seized pistons

[dreamer]

HELLO AFOURIANS! This is my first post and im a little nervous...but I have gotten so much great insight from these threads I simply cant resist! So here goes..My partner and I are taking apart a 73 A4 and we are down tothe exposed block, crank out but we cant move the pistons at all.We have been soaking the cylinders with penetrating oil for about a month and yesterday we tried using the hammer and 2x2 todrive the pistons down ward..nothing moved at all and before I take out the 20lb sledge I thought it would be prudent to see what the afourians would suggest. Any problems driving the pistons down through the bottom? Is muriotic acid safe to pour down there? Any advice would be greatly appreciated..thanks

[Sony2000]

I would use heat next. A plumbers torch on the top side of the piston, but mostly on the wall of the cylinder, then tap the piston head with wood or plastic. Move to the next spot and repeat, all around. The rings should dislodge. The piston head may already have started to separate from the lower section that holds the wrist pin. Check for microscopic cracks before reusing it.

[Dave Neptune]

Smackin 'em

Dreamer, first welcome to the MMI Afourian Forum.

Knocking seized pistons loose is not an easy task. First glad to hear you are using wood as a strike buffer. Nice soft wood seems to work well. You can use some 1X wood and tap a bit more gently while working your way around the diameter of the piston. When striking in the middle you can hit harder but still with wood. If you have access to a "dead blow" style hammer for the big hits they tend to work much better for knocking pistons loose. Worth looking for.

I'd go to the heat as a last resort if you are not somewhat experienced with it. Try thinning some ATF and dilute by about half with acetone. You can also use a heat lamp by placing it close and letting it sit for a couple of hours then let it cool~~repeat a few times. The hot cold cycle will draw the releasing fluids into the rust and that can really help. I have used a timer on the light while away and it works pretty good. 2 hours on 6 hours off for a day or so. This is not the same as using the torch but may be worth a try.

Dave Neptune

[hanleyclifford]

Can you post a few pictures of the situation? From the sound so far it seems likely the pistons are kaput. You may need to focus on not harming the block.

[wsulli]

Diesel and ATF and a little mineral spirits always worked well for me .Ready to use products such as Boshield and PB blaster also work heating and take it slow. Tap all around the edge with a 3/4" dowel.

[dreamer]

Thanks Friends

I appreciate all the good advice and like the slow heatlamp heat and cool process. Will try that with some varius mixtures and get some pics for my next post..

[hanleyclifford]

This stuff is good. http://www.kanolabs.com/