I put a set of heads on a short block I've had for a while, torqued the bolts to 25 ft-lbs initially then 45 then 65. The next day I went back over them all and on the very last bolt, on the second head, I was easing on the torque wrench and heard the dreaded "pop" followed by an almost instantanious click from the wrench. I would estimate the bolt turned about 1/16 of a turn. After a couple of choice words I eased on it again and just got the click from the wrench with no turning. Did I crack the bolt hole? Is there a way to determine whether or not I did with out tearing it all the way back down and having it magnafluxed?

 

It *could* have possibly been just the head of the bolt spinning on the cyl head under pressure, i have had the same thing happen to me on different things. or maybe it snapped off the end of the bolt, pull it out and see if you still have the whole bolt.

 

You should be able to tell without a magnaflux.
If it were mine,I'd start by pulling that head bolt out completely,and seeing how the threads feel.If they are iffy,pull the head back off.I've found that usually if the threads are jacked,it's visually noticable.There are heli-coil kits available for head bolts,though they are not cheap,might still beat a complete rebuild.

Sounds like a 400SB,thy are known for weak threads.

 

Well, I pulled the bolt out and its fine. Threads are all smooth. If the bolt hole cracked it would'nt necesarilly mess up the threads on the bolt would it? I guess I'll go ahead and pull the head back off anyway and see what I can see.

Man, this is a bummer......... This short block IS a new rebuild, block was decked, bored and align honed. All that machine work potentially down the drain, its just a 350 by the way.

 

I just pulled the head off. I can't see a crack but I guess that does'nt mean one is'nt there. Has anyone else heard a pop like this while torqing heads down and not had the bolt hole crack? I've never heard the pop before, but have heard about it and have been told it usually means a cracked bolt hole. What do you think about getting a big magnet and some metal dust for a backyard type of magnaflux?

 

wny not PT it instead of some home made ineffective mag test

 

PT?

 

Ohhhhhh, pressure test . Yeah I guess I could do that with it still on the stand. Though I wonder if it would leak with a micrscopic crack that has'nt had the chance to grow with heat and such.

 

PT = penetrant test

 

sorry i'm use to saying PT and forgot where i was at

 

What is a penetrant test and how do you perform one?

 

What kind of lube are you using on the threads? If you're using the wrong kind or not enough it'll cause the bolt to "jump" as you're torquing it. Stock head bolts you can use motor oil on the threads and under the head, and make sure to use sealant, and with ARP's you want to use their moly that they supply.

 

Penetrant testing uses a penetrating dye that seeps into cracks and is revealed with a developer or an ultraviolet light to make it fluoresce. Magnaflux makes Zyglo which uses UV fluorescence, and Spotcheck which uses a developer.

The noise could have just been from breaking stiction though.

 

Thanks Apeiron, I think I'm gonna go ahead with one of those tests, I've never heard a noise like that before with clean threads, new bolts and thread sealant.

 

Can anyone point me in the right direction to find a spotcheck jr kit. I just moved and no one local seems to carry it.

 

http://www.magnaflux.com/sales/sales.asp

Domestic Reps/Distributors: MO
B.C. MacDonald & Company Sales Team
1265 Research Blvd.
St. Louis, MO 63132
Covering: mo
phone: 314-993-2833
fax: 314-993-0405

Domestic Reps/Distributors: MO
B.C. MacDonald & Company Sales Team
304 East 32nd Street
Joplin, MO 64801
Covering: mo
phone: 417-624-2150
fax: 417-624-4130

 

GMGOD,PM me your phone #,I can hook you up with a dye/penetrant test.Lest ye forget,your living in the stainless steel capital of the US!