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Cox. 049 Surestart engine's glow head unscrewing

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Cox. 049  Surestart engine's glow head unscrewing  Empty Cox. 049 Surestart engine's glow head unscrewing

Post  barun on Sun Apr 12, 2020 11:52 am

Although in the cox engine manual it is shown that the glow head can be unscrewed using 2 nos of coxv wrenches, but practically impossible. If the glow head goes bad, then the glow head is to be unscrewed and a new glow head to be screwed in. Can any body help. I tried a lot but could not unscrewed by using both the wrenches. Pls guide.
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Post  NEW222 on Sun Apr 12, 2020 12:33 pm

Probably castor stuck. Use some heat on the cylinder and should then come off using the wrenches. Can use a heat gun, small torch, or even a lighter will work.


Last edited by NEW222 on Sun Apr 12, 2020 1:45 pm; edited 1 time in total
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Post  Cribbs74 on Sun Apr 12, 2020 12:42 pm

I agree with Chancy except concentrate the heat on the cylinder, not the head. Aluminum expands faster than steel.

A regular hobby heat gun should do it.
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Post  barun on Sun Apr 12, 2020 1:38 pm

This is a brand new engine never started ; if I start run and break in the engine for 3 nos of tanks, then will it be easier to open / unscrew the head.. Pls guide. My intension is to check the glow head if it is glowing or not
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Post  NEW222 on Sun Apr 12, 2020 1:44 pm

Thanks for correcting me Ron. Was typing while laying down and didn't notice my mistake. Oops. Off to correct that.

And as to your other question, yes, if you run it a couple of tanks, it should also be enough heat to loosen the glowhead. Still may be a bit tight, and take a good twist to loosen it. I had a similar situation on a Cox engine a while ago with a head that was tight. Even with heat, the first time to remove it still did take a good twist, but was all good after that.
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Post  barun on Sun Apr 12, 2020 2:05 pm

Just now tried withbheat gun - snd desoldering hot air gun - no it didn't budge for fraction if a mm - let me try to run it first
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Post  Levent Suberk on Sun Apr 12, 2020 2:07 pm

New engine cylinder and glowheads may be tight. I dropped plenty of machine oil between cylinder and glowhead, wait a little, then successfully removed glowhead.
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Post  Dave P. on Sun Apr 12, 2020 2:44 pm

Get the cylinder almost too hot to hold on to, then hold an ice cube on the top of the head for 5 to 10 seconds.  Put the wrench to it and it should come off pretty easily. The idea behind it is that the aluminum head shrinks pretty fast as it cools while the cylinder stays hot and expanded. This also works on backplates and cylinders.
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Post  OhBee on Sun Apr 12, 2020 3:29 pm

Hook your battery to the glo plug with the exhaust port open in the dark! You'll easily see if it's glowing ! If it starts ..it works! ....I wouldn't disassemble a new engine for no reason!
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Post  smooth_bill on Sun Apr 12, 2020 3:49 pm

I second OhBee's very good advice!

Leave it alone until you have to remove the head for some valid reason.

New Cox engines should be run approximately 30 minutes before the piston ball joint needs reseating. For that you remove the entire cylinder and head together, and use the proper seating tool from Bernie or Matt. Plenty of information on ball joint reseating on the web and even a few videos as I recall.

Others may disagree with the about the 30 minute estimate for reseating the ball joint, but it is not cast in stone, so consider them as well.

Bill
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Post  OhBee on Sun Apr 12, 2020 4:03 pm

I've never disassembled a cyl or glow head on any of my .049's . Some ran for years. Just got back into this stuff after a LONG layoff. Have one Bee that was in a box in a damp basement for so many decades that most of the fins on the glowhead are corroded off! ... With a prime it lit right off!.
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Post  barun on Sun Apr 12, 2020 4:47 pm

I have powered the head 2'minutes and the glow plug becoming very hot ; also the aluminum head is very hot ; this proves that the plug is glowing ; but honestly speaking could not have glimse of the light from the glow : the exhaust port being open. I think the glow head is ok
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Post  Ken Cook on Sun Apr 12, 2020 5:03 pm

When you say powered, do you mean you hooked the battery to it? Just because you did that doesn't confirm that the glow plug is working. I have had plugs that have shown continuity on my meter and didn't light. In addition, if the plug lights, it doesn't mean it's good. You need to fly it and see. The first two coils generally get white deposits on them and the plug doesn't work to it's maximum efficiency. Signs of glow plug degradation can be rpm drop when disconnecting battery, instant shut off when battery is removed. During flying, the engine can shut off or just run extremely rough. Glow plug life can be as short as 1 millisecond to several years.
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Post  barun on Sun Apr 12, 2020 5:28 pm

Hello Ken - pls rescue me from the problem - how to open / unscrew the glow head in a cox engine. Thank you in advance.
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Post  Oldenginerod on Sun Apr 12, 2020 5:55 pm

Being a new engine, if you run it through a few heat cycles (run, allow to cool, and run again a couple of times) then the copper head gasket should end up compressing slightly and will most likely allow it to loosen.
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Post  pkrankow on Sun Apr 12, 2020 7:01 pm

Huh. Normally it is the opposite problem, the head will not stay tight. At least 1 fresh gasket is needed as reused gaskets are work hardened and do not squish properly and the head will loosen too easily.

