Wrightpayne Posted November 28, 2017 Share Posted November 28, 2017 I'm pondering changing the M8 exhaust manifold bolts on my 911 as they look quite corroded. I think it is best to proactively deal with them rather than wait for something to happen at an inopportune moment. All the fixings on the exhaust system need changing TBH.Anyway, been researching and the manifold bolts are prone to shearing off so plan to apply penetrating fluid over several days. One of the tips I've read is to use an impact driver to 'shock' the bolt into moving.Now my question is....My Bosch cordless drill has a torque setting for putting in screws, which when it kicks in clicks/buzzes and seems to turn the screw in small increments. I wondered if this is the same action as an impact driver? I also have an old style impact driver that you hit with a hammer.Any other suggestions / ideas for removal of rusty bolts in aluminum greatly appreciated. Heat wise only have a blow lamp - no acetylene kit. Also planning to get a Stomski jig which is specifically designed for drilling out snapped bolts on porker heads on the assumption if I have the tool they will all come out!Ian Link to comment Share on other sites More sharing options...
DJ. Posted November 28, 2017 Share Posted November 28, 2017 I have to say, that if the exhaust is working well and is not in imminent danger of failing, there is no way I'd be looking for trouble by touching the bolts "as they look quite corroded". The guy who said, "If it ain't broke, don't fix it" was onto something.Duncan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 28, 2017 Member Share Posted November 28, 2017 My Bosch cordless drill has a torque setting for putting in screws, which when it kicks in clicks/buzzes and seems to turn the screw in small increments. I wondered if this is the same action as an impact driver?Someone once explained here why the action is different... probably in that discussion of cheap offers o power tools.... so plan to apply penetrating fluid over several days.Yes, but the real stuff, not WD-40.Heat wise only have a blow lamp - no acetylene kit.Blow torch should be fine. I use a tiny cooking blow torch. Watch some Edd China first to build up confidence?Jonathan Link to comment Share on other sites More sharing options...
Wrightpayne Posted November 28, 2017 Author Share Posted November 28, 2017 Duncan,I know what you're saying but some of the bolts are severely corroded - should be 13mm but look more like 10. When I had it inspected other bolts on the system were highlighted as needing attention - some of the nuts are not recognisable as hexagonal things! It is a case of when not if.Also, the OCD in me wants things to be as best they can be. I have lots of time, patience and the inclination to address the situation - I'll still ponder for a while!RegardsIan Link to comment Share on other sites More sharing options...
Jim 123 Posted November 28, 2017 Share Posted November 28, 2017 Bearing in mind Duncan's point, have you heard of 996 manifold bolts failing if left in situ as long as the manifolds are not in need of replacement?As I guess you know, this is a job with a reputation for the bolts shearing, and gravity is working against penetrating oil doing its best. Disconnecting the the silencer boxes first will alleviate stress on the manifolds to some extent.The inner cylinder bolts on each bank can pretty difficult to access with a good socket fit. I'd ponder before applying heat, as my thinking is that the mass of metal in the manifold flange will expand (i.e. thicken) with heat, and make the bolt heads more grippy. As Jonathan says lots of "real stuff" penetrating oil and lots of soakings. Proper impact driver and eternal patience with each bolt. Best of luck. Link to comment Share on other sites More sharing options...
Edzup Ezzer Posted November 28, 2017 Share Posted November 28, 2017 I believe induction heater tools are becoming available on the hire market. Might be worth exploring that possibility. All the demos I’ve seen are very impressive and are safer than any naked flame heat source. Ed China and Fuzz Townsend have both demonstrated how effective these tools can be.Ezzer Link to comment Share on other sites More sharing options...
ECR Posted November 28, 2017 Share Posted November 28, 2017 If the nuts are not recognisable as hexagonal things you are taking on a difficult job. However, if I was doing it, I'd buy/borrow a proper impact driver and use the tightest hex (not multi hex) socket I could hammer on. I would use plenty of plusgas for days before and cross my fingers when I started. I would also have an extractor system ready (as you suggest). I might try one of the freeze sprays as well (loctite do one I think) as the expansion/contraction is supposed to crack the rust seal (no personal experience ....) I understand your OCD Bon chance! Link to comment Share on other sites More sharing options...
DJ. Posted November 28, 2017 Share Posted November 28, 2017 Yes, I forgot to say good luck!My brother had a similar task when the manifold on his Esprit cracked. As the manifold was useless, he decided to cut the manifold up to help access the studs. Link to comment Share on other sites More sharing options...
elie boone Posted November 29, 2017 Share Posted November 29, 2017 I would not use an impact wrench, lots of penetrating oil on a warm engine and when the nut goes difficult you just go back 1/2 turn and forth 3/4 turn to avoid snapping, it's time consuming but the safest way. Link to comment Share on other sites More sharing options...
