Broken crankshaft bolt

Heads, valves, pistons, rods, crankshaft, etc...

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newfielady
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Broken crankshaft bolt

Post by newfielady »

Heard noise, found crankshaft pulley wobbling. Pulled out pulley found keyway chewed up pretty good. Decided to just change pulley and tighten it down as tight as I could. Never in a million years did I think this would happen. I broke the bolt. Think it bottomed out. Never used an easy out and really feel lost at this point. Please help this poor old woman figure out what to do. I do have pics of the crankshaft if anyone wants to see.
evolutionmovement
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Post by evolutionmovement »

The same thing happened to me, but I just broke the pulley and part of the keyway - I replaced the bolt instead of trying to reuse it (don't feel bad, I learned the same lesson the hard way on something else). How bad is the crankshaft keyway? If most of it is still intact, they can just put a new keyway in, replace the pulley if damaged, and you should be fine. If not, then you'll need a new engine (cheaper and faster than replacing the crankshaft) so you won't have to worry about getting that bolt out. I'd have someone experienced remove the bolt for me as it doesn't look easy to get at, but if you want to try it, I'd suggest removing the radiator and fans to get some room.

This problem usually happens because the bolt isn't torqued enough. It doesn't help that the Haynes manual and even the factory manual list it as too low. The spec should be over 100 ft/lbs. as it's what I use and my mechanic recommended (I use 110). Haven't had a problem since (120K miles later).

You say you're an old woman... How old are you? I wish my mother would have half as much of a clue about cars as you and the initiative to try to fix them. I'm lucky if I can get her to add oil on her own.

Steve
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
entirelyturbo
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Post by entirelyturbo »

I would think if the bolt broke roughly, that there might be a ridge that you can maybe get a hold of with a screwdriver and work the rest of the bolt out. Since the head is broken off, there is no longer any torque holding the remainder of the bolt in. I'm curious, though, how you could break such a heavy-duty bolt?

Replace the bolt and keyway, and you already have a new pulley. Then see where you stand from there. Steve is also right in that the manuals list the torque at a paltry 70-80 ft-lbs. Definitely do about 100-110...

I also agree that you know more already than many of my guy friends! :shock: Hats off to you! 8)
2000 Subaru Legacy B4 RSK

"Der Wahnsinn ist nur eine schmale Brücke/die Ufer sind Vernunft und Trieb"

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LegacyT
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Post by LegacyT »

Post those pics up, I'd like to see.

Mark,
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
newfielady
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Post by newfielady »

Guess I'm not that old but sure do feel it. I have arthritis in my neck, shoulder and back. I am 43 y/o. I was told to put the bolt on as tight as I could get it. Didn't think it would break. I am relieved to know that the torque won't be on it now that the head is broken off. I got new drill bits, ez outs and a corner motor drill and a female friend that thinks she can get it out. We are getting a steel sleeve made to put into the crankshaft as a guide. Bad news is the bolt is a special order part and won't be back until next Thursday. If someone could tell me how to post the pictures I will or I can email them . Thanks for your help, it really is greatly appreciated.
scottzg
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Post by scottzg »

is the bolt broken deep into the hole? if its on the surface, weld a nut to the end of it and use that as a new head to get the bolt out.
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LegacyT
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Post by LegacyT »

Here, email them to me and I'll host the pics for you :D

c150cglzp@yahoo.com

Mark,
Last edited by LegacyT on Sat Nov 29, 2003 5:23 pm, edited 1 time in total.
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
newfielady
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Post by newfielady »

Thanks for the tip Scott but the bolt is broken off about an inch and a half from the end of the crankshaft. Mark I sent the pics to you. Thanks for your offer to post them.
LegacyT
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Post by LegacyT »

Here are the pics:

Image

Image

Mark,
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
entirelyturbo
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Post by entirelyturbo »

newfielady, I wonder if you could put a slight amount of JB Weld on the bolt head, and then stick into the remainder of the bolt in the crankshaft. NOT so much to ooze out and then freeze the bolt to the crankshaft!!! :shock: But that may hold just enough for you to apply a reasonable amount of torque necessary to remove the bolt...
2000 Subaru Legacy B4 RSK

"Der Wahnsinn ist nur eine schmale Brücke/die Ufer sind Vernunft und Trieb"

*Formerly DerFahrer*

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LegacyT
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Post by LegacyT »

Maybe some places have heavy duty bolt extractors, where they drill a hole into the broken bolt in the crank, insert another bolt, lock it in there and remove both at once.. But I could see the motor having to come out of the car to do that, maybe even the crank out of the motor :(

