I did a search to see if this has been covered before and came up with nuttin. I've had major problems in the past removing exhaust maiifolds from 500-472 caddy engines with out breaking the bolts off. The last caddy I tried to get the manifolds off, I snapped off every single bolt. I spent hours TRYING to drill and e-z out the broken pieces but only suceeded in breaking off the EZ-outs....I eventually traded off the engine for a different engine to get rid of the entire situation. Ok, now I have another 472 cad motor and need to change from manifolds to headers without going through all the bullshit again. I need some real-world experiences with successfully removing these damn bolts! I don't need to hear about the wax-wicking unless you've actually done this and it worked for you. ON my other motor I even heated the head red hot to loosen the bolts and still no luck....any input? Thanks.. Rocky . ..
Here's a post of mine from a while back. Won't provide much help on getting them out without breaking them, but is a sure bet if you do break a few off in the heads. "tap/ thread the manifold hole and then screw in a bolt with a hole drilled through it. I start with a bolt that has a smaller hole and then work my way up to a larger circumference until you can re-tap the holes and chase out the remander of the fragments. This technique will keep your bit centered and allow you to drill out the bolt with no problem. Thing is, you need a high quality machine bit to drill through your seized bolt." <!-- / message --><!-- attachments --><FIELDSET class=fieldset><LEGEND>Attached Thumbnails</LEGEND> </FIELDSET>
If you do have to drill.....try to get a bit with a thinned web. IE a 135" split point works good and if you can find with Ti coating even better. Takes way less pressure than a regular 118' point. Keep clearing the chips and use cutting oil
Just take your time and do it right. Getting impatient will only lead to at least one messed up hole. And that will never leave your mind. These guys seem to have the right ideas. -----------Keep in mind that SHOULD you use a manifold as a guide for your bit, go from one to the next one and pay close attention to how things line up along the way. those manifolds warp over time and they are not perfectly in line. Other than that and making sure you have the right thermostat, as well as not over revving the engine, you will most likely enjoy the engine.
Rocky, One of the things that I have done is to TIGHTEN the fastener just a little before backing the bolt out, also using a impact wrench seems to work better than a ratchet because of the VIBRATION. Go Figure !!! 60'
Never had a problem with the two 472's that I've had in the past.Just patience and some Marvel Mystery Oil to lube things up near the threads.
If the bolts are parallel, take your torch and cut the heads off. Quench while hot with penetrating oil. Won't hurt the manifold. Work the manifold off. Heat and quench the bolts a couple times. Work with a pair of vice grips til loosened and screw out.
Heres how i got 4 busted off ex manafold bolts on my 500 caddy engine i had in a chevy pickup. First you need a set of torches, i did this with the engine in the truck. with the manifold off, cut the broken bolt flush with the head. now comes the good part. Take the cutting torch and hold it on the bolt and let it get cherry red after its good an hot hit the oxygen lever and blow that bolt out of the head. Belive me it works. the bolt melts way before the cast iron in the head does. if you want try it on junk head first. i learned this from a real old timer that has done it lots of times. Now quit scraching your head and try it. clean the threads out with a thread chasser after you blow the the bolt out. 8-Ball
I'd completely forgetten that trick! My dad showed it to me back in the "olden days" and yeah, it works........thanks for the memories and by the way, I went to that Caddy forum and got hung up for hours! Great stuff ther but after opening 86 pages, I never saw the problem addressed. I do believe i'll burn the heads off the bolts first and if I still break some off, I'll use the second trick with my torch...thanks fellas. I appreciate it.
My Grandfather can do that torch the bolt out thing. And mount a tire with a leaf spring. And cut up a junk car for scrap w/ an axe.....damn. People must have been superhuman in the good 'ol days! -John
Mount a tire with a leaf spring! And I was just thinking I'd have to spend a load of cash to buy a pair of tire spoons to mount up my "gum dippers" on my wide-5 wheels...bullshit! I'll take my trusty grinder to some left-over leaves from an old '40 front spring and roll my own spoons...
Hi, I ran into this problem on my derby cars. I install vertical headers on them. I run the engine to get it hot, that helps alot. If I can't break a bolt loose, I cut the head off and wiggle the manifold off, then cut the bolt down to the threads and use it as a stud. The header flanges are much narrower that a manifold so there is plenty of meat left to clean up the threads and use a nut to tighten the headers down. Rick
If you do decide to buy spoons,last time I looked JC Whitney had them pretty damn cheap. Not as cheap as free, but still.
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