2 ways to check if the head is good without removing it

Go into a closet or other windowless room, hook up power to the head, it will visibly glow from the exhaust ports. A cardboard box may also be adequate.
Or
Invert the engine and put a drop of fuel into the open exhaust...flooding is sorta the goal. Upright the engine, drain excess fuel from the exhaust. Hold the engine close enough to hear and hook up power. It should sizzle like bacon. (Careful, it may light off a small open flame. It shouldn't but does happen, disconnect power and blow it out like a birthday candle)

Having a glow head heat is not a guarantee of a good head the head may be fouled, or coils shorted together, or the plating gone, or the stem may leak. However good heat is a good indication of a good head.

So, new engine, new gaskets, new head... everything should be in order give it a run. Close the exhaust, hang a drop of fuel on the intake port that will fall in with the proper prime when the exhaust port opens. It should bark to life on prime after one or three flips. Then fuel, reprime, etc.

Phil
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Post  Cribbs74 on Sun Apr 12, 2020 9:26 pm

That’s a lot of suggestions lol.

Just go at it and use some force, if you break it I will send you a new one. The glow head is most likely shot anyways. If the filament is crushed it usually doesn’t glow and just heats up the head.

You could also pinch the crankcase in a vise between 2 blocks of soft wood. Gives you more leverage when using the tool.

Edit: I probably should have read Phil’s post first... but yeah same offer if you break it.
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Post  balogh on Mon Apr 13, 2020 7:37 am

My simplest recipe is drop the engine in a sealed plastic bag into the ice maker of your fridge (far from the crusher arm) and leave it there for 25 to 30 minutes. Given its higher thermal expansion coefficient, the aluminum glow head shrinks more than the steel cylinder. Try to unscrew it while still cold.
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Post  barun on Thu Apr 16, 2020 7:00 pm

Hello - the engine has spurted to life and is running excellent. Now kindly enlighten me on ball joint reset - how to open the cylinder along with head... An you tube video will be highly appreciated...
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Post  OhBee on Thu Apr 16, 2020 7:05 pm

I thought this was a new un run engine? Why all the screwing around with it?
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Post  barun on Thu Apr 16, 2020 7:28 pm

Hello OhBee, you are absolutely right - this is an absolutely un- run new engine - as I am new with Cox. 049 engine - so kindly tell me dies it require ball joint reset after 30 minutes of run - I am learning from all of your experience..
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Post  barun on Fri Apr 17, 2020 1:17 am

Hello Bill
Engine is running ok. Only ran for 2 minutes..at a stretch - with a 11 cc fuel tank and after properly tuning - I think it should run 4 minutes - pls guide a cl modeller who is very new to cox engine
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Post  smooth_bill on Fri Apr 17, 2020 9:05 pm

Hi baron,

Your engine may not need piston reseating yet, but the first pair of mine were very sloppy, so I reseated both before I ran them.

After running for a while this initial fitting will wear in even farther and possibly work harden a bit, so it should be checked and adjusted carefully later.

Once the engine is run a bit and reseated, I've heard that additional reseating is likely not needed. A higher performance engine such as used for Rat Racing and combat should probably be checked and reseated periodically.

Check the routine used by Paul Gibeault to maintain his championship Rat Race engines. A Google search for his name should provide links to Paul and his many contributions on the net. I'm using an Apple computer during my Shelter period at my Daughter's home, and haven't learned how to navigate between sites or I would include the links here.

As I recall - Paul dissembled his Rat Race engines after every race meeting, and checked the ball joint slop among many other things. He was the best Rat Racer on this continent (he lives in Canada), so his advice is highly regarded.

Bill
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Post  smooth_bill on Fri Apr 17, 2020 9:39 pm

baron,

I just checked this forum and Paul Gibeaults Rat Race engine maintenance article came up. It is rather long, but scroll down to the part about piston reseating if you wish.

I had to download the article, but can't figure out how to copy text from one page to another on an Apple computer?

Bill
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Post  Sunbird on Sat Apr 18, 2020 4:56 am

smooth_bill wrote:baron,

I just checked this forum and Paul Gibeaults Rat Race engine maintenance article came up. It is rather long, but scroll down to the part about piston reseating if you wish.

I had to download the article, but can't figure out how to copy text from one page to another on an Apple computer?

Bill


Ball-Socket Resetting: It is worth noting that new Cox pistons often come with the connecting rod ball- socket joint set too loose. Therefore it's a good idea to re-set the fit with a Cox factory tool to .002" slop, or less. Using the wrong piston holding fixture can result in a mushroomed head piston (totally ruined), so I don’t use one. Clean the socket area with acetone or brake cleaner first to remove the oil. Then lay the piston on a heavy piece of 1⁄2" plate glass or flat thick piece of steel (something quite dense like a vice). With the tool in place, tap with a 6-8 oz. hammer, rotate a bit, tap again and continue, checking often until all excess play is removed. Use lots of small taps & check the play often. It is necessary to check this joint after every contest. At normally low rpm’s this isn’t critical. However, at racing rpm’s (20,000+) a loose ball-socket joint reduces piston life to a few minutes.
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