BOLT BROKE OFF

[cdells]

Good morning everyone. Hoping for some advice from someone with a mechanical background. I pulled apart my exhaust/ coolant manifold to clean everything up since I was getting a lot of overheating. Unfortunately, when I was bolting the manifold back on to the aluminum coolant reservoir I over torqued the bolt. I have tried to drill it out so I can re tap the hole but I cant get anything that will work. I have used titanium dewalt drill bits and it doesn't seem to do anything. Also since the bolt broke off below the surface (and at an angle) I am doing damage to the aluminum trying to get it out. My question is: Can I just leave it as is? I replaced the gasket and there are 4 other bolts holding it together....maybe it would just leak slowly over time? The only other option I see is buying a new reservoir (500 bucks) and Im not even sure I would be able to get the old one off without breaking more bolts in other locations.

The photo shows the area I am talking about. I circled a bolt in red but the actual location of the broken bolt is in the lower right hand portion of the manifold but cant be seen.
Thanks in advance for any advice.

 

[sailme88]

If it is underneath you're best course of action is to remove whatever it is attached to. Cut your losses and bring it to a machine shop.

 

[kloudie1]

Yup, not good news but I agree. Take the whole manifold off and take it to a shop. They should be able to get it and the others out and "helicoil" or re-thread as necessary. That Westerbeke is a kinda rare one in the H-34.. I think it was done in some early ones before they switched to Yanmar. It is smoother running since it has 4 cylinders but it is a Westerbeke. Many were Mitsubishi tractor motors so they are basically decent and sturdy engines but some of the "marinizing" parts can be troublesome. Be sure to use anti-seize on everything when you re-assemble. Good Luck..

 

[jviss]

There's a really excellent marine machine shop on Pope's Island in Fairhaven, MA. Believe me, it would probably be worth shipping your stuff both ways. They turn things around quickly, and their prices are very reasonable.

R.A. Mitchell

 

[cdells]

Thanks for the responses. I just don't think that I can get the manifold off of the elbows without major surgery... everything is pretty rusty.

 

[jviss]

Thanks for the responses. I just don't think that I can get the manifold off of the elbows without major surgery... everything is pretty rusty.

PB Blaster helps a lot. Also, you'll ffeel much better diving in and getting it all fixed properly.

 

[Jake N Eggs]

You need to get a center punch hole in the broken part of the bolt as close to the center of the broken bolt as possible. Since it is below the surface and at an angle you may have to "chisel" the upper slope of the break angle to create a reasonably flat surface to engage the center punch. Grinding a small punch on an angle will allow you to chisel the material of the broken bolt. Once you have the center punch in the middle of the broken bolt you can drill it. Start with a very small drill bit, about 1/8", and drill a hole completely through the broken bolt. This will allow you to spray your favorite penetrating fluid into the closed side of the broken bolt. You can then start to drill with bigger drill bits in small increments. Will probably take 3 different sizes to get to a hole big enough for a screw extractor. You may have to start the bigger drills at an angle into the taper of the broken bolt in order to keep the hole in the middle of the bolt. The 1/8 drill should be at high speed and the next drills should be a bit slower. Most important is to get the first hole in the center. If it's off slightly you can adjust with the next drill by drilling at a slight angle to move the hole. Make sure you have sharp drill bits. Maybe purchase a few new 1/8 drill bits.

Have patience and good luck.

 

[jviss]

A machinist's trick my father taught me is to drill the center with a left handed drill - the broken bolt will often just spin out while doing this. You can get a set of LH bits at Harbor Freight.

You can use a flat ended grindstone in a a Dremel tool to flatten the end of the broken bolt.

One trick I used once was to stick a welding rod to the end of the broken bolt - an arc welder is necessary, or, if you have guts, use your house battery. . Be careful, and be ready to disconnect the battery quickly, once the rod sticks. Then you grab the rod with a vice grip and twist it out.

A caution: don't go too small on the drill, if you break it you'll now have a hardened piece of steel in the center of the broken bolt, which you can't drill! (Don't ask me how I know.)

 

[Hello Below]

Thanks for the responses. I just don't think that I can get the manifold off of the elbows without major surgery... everything is pretty rusty.

Any good mechanic worth his or her salt would have the skill, tools and experience to make short order out of this job. Why risk making things worse?

 

[RitSim]

One way is to bolt the exit elbow back on and buy/obtain a sleeve to fit snugly in the elbow with a much smaller ID - say 1/8". Then the drill has a guide to give you a chance. The drill will still tend to "walk" on the broken bolt. That being said, I would still remove the head, get a look inside the engine and a chance to remove the head studs as well.

 

[jviss]

That being said, I would still remove the head, get a look inside the engine and a chance to remove the head studs as well.

Who said anything about removing the head?

 

[jibes138]

A machine shop will likely have an EDM machine (electro discharge machining) to burn out the broken bolt. Once the minor diameter of the bolt is removed they can chase the thread with a tap. Since the EDM machine does not make physical contact with the bolt there is no drill walking concern. Think of a spark plug that melts tiny amounts of metal with each spark. A screw thread insert is also an option if the wall thickness in the area is large enough to allow for the oversized hole.