Mark,
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
entirelyturbo
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Post by entirelyturbo »

Mark, I'll bet that if you removed the front end of the car (grill, bumper, radiator and condenser, etc.) there would be a big enough space through the rad support to drill that bolt out as you're describing...
2000 Subaru Legacy B4 RSK

"Der Wahnsinn ist nur eine schmale Brücke/die Ufer sind Vernunft und Trieb"

*Formerly DerFahrer*

@entirelyturbo on social media, including Facebook, Instagram, Twitter, and TikTok
LegacyT
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Post by LegacyT »

maybe, but I know some places remove the part, lock it in place and move a rotating drill bit into the stripped bolt shaft. I dont know if its doable with a normal drill in hand. Getting the hole drilled into a small hard steel bolt shaft may be too hard with a normal hand drill. Its worth a try though.

Mark,
1991 Turbo Sedan, Aspen White 5MT, Sold RIP
1994 Turbo Sedan, Crimson Pearl 5MT, from British Columbia-no rust!
cbose
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Post by cbose »

Does your angle drill have a reverse mode? If so, go and get yourself a good quality
LEFT-HAND drill from a tool place and use that to drill the hole. Chances are, before
you get far in it will spin out the bolt from the torque and heat. If not, move to EZ out.
Start with a centre punch, and a small regular drill so you don't spin out and wreck
the internal threads on the crank.

It IS possible the bolt had a previous flaw (have a good look at the break for
any discolouration) but from the pics, I would guess that it bottomed
out. The pulley probably chewed up the keyway, and itself. When you torqued it
down, the whole thing moved in too far and the bolt bottomed out. What
is the pulley supposed to seat on -- the face of the gear? If the bolt
felt sort of funny and soft just before the break, then it bottomed out.
If it just let go with a snap, have a good look at the break for a reason.

The pics look pretty bad, frankly. The keyway is gone. If you get the bolt out, here
is a suggestion

1. get a good pulley from a wrecker to start. Yours is certainly all messed up in the bore.
2. Put on the good pulley with some JB weld to fill out the nose of the crank and snug
it up with a new (or wrecker-used) bolt. Use some extra washers so you don't
bottom out and just snug it into position.
3. JB won't hold much and certainly won't act as a key. After JB is set, remove
the bolt and drill in some soft steel plugs on the joint between the crank and
the pulley. This can be done by hand. Get the plugs and drill sized together from
a machine shop supplier. Drill two plugs approx 180 degrees apart in good
clean metal, maybe 1/2 inch deep. This is the new 'key'.
4. Torque down the bolt as usual.
5. Important: Stand well back when you start it up. If the repair works, it will
probably be good for many thousands of km. If it fails, you could have a major projectile
headed your way.

If the repair fails, I tend to agree with the new-engine prognosis.

Good luck, Chris
1991 Legacy VZ wagon,
Japanese castoff retired to New Zealand
Approaching 200,000km -- Yikes!
evolutionmovement
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Post by evolutionmovement »

I don't think its going to be that easy to drill the forged steel crankshaft. It's very hard and round so the drill's going to want to slip. Not much choice, though - that keyway is gone.

Steve
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
cbose
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Post by cbose »

Just to clarify, you want to drill in the plugs from the front of the crank, parallel
to the long axis of the bolt and centred on the joint between the crank and pulley.
The ends of the plugs will lay under the washer on the crank bolt.
Depending on the temper of the crank, you may need a cobalt drill, but
the nose of the crank shouldn't be all that hard. The missing keyway would
suggest that! If the front of the crank is not nearly flush with the front of the
pulley, you may need to make a temporary filler piece to bring it flush so you
can start the drill. I can't say I'm sure about all this on a subaru, but in the
mercedes community, this is a fairly common fix, and the crank can be drilled by hand.
The mercedes pulley assembly is not keyed in the usual way, but plugged, right from
the factory as I described.

NewfieLady, we're rootin' for you,

Chris
1991 Legacy VZ wagon,
Japanese castoff retired to New Zealand
Approaching 200,000km -- Yikes!
evolutionmovement
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Post by evolutionmovement »

This plug idea can't be done from the front - the crankshaft can pass completely through the pulley. The bolt's flange holds the pulley to the crank nose, not the pulley itself. I guess this is just as well since there's not much material on the crank end to drill into anyway. Basically this doesn't look good. I don't see any viable way of holding the pulley in place so I'd say you're looking at a new engine (cheaper and easier than replacing the crank). I hope I'm wrong.

