Hello. I've been trying to fix my leaky exhaust manifold (leaking round one connection where HE connects to head) and have discovered that one of the studs is threaded. I'm pretty sure I didn't do this and I think it's the reason for it leaking in that it can't be tightened. Does anyone have any tips for removing the offending stud for replacement? Engine is a type 4 and it's in my van and so I need to do it in situ with the push rod tubes partly in the way etc. Any tips would be much appreciated. Thanks. Nick...
If it hasn't snapped yet them try and get 2 nuts on there right and them back it out slowly. They normally budge quite easily. If you're saying that its spinning in its thread in the head then you also need to apply pulling force whilst turning, easier done with the head in a bench. If a new one fits in the head and the threads aren't knackered, great! I recommend tapping the old holes out to just over size and then having some high temperature inconel 718 studs machined to fit (if you can get your hands on it? You'll never experience this problem again then
Thanks Joker. The thread is knackered on the heat exchanger end of the stud rather than on the cylinder head end and so it's the nut that hold the HE on that is spinning rather than the whole stud - so I'm hoping that the thread in the head itself is OK if I can get the old stud out. I'll try the double nut trick, however with the engine access is really limited for getting a spanner in there on the double nuts, and also with half the thread missing on the stud where the double nuts would go I don't know if that is going to work. Nick.
Havent done this for a while but take extreme care not to cock the threads up in the head. If they are screwed already then thats a different matter. If the thread on the stud is too far gone then The best method is to weld a nut onto it - I assume the exchanger is off? gentle tap on the end when hot and wind out slowly once its cooled a bit!
If the threads are too badly damaged you can get a 'stud box' which has tiny rollers inside which grip the stud as you undo it. I'll see if I can find a pic
I can't get the picture but these are the things http://www.halfords.com/webapp/wcs/..._productId_530659_langId_-1_categoryId_165572
Thanks guys. sANDYbAY - do you mean something like one of these: http://www.ebay.co.uk/itm/321230818120 or http://www.ebay.co.uk/itm/131001778969 Dicky - sadly I don't have a welder and so welding a nut on would be a last resort as I;d have to get someone else involved.
you can also try putting 2 nuts together on the stud and tightening them, sometimes grips on the threads better than one nut and you may be able to get it tight enough to stop the leak
Thanks David - for the time being I've padded it with a few washers to get the nut on to the few non-stripped treads left on the stud but failed to get the leak stopped when tightening - am a bit scared to try tightening too much with only a couple of threads left intact! I want to take all the HE/exhaust system off anyway to move from the complex 75-78 US set up to the simpler 72-74 and so will try and replace the stud when I have it all off - just waiting on one bit of tin to arrive so that I can do the change over!
You might find that you struggle to get the stud out.... I've had a few where they just sheer off, and you end up having to carefully drill out the remnants of stud... not the sort of job you want to be doing laying on your back under a van!!
Just being the realist of the bunch here!! Ask @Joker as he had a mission with one of his not so long back!!
@Paul Weeding yes, what a fecking nightmare. I had a snapped stud in the head. took it to an engine shop who assured me they could get it out, see it all the time, no problem yada yada yada. they bust the head. God knows what they did but clearly applied way too much heat and/or tried cooling it too quickly, ended up with a great fecking crack between the valves. It now lives in the bottom of the recycling bin to stop it blowing over in the wind... spanner? You'll never get a spanner in there anyway. You need sockets. I know how tight the access is, I spend most of my spare time fecking around with them Get the heat exchanger off, don't try doing it with the h/x insitu, you'll just feck it all up. Get a nut that will act like a die (don't know what they are called but they exist) You need one a thread size down than what you have on there. Put one on to cut a new thread on the stud, then put the second on, nip them up so you can back the whole thing off. Its a b'stard, it will work or it won't. If it won't you'll have to get the head off and try drilling the stud out, its much simpler with it loose on a bench, trust me. Don't let any random 'expert' take a fecking great blow torch to it!!! Good luck!!
Nick, I have a stud removal tool if that helps? I would also suggest copious amounts of localised heat and penetrant sprays. I have those too if needed.
The problem with stud removal tools, is they are quite bulky... and the problem with type 4 heads, is that the space around the stud is very small... literally only enough space for a long reach 3/8 drive 13mm socket!!
Thanks for the suggestions everyone. Glynn - thanks for the offer of the tool. Shame I didn't see your message a bit sooner as I've already ordered one of the stud removal tool sets as pointed to by sANDYbAY. When you say copious amounts of localised heat - would a plumbing blowtorch be any good for that? I assume when heating the idea is to heat the head around the stud rather than directly on the stud itself so that the head hopefully expands a bit thus loosening the stud? Am hoping to have a go at this one day next week (if the weather holds!) and so will report back how it goes! Nick...
Good luck dude, I've had the oxy acetylene torch out on some square port heads that I'm reworking, and they still won't undo!!
I would get the stud hot and let it cool a few times. a few gentle taps on the end wouldnt hurt and I uraully put shed loads of pentrating spray on. Dont know if that helps but it makes life interesting when you put the lamp back on there. Ho knackered is the thread. Will it tickle up by recutting using a die nut and then an exhaust lock not (the copper type) If you can get some purchase on the nut and there is thread left behind it you can always wind a second nut on there!
Thanks Dicky. Where the thread is gone it's totally gone - the nut just spins on the stud so no chance of tickling the existing thread. However I did wonder about trying to re-thread the stud to a smaller size (7mm or more likely would have to be 6mm) with a die nut and then just use a smaller nut with a washer.
