removing rusty coupler set screws

victoria28 · #1 (**permalink**) 01-20-2010

Hi, I have a '92 Catalina 28 - Universal M3-20 engine with Hurth HBW 50-2R transmission and what appears to be the original coupler. I need to remove this coupler and have purchased a new one from Catalina. The problem is getting the heavily rusted set screws to back out. I have carefully soaked all the bolts with a petroleum based penetrating oil. I have had success with loosening the 4 bolts that connect to the transmission, but the set screws are giving me a real fight!
After much scraping & brushing to remove as much of the rust as I have been able to so far it seems like the square heads are now a slightly smaller width than original. As you can see in the attached photo it looks like I'm going to destroy the head and/or break off the screw If I can't find a way to loosen them up.
So please any ideas - helpful hints?
Thanks, Bill

scottyt · #2 (**permalink**) 01-20-2010

pb blaster and heat. spray them down ( well use a small brush as pb will eat rubber ) and use a propane torch to heat the coupler up some, you dont need red hot just real warm. do this over several days, then try again. also tapping with a small hammer can also help get them loose, heck even trying to tighten them a little can help break them loose

if this does not work split the old one off. ie cut it with cutting wheels in a dremel or if you have the room a grinder. just cut until you are almost thru but not in to the shaft, then use a cold chisel to split it.

downeast450 · #3 (**permalink**) 01-20-2010

Quote:

Originally Posted by scottyt

pb blaster and heat. spray them down ( well use a small brush as pb will eat rubber ) and use a propane torch to heat the coupler up some, you dont need red hot just real warm. do this over several days, then try again. also tapping with a small hammer can also help get them loose, heck even trying to tighten them a little can help break them loose

if this does not work split the old one off. ie cut it with cutting wheels in a dremel or if you have the room a grinder. just cut until you are almost thru but not in to the shaft, then use a cold chisel to split it.

Amen!

PB, heat/tapping and patience will loosen almost anything.

Down

WanderingStar · #4 (**permalink**) 01-20-2010

Also use a socket wrench, it will fit more surface. With worn down nuts, I sometimes manage with a slightly smaller socket.

TQA · #5 (**permalink**) 01-20-2010

As a last resort make up some shields from sheet steel, old car bonnets are a good source, visit a junkyard and get the gas axe guy to come over with his kit and cut the sucker off. Some one who uses this kind of cutting equipement every day should cut it off with no damage to the shaft or other flange.

Mind you keep some fire supression gear to hand.

BarryL · #6 (**permalink**) 01-20-2010

Hey,

You can try the heat / soak / try / repeat method. Or you can give up and take out a saw. What condition is your prop shaft? If you suspect it is worn, then just get a good sawsall and start cutting. Cut the shaft. remove the 4 coupler bolts, and be done with it.

On the other hand, if you are short of funds and are fairly certain that the prop shaft is perfect, you can keep on trying to remove those bolts. Once you round the head your best bet will be a large vice grips and a mallet. Heat and oil will help.

Good luck,
Barry

imagine2frolic · #7 (**permalink**) 01-20-2010

You can find a can of freezing spray in hardware places. That is one way, and the others are patience, and heat. If you do find someone to bring along a torch. Heating the area where the bolt is stuck is all that needed. I know I can cut away the bad piece from the shafdt, but the falling slag, spray, and excessive heat for a prolonged period of time is guaranteed grief. Fixing your problem has been my job for 33 years............i2f

tommays · #8 (**permalink**) 01-20-2010

I will NOT heat up things in the confines of cram packed motor area If soaking does not work as now you have flammable stuff sprayed on the part your trying to heat up

Its much better to drill out the screw and drill and split the coupling to remove it as its you should not really reuse it anyway

Sabreman · #9 (**permalink**) 01-20-2010

Here's another viewpoint.... you never replace the coupling without replacing the shaft along with it. The coupling and shaft MUST be machined together to ensure a snug fit. Otherwise, the vibration will shake everything loose. Thus, you can cut the shaft and unbolt the coupling from the engine in 15 minutes. Even if you get the nuts off, getting the steel coupling off the bronze shaft while still in the boat will be nearly impossible. Trust me, I've tried; those bolts are the least of your worries.

My recommendation is to replace the shaft and coupling together, the stuffing box (replace with a PSS seal), and cutlass bearing (why not?). I've done the job several times on various boats and it's quick and <$1000 if you do the work. I've posted the procedure several times on Sailnet.

victoria28 · #10 (**permalink**) 01-23-2010

thanks for the advice from all of you- I have hauled the boat and separated the the shaft & coupler from the transmission - but the coupler with both set screws removed is still not loosening - tomorrow morning I'll try the trick of putting a socket on the end of the shaft and try to use it to push the shaft out by reclamping the coupler to the transmission plate with longer bolts - wish me luck! a good soaking with blaster may help too!
Cheers from sunny and mild Victoria,
Bill