The Stovebolt Site Forums The Shop Area Engine Shop total and complete absolute IDIOT!!!!!!!!!!!!!!!!!!!!!!

in retorquing the main bearing bolts on my 292 I BROKE BOTH BOLTS ON MY #2 mains. Just thought I'd let you know.

Right now I'm at a loss for words

loosening? Why did you continue after the first?

Geez Tony M, The guy feels bad enough. You have to rub it in ??

I don't know about the other guys, but I have made a lot of mistakes. I give ftyler credit for admitting his..

Your question is valid, Tony M. All I can say is inexperience and idiocy. The torque wrench instructions said tighten and stop when you hear a "click". I did so with the first bolt. At the time didn't realize that the click was the bolt breaking. Went on to the second bolt and did the same thing. This time the bolt gave way and was very obviously broken. I was stunned. And still am, somewhat.

I've spent lots of time and money on this project and right now I'm evaluating my options. This sucks! :mad: Sucks even more when it's your own fault.

Now you are experienced in broken bolts.I like to break the last bolt on a head myself.
No options,remove the stubs, get new bolts,Practice with the torque wrench on a friends engine.

Fred was having trouble with his image hosting. Here it is!!! [img]http://pstr-m01.ygpweb.aol.com/data2/004/51/E0/02/62/quFD2zdLsftgJDRQ6094evr2-Wy9n5re0180.jpg[/img]

Ftyler'
As a last resort and you have to drill them out. Try using a left handed twist drill. You can get them at most machine shop supply dist or McMaster-Carr sells them. These drill will most likely back out a broken bolt once they bit into it. If it doesn't then you have a pilot hole for your easy out.

Clem

What I try to do in these situations is stop what I am doing and think things over..Clem has the right idea, get the proper size drill bits and work the broken pieces out with the easy out. You'll figure it out..

if they were turning easy before they broke,tap them with a punch to unjam them from the threads,then a reverse drill bit should back them back out.

As you guys can see by the photo the bottom part of the bolts lie 1/2 - 3/4 inches down in the block. Things may be made easier by the engine being already mounted to a stand.

This won't be fun but after I take a week or so to re-evaluate things I'll get back at it.

Thanks for the support!
-ftyler

You will need to replace all of your main bolts with new ones. I have to assume that they were already cracked, either by overtorquing in the past or hydrogen embrittlement due to acid in the oil. At least they broke now, rather than later. And compared to the price of an engine, bolts are cheap.

I assume you had lubed the bolt threads with motor oil since that is how the torque specs are established.

I meant no offense. I was trying to figure out why two bolts would break and not just one.

Fred the answer is, unfortunately, no. I didn't have the bolts lubed. Will I remember to do it for subsequent builds? -> You bet your sweet a**!!!

In hindsight, common sense should have lubed the threads. But I didn't. A learning experience, but potentially a costly and disasterous way to learn.

This whole thing has me re-thinking the small block again, but I don't give up quite THAT easy.

-ftyler

I have only broken one hardened bolt, a head bolt. It was a complete surprise because they don't really twist at all they just snap. With my experience, the head bolt extracted really easily once there was no tension on it. If I remember correctly, I used the top stub to turn it out, once the head was off. This was because the fracture was a perfect fit between the two halves.

Why would these hard bolts break? Too much torque? Bottomed out in hole? Did you have any machining on the block to reduce metal depth? Did you torque in "steps"? About 1/3rd of torque, half, 3/4, and full? In pattern shown in book? I do know that modern small head bolts are to be replaced cause of "stretch" they go thru when torqued. I've never heard of this on older engines. Is it a cheapie import torque wrench and maybe it's not really setting at torque you have it set for? Something is fishy here, these bolts shouldn't have done that. Check your procedure and specs for next ones.

Breaking on the way in is OK - they usually back out pretty easy. Learned a cool trick from a mechanic that broke a head bolt going in and didn't want to pull the head. You need a stick welder. Remove the flux from the tip of the rod, position it in the hole on the broken stub, then flip on the power momentarily. The stick welds to the stub and you can just spin it out.

