mmabc

My Feedback: (1)

I have an OS 61RF with pump. I'm trying to disassemble it for inspection, clean up, and possible bearing replacement.

How do you remove the connecting rod?

It has sat up for 20 years. What can I do to clean up, inspect, and restore the pump? The instructions say to never disassemble or it may not ever function again.

T Brooks

I suggest you start with a heat gun. Warm the engine up so it is just slightly too hot to hold with a bare hand. The heat will soften the gummy oil. Whatever you do, do not force then engine.

Once you can turn the crank you should be able to get the liner out through the top with the head off. As the piston comes to TDC it will probably push the liner out.

With the liner out you can wriggle the conrod off the big end and slide the whole lot out the top. Again a bit of heat will help loosen the gum in the wrist pin.

Once in pieces put the whole lot in a jar of methanol and let it sit. Mainly the pump. Dont disassemble.

A brass bristle brush if good for scrubbing the engine exterior parts. A kitchen pot scrubber pad is quite good for cleaning internal parts. My own method is to boil the engine parts in water with dish wash liquid. The gum will form a brown crud that can be scrubbed off. it is more time and labor intensive but doesn't change the exterior surface.

Cheers
Tarquin

N1EDM

My Feedback: (2)

Oop, I see that T Brooks answered your question as I was typing mine. IWe're both saying the same thing, i.e.;

Does the piston ride inside a cylinder? My reason for asking is because I just had a stubborn engine like that and had to heat the case to expand it and also to soften the caster that was 'gluing' the cylinder to the wall.

I don't recommend prying the cylinder out with anything but if you must, use a soft piece of pine, no metal tools. On my engine the fit was almost perfect (meaning tight - no play).

Before you go through all that, take notice of the position of the cylinder as well as the piston so that they go back the same way ion relation to each other, and in relation to the case. I usually notice that the piston is a bit more scorched on the exhaust-port side. And, if I'm not preaching to the choir, take notice of which cylinder ports are located on the exhaust side. Installing the cylinder sleeve backwards will detune the engine. Once you slip the sleeve up and out (leaving the piston behind), you should have enough wiggle room to get the piston out.

When it comes time to reinstall the piston, if it's a ringed engine, you will have to slip the piston inside the sleeve just enough to trap the ring, then slip the whole assembly back over the crank pin. If you try to mount the piston on the crank pin and then slip the sleeve over it, you could be in for a lot more work.

Clear as mud, right?

Just my $.02

Bob

mmabc

My Feedback: (1)

I put it in boiling water for a few, and that really did loosen things up. The sleeve isn't budging though. I'm trying to remove it gently with the piston all the way down.

Would it help to soak it overnight in the fuel as is?

mmabc

My Feedback: (1)

Excellent. I got it. Read another thread that said to put a servo control horn through the exhaust port. A couple of heat cycles plus that, and it popped right out.

mmabc

My Feedback: (1)

I'm pleased the rear bearing looks pretty good. There's gunk but I don't see any pitting or anything. Now that the piston is out, it's got a real smooth action to it. What about the crankshaft? Does that only come out with the bearings? At this point, I'm just going to soak it with fuel overnight and take another look tomorrow.

T Brooks

Hello

The crankshaft comes out the back. You will need a press to do this. any attempt at whacking the crank out will most likely end in tears i.e damaged threads or bent shaft. Bearings will stay inside the case.

If you search well on google you will probably find an exploded view. alternatively I am sure that some users here will have it as a pdf.

Tarquin

flywilly

My Feedback: (121)

A drill press works great for this, but if you heat the case in an oven at 250F for 6-8 minutes the crankshaft may just slide out. You can also rap the back of the case against a wooden block or place a block on the front of the crankshaft and TAP it out. Sometimes the rear bearing will come out with the crankshaft, too.

Roguedog

I use a heat gun to heat up the engine to where I can't toucn it then with the prop nut threaded flush to the end of the crankshaft I set the crankcase on a 2 x 4 and use a brass hammer or brass drift to knock it out.

Once you get it started it usually comes right out. Never pound on the threaded portion on the crankshaft without the prop nut threaded flush at the end.

Bryan

Jim Johns

Bryan,

You and I must have gone to the same school of model engine rebuilding.

flywilly

My Feedback: (121)

Good point Bryan! Though I think the real caveat should be to avoid 'pounding' at all costs. I've repaired the results of some 'pounders' and it is never pretty [X(]

bjr_93tz

Engine rebuilding time is when owning a gas cooktop comes into it's own.


...Actually I have a mate that's installed an induction cooktop, that would probably heat things up a lot faster and maybe more evenly? I wonder if his wife will let me try it out?

Roguedog

I'm sorry to say that when i was younger that was a school of hard knocks, I had to learn the hard way til I decided to use my brain instead of my brawn.

Will,

Yea, I agree that it's not a good idea to pound on these engines. I have a drill press but so far as long as long as I heat up the engine before hand all it takes is a tap or two to get the crank moving. If it doesn't budge then it needs more soaking, heat, WD 40, or a combination of all, or else something else is wrong e.g. bent crank, wedged bearing.

So far the biggest problem I've had is getting the conrod moved over to the relief area of the piston to get it of the crank. Just have to work it out with heat , fuel, and/or WD-40 and use an allen wrench to lightly pry on the back side of the conrod until it slides over far enough to get it off the crankpin.

Most of the time the rear bearing comes out with the crankshaft if heated enough.

Bryan

Iflyglow

My Feedback: (79)

I clean all my engines in a crock pot with straight Prestone antifreeze and the engine comes out looking like new. To go through this all and not replace the bearings is kinda sily in my mind, since an excellent set of high speed polyamide retained bearings will cost you under $15. I rebearing engines all the time for several club members and use only bearings from rc bearing. Paul's quality is as good or better than Boca for half the price. His service is second to none.

8178

My Feedback: (17)

Take a look here and you will see why you never, never want to mess with taking the pump apart http://sceptreflight.net/Model%20Eng...%2061SF-P.html

T Brooks

Now would be the time for the original poster to look at the liner for signs of peeling. I dont know if the RF-P was as bad as the Hanno for peeling but the one I got certainly had a peeled liner.

mmabc, when you look at the inside of the liner it should have a consistent shine to it. If you can see little bubbles in the coating or brass color showing through then I have bad news for you. If you run your finger past any of these discolorations you will probably feel an edge. If the liner has peeled it is toast. Unfortunately the small bits that flake off are murder on the piston and bearings.

There are few options if it has peeled: try to get a genuine replacement, or try to get someone who has one of the performance specialties replacement Hanno piston and liners. Both are about as rare as rocking horse *****.

Of course if it hasn't peeled then ignore everything I said and your good to go


Cheers
Tarquin