HELP NEEDED!!
Yamaha 1993 40 HP, broke 4 of the 6 bolts that hold the lower unit on. (I was going to change the water pump)
Can anyone tell me the best way to get the bolts out without snapping them off flush?
I have cleaned the bolts, removed all of the white corrosive powder that binds up like concrete, just horrible stuff. I have been spraying the bolts daily for a week+ with Kroil but I am afraid to try and turn them with vise grips or something. Don’t want to snap the off flush with the motor cause then I know a machine shop is my only option.
Any help or suggestions of who can do this would be appreciated.
You might try a little heat with a propane torch. Don’t get carried away, just heat to where it’s pretty hot to the touch. You also might try tightening the bolts just a hair. Once again don’t get carried away and horse down on them. Just see if they move at all. If they do, you could probably work them back & forth till they come out.
Bob Van Gundy
Marine Designs,Inc.
Custom Aluminum Fabrication
803-727-4069
It generally requires some heat on the housing around the bolt with a torch. You don’t want to heat the bolt, heat the housing, then cool the bolt. We used to use something in an aerosol can that was a freezing spray, don’t remember what it was.
This will burn off the paint, not much way around that.
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
You can also heat the bolt housing area with a torch and when the bolt is hot spray with the kroil or pb blast or whatever it will generally pull the oil in the threads, had the same thing happen on a head and the heat and oil worked, good luck stainless bolts broke in aluminum suck.
SEMPER FI
30 gw marlin
35 donzi sfc (sold)
25 pursuit cc(sold)
45 egg harbor sportfish (sank hurricane)
heat and a lot of it.
heat spray with penetrating oil, let cool
repeat
repeat
repeat
repeat
repeat
repeat
repeat…
just remember, once you have done this, and if it still breaks off, it will be VERY difficult to drill
It can be prevented by the use of an anti cease compound applied to the bolts before assembly. I would also like to mention to only use a PROPANE torch to heat the housing. Don’t use an acetylene. It gets to hot and can damage the housing.
quote:Dang, I am getting ready to put a new impeller in my 70 hp yammy. Seeing this scares me a bit. Is there anyway to keep this from happening?
Yes, remove it once a year or so, no matter if it needs it or not, and as said above put an anti-seize compound on the bolts. Most people wait for the water pump to quit before removing the lower unit and that could be 3 or 4 years. I’ve also got a 70 Yamaha and change the impeller about every 18 months, it never needs it but it keeps the bolts from freezing up.
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
please guys DO NOT USE regular ANTI-SEIZE
it has copper in it
you are already dealing with stainless and aluminum
the copper will only make the corrosion worse in salt water
we use OMC blue grease to coat all the threads
it acts as an anti seize and a sealant to keep out the salt water, plus its a lubricant
On the heat thing… remember you are dealing with an aluminum housing. I’ve seen a couple of people get carried away with a torch.
What Cracker said about heating the housing, right on spot. Heat causes swelling and you don’t want the bolt “growing” but the housing to expand before transferring heat to the bolt. Only a short window of time before letting the entire thing cool off and starting again.
Chris is also spot on about having to drill out the bolt … more heat more tempering of the bolt making it much harder to drill…
From the picture you posted I would follow Chris’s advice and do the repeat thing with a good penetrating oil and patience then with the length you have plenty of room for vice grips.
If you do have to drill. Make sure you center punch and drill dead center so a key-insert or heli-coil will be in exact alignment.
Good luck! Welcome to the world of dissimilar metal corrosion.
I was going to suggest weld a nut on it too. Certainly worth a try and really easy to do with all the bolt you have exposed.I’d still hit it repeatedly with PB Blaster before trying to loosen them and probably need to heat it too. I wouldn’t just weld bolts on and try it again considering there’s a reason they broke to begin with. I wouldn’t leave heat on but a short time, that aluminum is going to heat up a lot faster than the steel bolts. Also try to tapping the bolts with a hammer prior to all of this.
Happy Bob, no I have not got the bolts out yet. My Brother wants to put vise grips on them and just try and winch them out, I have vetoed that idea cause if I break them off flush I know the only option is a machine shop to properly drill them out and put in a heli-coil (don’t know if I spelled that right).
Anyway, here is a picture of what they look like now after I pressure washed them, don’t be deceived, they look like they will just spin right out but they are set in that concrete like white corrosion that Yamaha’s are famous for. A trusted source from a reputable machine shop said he could get them out by welding a bolt on them and using a little heat, I believe him but they are backed up with work and can’t get to it anytime soon. I have been spraying them with kroil everyday to help loosen them up. The only guy I know with a welder can’t weld stainless. Unless you can offer stainless welding and experience in this type thing I guess I will just have to wait til the machine shop can do it, the motor is worth it and I have another boat so I am not exactly stuck at home. As usual any help or suggestions would be greatly appreciated.
Thanks
Heat housing up with a torch from the inside so you don’t destroy the paint. It won’t take to much because aluminum is very conductive of heat. DO NOT heat the bolt itself. You want the housing to expand and leave more room for the bolt to spin out. Just wrenching them out with vise grips isn’t going to work if they broke off in the first place you NEED heat! Heat the housing up and quickly try to turn them with the vise grips. It’s not gonna hurt to try as long as you don’t go crazy and break them off flush. Put some pressure on them and see if they budge if they don’t try heating the housing again. You want the bolt itself to stay as cool as possible so if you have to wait a while for it to cool down then do it. If it doesn’t budge then your next step is going to be welding the nut on them. If you’re friend can weld then he can weld stainless. You can weld carbon steel to stainless with a carbon rod or mig it doesn’t have to be stainless. I do this everyday for a living. Weld that nut on let the bolt cool down. Heat the housing up and try turning it out with a wrench. Patience is your friend! You DO NOT want to break them off flush if you can help it.
It is easy and simple to change the WP in that motor.