommend oem parts. That particular O ring (670-O RING,14MM-670B2014) is only $1.99, and while it may look exactly like what you can find at a hardware store, there will be a minor difference, enough to prevent it from working. The metal elbow that it goes on has a small tab with a hole in it welded on, and there is a bolt that goes through that hole and into the head to hold the elbow in place. If that bolt is loose, it can allow the elbow to wiggle around and leak. If it is missing, the elbow can come out altogether. I recommend using spark plug boot grease when installing the O ring and elbow. It can help prevent the O ring from being damaged from installation.

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