200HP HPDI frozen bolts

[Yamaha2012]

I have 2012 200 hp HPDI’s . Trying to change the water pumps and some of the lower units bolts are frozen. I an afraid to put too much torque on them for fear of snapping. What is the best way to remove and preserve the existing threads. Thanks

[Keithbaja]

Some very hot heat as the gearcase acts like a heat sink.. BTW MAP gas comes in the yellow cans. That might do it. Forget the blue can stuff. Also a brass drift that fits in the crown of the bolt heads,, struck VERY hard to break/loosen threads can help..

[zenoahphobic]

Depends how you value the paint on your outboards, as above: heat.
But if you are going to keep them and don’t want to repaint them, then some belts with a drift and carefully increase torque and not worry about breakages. Then remove stub and rethread with Helicoil. Takes longer but then future removal a piece of cake.
Either way junk the bolts that were extremely hard and get new ones. A messy job.

[Yamaha2012]

One idea was to cut the heads off. Try to get the lower unit off. It is a smooth shaft. Then with the stub try working it out of the threads with heat and liquid wrench. Has anyone tried that?

[DennisG01]

I'd save cutting the heads off for later. I'm not sure that really gets you anything different than you have right now - right now you have a good head. It would be silly to get rid of that as you can do everything you proposed with the cut shaft the same as you can with the intact head.

Spray some good penetrating fluid like PB Blaster, or similar, at it a couple times a day over the course of a couple days. You could also try some 30% vinegar which is available at HD (household vinegar is only about 5%). It's very good at eating salt.

Then come back with the whacks on the head and even an impact gun. Use the gun lightly, though - alternate back and forth between fwd and rev over and over and over - only a 1/2 second in each direction at a time.

[boscoe99]

Agree with Dennis on the use of an impact gun.

[Yamaha2012]

I like that idea Dennis. Thank you

[zenoahphobic]

Agree with Dennis on the use of an impact gun.

I’ve had a lot of success using an impact gun on high torqued bolts. Less success on corroded in bolts, that have formed a tighter bond.
The suggestion that cutting the heads off the bolts has merit only if you know they are too tight, but the big problem is is how do you really know this? It helps in that you will be able to drill into the stub much easier than into a twisted and consequently HARDENED uneven break.

[99yam40]

I believe I remember Rodbolt saying aluminum corrosion is totally different than rusted bolts, and need a different type of penetrating fluid.
problem is I do not remember what he used if he ever said.

remove what bolts you can and then work on the ones you cannot get out.
seems to me it is corrosion along the shaft itself a lot of times, not just the threads so even if you cut the heads off the shafts will still be holding it

[Keithbaja]

Whack the heads/crowns. Slightly tighten,, then loosen. Then again slightly tighten then loosen.. Whack heads/crowns and keep repeating... NOTHING WRONG WITH PRAYING AT THIS POINT.. DO NOT CUT BOLTS.. EVER !! THE SHOULDER IS usually Corroded the most. With constant finesse and luck you will get lucky,,,, Sometimes........

[ausnoelm]

I have had great success with a rattle gun, back and forth, or......the hit, tighten, hit loosen, hit tighten as mentioned above, do NOT just keep turning one direction! The shaft/shank of the bolt is corroded, not the thread.....usually.