Engine Freeze

Cheesehead · Post by **Cheesehead** » Mon Dec 30, 2013 4:39 am

Hi all-

I purchased a '67 'hawk from the original owner, and finally have the time to begin working on the engine.

Although the bike was complete, the engine had been removed from the frame and the cylinder head removed from the engine. As a result, pistons are froze in the bores.

Before I began using some of my own ideas, I am looking for suggestions on how to free the pistons. After squirting some WD-40 on the bores, I am contemplating my next move. There is a fair amount of rust in the bores, so I am fearful this will not be easy.

Any suggestions are appreciated..!!

Regards,
Tom

G-Man · Post by **G-Man** » Mon Dec 30, 2013 6:45 am

Hi Tom

You can try heat cycling the cylinders with a hot air stripper or propane torch. With a hammer and a block of wood you can see if you can get the piston moving. Take care that your pistons are not at bottom dead centre as you will be whacking the big end bearings. If this is so, you will need to split the cases to stop the force being transmitted to the crank as you push on the pistons.

Some people make up a "puller" out of a plate bolted to the cylinder studs and push on the piston with that.

Whatever you do, patience, penetrating oil and heat are your friends. Take your time. One of mine was so bad I had to smash the flange on the liner then withdraw the cylinder over the piston and liner together. The liner had to be cut from the piston but the cylinder casting is still usable......

Enjoy the journey.

G

malcolmgb · Post by **malcolmgb** » Mon Dec 30, 2013 2:35 pm

If you go to the Motors section and look for the thread 'Motor can not turn , can not use Kick start ' look for my post and you will see how I did it, it may help, but like Graham said don't try it if you have a piston at the top/bottom of the bore, my chemical of choice was Coca-Cola for its Phosphoric Acid.

Cheesehead · Post by **Cheesehead** » Mon Dec 30, 2013 2:37 pm

malcolmgb wrote:If you go to the Motors section and look for the thread 'Motor can not turn , can not use Kick start ' look for my post and you will see how I did it, it may help, but like Graham said don't try it if you have a piston at the top/bottom of the bore, my chemical of choice was Coca-Cola for its Phosphoric Acid.

Interesting choice! I will assume the Coca-Cola had no adverse affects on the lower half of the engine as it would probably end up there?

65hawkchopper · Post by **65hawkchopper** » Thu Jan 02, 2014 8:33 pm

Welcome to the site fellow cheesehead. (I live in West Allis, suburb of Milwaukee) I havn't visited the site in quite some time. In regards to your frozen pistons, I was once told by a buddy, that he poured liquid Drano in the cylinders of his siezed snowmobile engine and freed them up. I havn't heard it from anyone else, so I don't know if he was lucky, or if that is a common method. Granted ,that your liners will need boring anyway, and you probably need new pistons/rings, I don't see any real harm being done.

malcolmgb · Post by **malcolmgb** » Fri Jan 03, 2014 12:50 pm

Cheesehead, the 'coke' leaking through did cross my mind and so I tried to spray as much oil as I could through the cam chain opening onto the crank, I only used enough 'coke' to soak around the perimeter of the piston, when it finally freed it didn't appear to have suffered, until the crank is stripped and cleaned I will not be 100% sure.

Cheesehead · Post by **Cheesehead** » Mon Jan 06, 2014 2:03 am

65hawkchopper wrote:Welcome to the site fellow cheesehead. (I live in West Allis, suburb of Milwaukee) I havn't visited the site in quite some time. In regards to your frozen pistons, I was once told by a buddy, that he poured liquid Drano in the cylinders of his siezed snowmobile engine and freed them up. I havn't heard it from anyone else, so I don't know if he was lucky, or if that is a common method. Granted ,that your liners will need boring anyway, and you probably need new pistons/rings, I don't see any real harm being done.

Howdy Hawkchop! Nice to see a fellow Cheesehead on here. I am up near Green Bay (yea, long day around here..!). Thanks for the comments, I appreciate them. Malcolm, thank you, too.

My concern is that the engine has very low miles and the bottom end is clean and solid. I bought the bike from the original owner. His brother removed the head to "clean it and never put it back together. I was stored in a dry garage, etc., but of course the top end rusted over time. I want to be careful about what I do to free the pistons as I don't want anything bad to end up in the crankcase.

In the past few days, I have managed to free the left piston. Moves freely. The right piston is still stuck, although I have managed to move it down with a piece of wood and a rubber mallet.
However, it moves only a little at a time and that requires a hefty blow from the rubber mallet.

Here's my next question. With the cylinder head removed and with one piston at TDC, does the piston become almost flush with the top of the cylinder I have one piston about a half inch from the top, and I don't want to be pounding on the other (stuck) piston if that piston is at BDC.

Hope this question makes sense. Thanks for any help you can provide..

Cheers!
Tom