Hello everyone, I'm working on my van motor over the winter here in Canada I've made a large mistake and now I need help! After refreshing the rings and cleaning everything, I'm reassembling the motor and have made it as far as fitting the left side heat exchanger, BUT I've found one of the #4 exhaust studs are striped, (the outer end where the nut is). I've tried to lock on a pair of vicegrips and heat from a propane torch on the head. I've tried welding a nut on the end of the stud and heating (twice) All that happens is the nut twists off the end of the stud. All wards of wisdom are welcome. I know, I know, should have double checked the studs while the heads were laying on the bench for the month awaiting parts, But...... What have you tried that worked for these????
Only tired what you're doing. If that doesn't get it out I don't know what will. I've shattered the sometimes very thin casting around these studs a couple of times - luckily heads were duff and I was after the studs One of them you could see the edge of the stud threads poking through! Good luck. Try turning up you welder and get the nut almost on the stud first so you're not trying to weld down a hole?
That is one of the issues with these heads!! If the stud doesn't come out with an oxy torch, then all you can do is get it machined out... bit of a pain as you've built the motor up, but unbolted, that exhaust will blow like a bitch!!
You seem to be doing just the right things. Persevere with what you are doing. once its been hot and cold a few times it should move. try moving a little at a time with a socket if you can get one onto the nut. Also a few blows with a hammer (not a big one) on the end can help to free the threads. Good luck. Always been lucky getting studs out but unlucky with heads stripping. Used a few helicoils in my time on these (which do work)
is the engine in the van? Don't use heat, you want it cold. Get the head outside and as cold as you can get it (freezing can't be too hard at this time of year in Canada ) You want to put 2 nuts down onto the bolt - tighten the 2 together and then turn it back using the bottom one. Once you have it out you want to get some new bolts made with over sized threads. Tap the old threads out very carefully. There is not much meat in there so take it easy. I think I used M8? I'll double check for you. I used Nickel. Inconel 718, its a jet engine grade alloy, you should be able to get small off cuts from a stockholder. I then had this turned, M8? on the end for the head, and then M6? on the other end. This material won't rust, won't cross thread and won't strip the threads out of the heads. I don't know where you are in Canada but if you're anywhere near Toronto or Montreal call around any of the places local to Pratt and Whitney, Bombardier, Messier Dowty etc - any engineering workshop local to these guys will be able to help you out with some small pieces. Or if you're in the west or far north try any of the oil and gas fields - anyone using very high grade superalloys will do. These don't get used in auto applications due to their very high costs, but trust me, they are developed for mega high temperatures and are ideal for keeping our old buses on the road. I know, half of my engine is held together with bits from Rolls-Royce and Airbus
Some early heads have M8 studs both ends. Studs are M9 into the head and M8 the other end. If he could get two nuts on then he wouldnt need to take it out I would have thought. will shear for fun turned out cold!
Niall, have you heard of the Ralin Group (based in Brum) they do Inconel nuts and bolts of varying grades and do custom thread sizes too - we have used them before, they offer a good machining service, they might be able to make them oversized..
Pretty sure as above, 1700 heads are M8/M8 so you can tap M9 and get the later stud, or helicoil back to M8. I'd do them all while you're at it.
sometimes these things can only be drilled out as the amount of heat required will destroy the head and are best sent to an engineers to be done. by the time you buy the proper drill bits and get head off and faff around trying to get the hole dead centre you may as well pay to get it done properly and use the time saved to get on with something else. get them all done at the same time as it will be more cost effective
Thanks, so far for your replies. I've tried everything you've mentioned , except the double nut on the stud, can't as the stud is striped and will not hold the nut on. It's head off the motor and over to a machine shop first of the week. I'll mention to the shop about the increased grade of stud to use. Thanks a bunch.
