Rust seized pistons, best mixtures to use to free, and ATF questions

[Chuck78]

I always hear people saying to use a mixture of automatic transmission fluid and penetrating oil, or automatic transmission fluid and acetone, etc to free up rusted piston rings. What is it that is so special about ATF that helps with this? Is a straight mixture of PB Blaster or other penetrating oil just as good? Or is there some miracle cure as far as rust and the ATF?

[Chuck78]

This 7,000 mile 1st week of production June 1976 GS750B is my last parts bike to break down now. The bike was in pretty bad shape after sitting outside for so long, but I am really wanting to tear down the bottom end in hopes that the transmission, shift forks, and especially the crankshaft may be in usable condition. I don't have too much hope for everything as the cylinder head looked to have had water sitting in it on the exhaust camshaft/valve side (the mo st rusted up camshafts ive ever seen in an engine!!!), and I think the bike may have been crashed into a body of water of some sort, as the handlebars were bent and the ignition cover was broken, and I did 1.5 or 2 cups of water out of the oil pan as well.

I pulled the head, but I absolutely cannot get the cylinder block to budge. I dumped a fair bit of PB Blaster and engine oil down through the spark plug holes before pulling in the head, and I still could get nothing to move at all. Most recently, I took my oxy acetylene torch and tried to heat up the ring area of the pistons and the sleeves, and I still could not get the block to budge. Usually I can get a seized piston engine to rotate the crankshaft once I break loose the base gasket and can lift the cylinders despite the piston rings all being seized, but the base gasket may also be stuck extremely well here. I filled up the cylinders with PB Blaster again, and will give it another shot with this method. I wasn't sure if I should try mildly heating the base gasket area with my oxy acetylene torch as well, or if that was unheard of.

The only other really really stuck engine that I have unseized so far seemed to be very very stuck, but I could get the crankshaft to rotate enough after breaking loose the base gasket, to get a ratchet strap under the cylinder block, and I suspended the entire engine underneath my workbench hanging from a ratchet strap suspended from my bench vise, and used a block of wood and a hammer to pound the pistons down through the cylinders. Looking at the cylinders afterwards, I could probably run them and have acceptable compression as they weren't rusted too terribly, just a little pitting at the top of one cylinder...

This one is far worse...
I do have a GS1000 engine as well that was sitting for awhile with no head on it in a warehouse, so I can put this method to use once more in the near future...

[Hinermad]

I always hear people saying to use a mixture of automatic transmission fluid and penetrating oil, or automatic transmission fluid and acetone, etc to free up rusted piston rings. What is it that is so special about ATF that helps with this? Is a straight mixture of PB Blaster or other penetrating oil just as good? Or is there some miracle cure as far as rust and the ATF?

I just saw this video recently where a guy tested a bunch of penetrating oils on rusty lug nuts and studs, and the best product in terms of the least torque needed to loosen the nuts was Liquid Wrench, followed by ATF + acetone. Heating the nuts with a torch worked better than both of those. (You can see a chart with his results at 8:35.) https://www.youtube.com/watch?v=xUEob2oAKVs

Granted this was on a different application than frozen piston rings, but rust is rust, right? (grin)

[Nessism]

If you have acetone and ATF on hand and no spray penetrating oil then it makes sense to mix up a batch. I'd just use the spray though if you have some. Heating with a torch should help but you may have to get primal to get the pistons free at this point.

[Chuck78]

I'd just use the spray if you have some. Heating with a torch should help but you may have to get primal to get the pistons free at this point.

I think I may really just have to get primal after some substantial soaking with top grade penetrating oils... Kroil was one of the more obscure ones that i have heard some extreme praise of. They sell it at some of my HVAC suppliers. Rusted fan motor shafts are a pretty serious application for serious penetrating oils, when trying to save and reuse fan cages / fan blades...

A 10lb sledge and some blocks of wood will be in the near future of this early production GS750... I'm really trying to save the bare cases at least for the very low engine production number. The clutch area parts were not so useable, but I'm really hoping to save a little more out of the low miles bottom end.
I got a good and nearly brand new 1980+ 18-pole stator and matching rotor out if it at least... wild to imagine the original regulator&rectifier and headlight switch stator phase disconnect loop caused total destruction if the original 12-pole stator in less than 7,000 miles!

