Dealspeed

My Feedback: (17)

in the last 6-8 months I've disassembled over 25 glow engines, sizes ranging from .25 up to 1.20, some were full rebuilds and others were just clean up and bearing replacement from being stored improperly.
Im telling you this so that you understand that I know what I'm about, and I know most the tricks out there as far as disassembly goes.
Ok so I've got a nearly new Irvine 72 Mk2 that was stored very badly after being bench run, bearings need to go and the crankshaft needs some major rust removal, problem is that I Cannot for the life of me get the Conrod to come off the crank, it will slide off about 1/3 of the way and that's it, I've tried all the tricks I know' yes I've gotten it very hot ( put in oven at 300+ degrees for 20 minutes) I've very carefully tried needle nose pliers, mini pry bar etc etc.

I don't want to damage it as parts are hard to find, so does anyone have anything that may help me?

Hobbsy

My Feedback: (102)

I gotta ask, is the sleeve out?

Dealspeed

My Feedback: (17)

I would have asked the same, and yes the sleeve is out.
the last time I tried was after a good soak with PB penetrating lube, I sprayed the whole inside of the motor with PB before I started disassembling the motor from the start to make things go a little easier, I'll post pics here soon so you can see how bad it is.

downunder

Is the small end of the rod sliding freely along the wrist pin?

Dealspeed

My Feedback: (17)

It's tight but moving

the pope

is the crank pin at about 11 oclock ?

Dealspeed

My Feedback: (17)

Yes, I'm thinking the conrod isn't as far over on the wrist pin as it could be, I'm going to spray the wrist pin with pb and let it soak a little.
I'll post if I have any luck

Hobbsy

My Feedback: (102)

Some gentle prodding with a long hex/Allen wrench will get the top end scooted over It sounds like you're making progress. My Irvine .72 is one of my finest engines I mostly learned to fly with it.

Mr Cox

On some engines it can help to have the crank rotated near BDC, the piston can then move into the rear transfer channel a little, and the conrod can slip of the crankpin.

1QwkSport2.5r

Acetone works better to dissolve oil residue than almost any petroleum product. So far the absolute best penetrating oil I've used didn't come from an aerosol can. it came from a can of acetone and a bottle of Dexron ATF. Mix at a 50/50 ratio. Apply liberally, and wait awhile. There's some videos on YouTube showing it's effectiveness compared to the likes of Liquid Wrench and PB Blaster, WD40, etc. The latter are mostly comprised of stoddard solvent (basically paint thinner/mineral spirits), some surfactants, and a small amount of light petroleum oil.

The engine parts have to come apart the typical way as that's how they were assembled.

earlwb

One thought that I have is maybe the crankshaft has somehow gotten set back slightly in the crankcase. Sometimes on a hard landing on the nose with a hot engine, it can push the crank back a little. So if all else fails and since you are replacing the bearings anyway, heat up the engine and try to tap the crankshaft forward some. Maybe it'll work, maybe not.

Dealspeed

My Feedback: (17)

I did try that, no go.
And I always use acetone when tearing a engine down, this time I've stayed away from using it on the crankcase because I don't want to ruin the paint.
Haven't had any time to work on it recently but I'm hoping to tonight.

Dealspeed

My Feedback: (17)

Just thought I would post an update, I did finally get the con rod loose from the crank, after 25 minutes in a 300 degree oven I was able to get the con rod to slide all the way over on the wrist pin, this motor is very tightly made, the con rod had very little to move on the wrist pin, almost hard to tell it even moved but the con rod finally came off the crank right afterwards.

1QwkSport2.5r

You think that Irvine was tight. You'd probably have a heart attack taking a Picco apart. LoL. When I tore my Picco .28 apart, I had to put a zip tie around the bottom end of the rod and pull quickly and briskly to get it off the crankpin. It went back in far easier. It helps to put some oil on the big end of the rod to aid in getting it off the crankpin in engines that are tightly fitted.

Glad you your engine apart.

Dealspeed

My Feedback: (17)

I can understand a Picco being tight, not a Irvine, I had to fight to get the rear bearing out of the crank case after I got the bearing loose from its position in the crank, it just did not want to come out of the backplate opening.
I've torn down a lot of engines in the last year and not a one was this bad.
Im currently working on my first Enya it's an old 49x, aside from being a bit filthy it's in great condition, might have seen 2 gallons of fuel at most.

jeffie8696

I have had the same problem with a few engines, very tight at the wrist pin and hard to get the rod off the crank. I have an older Irvine 72 that I have never been able to get reliable which in my experience is highly unusual