Stuck piston on J 70 need advice

[ronboonville]

1934 J 70, have tried soaking with pb blaster and also heating a little. afraid to tap on exposed part of skirt. clamped rod in vise using a socket for rod journal and tapped on cylinder trying to drive outward, away from piston. maybe try to drive in further? heating in oven? fill cylinder with water and plug plug hole and freezing? none of this sounds like a good idea. maybe just wait more days with pb blaster? any help appreciated. maybe make it a wall hanger or table lamp, lol. thanks, ron

 

[Joe Reeves]

Re: Stuck piston on J 70 need advice

What is the model number of that engine?

 

[Chinewalker]

Re: Stuck piston on J 70 need advice

Joe - the Model number is J-70. It's a little single cylinder motor from 1934.

Ron - I've had success using the grease-gun method. I have a fitting made from a spark plug with the porcelain and eletrode knocked out and a zirk fitting welded into place to allow me to force grease into the cylinder and push the piston out. Works well until the ports are uncovered. Certainly doesn't hurt to soak it longer, either. More soakage with an ATF and acetone mixture might work, too.

 

[ronboonville]

Re: Stuck piston on J 70 need advice

as you can see in pics a little of the skirt is visable, and it looks like the lower ring.

 

[Joe Reeves]

Re: Stuck piston on J 70 need advice

Joe - the Model number is J-70. It's a little single cylinder motor from 1934.ight work, too.

I should have picked up on that. In a hurry, glanced at it, thought someone was in a bigger hurry and just entered "J" for Johnson and "70" for the horsepower. Never gave a thought to it being a 1934 1.4hp Johnson.

 

[Chinewalker]

Re: Stuck piston on J 70 need advice

Ron - have you tried a wooden dowel to tap the piston inwards a bit, tapping on the piston dome's underside? Maybe once you break it free in the bore, it might move easier with other methods. Doesn't look terribly crusty, just varnished...

 

[RogersJetboat454]

Re: Stuck piston on J 70 need advice

If all else fails trying to get it out;

This gentleman is restoring a Maytag washing machine engine in this video. They had iron cylinders with iron pistons, so when they rust, they rust solid. He's actually quite entertaining to watch doing his restorations. I check out his Youtube daily.

 

[gm280]

Re: Stuck piston on J 70 need advice

View attachment 188342View attachment 188343View attachment 188344 as you can see in pics a little of the skirt is visable, and it looks like the lower ring.

Looking at the very first picture you posted, have you tried using two tapered wooden wedges? Take the same setup you show in your first picture with the rod clamped in your vice and take two (one on either side) tapered wedges and tap them down along side of the piston and crankcase and keep taping them with some liquid wrench penetrating oil and/or ATF or even some Marvel’s Mystery oil and see if you can force the crankcase off... You really have to keep the vice tight for that to work properly though... It is a simple compound levery issue with the wedges...

 

[ronboonville]

Re: Stuck piston on J 70 need advice

Have been throwing away some wooden shims today! will dig them back out of trash! I like the idea. also thinking about a piece of 1 1/2" pvc pipe that would fit over rod and then against piston. then tapping on the cylinder itself.

 

[ronboonville]

Re: Stuck piston on J 70 need advice

Just watched the video, liking that idea too. maybe I could build that puller out of scrap angle iron.

 

[HighTrim]

Re: Stuck piston on J 70 need advice

For small powerheads, I take an old crock pot, fill it with antifreeze, and boil the powerhead in it. The heat is what is important here, not the medium.

 

[ronboonville]

Re: Stuck piston on J 70 need advice

I do have alot of anti-freeze, maybe use a coffee can set down in crock pot without the crock or put it on the grill, fish cooker is at the lake along with my acetone and atf. the connecting rod is pretty light weight so I don't think I should use it to break it loose. my pvc pipe fits real good but didn't seem to budge it. I think if I can get it to move like 1/8" then soak it some more I'll get it. I do remember heating bearings in can with oil to make them slide onto shafts, so maybe the boiling might expand the cylinder evenly, the aluminum piston should cool down quicker, but then again it's probably the rings that are stuck not the piston,