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Broken Thermostat Cover Screw Thread

J

jmcgurl

New member
Hello,

I have a 15 HP short shaft remote outboard from 2004. The gasket between the themostat and water jacket was leaking. Unfortunately, the 2 screws (90002-ZW9-000) were corroded and broke off when I attempted to remove them. I need to drill out the screws and tap the hole. Does anyone know the thread size of the 6-36 screw 90002-zw9-000? I have a 6 buy one tap that I hope will work, but I am not sure. I emailed Honda directly and even though they use this screw a lot, no one in customer service could get me the thread size. Any help would be appreciated. Thanks!
 
I agree it's probably the most common size/thread used on that motor. That in mind, maybe pull another bolt and see if it matches the tap you have in mind?
 
And when it's fixed make a point of checking your thermostat annually and then greasing the bolts when refitting. While you're at it, it might be a good idea to remove the whole water jacket and replace the internal anode which is probably now non existent. And again, grease the bolts at reassembly
 
Pulling that water jacket might be just looking for trouble at this point. Would be nice to inspect it and replace the gasket, but I'd say the chances of a broken bolt are pretty good. My luck being what it is, would have me breaking one for sure....
 
Order 2 new screws from Honda, if you can’t find one that comes out easily elsewhere on the outboard. Any bolt on there with the same size head will be the same I’d guess. I use anti seize on any bolts going into aluminum, lasts forever and heat doesn’t affect it.

I assume you will heli coil it?
 
It's just a t-stat bolt. If he drills and taps to the original size he should be fine. If it were a head bolt it might be a different matter.
 
You're going to damage the threads when drilling, no doubt. Then you're going to cut new ones with the tap.

Heli coil available for worst case scenarios maybe (which are not likely if you are careful drilling the broken bolt).
 
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