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Before I cut the con-rod...

Old 11-23-2014, 09:58 AM
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Bluebrew
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Default Before I cut the con-rod...

I want to hear any suggestions you guys may have.
It's an old OS 40FP that I'm taking apart to clean/check. Got to the point of slipping the rod off the crank pin and found the wrist pin is stuck to both the piston AND the rod bushing! The case was full of gunk(possibly castor) that cleaned up easily with glow fuel. I've soaked the area in penetrating oil, carb cleaner and tried heating. No budgy. I had an allen wrench snap in my cold numb(25F) fingers while prying on the rod against the crank OOOOOOOOOWWWWWWWWW!!

Got it on ebay(I know) years ago and I have never run it. I may have another rod stashed somewhere so I'm just about ready to cut the rod and go from there.

Last edited by Bluebrew; 11-23-2014 at 06:48 PM. Reason: not FX,orFS,Finally got it right
Old 11-23-2014, 10:10 AM
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Jim Thomerson
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I'd put it back together, run it a couple of times, and see if that wouldn't loosen things up.
Old 11-23-2014, 12:20 PM
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Well another method is to soak the engine in acetone for some period of time, like say overnight. The acetone can dissolve castor oil and castor oil residue. But if there is a lot of varnish residue, it may or may not work. But it is worth a shot.
Old 11-23-2014, 12:27 PM
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Mr Cox
 
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With the backplate off you can heat the conrod gently and get it loose. It is most likely congealed castor and it usually softens with a little heat.
Old 11-23-2014, 02:31 PM
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Propworn
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Have you taken out the cylinder liner first? If so the rod should slip off quite easily. Perhaps it was in a crash and the crankshaft has been pushed back in the bearings. You can try tapping the crank forward see if that gets you a little extra clearance. If you attempted to tap on the end of the crankshaft to remove the thrust washer you may have pushed the crankshaft back far enough the rod will not come off even with the liner removed. Try rotating the piston to top dead centre which will expose the centre point of the rear of the crankshaft. You will need to place something solid against the middle of the exposed crankshaft face and try tapping it forward.

Dennis

Last edited by Propworn; 11-23-2014 at 04:13 PM.
Old 11-23-2014, 06:21 PM
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Bluebrew
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Thanks for the replies guys. The sleeve is out and I can see the con rod is not sliding on the wrist pin. It looks fairly clean under the piston.
I doubt it would run as it was REALLY tight before removing the sleeve. With the sleeve out, the crank turns free around TDC & BDC but the piston still scrapes hard on the bore anywhere else.
It was soaked (entire block) in carb cleaner for days, is acetone more aggressive? I'll try heating the rod next, as I've already tried gently heating the piston.
Has anyone else seen a pin stuck to both pieces like this? I'm thinking it's toasted!
Old 11-23-2014, 07:27 PM
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earlwb
 
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Well acetone is a solvent for organic substances. Since castor oil is organic in nature, acetone can dissolve it.
It sort of has me wondering if the engine had run abnormally lean at one time or another and the connecting rod seized to the gudgeon pin maybe.
Old 11-23-2014, 08:07 PM
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I have had a couple that were quite stiff. I poured fuel in from underneath and let it soak for a few minutes, rocked the piston a bit, and tried to slide it. It took a while, but eventually it softened and slid back. You could tell it was looser in the center of the piston than when it was slid back. I would imagine acetone, laquer thinner and carb cleaner would work as well as fuel. Sometimes just wiggling it the right way makes the difference, TDC and your finger behind, and up as high as you can......
Old 11-24-2014, 05:42 AM
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Looks like a nice day today so I'll mess with it some more.
I'm thinking along the lines of what Earlwb is saying. I think it's been cooked.
My previous glow engine experience was limited to the car and truck realm, but they don't ever do a 150 ft nose dive. I have no idea what kind of damage that could do.
Am simply curious now and want to see the carnage.I've pretty much given up on this engine being a runner in its present state.

These engines were the LA's of their day weren't they? As in cheap,entry level. The air bleed carb sort of makes me think so. Or are they desirable because of the crank bearings? Considering the cost of sleeve/piston set and rod is it really worth it? I have another 40FP, but a back-up would be nice.
Old 11-24-2014, 06:36 AM
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Originally Posted by Bluebrew
Looks like a nice day today so I'll mess with it some more.
I'm thinking along the lines of what Earlwb is saying. I think it's been cooked.
My previous glow engine experience was limited to the car and truck realm, but they don't ever do a 150 ft nose dive. I have no idea what kind of damage that could do.
Am simply curious now and want to see the carnage.I've pretty much given up on this engine being a runner in its present state.

