The message from Chris Street contains these words:
If you mean "will it release existing stuck items", then no. WD40 is crap, too. Proper penetrating and easing fluid with graphite works wonders if put on well in advance.
As a prophylactic, it's smashing, just don't use it on anything that's going to be moving, like inside bearings etc. as it's not really that sort of lubricant.
What a bastard. I annointed the top of the threads with a few drops of acid, left for a few hours. That ate away the rust in the top 1mm or so of thread. The acid was blasted off with a lot of wd40, which was left overnight (should have used paraffin, I think, or Plus Gas "Formula A" if I could find any). A quick zoom along the road probably undid any benefit of the above. More WD40 was applied to the hot manifold, and I applied an impact socket on the end of an impact driver. No result. A gentle wiggle from a socket on an extension removed a bolt. Careful repeated back and forth wiggling, hammering and more crap WD40 with the application of heat from a gas torch produced two sheared off bolts. The manifold was removed to attempt removal of the last bolt. That sheared off, too. Off to the Motorbits shop (on foot) for 2mm drills, bolts, 8mm tap. Drilled out the parts of the bolts left in the manifold. Bloody Draper drills, had to sharpen them repeatedly, and it wasn't because they were hitting white iron, either, it was all grey. They had trouble going through the bolt material, too, but sharpen, sharpen, sharpen, eventually they got through. The bolt thread halves were knocked out with a punch, and the holes cleaned up with the (bloody crap) Draper tap. Put the lot back together, using new BZP
8mm bolts. Will have to keep an eye on the joint as the threads, while the bolts are tweaked up, are not quite what they were.
Use Rocol anti-sieze compound J166.
well done. like I said it is probably as easy to cut the bolts off and remove the manifold in the first place (thus avoiding so much junk in the face and the annoyance when the final one snaps.
mrcheerful
Not possible to use studs and brass nuts? That's the traditional way.
I thought that, given the age of the car, it's likely that it won't need another downpipe change - anyway, the bolts won't be quite so hard to get out next time! I have seen studs and brass nuts used before, they make a nice squeaking noise when undone.
The message from Chris Bacon contains these words:
Make sure you use good thick washers if you're using brass nuts - and make sure they're a close fit onto the stud, otherwise the metal seems to draw down the gap and they loosen.
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