If you do decide to drill, pack the hole with thick grease and put a ring magnet (there's got to be one on the fridge) around the bolt hole. Tape/mask the exposed crank just in case. Drill slowly. You might not have to take it apart to clean up all the filings.

Hey Ftyler, how strong are you, man? The "click" on a clicker torque wrench takes a feel to get used to. But these bolts shouldn't have broken unless you were REALLY bowed up on them.

Center punch the broken bolt. Get the reverse bit and eazy-out of the right size. The large magnet is a good trick to catch the shavings you'll make. You must use the bit and eazy-out of the correct size. Too small a bit/eazy out and it'll break off. Too big and you might drill into the block threads trying to get the bolt out. Whatever you do, do not break the eazy-out in the bolt. Eazy-outs are made of a hardened steel that is about impossible to drill.

Only work on one bolt. If you can't get it out, do not try the other one. Bring it to a shop if you can't get the first one out yourself.

Post a pic of the broken bolt shank, so we can see if the bolt looked weak. To be fair, you did ask about replacing them in an earlier post.

best of luck
Chip

Not lubing the threads shouldn't have been enough of a problem to break the bolts. GL asked the right questions. From the looks of the picture, the bolts broke right above the block, and will require some tlc to remove. Not a job for the inexperienced.

Procedure should be: remove the crank; grind the shank flat; punch the hole dead center; drill out using left hand bits, starting with small and working up to larger. If the bolt still isn't out, use a good easy-out, the spiral shank ones work best. Be careful not to break the easy-out. If the easy-out doesn't get it, continue to drill out the the proper tap size for the thread, then run a tap down the hole.

If you aren't comfortable with this, get some help, either from a friend or take it back to the machine shop and pay them a few bucks for the repair.

Forget it guys. I'm the idiot [censored] here. totally pure idiot on my part.

No need to scratch your heads any more. I was torquing the bolts to 95 ft/lbs instead of the required 65 ft/lbs. :rolleyes:

The other bolts are probably good. Me?

STUPID, STUPID, STUPID! :mad:

I just hope this isn't contagious!

Actually Fred the bolts are broken 1/2 to 3/4" beneath the surface. Even worse than you stated. :mad:

-ftyler

Oh furd. Torquing to 95 ft-lbs will make them buggers hard to remove. I'd be on the phone to see how much moola is needed.

I've been told that confession is good for the soul. You should really be feeling good on this one.

I previewed this message, and found that furd spelled with an e or 0 is now verbotten!

I'm thinking of just trying to locate a block, have it tanked and bored .060 over and just starting over.

Seems to be the most cost effective solution at this point. Those broken studs are in there tight. REALLY tight.

Bolts shouldn't be tight there unless threads were damaged! It's the heads pushing on stuff that make them tight. Did you take a long [censored] or straight punch and try to tap around some? Maybe the welder rod idea sounds good now. Maybe a good weld shop has worked with broken bolts before. Have one nearby?

Like someone said, the pressure is off with the heads so they should not be tight. If the threads were clean then they will back out very easily. I would at least try the left handed bit idea, I bet they will back right out.

If the left bit or welded rod works then I'm sending 50 bucks to everybody who recommended it!

I was going to say that. Does that count?

take your 292 and the 50 bucks to a machine shop. That will take care of your problem without damage to your block. Ya might have to put a little more with the 50, but I doubt it. Mike

Snap-On (Blue Point) markets an easy out which is made by Ridgid. These easy outs are a stem with 'flutes' on it. The flutes bite the bolt you are backing out. The kit I have has drill pilots that allow you to perfectly center the drill bit. After you drill the hole in the bolt, you drive the extractor into the hole and slip the driver over the extractor. The driver is SAE hex sized and you can rock the broken off piece back and forth to loosen it up. This is something you cannot do with a regular easy out.

These are not real expensive (less than $40, I think) and would be worth your time to have around.

Chuckthetruck's idea of using a welding rod is an old trick... But don't use just any rod that you have removed the flux from the end of. YOU CAN DAMAGE THE THREADS!

