Freeing up potentially rusted piston rings to cylinder

[Grumblebuns]

I have a spare TC motor that has been sitting various garages for the past 20 plus years. I need to rotate the cranksshaft by hand in order to perform a leak down test. Before I do that, I need to make sure that the piston rings are not rusted to the bores. What are recommended lubricants to spray down in the cylinders to free up the rings. I'm thinking of ATF/acetone solution letting it soak for a week or so. Any other magic elixirs you have used?

Joji Tokumoto

[TurboFource]

I have heard of people using Marvel Mystery Oil but the atf/acetone mix you mentioned is supposed to be a pretty effective penetrant.

[Richard48Y]

I once freed a Jag XK120 that had sat for decades using a 50/50 mix of MM Oil and Diesel.
I expect there are a lot of mixes that would work.

[EuropaTC]

Hi Joji,

It's one job that I've not had to do (yet) but if I had to I think I'd use Richard's oil/diesel mix. I've heard of diesel being used before with seized engines and that would probably work on it's own, reasonably thin, not going to corrode anything and won't evapourate as quickly as petrol..

I'd question acetone, I think that will work fine as a penetrant but if your ambient temperatures are high (or even just warm) then I think it might evapourate leaving the thicker ATF fluid behind over a week. Maybe replacing the spark plugs would stop that ?

Brian

[4129R]

I used WD40 and then just engine oil to free 4 stuck pistons.

The fun starts when the pistons are out of the bores and then you start trying to free the stuck piston rings from the pistons. Of the 3 x 4 rings, I managed to break only 2. But when you take the rings off the pistons, note which ring is top is which is middle, and whether they have a top and bottom side, mine did.

[Bryan Boyle]

I once freed a Jag XK120 that had sat for decades using a 50/50 mix of MM Oil and Diesel.
I expect there are a lot of mixes that would work.

I'd agree; diesel is an oil (versus solvent, such as acetone or gasoline) and has a lower vapor pressure, so will remain on the surface longer than acetone.

A long-time colleague of mine (inventor of CamGuard, which is an approved additive for aircraft engines) modified the formula and has an automotive oil additive..I know, some think it's snake oil, but he was a lube scientist at one of the big 3 oil companies, (it's based on the additives that most blenders such as Castrol etc use) that does a good job, when the engine is operating, keeping the rings free and grooves in the pistons clean.  Also has seal softeners that help keep natural and common polymer seals flexible...just a thought when/if you get the mill turning again, Joji.

[Grumblebuns]

I remembered that I bought a borescope a while back and used it to look down the the cylinders. That borescope is an amazing piece of equipment. #1 &#4 pistons were on the bottom and #2 &#3 near the top. #1 &#4 pistons looked amazingly clean and carbon free and the bores free of rust. #2 &#3 were at the top and the camera couldn't focus close enough to get a clear picture. I feel comfortable enough to just use WD-40 initially and let it soak for a week or so, then attempt to rotate the crank. If unsuccessful, regroup. Thanks for the suggestions.

[EuropaTC]

I feel comfortable enough to just use WD-40 initially and let it soak for a week or so, then attempt to rotate the crank. If unsuccessful, regroup. Thanks for the suggestions.

Hi again,

This isn't nit-picking because I get why you'd use WD40 and I can't see why it shouldn't work, but I'd advise to top it up with a quick squirt every day or so.

Many years ago our maintenance guys loved the stuff and were forever spraying it around because "it lubricates great". One of my colleagues was very skeptical and so did an experiment to find just how much lubricant was there and how much of it was volatiles to get the aerosol spray to work. A row of test tubes of different brands with a marked measure in each, left on his office window sill for a week...  (we did high tech stuff back then     )

The result was surprising, before the end of the week the levels had dropped dramatically and he was right, there was very little left because most of it evapourated away.  In defense of WD40 I don't think it was the worst but even so I remember every tube was almost empty.

Brian

[Richard48Y]

Yes, over time WD-40 becomes a near solid when the solvents evaporate.
Many gunsmith's hate it.
PB Blaster is a common replacement these days, not sure what the silicone content does.

[4129R]

I had an engine that I had rebuilt, and after it was not used for a long time, it was near impossible to turn over with a long extension lead on a socket on the crank pulley bolt (5/8" I think).

I used a mixture of WD40 and engine oil, left it for 2 days, and gradually it freed up by turning the nut on the crank pulley.

I bought a new high torque starter motor, and eventually the pistons were free enough to turn over with the starter motor.

But, this was a rebuilt engine so I knew there was no blown head gasket/water leak problem, it was just condensation of air in the bores which caused it to partially seize.

It did start, smoked a bit as it burned off all the oil in the bores, but now starts and runs with no apparent problem.

[Grumblebuns]

I was pleasantly surprised by the condition of the cylinder walls and the top of 1 & 4 pistons. There was saw no rust on the walls and the tops of both pistons looked like shiny aluminum. Pistons 2 & 3 were near the top of the stroke so the borescope couldn't focus in but bodes well for the overall condition of this engine. I may be overly cautious at this stage but I at least want some lubricant on the rings when the crank is being rotated; acetone/ MMO or a light oil mixture may do the trick.   

[Richard48Y]

Another thing to watch for.
Dry bearings!
I think the Ford engine oiling can be primed fairly simply.

[Grumblebuns]

It took a little bit of effort but I got the engine to break free and rotate freely. I was initially going to use ATF/acetone mixture but I discovered that my can of acetone had evaporated away long ago and my can of WD40 had lost its air pressure. At that time I was tired and most likely too lazy to make the 25 miles round trip to the hardware store in town. I did have a can of PB Blaster which I decided to use. The piston rings probably were not too badly rusted to the cylinders but the PB Blaster did the job. Once I finish the leak down test I'll pour in some light lubricant to coat the piston walls for long term storage.