Mr E, welcome to the forums.

Not sure which bolt you snapped off. Getting a steel bolt that seized in aluminum is a hard task but can be done with skill and the correct equipment.

1. Some times the bolt sticks out the back and you can get 2 thin double nuts on and turn it out a bit.
2. Heat the aluminum up a little while using a center punch, gently rap on the bolt a few times to shock the seized threads loose.
3. Center punch the bolt like in #2 above and then using a "LEFT Hand" twist drill bit try to drill the center of the bolt enough to get the extractor in. Sometimes just drilling with the left twist drill bit can walk the bolt out. Extractors should only be the last results and ONLY by a professional.

Now, which bolt snapped? I numbered your picture

 

It's number one. The thread is still in the body. #2 and #3 are also tight. #4 is empty. I probably should take out 2 and 3 and remove the water pump but I am worried about breaking them. I don't have a torch.

 

Apply heat, possibly with heat gun, or dremel torch make casing surrounding bolt heat to approx 80-100 degrees celsius (i dont know what is Fahrenheit value) then CAREFULLY with spraying wd40 try to slack the bolts with spanner not socket ratchet or anything that can apply too much force on bolt, if they refuse to go apply more heat, aluminum will heat fast, for sheared bolds you will have to do as Dave told you, drill center hole with high quality drill, start with 2 mm then enlarge it to 5, 6 mm if its M8 , than use extractor but be CAREFUL extractors are very brittle they brake easily especially small sizes. If you have enough thread left sticking out you can try two nut method, with applying heat., heat is your friend on stuck bolts.

 

All the above is good advice. However I would not use an extractor the break and once they do it's all over. Drill it as advised then just retap it those bolts only need about 10n. Did I say dont use an extractor

 

You can try drilling all the way to 7 mm, then you will have half millimeter on each side which will make bolt come out easily but with this you have to make perfect center for drill, yeah you can retap to m10 but you will have to drill through existing thread on pump. Good luck

 

I am confused. From your photo are you trying to tighten bolts 2 & 3. You said you are scared to remove the remaining two bolts which suggests that 2 & 3 are the ones you have screwed in and they have become tight. Is it just me or should not there be an outer cover on the pump, in which case you will need to fit the outer cover from the pump, otherwise the bolts will bottom out and become tight which is why one has snapped off and the other two are tight.

 

I edited my post about extractors.
I have seen and broke a casting when the extractor did not work.

 

Can you continue forward and bring the bike up to temp and see if it leaks? If no leaks you may be ok for a good long time.

 

As Daris said I would be tempted to leave it and reassemble. There is a screw right next to it holding the outer case so water wise you should be ok. You may end up with a small oil leak. If you do you can always come back to it and try and drill the bolt out, but unless you have experience in doing it I would leave it to a a good mechanic.

(Admin note, changed Dave to Daris.)

 

Like Daris and Cooperman said, try to see if it can go back together and run.

I'd smear on some Permtex Super 300 Form a gasket on the mating surface and bolt it together.

Super 300 is safe for antifreeze. $12.89 on Amazon

https://amazon.com/Permatex-80057-S...d=1&keywords=Permatex®+Super+“300”+Form-A-Gasket®+Sealant&qid=1613609375&sr=8-1

 

I did think about just putting the cap back on and see if it still leaks. The seal is really tight with just 2 bolts and the cover has 2 screws. I practiced drilling one of the bolts in a vice (see photo) and the extractor felt like it was about to break.

 

If you can drill a hole in the bolt that is stuck, say 8mm, just tap it and use a smaller bolt in that position.

 

I can assure you the extractor will break. They are a devils tool and made explicitly to make your life more miserable avoid. On the hole where you have broken the bolt there appears to be 1/4 of free thread cut a 6mm bolt short and just nip it up with some gasket sealer as suggested by Dave

 

Do not use RTV for this sealing. The Form A Gasket is more of an adhesion sealer.

 

The big question is why did you sink the bolts fully home into blind holes to start with.

 

After a forty year + career as a millwright, pipefitter and heavy duty mechanic which included helping train many apprentices I'm offering my opinion, which is worth what you are paying for it. Put down your tools and back away from the machine. If you did what maccect suggests in the above post you have done all the damage you need to do. I don't think you can be trusted to drill a straight hole into the bolt. Find someone who knows what they are doing; leave it alone.
Happy Motoring and thanks for playing

Pro Tip: Never screw a steel fastener of any size into aluminum without wire brushing the thread and using a tiny bit of Never-Seize. Nuclear grade with nickle is my recommendation.

Answer the following questions before you continue to use any tools.
1. What are the three basic machines?
1a. What are the classes of one of these above referenced machines?
2. A threaded fastener, or screw, consists of which two of the above referenced machines?

The thing I miss most being retired is not having an apprentice to do the scud work.... and to beat when they do something stupid, like using more than two fingers to tighten a tiny bolt. But I digress.

 

They make never sieze in a stick too, best shyt ever
anything aluminum or stainless, a little dabble do ya,

Tiny extractors break

Know what's even worse, Tap Extractors, Go ahead try to extract a busted 6mm tap out with a tap extractor
I'll watch

Sometimes depending on the specifics, a dremel cut off wheel can cut a slot in the busted screw & take the piece out with a screw driver

Gluing it together is a good plan

 

If you can drill a hole dead center in the bolt you can make the hole big enough to use an extractor. The biggest cause of broken extractors is too small a hole, usually crookedly drilled off center, which fail to release the tension. The male threads of fasteners fill less than 100% of the female threads in the casing. There are many sizes of drills to get a correct sized hole; inch, metric, number and letter sizes. New sharp drills of appropriately hard material work best. Over tightening of fasteners by big armed goons or rookies stretches the threads and makes the job much harder, as does screwing dirty unlubed fasteners into your housing. Either of which probably caused your problem in the first place.

Happy Motoring and thanks for playing nuf sed on this topic class dismissed

 

Just out of chance, I came upon this YouTube video that might interest you:
Extract Broken bolts from deep hole NEW easy WAY - YouTube
Involves MIG welding (which I can't do) but hey, might work for you.

 

Thanks for sharing that.

 

Thanks for all the positive advice. I got the micro torch but I'm going to try the safe route and put the gasget seal and see if it leaks. If it leaks I'm going to use heat and try to remove it. I will keep you guys updated on the results.