Screw heads broken off tilt/trim sending units... advice?

[bigblock454]

Greetings,

I've never posted in this section, but I believe this is the appropriate place for the help I seek. Anyway... The heads are broke off the screws that held the tilt/trim sending units to my alpha one (gen 2). There is quite a bit of the screw left proud of the surface. I've been soaking it for the past few days with PB Blaster, and tapping the remainder of the screw with a hammer daily, in hopes that the Blaster will work its way in there. I haven't tried to grab it with the vice grips since I started this "treatment". Looking for further advice/experience with this. Thanks.

Norm

 

[gm280]

Well once you do grab it with a vice grip, go slowly with back and forth efforts. And if that seems to work WALA, you're home free. However, if that doesn't work, maybe a little heat application. Either way, once you do get them out, use a thread tap and chase all the holes before installing new hardware. JMHO!

 

[JustJason]

Get a small pencil butane type torch and heat the area around the screw (and do not heat the screw itself). Grab the nub with vice grips and try to work it out.

 

[Scott Danforth]

If there is corrosion around the area, you may need to drill the fasteners out.

Either way, use tefgel on the screws when you install the new ones

 

[bigblock454]

Thanks guys. The butane torch idea sounds good. I will certainly chase threads with blind tap if/when they come out.

Norm

 

[stonyloam]

Alternate solution, file the screw remnants flat, and drill and tap new screw holes. Take note of the current position of the screw heads on the sender and drill the holes above or below the existing screws so the new ones are in the adjustment slot. You can also reposition the sender on the splines to give a new surface to drill into.

 

[bigblock454]

Wow... Good stuff there!! I was thinking that if I broke them off flush, that I would have a heck of a time drilling into what I believe are stainless screws. Your tip just eased my mind a lot!! Thanks Terry!!

Norm

 

[mr300z87]

Same thing happened to me a few years ago, actually 3 out of 4 broke. Drilled and tapped new holes have not looked back. As part of my winterizing maintenance I remove each screw 1 at a time and put a dab of marine grease on the threads and tighten back up. Even after sitting in salt water all summer they came right out. Good luck.

 

[bigblock454]

That's awesome... I can now go at them with reckless abandon!!

 

[DeepBlue2010]

If you have a Dremel tool, use the cutting disk to machine a small slot on the protruding part of the screw that is still showing. It is like cutting a channel to fit a regular screw driver. Use a torch to heat it up, insert a small screw driver and give it few - reasonable - hits with a hammer and then try to turn it. Sometimes, this will work

 

[bigblock454]

Thanks again DeepBlue (or is that DEPblue ). I've been soaking with PB blaster, and tapping with a hammer for four days, Last night I grabbed with vice grips, and heated with a torch... she didn't yield... yet. I wasn't ready to break the remaining stub, so I gave up for the night. I will go out soon and try again, hoping that the heat, taps, and PB may have sweet talked the screws over night. Thanks again!

Norm

 

[thumpar]

You could also try grinding 2 sides down a little so that you have flat edges to grab onto. It may give you a little more leverage on the screw without it spinning in the vice grips.

 

[bigblock454]

Thanks thumper. Right now it still feels like the screws want to snap if I put much more on them. I'll continue to soak and tap with the hammer. If I have a problem with the vice-grips slipping, I will certainly remember your tip!

Norm

 

[bigblock454]

Thanks for your help Gents... After a week of PB Blaster, a few hot cold cycles with mapp gas torch, and some occasional love taps with a hammer, I grabbed the screws over the weekend with a pair of vice grips and they finally yielded to me. I will chase with a bottoming tap. I also got my hinge pins broken free, so I will be moving ahead with my transom assy rebuild soon! Thanks again!

Norm

 

[Bondo]

Ayuh,.... Cool,.... I love a Happy endin',.....

 

[bigblock454]

Thank you Bondo. I got a buncha parts in! I think I have everything to rebuild transom assembly except a puller to get old gimbal bearing out. Actually, as far as "specialty tools", I only have hinge pin removal tool and shift cable removal tool, so I will need to borrow or purchase the rest. But at least I should be able to get everything apart so that I can clean, de-oxidize and paint. I got some "moderate" sea growth on my tilt cylinders. I bought a paint stripper/rust remover drill attachment, thinking that would remove barnacles, corrosion, dead paint, etc. Any better ideas to getting all of that ready for some ZC primer and topcoat? I'll attach a pic so all can see my definition of "moderate" and perhaps better direct me. That reminds me... Gotta look for new "merc" decals after sending this! I've seen and will re read all I've found on "bellows replacement" and such, but any "insider" tips are always appreciated! I saw where someone snaked a wire up the shift cable outer sleeve (after removing the core", and tied it off in the engine compartment, to better facilitate re installation. I thought that was brilliant! I'll be happy to post my progress here. Here's what just came in. Transom rebuild kit from sierra, including bellows, gimbal bearing, gaskets, hoses, etc. Got a lower shift cable (with another shift cable bellow), bellows adhesive. Got QS tilt/trim send units. I also got an exhaust "tube" separate from the exhaust bellow that came with the kit. I hear they are easier to install, and I don't mind (a little) throatier of a sound, if there is indeed a difference. Got my Moellers Zinc Chromate and gloss black acrylic urethane (got the latter from Summit Racing). Got some "perfect seal". I think that's about it. Also ordered a QS water impeller kit, but that's not in yet. now I just gotta go out and brave some low northeast fall temperatures! Here's my transom assembly as she sits.

 

[bigblock454]

I did just post a more "current" thread in the mercruiser sterndrive "repair" section to get on track, and probably more views than the "broken screw" thread in the wrong section! Not to mention... we nailed that one down! Thanks again.

Norm