These engines were the LA's of their day weren't they? As in cheap,entry level. The air bleed carb sort of makes me think so. Or are they desirable because of the crank bearings? Considering the cost of sleeve/piston set and rod is it really worth it? I have another 40FP, but a back-up would be nice.
Yes. These were the inexpensive engine offered by OS in their day. They were solid runners and lasted a long time when cared for. I have one that has been in use for more than 20 years. Nothing more than the occasional cleaning required. Sounds like yours may have seen a little more action than it could handle.
Old 11-24-2014, 06:46 AM
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Some people like the FP better than the LA. I think the LA was just engineered more. Whether it is better on not is up to the user. The head is square, so there is less material to add for the casting which is lighter, and of course cheaper to make. There are 4 bolts on the head. Cheaper to machine, fewer bolts to supply, maybe lighter, then again maybe not sealing as good. One less port in the liner. Cheaper to make, but seems to run just as good with the smallish carbs used. Plastic backplate. Cheaper to make, needs to be replaced with the needle valve on there-more money for the company later on. It is lighter though. Overall I think it is a wash, I like them both and would try to salvage your FP if possible. If it runs, I would just run it to see of it loosens up as has been mentioned. If it is bent, well that is a decision you have to make.
Old 11-24-2014, 08:07 AM
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Bluebrew
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Well today I think I'll see if the other FP I have runs, if it does I'll let it be, if not, I'll take the two and try to make one runner.
Been checking price and avail. on needed parts and it looks to be $60-70 to fix the stuck stuff. Piston&sleeve seem kinda hard to find.
Nice thing about this hobby is I don't have to make up my mind RIGHT NOW. I've got a few more in the basement I want to get running.
Old 11-24-2014, 10:31 AM
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Bluebrew,

I want to make sure that I am clear on your issue as I'm not sure if you are having a problem at the piston end or the crank end. You have mentioned wrist pin but you have also said you have been prying on the rod against the crank.

Have you removed the piston/conrod assembly from the crankshaft? On that engine, you should be able to do so if you have removed the head, the liner and the back-plate. There should be plenty of clearance to do that. If not, then I do understand that your issue is with the conrod/crankpin and I suppose there could be gunk buildup or the pin damaged that would cause that hang-up. Another suggestion for removing the gunk would be to put your engine in a old slow cooker with ATF fluid overnight. If damage due to a crash or something is the problem, then "hard persuasion" may be your only answer. You'd want to "persuade" it out minimizing damage to the case, but you will probably need a new crank and/or rod. It really depends on the damage and what additional damage you do to those components getting them separated.

If your issue is with the wristpin side, then you should be able to get the piston/conrod assembly out of the engine first and then separating the piston from the conrod will be much easier as it will be much more simple to work on. I don't believe the .40 FP uses a circlip to hold in the wrist pin but I'm not certain. Someone here will know.

Lars
Old 11-24-2014, 10:42 AM
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Using a little of everyones suggestions I got her freed up!
First I heated the rod and the piston would rock ever so slightly. Still wasn't sliding though.More carb cleaner! Still had doubts it would run on it's own, then realized I could provide the horsepower. So I put the sleeve back in and bolted the head on. Filled the bottom of the piston with carb cleaner and then turned the crank with a wrench, forcing the piston to pivot on the pin. After about 10 min. of this it was turning fairly nicely and felt normal.
Took it apart again and with a little coaxing the con rod slipped easily off the crank. More cleaning and lubing and now the con rod slips smoothly on the wrist pin, but the pin is still stick in the piston. I think I'll let that be. Everything looks in decent shape and the pinch feels good. My only concern is/was the crank end bushing in the rod looked thin on one side. But i think it's beveled to aid in installation/removal. The fit to the crank pin feels perfect.
I pulled the crank to check the bearings and OOOPS! It's a bushing engine! I guess the OS manual I found online was for a different engine. Good thing I didn't go ordering parts with those P/Ns.
I dug out the other FP I was gonna run today, and was shocked at how clean and new it looked. I'll save that for another day.
Thanks for your help guys!
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Old 11-24-2014, 12:03 PM
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aspeed
 
