Stripped head bolt

[94fordguy]

So I've got a stripped head bolt on my 900... it was leaking coolant this last trip and I could see it seeping from one of the bolts when it was idling. I pulled the bolt out and about 5 threads of aluminum from the cylinder came out with it

Is there any way to fix this with a larger bolt and thread tapper or am I looking at a new $500 cylinder?

If I wind up replacing the cylinder then I might as well do a complete rebuild on the entire engine since it's been 2700 miles since the last bottom-up engine rebuild. The sled has 4,760 miles. Motor has an '06 crank, 06 pistons, and 1 newer cylinder (the one that's stripped too) Otherwise the rest of the sled and engine are pretty much stock from '05 and in really good shape.

 

[sloan188]

I've fixed the same thing with a helicoil or thread insert.

 

[joshkoltes]

can you drill it deeper and bottom tap it for more threads? useing a longer bolt. bigger diameter is hard to get equal torque. maby a shop can re weld the hole shut and re drill and tap it? i wouldnt trust a helicoil there

 

[ja992]

Heli-coil you can get the kits at Napa.

Youtube Heli-coil Video

 

[SnoBusMan]

Having much ecperience with Helicoils I would reccomend that BUT... I would use Loctite on the Helicoil and carefully clean the inside of the Helicoil before inserting the bolt (torque loss) I have used Helicols on many high strength junctions over the years from exhaust manifolds on Ford Modular engines to engine mount bosses in aluminum blocks. Unless there is coolant below the hole (through hole) it should work.

 

[mtncat1]

use a heli coil.i have put hundreds of them and if done properly the repair is stronger than the original don,t worry about loctite they don't come out. don not drill deeper or over size the hole your only asking for trouble if you do.

 

[LoudHandle]

Heli-coil it. Everything else is weaker, especially welding it. They should all be Heli-coiled or studs from the factory in my opinion. I Heli-coil all my stuff when brand new for the piece of mind. I use permanent Loctite on the Heli-coil and blue on the bolt if desired. The additional advantage to the permanent Loctite on the initial coil install is if you ever bugger it up you can retap / chase the threads.

 

[94fordguy]

Having much ecperience with Helicoils I would reccomend that BUT... I would use Loctite on the Helicoil and carefully clean the inside of the Helicoil before inserting the bolt (torque loss) I have used Helicols on many high strength junctions over the years from exhaust manifolds on Ford Modular engines to engine mount bosses in aluminum blocks. Unless there is coolant below the hole (through hole) it should work.

Unfortunately it is a through hole.... I put new O-rings in the head about a month ago so I was able to see how the cylinder was made, this bolt just seemed like it didn't want to click to torque so I stopped fearing it would strip if I continued, apparently it did All the others torqued up correctly and I didn't have any issues and didn't lose any coolant on the first ride.

I guess I'm not so worried about the bolt taking the proper torque, I just want to stop the resulting coolant leak.

 

[m8magicandmystery]

big lag bolt wrapped in a Trojan..

 

[SnoBusMan]

Looking at how the head is set up and with the bolt torque at 22 ft lbs maybe try Helicoil and a copper washer like rrom a brake caliper on top? then retorque after a few runs?

 

[LoudHandle]

Unfortunately it is a through hole.... I put new O-rings in the head about a month ago so I was able to see how the cylinder was made, this bolt just seemed like it didn't want to click to torque so I stopped fearing it would strip if I continued, apparently it did All the others torqued up correctly and I didn't have any issues and didn't lose any coolant on the first ride.

I guess I'm not so worried about the bolt taking the proper torque, I just want to stop the resulting coolant leak.

Heli-Coil it and never worry about it again. If you only do the one you will soon wish you had done them all, as the rest are not far behind. Thru hole or not it does not matter, as the seal is made at the top under the flanged head. The newer engines use RTV or similar to seal it here. The older engines used copper washers, the copper washers can be used over and over but need to be annealed every time to soften them for reuse. This is accomplished by heating them to a dull red color with a propane torch and quenching them in water while hot. Re-install head and torque. Simple.

 

[94fordguy]

Correct me if I'm wrong, but no matter what fix I do to this thing at this point, I'm going to have to pull the cylinder so I don't get any aluminum shavings in the coolant system right?

 

[LoudHandle]

Correct me if I'm wrong, but no matter what fix I do to this thing at this point, I'm going to have to pull the cylinder so I don't get any aluminum shavings in the coolant system right?

Yes, it is best to do it pre-assembly but it can done without removal, here is how I go about it.

Drain the coolant down to below head height. Remove the head, apply sticky grease to the drill bit (the grease will collect most, if not all the chips, if you want to be really anal about it you can mask the whole top of the engine with Blue painters tape or similar), run the drill into the stock thread depth, remove drill and wipe off the grease / chips. Apply the same grease to the tap, tap to depth, remove tap and clean grease / chips off. With a Q-tip or similar soaked in acetone or brake clean, clean any grease residue out of the newly formed threads. Thread Heli-coil onto installation tool, apply permanent Locktite, thread in until the last coil is 1/2 to 1 turn below deck height, remove install tool and let cure. If desired repeat on any / all other bolt holes.

 

[05900]

Exactly as above and you should be better than new. Do as many as you can now.!

 

[Z-Man]

Wow, a ton of responses on this already. Both Sean and I had issues with this on our 975's. I had indydan put steal inserts in all the bolt holes on the cylinders for my 900 turbo.

cylinder can be pulled off easily with engine in the chassis. I would pull it and have inserts done on all the holes so you don't have it happen again. According to Dan the metal is pretty soft and on these cylinders.

 

[Dartos]

Good thread I was putting my 975 together today and stripped thread on 1 bolt.

What size helicoil are you using?

 

[Z-Man]

Sean tried to helicoil the threads on his 975 and he ended up towing it off the mountain when if leaked all the antifreeze out. I had threaded inserts installed after stripping two different cylinders.

 

[SnoBusMan]

Good thread I was putting my 975 together today and stripped thread on 1 bolt.

What size helicoil are you using?

It calls for M8x1.25

 

[05900]

All this and a torn track? Some people can't have nice things..........with thousands of miles on 'em.

 

[Z-Man]

Damn unreliable 900's only lasting 8 years before falling apart like this.