Typically the female nut is welded on the back side of the frame to where the bolt will thread into. So in other words, there is nothing on the back side to bottom out. Try taking some diesel fuel and apply on the top side of the jammed bolt so it will seep into the threads. Diesel fuel is a good seize breaker. After it sits/soaks for 30 minutes or so, take a self tapping bolt (smaller in diameter that the original) and screw into the "seized" bolt. It should break free and run out through the top. At that point you should be able to grab the original seized portion with vice grips to hold while you back out the self tapped bolt. Just a thought and something to try. Good luck.

 

abrams57, I'm going to give that a go... On two of the three bolts, it is actually easier to drop it through the bottom as if the bolts were being tightened (as you suggested), as for the other one, it is 50/50 either way. I will see if I can find any self-tapping bolts in my garage or pick up ones at the local hardware store and try tomorrow...

 

If you don't have any diesel fuel, pick up a can of PB Blaster. Both are great at freeing up seized threads. WD-40 just doesn't cut it. Just let it work its magic between 30-60 minutes.

 

If none of the above work. Pick up a Screw Extractor set from Harbor Freight. The idea is you turn a smaller reverse threaded self-tapping screw into a hole drilled in the sheared bolt. As you turn the extractor counter-clockwise, it will dig into the meat of the bolt shaft and ultimately turn it out of the binding.

You may then have to use a Tap and Die set to re-allign the threads where the bolt used to turn in.

 

It seems that the engineers forgot that bolts need to be strong enough to be removed, not just a one-off. I've tolerated almost all my skid-plate bolts shearing off over the last few years, but am finding myself spending more and more time dealing with sh*t I shouldn't have to deal with because Toyota wanted to save $0.02 on a bolt.

If your skid plate bolts are breaking that's a clue to overtorquing and lack of lubrication. Put some Never-Seez on the threads every time you install them and use a torque wrench or keep Mr. Gorilla in his cage.

Also, it doesn't matter how strong the bolts are if they're rusted in place. I've learned to be patient and will apply Kroil to the threads days or weeks ahead of time - several applications if possible. I try and plan ahead and Kroil the bolts for the next job as I'm doing the current job.

Another trick I use is a cordless impact wrench. I have a 3/8" and a 1/2" DeWalt for different size bolts. These tools apply a repeated hammering torque that is not high enough to break the bolt but usually gets them moving. For stubborn bolts, repeated cycles of heat from a propane torch and Kroil. When they start to move, alternately loosen and tighten the bolt while applying more Kroil to the exposed threads.

If you break the bolts you must use high quality drill bits. If you break a bit inside a bolt use a carbide burr on a Dremel or similar tool to remove the broken drill bit.

Skill at removing rusted fasteners is what really distinguishes a top notch shadetree mechanic.

And I've just noticed you're in California so you have absolutely NO excuse.

 

A bit of heat goes a long way in loosing rusted fasteners. The problem with newer vehicles is all of the plastic parts, so use a torch where you can and soak for several days with penetrating oil where you can't.
Kroil is great for getting fasteners loose when they are rusted in place because it creeps into the threads really well. Never Seize compound is best for keeping them from from rusting solid. Use it whenever you install anything under your truck.

 

This is not meant as a carve to the OP at all but something seems strange here. You live in Cali so are they salting the roads where you live or are in in an area that promotes extra rust? I don't understand you your skid plate bolts could have just sheared off from rust. You take the skid plate off to change the oil so this is something that has to be done relatively often. So how is it they could even be that rusty in the first place? And where I live they do salt the roads and I have never had any problems removing my skid plate. Like Mibro said maybe they were over torqued in the first place. Sucks to be in your situation but I am not so sure it has to do with cheap bolts.

 

Its 7 to 8 years old by now. Its likely that bolts and screws will be stuck at this age. I agree with cheapskate... how have you changed your oil since 2007 without taking off the skidplate? Either way, there are methods for removing stuck bolts. If you don't have the tools or patience (I sure don't...) take it to a mechanic and let them work on it. Heat works well, penetrating fluid (not WD-40... its not a penetrating lubricant...) and impact helps. Worst case scenario you drill and tap for new bolts.

 

This is not meant as a carve to the OP at all but something seems strange here. You live in Cali so are they salting the roads where you live or are in in an area that promotes extra rust? I don't understand you your skid plate bolts could have just sheared off from rust. You take the skid plate off to change the oil so this is something that has to be done relatively often. So how is it they could even be that rusty in the first place? And where I live they do salt the roads and I have never had any problems removing my skid plate. Like Mibro said maybe they were over torqued in the first place. Sucks to be in your situation but I am not so sure it has to do with cheap bolts.

I lived in MD up until early of 2013... they definitely use salt and sand on the roads there... I've used oil to lubricate the bolts on the skid plate. What annoys me is that there isn't much indication with these bolts that they're going to sheer. It isn't sheering right off the bat. In both of these cases, I'm actually moving the bolt along pretty well, when it will suddenly snap off. I'm no expert, but I've replaced almost everything on the truck myself save the headers and have not had much problem save for these black bolts... they've been a complete nightmare...