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The chamfer on the rod usually goes on the crank side to aid in oiling, rather than the backplate side.
Old 11-24-2014, 12:43 PM
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The chamfer on the rod is there to prevent the rod bushing from galling against the crankweb face. The chamfer always goes towards the crankweb for this reason. Some rods have an oiling hole drilled on the front of the rod so the incoming fuel charge hits the front of the rod forcing the oil into the hole and through the rod bushing. Some rods have holes drilled for lubrication on the bottom and/or bottom front of the big end of the rod as well.
Old 11-24-2014, 02:32 PM
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Originally Posted by 1QwkSport2.5r
The chamfer on the rod is there to prevent the rod bushing from galling against the crankweb face.
To be more specific, when the crankpin is ground to size it leaves a small radius where the pin meets the web. This is needed to avoid a stress raiser which could lead to the crankpin shearing off. The chamfer in the rod bush is simply there to give a clearance for that small radius. Most rods only have this chamfer on one end so the rod can only fit one way. Some engines use a pressed in crankpin which means there's no need for any chamfer.
Old 11-24-2014, 02:41 PM
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Originally Posted by downunder
To be more specific, when the crankpin is ground to size it leaves a small radius where the pin meets the web. This is needed to avoid a stress raiser which could lead to the crankpin shearing off. The chamfer in the rod bush is simply there to give a clearance for that small radius. Most rods only have this chamfer on one end so the rod can only fit one way. Some engines use a pressed in crankpin which means there's no need for any chamfer.
That makes sense. Thanks for the clarification.
Old 11-24-2014, 02:45 PM
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ASpeed is right on for getting these to loosen up.
Old 11-24-2014, 03:09 PM
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Got it together and mounted on a test stand. Ran into glo heater problems, so no running today.

Lars, the problem was on the piston end. The piston, pin and rod were as one piece. This wouldn't allow the con rod to slide toward the back of the engine so I could free the rod from the crank pin. I used a "L" shaped allen wrench to try and leverage the top of the rod to slide enough to clear the bottom from the crank pin.( describing boring, dry tech stuff with text isn't my forte'.

BTW, every time I wrote "chamfer" spellcheck told me I goofed so wrote "bevel" instead.

Last edited by Bluebrew; 11-24-2014 at 03:13 PM.
Old 11-24-2014, 04:50 PM
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Had the same exact problem with a .32SX awhile back. No amount of solvent and heat kept me from having to cut the rod. Glad to hear yours worked out.
Old 11-24-2014, 04:58 PM
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badgerord
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Here's one you will not believe, I didn't until I saw it with my own eyes.

I flying buddy of mine had a couple engines that were covered inside and out with burnt oil, tried a dozen different ways to clean them with poor results.

Then a mechanic friend of his said...and I still can't believe it, take an old crock pot, NOT YOU WIFES GOOD ONE! add antifreeze and boil the engines disassembled for a day.

They looked NEW! I still think its witchcraft, but I am going to have him slow cook a couple of my old near and dear engines.

Hope this can help someone.
Old 11-24-2014, 05:14 PM
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Bluebrew
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As luck would have I do have an old crok pot I never use. This engine cleaned up pretty well, but I have many more to work on and will keep that in mind. Have heard of that witchcraft before.
Old 11-25-2014, 09:51 AM
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The crock pot method works wonderfully well if you are careful in just a couple of areas. Number one, don't boil the engine. Excessive heat in the crock pot can turn some aluminum alloys a dark, ugly gray instead of shiny natural aluminum color. Number two, use the old ethylene glycol green stuff. Some of the newer pink or yellow (or other colors, perhaps) don't work as well. Do this outside as the fumes will be strong so don't do it inside the house. I set my crock pot between 200 and 250 degrees and watch it to make sure it doesn't boil. Leave the stuff in there for several hours, eight or ten, and it comes out beautifully. While still hot, brush vigorously with an old tooth brush or a brass brush and flush thoroughly with water. Anti freeze is water soluble, so don't spare the water. Blow off with compressed air and normally these things emerge as new. This method will also get rid of gunk in your needle valves or carburetors if the engines have been stored for awhile. Blowing compressed air through these small openings after the stuff is dissolved is an aid to cleaning as well.
Old 11-25-2014, 11:01 AM
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So what's a 40FP worth today?

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