Engine disassembly problem

[rhagen]

I'm disassembling a glow engine for the first time. I bought it 2nd hand and it is royally gunked up. I want to take it apart and clean it up good.

It is an OS 35 FP (two stroke, no rings)

I removed the head and backplate. Got the piston sleeve out, but cannot for the life of me get the connecting rod to come off the crankshaft pin. I've tried it with the piston at TDC, BDC, and all positions in-between. I am using my fingers and also tried prying a little with a popsicle stick, but it will only move about halfway off the pin. I can't see how it can come off since the piston is up against the cylinder wall at that point.

I'd greatly appreciate any suggestions anyone might have. All the writeups I've found on the web imply that it should come right off, so I'm stumped.

[proptop]

It's possable that the rod is stuck on the wrist pin?
Quite often you will get varnish on the wrist pin and that prevents the rod from sliding back far enough to come off the crank-pin...

Shoot some carb cleaner in there to see if that helps.

[E-MO]

Use an awl to slightly rub off the varnish...or an old toothbrush to gently rub away the varnish...Got pic's ?

[rhagen]

OK, I looked up under the piston and it did look gunky. Shot a little degreaser in there, and waited a while. It moved a little farther, but still wouldn't come off. I put a loop of strong string under the rod so I had something to pull on and that did the trick.

Thanks proptop. Man these forums are fantastic for getting help!

[proptop]

Glad I could help... :D
I've learned a lot myself by hanging out here and @ RCU :cool:

[RHarding]

I've got the same problem. I'm going thru some of my old ventage engines and cleaning the up. Have a Veco 45 apart but can't get the con rod all the way off the crank pin. Everything feels loose, but it will only come about half way off. I've cooked it in anti-freeze, soaked it with alcohol, sprayed carb cleaner, etc. to no avail. It went on so it must come off. I've been rebuilding engines for 40 years and haven't had this problem. Any answers?

Richard

[turk1]

By the way,mark the conrod face before remove cause its important the conrod position original (lubrication issue)

[imack]

Try using a heat gun in combination with carb cleaner / pentrating oil. Wear gloves so you can get the whole engine to the point where it would be too holt to hold without the gloves on.

It may take several cycles before you loosen up the gunk on the top end of the con rod, but if you keep at it you'll get there!

Ivan MacKenzie.

[downunder]

Have a Veco 45 apart but can't get the con rod all the way off the crank pin.
I don't know the Veco 45 but some engines can be very tricky to get the rod off the crankpin. If the rod rides in a groove machined in the crankcase (usually done if an engine's been stroked for a larger capacity) then you have to turn the crank around to put the end of the rod near the transfer port to get the additional clearance. Some engines have a hole (plugged with a screw sometimes) in the back of the crankcase in which case the liner has to be removed to gain access to the wristpin to draw it out through the back of the crankcase. This frees the piston and then gives enough movement to take off the rod. I hate them :).

Other than tricks like that, you need the liner out then the piston hard up against the back of the case with the small end of the rod slid against the rear piston boss.

Marking the rod so it goes back in the same way isn't really a lubrication issue, it's because generally only one end of the lower rod bush has a chamfer to clear the radius machined onto the crankpin where it meets the crankweb. The unchamfered end will bind on the radius.

[Hydrocat]

OK, I looked up under the piston and it did look gunky. Shot a little degreaser in there, and waited a while. It moved a little farther, but still wouldn't come off. I put a loop of strong string under the rod so I had something to pull on and that did the trick.

Thanks proptop. Man these forums are fantastic for getting help!

RHAGEN...... Had to do the same job on the same motor (OS maxIII 35) yesterday. You probably damaged the big-end some by pulling it off at an angle. The proper procedure is to turn the motor to top dead centre (with barrel removed)....which will allow you to push out the small end pin and remove the piston. With the piston removed there is enough side clearance to slide off the conrod without any tension.

I get these old gummed motors squeeky clean by boiling the parts in a washing powder/water sollution for a few minutes. Just be carefull not to boil the rubber and nylon parts. After drying the parts, oil them well to prevent the steel parts rusting. :cool: