Well today turned out to a bad day. I went to drop the oil pan on my 65' buick 300 thats for my T, to clean the sludge out and put a new gasket in. Then I found a head to a bolt, so I looked and I found one of the bolts to the mains brock and held on by just a couple threads. then found anouther really loose when I tried to unscrew it it was brock off in the middle???? all the others seem tight. What would cause this??? over heating expanded the cap and sheered the bolt??? does it need rebuilt or just new bolts torqued down to proper specs??
In my mind, that's a red flag. I would tear it down and check out everything. Generally speaking, those bolts don't just fall apart.
I agree ! That is not good at all . Pull that crank and rod bearing to see how bad the news will be on the bottom end . I would be replacing all the bottom end bolts ! Keep us informed on what you find ! Good Luck .
Reused too many times bolts that were either over torqued and cracked or under torqued and got loose and cracked. Caps might be in the wrong locations too. Tear it all down and replace all the bolts nuts and studs in it with NEW (made in America!) ones on re***embly. Have the crank at least checked for trueness
I agree with Dr J. Probably from over torqued or caps on wrong. This is not a good thing. If it ran this way it could have spun the main bearing on that throw. Take it apart and get it checked out. The Wizzard
Looking at the picture it looks like the bolts are pretty new. How long ago was the motor built or rebuilt? Just wondering since I see Twelve point nuts on the Rod Bolts. Also what could have happened was the bolts bottomed out in the hole and when it was torqued it twisted the bolts. No washers?
I dont know when or if the motor was rebuilt. My neighbor bought it out of a freinds salvage yard, then had it sitting in his garage for about 2 years covered, Then I bought it about a year ago. Thats a very good point there were no washers. did buick not have twelve piont nuts from factory in 1965??
I just looked at Buick motor that came in for a customer for a build up (350). It does come with twelve points. I would take it all apart like everybody said. and have everything checked. The main bolts on the Buick 350 have washers. At least you caught before anything major happened.
yeah before this I havent seen anything wrong with it, it spins freely and has good compresion I was debating on just running it but desided I didnt want it to leak oil. Kinda makes for a bad day but at least I know now and not on the side of the road with a siezed motor. anybody know were I can get a set of new bolts from?? I looked at T and A nothing much for the 300. its a stock motor so oem would be fine. also how would I know if the caps are in the right spot are they stamped??
If you can not find any you can call Specialty Fasteners at (626) 969-6789 and give them the dimensions of the bolts you have. Same with ARP but more expensive.
I doubt a cap would be on wrong as it would bind up the crank when trying to rotate it to install the rods. I have no clue how hard it has been run but take the caps off. Look at the cap itself and see if there is a little bump of metal between the bolt hole and the edge of the bearing area. Then look at the corresponding area on the block and see if there is a pit. If so the motor had severe crankshaft chatter which would answer the "WHY" on broken bolts and a transfer of metal. Another reason would be they were never torque down to begin with
Could be a number of reasons. The bolts could have been over torq.d from the factory,,or possibly a bad production run of bolts,,since several are bad. I would pull the caps and look at the bearings,,if they look good,,put in new bolts,,and call it good. Even if it turns out you need to rebuild,,not a bad core. It looks good in your pic,,very clean,,,go for it. Tommy
I'd check the head bolts also. The same idiot who was saving time with his impact gun on the mains might have put the heads on, too.
If you have trouble finding correct replacement Bolts just go to ARP studs and Flange nuts. Cheep and readily availoble at any Good machine shop. The Wizzard
Recently rebuilt a 66 401 buick virgin block when dis***embling prior to rebuild 2 main bolts broke in the same area,replaced them all.
New problem, besides not finding replacment bolts without special ordering them. how in the hell do I get the broken bolt out, it brock off right flush with the block, I know they have those left hand screw type things that you first drill a hole in the center of the bolt but would it work on something torqued down this tight ecspecialy if its botomed out on the threads??? any advise?? at least the bairings are all ok and the mating surfaces on the block and main caps are all good.
i bet a bent crank could pop a cap pretty easy look at the wear marks on the bearings they should give you a better idea as to what happened either way sounds like its time to tear it down mic everything and do a rebuild
a big *** bolt takes a big *** easy out your chances are best if you use an easy out from snap on , mac or a tool and die supply cheap easy outs break then your truly ****ed oh yeah soak that **** good with kroil for a while before attempting to get it out be carefull not to booger up the machined surface when drilling it out
If the broken off bolt is actually bottomed out it would be best for someone with a milling machine center drill it, then drill it out in increments starting small and eventually getting to the point that you can see the tops of the threads in the block, then they can be removed with a pick. On the other hand, if it's not bottomed out it should spin out fairly east. Try a center punch off center, then lean the punch and tap it gently in a counter-clockwise direction as it unscrews. Caution: Breaking of an EZY-Out in there could be tragic and may result in the need for a sonic whatever to shatter it in order to get you back where you are now (actually worse because you probably have a hole drilled off center).
I've got left hand drill bits from Eastwood, not cheap, but they are the only thing that I have had 100% success with when removing sheared bolts.The heat it genertates seems to free off the threaded part somehow, plus the direction of travel of the drill is going the right way to unscrew it.Snapped an easy-out off in an engine block once, ended up junking it. Good luck with it!!
I don't like Easy Out's period. They are designed to EXPAND the broken bolt in order to get a grip on the shank of the bolt. Not a good thing when its already to tight to turn out. I always plug weld a nut to what's left of the bolt. The heat generally brakes the bond and you have a Hex nut to put a socket on. This has always worked best for me. The Wizzard
Did you find the washers in the pan? If not, and if the other main bearing cap bolts have washers under them, then perhaps someone forgot to put the washers in, as someone suggested, and the bolts bottomed out and broke. Check to see if the main bearing caps have punch marks to indicate where they go. WHeether they do or not, I would carefully eyeball and measure on re***embly to ensure that you are putting each cap on in the proper place. Is it possible that this is a cap from a different motor? You will not have any problem getting the broken bolt out. Just be sure to center punch accurately and to drill accurately. If you use a left hand drill the stub will likely spin right out. Even if you use a right hand drill, an EZ out will get it right out. Old cave man trick: drill a small hole down the center of the broken end of the bolt and use your cutting torch, aimed sstraight down. The bolt will melt and get blown out with little affect on the threads, just use a chase to clean up the threads. Note this is a last-resort method as I am 99.9% sure that that bolt will come right out. I have even backed out broken bolts like this using a tiny chisel punch and a hammer, tapping around the diameter to use the punch to rotate the bolt out - have done this when these were the only tools available. I'll bet that whatever it is is not too bad and that you will still be able to use that bottom end.
Yes, that is a good trick too. Don't sell EZOuts short, though as this is what they are designed to do. Without that bolt compressing the main bearing cap down, there is really little if any tension on the broken piece of bolt and it will spin right out. BTW, for you who break off EXOuts there are tools made to get them out. They look like two skinny tool steel fingers - almost like a tweezer - you insert down the flutes of the EXOut and rotate the broken piece out. That's why the EZOuts have those flutes - they are well-designed tools. Or, you use the oxy-acetylene trick and the tool steel EZOut melts/blows right out. As you see there is always another road home.
Prior to doing my weld the Nut trick I always start with a Left hand drill bit. If the bolt is in fact loose enough to spin out, the drill will spin it out before it goes all the way through. No mater what method you choose there is a certain amount of Luck needed. The Wizzard
Thanks for all the feed back, the nut trick is smart I will keep that in mind latter down the road but it is close to alot of machined surfeces that I would hate to get weld spatter on. I think I will try to find a LH drill bit. heres a pic, and boy is it in a bad spot.
Where at did the bolts break? I see a head broke off and you said that one broke flush? If there all broke at the fillet under the head, the first thread after the shank or the first thread that is engaged in the block which are all common places for a fatigue break to happen, could be caused by cyclic overloading over time if they were torqued properly, or if they were not torqued properly or bottomed out normal loading could cause them to fatigue and break because there not applying enough clamping force. When you get the broke parts of the bolts out you should be able to look at the end and tell if it was bottomed out for sure. What do the breaks look like? are they smooth and dull looking most of the way or rough and crystalized looking? Do the bolts look distorted in any way? any pics of the breaks? you can look at the main cap and block mating surfaces too and see if there is any signs movement. If all the machine marks are polished off the cap and block and it looks pretty shinny than it would have been moving around while it was quite loose, If you can see fretting(gaulling) than the cap was moving around while it was tight but probably just not torqued properly, may not of been any movement too depending on how tight the cap fits into its seat on the block. -Chris Hey, I just missed that last pic. From here it looks like a fatigue break (the light area, if it is smooth)
Something I did not know came to light when I put my 308 SBF together. Now this is probably the 20th SBF I have done!. As I an torquing the head down one of the bolts breaks off. So I stop. Take it over to my Machinist and ask WHY??? He then informs me that you should never reuse head bolts or crank bolts. This was news to me. He tells me that once you torque the bolt it may change to bolt characteristics of the metal. I bought a ARP stud kit and finished the motor. This may be what happened to you. Also a side note you may want to check to see if your Harmonic balancer has slipped or come loose causing a crank vibration.
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