TomB Posted November 29, 2017 Share Posted November 29, 2017 If they are that knackered can you cut a line in the nut parallel to the threaded stud, then open up a touch with a flat headed screwdriver to break the bond? Link to comment Share on other sites More sharing options...
Jim 123 Posted November 29, 2017 Share Posted November 29, 2017 Tom I think the challenge here is that the 911 has steel hex bolts fixing the manifolds into the alloy heads, and not the more sensible stud and nut configuration.Ian, from your earlier descriptions of the condition of the bolts, and just to speculatively add to your ideas pot..... To get the initial purchase to loosen the bolts, the main resistance is likely to be from the corrosion formed between the steel bolt heads, steel washers and the steel manifolds (esp as the more exposed fixings will be exposed to road crud). Taking Tom's idea as a basis, is it worth looking for a way to split / shift the washers a miniscule bit to encourage sheer slippage in the corrosive layer that they are sandwiched into between the bolts and the manifolds? Working from underneath, without the luxury of a ramp, and with lousy access to the bolts on the inner pots, this is not a panacea, but might work with a couple of bolts. Link to comment Share on other sites More sharing options...
Wrightpayne Posted November 29, 2017 Author Share Posted November 29, 2017 Thanks all - they are bolts into an ally head. 2 options for replacement - new bolts with coppa slip and scheduled loosen & tighten every year OR replace bolts with studs and brass or copper bolts like the good old days!!Jim - getting the washer moving sounds a good idea.I have some very old unipart penetrating fluid but will probably get some plusgas and freeze spray and a cooking blow lamp!RegardsIan Link to comment Share on other sites More sharing options...
elie boone Posted November 29, 2017 Share Posted November 29, 2017 Depends on acess but a good way of local heat is to heat up the bolt with a weld from a welding rod Link to comment Share on other sites More sharing options...
Wodybode Posted November 29, 2017 Share Posted November 29, 2017 Ian, sounds like a very tricky job, small corroded bolt heads, awkward access, seized threads etc. etc. One of those jobs that requires a bit of touch and feel for whats happening to the bolt. As has already been said, will require penetrating oil, if you can get a clean hit directly onto the head of the bolt this can help break the thread seal, then working the bolt back and forth to get it unscrewed and of course.... lots of patience. I always pick the most awkward one to start with. Make sure whatever socket you can get to fit is on tight and square. If you have to drill out a sheared bolt you will have to be very (very) accurate. I'm not familiar with the kit you mention but the drill should at least be a cobalt one as they will be HT bolts I would have thought.Good luck. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted November 29, 2017 Member Share Posted November 29, 2017 Lots on unsticking what's stuck, but not so much on getting hold of a damaged bolt... is the definitive method still welding a lever on the head?Jonathan Link to comment Share on other sites More sharing options...
Ngh30 Posted November 30, 2017 Share Posted November 30, 2017 Some good advice so far , from my experience I've used penetrating spray ( and left it for a few hours to work ! ) once the bolt has moved , gently tighten and loosen the bolt until it's seems free to undo fully . If you need to use any drill bits and taps let me know I can loan you mine no probs . Link to comment Share on other sites More sharing options...
brianjhall31 Posted December 1, 2017 Share Posted December 1, 2017 Penetrating oil (as said the real stuff), leave to soak in and reapply, then heat and, if the hex heads are suspect or rounded, use something like Irwin Nut remover socket (Screwfix) I used this method on my son's Ford Focus Sump Plug (notorious for seizing and rounding off hex)Worked a treat! As always luck will come into whether the bolts shear, but you have to try Link to comment Share on other sites More sharing options...
Jim 123 Posted December 1, 2017 Share Posted December 1, 2017 A great tip Brian. I personally was not aware of Irwin products. Link to comment Share on other sites More sharing options...
Wrightpayne Posted December 1, 2017 Author Share Posted December 1, 2017 I have an irwin adjustable spanner and I'm confident to lean on it unlike others I have.Ian Link to comment Share on other sites More sharing options...
Wrightpayne Posted December 2, 2017 Author Share Posted December 2, 2017 Jig has arrived which should hopefully make any drilling easier...Bought second hand (only used to drill 1 bolt). Link to comment Share on other sites More sharing options...
Jim 123 Posted December 2, 2017 Share Posted December 2, 2017 Hopefully it will remain unused with some luck. Link to comment Share on other sites More sharing options...
Martin J Posted December 2, 2017 Share Posted December 2, 2017 Good luck Ian, my experience is on boilers but similar in as much as often its steel bolts in alloy castings.It's a great feeling when they let go & it unscrews in one piece. Link to comment Share on other sites More sharing options...
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