Steve
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
ciper
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Post by ciper »

If its any consolation a Legacy is probably the easiest engine removal you will ever do. All the wiring comes into one location (three large plugs) and the engine so so shallow that you dont need to worry about clearance. Ive only done it on an Auto but it took very little time to disconnect the transmission from the engine.

Heck, even two guys who have never worked on Subaru's recently removed a Legacy engine in about 90 minutes. The guy bought the legacy cheap to be used for a VW swap.
evolutionmovement
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Post by evolutionmovement »

This is true, a decent mechanic installing a relatively low mile N/A engine should be able to do the whole job for about $1200-$1400.

Steve
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
newfielady
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Post by newfielady »

Thank you all for your help. :D I haven't tackled the job yet. Still trying to decide what to do. I do think I am going to take a shot at it before I go the engine replacement route. I was wondering if anyone knows what would happen if I replace the pulley without the key. My mechanic neighbor recommended this. I am unsure about this. :oops: The key has to be there for a reason. What do you all think about not putting the key back?
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Post by ciper »

Put a monster lock washer between the bolt and pulley?
cbose
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keyless fix

Post by cbose »

Uh, well, you could try loctite bearing mount. It's thick
and green and fills up big (up to .005 in?) spaces. Slop it on the pulley bore
and on the crank nose and bolt everything together. Let it sit overnight.
It should fuse the pulley to the crank for good. Keep the bolt torqued as usual
of course, for safety.

Kind of a one-way fix. I think the only way to get it off, provided it fixtures, is
to heat everything up quite hot, destroying all the seals, the crank temper and
probably the pulley in the process.

I would have three questions. How will you get the position of the pulley right --
aren't the timing marks on the pulley? Will the loctite be strong enough
to take the torque and shock of startup and acceleration? Finally, has the crank
nose been chewed up so much that the pulley will seat crooked, or the fit of
the bore is too lose for even bearing mount to fixture?

If your only other option is a new engine, you have little to lose. You're
only destroying the crank and pulley which have no value
in a rebuild anyway.

Chris
1991 Legacy VZ wagon,
Japanese castoff retired to New Zealand
Approaching 200,000km -- Yikes!
DOA
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Post by DOA »

Erm, piece of advise from an engineer, use a key (get some oversized keysteel and file it to the same shape as the knackered keyway and to fit the new pulley SNUGLY or itll just fret and knacker up again) to locate the pulley as if the pulley slips round (and it WILL do eventually using bearing fit from locktite and just the bolt) it aint just gonna be your pulley and crank thats knackered, youll find peices of valve and piston coming out of your exhaust from the valves hitting the piston as the cam timing goes out too far.
On the bolt removal front have you tried putting a bit of heat on the bolt area (obviously not masses of heat) and hitting the remains of the bolt with a FLAT ended drift to see if it will losen up enough to twist out with a screwdriver or easy out.
Good luck and DO use a key when you replace the pulley, its your engine not someone elses remember!
There is only one other way to get round using the key and bolt but it involves boring the pulley out and fitting a hydraulic lock bush but you wont find a mechanic who will know what one is and Im rather too far away to show you how to do it properly lol. I could try and describe what you need to do but I dont have a clue where you would find the parts in the states.

AH! just looked at the picture again and noticed the condition of the keyway, best bet to repair that is to braze it and after re-filing the keyway back to shape make sure that the key is a very good fit in the new slot. Ive left the bit in above in case anyone else gets the daft idea that its ok to "just not use a key". Also looking at the picture you can tell by the way that the key has fretted the keyway that if you did just bolt the pulley up it would undo the bolt (shortly before wrecking your engine completely) as it turns in the wrong way for the bolt to lock it, the bolt is just there to stop the pulley from moving off the end of the shaft.
If only I hadnt bought the bike, this would feel fast :P
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Post by DOA »

Damn, couldnt edit that again :? .
There is another option if you know of any small engineering workshops in your area. This would involve boring out the pulley and fitting a hydraulically locked bush into the pulley. These are like top hat shaped bushes that are locked in place when a set of screws are tightened, theyre good for high torques (much better than taper lock bushes) and a far cheeper option than replacing your engine but I wouldnt know where you would source one in the states. Its a sort of last resort option if the brazing cant be done.
If only I hadnt bought the bike, this would feel fast :P
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Post by vrg3 »

Just a quick note -- valves and pistons don't collide in our engines, no matter how screwed up the timing gets.

I agree that filling with braze or weld and then filing back down to shape is probably the best way to go.

But if you do a ghettoer repair and it fails, it won't cost you a new engine (unless your engine suddenly losing power causes an accident which damages it).
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