Anyone used this trick before?

[AlanS]

I presently have an engine out of a TZi (don't ask; "no son, all the red lights on the dash doesn't mean it has an electrical short") and when I stripped it, there was a deafening bang followed by a sudden loosening of one headbolt.......yep, sure enough, one managed to snap. Not just snap, but snap right down inside where the actual thread starts which on one of these is around 55 mm below the face of the block. A closer inspection revealed that coolant must have been seeping down a couple of bolt holes for some time with the result this one had rusted in.
The thought of drilling a hard steel bolt out of an alloy block is a bit daunting, but we made a steel guide up for the drill. It still wanted to run off, so we made a longer guide, 55 mm long with the intention of using it so we can pop it, drill it and possibly if we're lucky, get a drill to bite and screw it straight out through the bottom..............wrong again; the hole tapers about 2mm from the face to the thread, obviously so as to allow for the head to slightly move and to allow the headbolts to self centre on the threads when being installed, so we now have to wait to get the guide remade with a 2mm taper.
The head is over at the machine shop to get the full treatment, but I mentioned the snapped off bolt to the machinist and his first response was "what are you using to loosen it; white vinegar?" When I asked a bit more, he tells me that with alloy engines, a trade trick is to fill the hole with white vinegar and allow it to creep down the thread where it will react with the corrosion and foam it out. It seems in some cases it will actually foam, but more often, it just softens it and enables the offending part to be removed fairly painlessly.
I haven't as yet seen any stuff coming out, but by weekend, we'll give it a try and see what happens. They reckon the vinegar will attack the white rust without attacking the actual alloy of the engine.
Anyone here ever tried this before and if so, was it successful?


Alan S

[stuart_hedges]

Never heard of this trick, but it sounds plausible.

With these things, the added ingredient is usually "patience." Professionals can put in the vinegar, or whatever, and work on something else until the next day - people like us who have set aside a day to work on the car expect instant results.

[docchevron]

Never tried vinegar I have to say, but it makes perfect sense.

I've used Cola to good effect under much the same circumstances though.

If you get really stuck I have a block I could squeeze into a suitcase and bring over next year!!

[AlanS]

No, it was halfway down at the back.
I've had it soaking for almost a week now. No rush as he has another car to drive and I'm not all that keen to get too involved as I have another interstate trip coming up to collect a bit of specialised refrigeration gear I bought off eBay and trying to get freight organised and the prices they want to charge makes a 3 day interstate trip a viable proposition.

I'll do a write up on the removing procedure as soon as we get it beat as I suppose the older these cars get, the more the chance it will happen. It is a really touchy job and we're thinking a "kit" containing all the necessary tools at a reasonable price may be a worthy project to help preserve the beasts.

Alan S