[Tom R]

Kroil does work wonders if you can get your hands on some. I had a swing arm pivot bolt on a t500 that wouldn’t budge with any of the other penetrating oils or mixtures you’ve already mentioned - and I was giving it a thorough beating. A few days of kroil and it popped right out. I’ve had lots of success with various other stuck nuts and bolts too. I dunno could have been combination of all of them and the right amount of time, but a lot of people swear by it. It’s not cheap though.
I have mine in a spray bottle; it always creeps down the sides of the bottle or drips out the nozzle a bit just sitting. Maybe other oils would do that too, I don’t know because I don’t have any others in a spray bottle like that, but the stuff really creeps.

[mikerophone]

I also swear by the ATF and good hardware store grade acetone 50/50 mix, but it sounds like the use of brute force is in order here.

Sad to see the conditions some of these old bikes sat in, and the stories they’d tell if they could talk!

Crazy about the stator too but given the sub par electrics, stupid headlight loop and wiring that Suzuki and other late 70’s/early 80’s manufacturers used, its not too surprising.

I fried the 4500 mile original stator and tiny R/R on my 83 750ES when I upgraded to all LED’s thinking visibility was more important and that less electrical strain would benefit the aging battery, ended up replacing all of it, including my new LED headlight bulbs!

Good luck with the fight. A BFH and block of wood, your torch and oil concoction of choice and some muscle is likely your best bet. Heat, soak, beat and repeat...

[headsbikesmopars]

With the head off you might have to collapse the pistons to free it up. Drilling holes into the piston tops and chiseling it out enough to free up the rusted rings will save the cylinder and crank also the cases. But I feel the pistons are already gone right now anyway. Keep us informed.

[prichmon]

+1 on atf and acetone. Be careful I had a bad reaction to some on my arm.

[Carter Turk]

In the past I've thought of using narrow steel strips to run thru where the head bolt studs are going thru head and ratcheting straps to keep from replacing a base gasket.
Maybe with the strips running thru cylinder block ratched to the upper frame with all the engine bolts removed except maybe the bottom rear, gravity and whatever concoction of penatrating oil might free it up with weight of the bottom end constanly pulling down.

Or with the steel strips running thru cylinder block pulling up against the upper frame spine, running a 2 by chunk of wood or the like behind cylinders with and adjustable bar clamp on both sides stood off the lower frame rails under constant tension over a few days.

Probably won't work, but just a thought.

[DanSkor]

Rust takes up a lot of space, expanding to wedge components in place. Aluminum oxide does the same thing, and forms when rust and water touch aluminum. Oil, including penetrating oil, does not get rid of metal oxides. I would not dare use electrolysis given the metal pairing. Nor would I use vinegar, naval gelly or any strong base, again for the sake of aluminum.

If I were faced with heavily rust seized pistons I would pour a chelating agent down the bores and let it sit nice and cozy over a hot light bulb. The stuff they sell where I live is Metal Rescue. Surface prep involves degreasing because this is an aqueous solution. Dilution and temperature have to be correct.

The big ends, wrist pins, and every bearing in the bottom end are presumably rust seized as well. I am unsure as to the best way of degreasing and derusting a sump. If I had the space and budget I would get a rotating engine stand.

Gradual even heating, as opposed to a blowtorch, should be used to expand the block. New penetrating oil may be reapplied. You can shrink pistons down relative to the hot bore by cooling them.

Then you get to have some fun with a block of wood and a hammer.

[rphillips]

Hard to imagine this thread without the mention of "Marvel Mystery Oil". It seems like forever, anytime the words seized or stuck eng. came out, "Marvel Mystery Oil" was the go to remedy.

[LAB3]

Hard to imagine this thread without the mention of "Marvel Mystery Oil". It seems like forever, anytime the words seized or stuck eng. came out, "Marvel Mystery Oil" was the go to remedy.

Same for Coca Cola, the old timers didn't need $15 a can chemicals to do what they had on hand did just as well.

[1978GS750E]

Hard to imagine that he is still looking for a solution, since the thread was started in June!