 

Just a quick update... got the bolts drilled out!! My brother-in-law had much better bits than me. Still it took about 3 hours to do given that the tips of my bits broke off initially in two of the bolts. Auto part stores didn't stock the replacement bolts... M8 x 1.25, but I did find M8 x 1 with flanges and made out of a hardened steel similar to what is used to hold the tail lights in place (but without the T30 Torx head) and those should do the job. I got lock-tite in case the holes are slightly larger (we had to tap at least one of them).
In any case, mission accomplished so far, just hope I can get my new bumper on. I hope I can do the same for the bolts that sheered off by the skid plate. I'll replace those with the hardened steel equivalents as well. I just don't see why Toyota used these cheap bolts when the good ones are clearly available in so many other areas of the assembly of the truck.
And just a note of clarification... the bolts were NOT rusted though I suppose my previous post implied that because of the salt and sand used on the roads in winter in Maryland. But honestly, there was no rust. In fact the bolts themselves are slightly tapered at the bottom, which, theoretically, should be easier to back-out as you move them along. Neither were the heads rusted out or damaged. It was really just a case of the bolt being seized so harshly in the threads and without the usual signs of it giving or twisting before sheering off completely. I think this soft steel that was used for the bolts is just a menace... Wherever I find them on the truck, I'll be sure to replace them with stronger alternatives.
I didn't take photos today, but will try to tomorrow... Thanks for all the posts!!

 

Auto part stores didn't stock the replacement bolts... M8 x 1.25, but I did find M8 x 1 with flanges and made out of a hardened steel similar to what is used to hold the tail lights in place (but without the T30 Torx head) and those should do the job.

So you're putting M8-1.0 bolts into M8-1.25 nuts? You know that's a different thread pitch, right?

M8-1.25 should be easier to find than M8-1.0. I guarantee you can find them in the fastener drawers at Home Depot or Lowes.

And just a note of clarification... the bolts were NOT rusted though I suppose my previous post implied that because of the salt and sand used on the roads in winter in Maryland. But honestly, there was no rust. In fact the bolts themselves are slightly tapered at the bottom, which, theoretically, should be easier to back-out as you move them along. Neither were the heads rusted out or damaged. It was really just a case of the bolt being seized so harshly in the threads and without the usual signs of it giving or twisting before sheering off completely. I think this soft steel that was used for the bolts is just a menace.

All news to me. I had a Dodge truck once where some of the bolts were so crappy the bolt heads would just drop off, but I haven't heard of this problem with Toyotas.

 

So you're putting M8-1.0 bolts into M8-1.25 nuts? You know that's a different thread pitch, right?

M8-1.25 should be easier to find than M8-1.0. I guarantee you can find them in the fastener drawers at Home Depot or Lowes.



All news to me. I had a Dodge truck once where some of the bolts were so crappy the bolt heads would just drop off, but I haven't heard of this problem with Toyotas.

Not sure what the issue is... M8-1.25 is exactly the same as M8-1.0 only it is 1 inch instead of 1.25 inches in length. Thread count is on the bin and specified as either 13 or 18 or whatever other variants there are, but that wasn't an issue since we were only looking for bolts with the same thread count. In any case, the bolts worked perfectly without issue. The black bolts Toyota used in these areas are notoriously bad... the moment I mentioned the problem to my brother-in-law he asked me if the bolts that broke off were black bolts. He has seen the same thing on the Ford trucks he works on.

 

Not sure what the issue is... M8-1.25 is exactly the same as M8-1.0 only it is 1 inch instead of 1.25 inches in length. Thread count is on the bin and specified as either 13 or 18 or whatever other variants there are, but that wasn't an issue since we were only looking for bolts with the same thread count.

I'm glad you got the right bolts but it was for the wrong reason.

The thread length of metric bolts is not measured in inches, obviously, it's measured in millimeters. And the thread pitch of metric bolts is not measured in turns per inch, it's also measured in millimeters. So a thread count of 13 or 18 will only apply to SAE bolts with UNC or UNF threads - e.g. 5/16-18.

M8-1.25 does not mean an M8 bolt that's 1-1/4 inches long, it means an M8 bolt with a 1.25 mm thread pitch. Likewise a M8-1.0 bolt is a M8 bolt with a 1.0 thread pitch. An M8 bolt that's approximately one inch long will be specified as M8-1.25 x 25 or M8-1.0 x 25, etc.

 

OK, well, look I won't argue about this... I'm no expert and I'll trust you on this the next time I go get bolts. But for the record, the bin literally said M8 1.0, 13. Another bin said M8 1.25, 13 and there were others that had different thread counts such as 18, etc. The assistant said they were all out of the 1.25 inch length bolts, but that they had the M8s in 1 inch lengths and also had flanged versions if needed. Those are the ones I purchased and they went in without hassle. In any case, I always bring in a sample of what I am trying to replace unless it is physically impossible to do so. And logically, what you said makes more sense; I can't see much reason for a bolt to be categorized metric in one measure but not the other, so I'm thinking this is probably just the way the store labels their goods.

This is the area where the bolts broke off... the left bolt on the lip of the metal brace and both bolts just above the exhaust. An additional bolt broke off in one of the supporting braces, but those were being replaced anyway, so not a big deal.