'87 Mercury Blackmax 135Hp Temperature Sensor

[astor]

broke the temperature sender trying to remove the nut, anyone else run into this problem, whats the best way to remove the broken piece? Thanks for any helpful suggestions, I've got plenty of time to get this done before the ice thaws.

 

[Texasmark]

Re: '87 Mercury Blackmax 135Hp Temperature Sensor

If yours is like mine you have a thermal spst switch that is mounted in the water jacket(s) and held in place with a 1/4" SS bolt. Corrosion apparently took it's toll and you attempted to unscrew the bolt and broke it off. Preceding is conjecture, but if true, continue: If you can flatten the top of what's left of the stud, do it to give you a flat surface; works best. Using a punch, the brass spring loaded things from Harbor Freight do a great job, locate the center of the stud and operate the punch a dozen times to get a good hole for starting the drill.

Using a drill bit that is the size of the bolt less the threads, drill down into the stud half an inch or until you stop getting SS debris. Using an easyout of suitable size and good penetrating oil like PB Blaster, and a hammer to "impact" the stud, work the stud out.

Once out, get a tap of the same thread and size as the screw and clean up the threads. Reinstall the new sensor using Blue Locktite thread sealant which will help you to install the new SS bolt and help to remove it if needed in the future.

Mark

 

[astor]

Re: '87 Mercury Blackmax 135Hp Temperature Sensor

Thanks, for the response, mine is/was a brass stud, but still was able to take your advice, it came out pretty easy. I haven't always had luck with broken fasteners/threads

 

[Texasmark]

Re: '87 Mercury Blackmax 135Hp Temperature Sensor

Thanks, for the response, mine is/was a brass stud, but still was able to take your advice, it came out pretty easy. I haven't always had luck with broken fasteners/threads

Glad you were successful. Guarantee you being brass had a whole lot to do with it.

Mark

 

[Chris1956]

Re: '87 Mercury Blackmax 135Hp Temperature Sensor

Mark, If you drill SS, and do not go real slow and keep it real cool, the SS will harden and trash your drill bits...... I found that out when trying to drill 1/4" hole into SS trim tabs. The machine shops always punch holes in SS!

 

[Iceman66]

Re: '87 Mercury Blackmax 135Hp Temperature Sensor

It`s no problem to drill in stainless steel, use a pro drill bit ment for a job like this, it`s like drilling in butter.
REAL Cobalt bits or REAL Titanium bits, not the coated garbage from China!

Hell of a price, but worth it.

 

[Texasmark]

Re: '87 Mercury Blackmax 135Hp Temperature Sensor

I did this with my shop drill press and a 1/4" bit from a set of tungsten plated bits from HF I paid around $70 for. It wasn't easy but there are 3 of these in this prop drilled with the same drill bit. Agree gotta keep the rpms down and the lube up. I used PB Blaster penetrating oil for the drill oil. It works great when you run out of cutting oil.

I guarantee you that drilling out a SS bolt that is broken off in an alum. housing, especially of the smaller diameter, is challenging, but "gotta do what you gotta do".

Mark