Broken bolt in thermostat housing

[Douglasdzaster]

I’ve been doing a lot of catching up maintenance on a 1992 Yamaha 40 MSHQ that I purchased. Today I decided to replace the thermostat and gasket, figured no big deal. I was wrong. Of the 2 bolts the first one was a little tight but I took my time and it came out and even looks good. As soon as I applied a little pressure on the second the head twisted right off. Kind of a sick feeling. I had to prey on the cover on that side to get it to come off. It’s like one side stayed new and the other took all the corrosion. Since some of the bolt is sticking out I soaked it with penetrating oil went and got 2 nuts that fit it and jammed them together and started trying to slowly back the bolt out. Would not budge. So I’ve soaked it all day and tonight. Tomorrow I’ll try a stud puller or some vise grips. Should I try heat as well? I’m a little shy about putting a torch on the aluminum or would a heat gun help?
Any advice from the more experienced is greatly appreciated.

 

[CedarRiverScooter]

Try using homemade penetrating oil - ATF + acetone 50/50. It is much better than the common retail stuff.

Give the penetrating fluid several days to work. Apply several times.

After that, I would use a torch to heat the screw shank. Get it pretty hot, then let it cool. The difference in thermal expansion coefficients will help break the bond between the bolt & block.

 

[Weldorthemagnificent]

I regularly use heat to remove broken bolts. Yes aluminum won't turn red or give you any warning whatsoever before melting. That being said, aluminum transfers heat quickly and not a lot of heat is needed. With oxy fuel, heat the area around the bolt moving around quickly and try not to heat the bolt. Once the bolt heats up, it expands as well. Often 10-15 seconds of heat is all it takes. Never hold the flame still, always moving. The key is to heat the area quickly so that the aluminum expands before the steel of the bolt has time to. Heatgun or propane torch may not work as well as oxy/acetylene or oxy/propane. Mapp gas torch will work. Keep a rag and a bucket of water close so you can cool it down quickly. Whether the bolt moves or not you don't want that heat to go far.
You can also try heating the bolt as mentioned, that sometimes works and is easy to try. I've had better luck this way. I have worked at a machine shop for 30 years and have removed countless broken bolts. Keep at it with the penetrant between rounds if it doesn't come right out.

Sent from my CLT-L04 using Tapatalk

 

[overboard]

Might also tap "LIGHTLY" on the top of the bolt if it won't budge, if you use the homemade penetrating oil, and do as posted above, it should come out, a little patience is the key.

 

[MrGiggles]

I would get it to a welder and weld a nut on it. That is by far the best way I have ever found to remove broken bolts. The thermal shock of welding works wonders.

 

[DaleH]

There were some GREAT ideas in this YouTube video!

https://www.youtube.com/watch?v=dJfkCj3FWBs

 

[eeshaw]

I've heated the areas up with a torch like weldorthemagnificent only when I did it I used bees was to wick into the threaded portion. Acts like a lubricant.

 

[eeshaw]

I've heated the areas up with a torch like weldorthemagnificent only when I did it I used bees was to wick into the threaded portion. Acts like a lubricant. The tip will make a difference also when heating the material. Some cases a brazing tip will work better than a rosebud to control and concentrate the heat to a smaller area. You have to really be careful when using the O2 setup.

 

[Douglasdzaster]

Thank you everyone for the response. I was up late searching different forums etc. and the atf and acetone was mentioned a lot. I wish the bolt was vertical so it could really soak in. I’ll be mixing me some up though and replace the penetrating oil I’ve been using. My only means of heat are a propane torch or heat gun but while I’m soaking this thing I’ll ask around our small community here. The housing is on the side of the engine (not far from the carburetors fuel lines) and part of the power head itself so if I mess up (like over heating it) it’s shot. I know my anxiety is because I’ve never done it before otherwise it would probably be just another day. Lol Again I really appreciate all the advice and tips. Wish me luck. I’ll give y’all an update and let you know how it goes.

 

[nccatfisher]

I have had a great deal of experience with stuff like this. I am guessing you most likely have limited tools to work with. Welding a nut on that stub would be the #1 way to proceed if at all possible. If you have anyone that has access to a welder I would highly encourage you to go that route.

#2 would be the soak with good penetrant heat cautiously and firmly but cautiously smack that stud on the end. Don't get carried away hitting it just enough to shock it and hopefully break the corrosion loose that has it stuck and allow the penetrant to do it's job. Then cautiously try to back it out. IF you break it off flush and have to go the drill it out route it is imperative that you get your pilot hole in the center. Don't rush and get that hole centered. Use a good variable speed drill and use a good cutting oil going slow. I would recommend left hand drill bits hoping the heat and friction all the time would dislodge the bolt and whatever you do do not break off a drill or extractor in it. If worst comes to worst you can drill right to the edge of the threads and stop and take a small sharp chisel and break the bolt inward then use a pick and work the bolt out then use a tap to clean the threads up. Remember you have all the time in the world to accomplish your goal. You get in a hurry you will be looking for a block.