Chuckthetruck's idea of using a welding rod is an old trick... But don't use just any rod that you have removed the flux from the end of. YOU CAN DAMAGE THE THREADS! Go to your local welding shop where you can purchase speciallly made rod just for this purpose. The flux on it protects the threads, and you'll get better results!

ftyler, You honestly don't have a big problem at this point. What I am wondering- is this possibly a case of the wrong bolts in the wrong holes? I'm now concerned that maybe they were bottomed out in the holes. Then I have one more question- are you 6'6" and weigh 275lbs??? and your brother's name is Arnold?-LOL Maybe you need to torque them like the post awhile back about head bolts- torque them untils they squeal.-LOL
You will have it fixed in a jiffy and be dang proud of yourself- taking a breather and thinking about it, is good- then remember, If you break it you fix it- Right? This engine rebuilding stuff can really have a steep learning curve.
Years ago I broke quit a few head bolts taking apart old flat heads until I figured out to always hit them first with a big sledge hammer. So if you see me packing around a sledge hammer, it is for whacking head-bolts.-LOL I don't think you will ever forget this one.-LOL
FIX IT!!! (you broke it)-LOL

I keep one set of the left handed drill sets in my box at work. The Snap On set was about $40 and came with 5 left handed drills and matching extractors. The other guys are right, be DEAD CENTER with a sharp center punch. I have removed many bolts with only a pick after a sharp strike with a punch.
Good Luck
Brad

Along with all the good tricks and info stated by the other broken-bolt experts, use a torch to warm the sides of the main web area on each side of the bolt.This will help to expand the hole that the bolt is in.
.What brand of torque wrench were you using???

I have another question,,,,,when assembling an engine, do you do one part then go to the next step?I noticed that the rods and pistons are installed and I was wondering why the mains were not torqued when they were installed. :confused:

Mechaniac,

The ONLY reason I was fooling with the main caps bolts is that the engine shop that I bought the short block from put the oil pickup tube bolt on the #2 main instead of the #5 main. Instead of hoisting the engine back on the truck and driving 20+ miles to the shop, I decided it made more sense to buy a good torque wrench and swap the bolts myself. Problem only came about when I failed to walk 10 ft, pop my trunk and note that the bolts' peak torque is 65 ft/lbs instead of the 95 ft/lbs I attempted to apply to them.

I figured the torque wrench made sense since I was going to have to install the head myself anyways. I would never in a million years test or play around with my torque wrench on an engine I plan on running in a vehicle.

Something to think about, I don't think this could happen but I'll throw it out there. Could torquing to 95 instead of 65 maybe flatten that bearing?

Warning! When drilling the offenders, watch out for bits of metal flying in the engine!

I would take some plastic dropcloth and cut a small hole. Then apply this over the entire engine and only let the offending area stick through the hole. Now tape it together. This would be similar to the sterile field in an operating room. Clean the area with solvent first so the tape will stick to the metal.

ftyler, I was not inferring that you were "playing" I understand now that you bought a short-block.This does raise another question.How well did they inspect and biuld the short-block assembly???Have you talked to the builders?I am not saying that they did a bad job, I am just wanting you to have a properly assembled and great running engine.I hope everything else is ok on the engine.

Mechaniac,

One can only wonder about the rest of the build. From what I can tell everything else looks great. Wish it had only been bored .030 or .040 over instead of .060. But I've been told that these later cast blocks (this one is a Mexican cast) can run .060 with no real dangers provided everything is balanced and torqued right and the engine is kept properly cooled).

Being that it's a short block, the engine came pretty "naked". Makes it easy to inspect. The short block wasn't exactly cheap, but I went this route because my local machine shop wanted more money to rebuild the core I pulled out of the C60 from the salvage yard than buying the new shortblock. The core charge towards the new engine was more than I paid for the salvage shortblock, plus I got to keep the brackets, oil pan, motor mounts, timing cover, etc. It would have been an even sweeter deal if I hadn't screwed myself.