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Recently replaced the harmonic balancer on a 1990 Honda accord ex. Previous owner put in a bigger bolt. Tried the stock 19mm bolt and it goes in fine but will not tighten. The bigger bolt is 23mm and that wont tighten either. I have never heard of this problem and would appreciate any suggestions. Thanks
Note:
– Friend only paid $450 for the car
-threads seem messed up
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Are the threads into the crankshaft damaged ? I’m assuming your using a tool to keep the crankshaft from spinning as you try to tighten it ?
You might want to try running a tapIt sounds like the threads may be stripped. This is a problem because the crank is case hardened steel. That means that using a tap can be problematic and it might break if you go to big. Break a tap in that engine and you might as well write it off because you’ll need to send it to the machine shop to have them remove the broken tap.
All that said, you might try a different bolt to see what happens. If you can get the threads to catch, consider yourself lucky and move on with your life. If it doesn’t, I think we need to get someone with machine shop experience to weigh in here.
Keep us posted and good luck.
Basically, you’re boned.
Sounds like stripped threads in the crank and that is going to be a difficult repair for a lot of reasons.
First off I am not sure of the specifics of that crank but it may, or may not, be hardened in that area. Many cranks are only hardened in the bearing journals but some are hardened in other places. Depending on how, where and to what degree it has been hardened it may be difficult, but not impossible, to tap just from a tooling point of view.
Then you also have the factor of how difficult setup is going to be and that is dependent on how much room you have in the engine bay. Crank bolts are actually not often a super high precision thing, they usually just provide flat clamping force and do not have a precise fit on the diameter of the bolt do you do not have to be perfect on center, but you do need to be straight on the bore of the hole or you will have uneven clamping force putting strain on the bolt.
Do you have enough room to get a drill on the front of the crank in a manner that you are confident you can drill a straight hole? Do you have room to get a tap handle in on it that you can turn easily?
If you do carefully drill it out to either the next thread size or the proper size for a threaded insert for the OE bolt. Once it is drilled out get a HIGH-QUALITY tap and gently tap the hole. Be careful not the break the tap because of you do like Eric said you are really boned. They do make a tool for removing broken tapes but they are expensive and, honestly, only work about 60% of the time.
If you mess it up you are pulling the engine and swapping cranks; then again you are going to have to do that anyway in this situation so how much effort do you want to put into maybe saving yourself a lot of time and money?
1st I’d try a new 23mm bolt. If the end of the crank was case hardened the previous owner actually used up the One Shot Fix. The 23mm likely broke through the hardened surface of the threads (I can’t remember for sure but I think it is like max .010″ but likely .002″ – .005″ for case hardening 4mm blows way through that). It tightened when they did it but, it was only (likely) going to do it once. I’d did a timing belt on a civic and the harmonic balancer almost stopped me. I bent extensions out of round but the 5 ft cheater pipe started ad 12 o’clock and the bolt didn’t break loose until I got to nine. Those things get real tight. As far as the drill/tap it would still be a do it once and the next time the HB comes off, re-tap. Likely have to pull the crank and get it on a milling machine to do the drill/tap. You might be able to give the old 23mm bolt to someone with a lathe and they may be able to make you one. That would likely be, next time the HB is pulled = new crank. All of those may be really expensive compared to an engine swap or a new crank. If the car was actually worth $450 (hopefully more) an engine swap shouldn’t be out of the question.
[quote=”bsquared5150″ post=143664]1st I’d try a new 23mm bolt. If the end of the crank was case hardened the previous owner actually used up the One Shot Fix. The 23mm likely broke through the hardened surface of the threads (I can’t remember for sure but I think it is like max .010″ but likely .002″ – .005″ for case hardening 4mm blows way through that). It tightened when they did it but, it was only (likely) going to do it once. I’d did a timing belt on a civic and the harmonic balancer almost stopped me. I bent extensions out of round but the 5 ft cheater pipe started ad 12 o’clock and the bolt didn’t break loose until I got to nine. Those things get real tight. As far as the drill/tap it would still be a do it once and the next time the HB comes off, re-tap. Likely have to pull the crank and get it on a milling machine to do the drill/tap. You might be able to give the old 23mm bolt to someone with a lathe and they may be able to make you one. That would likely be, next time the HB is pulled = new crank. All of those may be really expensive compared to an engine swap or a new crank. If the car was actually worth $450 (hopefully more) an engine swap shouldn’t be out of the question.[/quote]
Why would you need to ever re-tap te threads if you repair it like that if you tap to the correct size or use an insert?
If you are going to try tapping the bolt hole, you will need a special tap called a “bottoming tap”, which is meant for threading blind holes. They aren’t as common as regular taps, and it might be a bit difficult to find one in the size you need.
Regular taps are meant for through holes.
I said the 23mm bolt was a One Shot Fix. I would guess that the previous owner stripped both the bolt and the hole threads. I don’t know for sure but, case hardening is likely the best way to harden a crank since it would be less likely to cause warping. However, case hardening doesn’t go very deep only about .002″ – .005″. When it was first stripped the hardening was destroyed. It’s like the metal under it has had nothing done to it. Because of that, the previous owner “got lucky” by putting in a bolt with oversize threads. It worked because it cut some new and unknown size thread in soft steel (it blew right through what was left of the hardened material). So in other words it’s scrapped.
No matter what is done from here on out it’s a one time fix. The hardness of the metal has been greatly reduced. Whatever is done, heli-core or drill and tap, when the bolt comes out next time it will destroy whatever has been done. The metal in the crank just can’t take the stress. I highly doubt that it is possible to torque the bolt to OEM spec no matter what is done. The now soft metal in the bolt hole will relax/soften when it gets hot and the bolt will slowly torque up but, when the bolt is removed it will strip the threads.
[quote=”bsquared5150″ post=143751]I said the 23mm bolt was a One Shot Fix. I would guess that the previous owner stripped both the bolt and the hole threads. I don’t know for sure but, case hardening is likely the best way to harden a crank since it would be less likely to cause warping. However, case hardening doesn’t go very deep only about .002″ – .005″. When it was first stripped the hardening was destroyed. It’s like the metal under it has had nothing done to it. Because of that, the previous owner “got lucky” by putting in a bolt with oversize threads. It worked because it cut some new and unknown size thread in soft steel (it blew right through what was left of the hardened material). So in other words it’s scrapped.
No matter what is done from here on out it’s a one time fix. The hardness of the metal has been greatly reduced. Whatever is done, heli-core or drill and tap, when the bolt comes out next time it will destroy whatever has been done. The metal in the crank just can’t take the stress. I highly doubt that it is possible to torque the bolt to OEM spec no matter what is done. The now soft metal in the bolt hole will relax/soften when it gets hot and the bolt will slowly torque up but, when the bolt is removed it will strip the threads.[/quote]
The threads themselves were very likely not hardened at all. Most cranks use induction hardening and that does not get the bolt holes really. But regardless of that just because it is not hardened does not mean the bolt is going to pull out threads. If that was the case head bolts in iron block motors would have ruined threads after every use.
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