 

[maintenanceguy]

Soak with penetrating oil
Heat with torch (be careful, easy to melt aluminum or damage gaskets)
Weld a nut on
Find a machine shop that can EDM the bolt out for you. This will take 5 minutes and cost you less than $100.

Usually soaking and heat while slowly rocking the bolt back and forth works. If you don't have enough bolt showing to get a grip on it, you'll have to drill out the bolt and use an EZ-Out. Get the ones with the straight flutes that you drive in, not the spiral ones. The spiral ones are usually not as hard and break easier.

If none of that works, drill the bolt out with a left hand drill bit hoping the bit bites into the bolt and starts to turn it out. If the left hand drill bit does not bite, just drill the bolt out to the root of the threads and then you pick out a spiral bolt thread that's left.

To do this, you need to perfectly center the drill bit. If the bolt stands proud of the surface, get two drill bushings. One that has an ID the same size as the bolt and slip it over the bolt. The second drill bushing goes inside the first and centers the drill bit. Choose an ID that matches your drill bit (1/8" works well) and and OD that fits tight in the outer drill bushing.

If the bolt is broken off below the surface, get one drill bushing. The OD should fit inside the hole and the ID should fit your drill bit.

 

[Douglasdzaster]

I chickened out and contacted a high performance auto shop near by that does some machine work. Depending how stubborn that bolt is I’m looking at $35- $100. Well worth me not looking for a new power head. I really appreciate all the tips and advice from everyone and I’ll let y’all know how it goes.

 

[nccatfisher]

I chickened out and contacted a high performance auto shop near by that does some machine work. Depending how stubborn that bolt is I’m looking at $35- $100. Well worth me not looking for a new power head. I really appreciate all the tips and advice from everyone and I’ll let y’all know how it goes.

From someone that is used to doing that job I can still understand why you would do this. Especially if you are limited on equipment. It will be money well spent as opposed to some of the total mishaps I have seen some folks do that are totally the opposite and just jump in and ruin major components, some that can't be replaced.

 

[Douglasdzaster]

Dropped it off this morning. He even commended me for not waiting until I broke the bolt off and a drill bit or 2 inside. Just waiting on a phone call. This is the first thing I haven’t done to the boat myself. Drive way sure is looking empty right now.

 

[nccatfisher]

Dropped it off this morning. He even commended me for not waiting until I broke the bolt off and a drill bit or 2 inside. Just waiting on a phone call. This is the first thing I haven’t done to the boat myself. Drive way sure is looking empty right now.

You probably saved yourself about $50 by stopping at that point.

 

[Weldorthemagnificent]

Good choice. Put the aces in their places.

Sent from my CLT-L04 using Tapatalk

 

[Douglasdzaster]

I couldn’t stand the wait so I dropped by this afternoon since I was in town just to check on my boat. They were just pulling it into the shop. I got to hang out and watch this man try everything that I was told to do and some other neat tricks. We both thought by looking at it some heat and it’ll probably come right out. He tried it all until he finally had to start drilling. Starting with the smallest bit I’ve ever seen and stepping up one size at a time until he was were he could pick the threads out that still weren’t giving up without a fight. 2 1/2 hours and I’m hooking up to bring her home. Best $50 I ever spent. Gotta love being in a small town. Thank you everyone for your advice and sharing your knowledge. I really appreciate this forum. I’m looking for questions that I can help someone out with.

 

[nccatfisher]

Some are like that. You ought to have to lay under heavy equipment to do that with grade 8 bolts that you have had to heat cherry red and let cool naturally to loose their hardness then do what he did. Done it for hours/days on end.

 

[Douglasdzaster]

One more question. Do I use a sealant on the new thermostat gasket? If so what’s the best?

 

[RaisedByWolves]

I couldn’t stand the wait so I dropped by this afternoon since I was in town just to check on my boat. They were just pulling it into the shop. I got to hang out and watch this man try everything that I was told to do and some other neat tricks. We both thought by looking at it some heat and it’ll probably come right out. He tried it all until he finally had to start drilling. Starting with the smallest bit I’ve ever seen and stepping up one size at a time until he was were he could pick the threads out that still weren’t giving up without a fight. 2 1/2 hours and I’m hooking up to bring her home. Best $50 I ever spent. Gotta love being in a small town. Thank you everyone for your advice and sharing your knowledge. I really appreciate this forum. I’m looking for questions that I can help someone out with.

You should drop off a case of beer for him, $50 for that much work is a steal.

My saga.

https://tinboats.net/forum/viewtopic.php?t=43933&p=442421#p442421