010 head stops glowing

Thanks aspeed, other than this particular set of aftermarket heads , I have never had issues with 010-s. They start at the 2nd or third crank with the spring and the TeeDees of all sizes are my most dependable runners of my fleet of 80+ COX engines. I am still battling with the seal surface of the head, no matter how I polish it with toothpaste, it leaks compression with new gasket too.
I will cannibalize my old stock heads from my shelf queen 010-s if the seal does not improve.

Andras, maybe you should get some proper metal polishing paste? Toothpaste is not like it used to be, it contains a lot less abrasives than a few decades ago. Absolutely worthless for any polishing work. An alternative would be 1000 grit or finer wet sanding paper with some oil.

As you probably know, the head gaskets work harden every time you tighten the head, so these should be annealed or replaced every now and then, to avoid leaks.

As for the coil not glowing, it could be that the thicker material conducts the heat more efficiently to the head, and the tiny amount of fuel in that tiny combustion chamber just isn’t enough to keep it glowing? I would imagine that what works ok in a 5 times larger engine (049), might not necessarily work in a tiny one.

Hopefully this will get solved. Not a lot of people run these engines, most 010’s are probably shelf queens, like mine. Shelf Queen or not, I still want them to be operational.

Thanks Kari, I bought some 1200 grit class wet sanding paper and will take on the head with that.

I have many tens of hours of 010 flight time under my belt and have never met such stubborn issues with these absolutely easy to start and easy to run critters. But I will manage and bring it back to the airspace..

A mute point now, but when I was flying 1/4-A R/C, my go-to engine was the .020 Pee Wee. It was considerably cheaper than the TD and did a fine job of powering those smaller airframes.

As time progressed, the .010 TD became more and more unattainable, in short supply even when available. Plus, I moved to high desert higher elevation places where the smaller engines struggle. But, this lack of availability probably accounts for why now they command exceptionally high prices.

Those who have them now have a rarer engine to treasure.

To check sealing, mark the sealing face of the head lightly with a permanent marker. Now screw it in lightly a couple times without a gasket. This will give an indication of contact points. Flat is one thing, but it also must be fairly perpendicular to the threads. Something the size of the .010 head is tough to handle while sanding. It would be quite easy to go to far reducing the high spot or not the direction you want.

Resistance is directly related to length and diameter. Wire diameter also influences heat range. Thicker wire results in a colder plug. It appears as though the wire in the photo is larger in the new head. I was able to measure wire size with calipers, even in the .010 head.

Thank you Greg for the advice. I sand the head by slightly pushing it down on the sand paper and rotating it around its centerline. Rather than sliding it to the left and right. This rotation may keep the surface perpendicular to the centerline, and as flat as the surface underneath.

I apply silicone grease on threads of glowhead before use. Compression is better in this way. Any grease works well.

Hi all I've had some problems with my new .10's also. first off I'm going to say I have been building several and buying parts from several sources. ok I'm having problems with sealing the glow plug to the cylinder. on some I noticed the cylinder had a high lip machined into top where the glow plug screws in.. I did some ink testing on the surfaces and noticed it wasn't sealing down at the bottom. it was sealing on the bottom fin of the glow plug. on several I had to add several copper gasket to get compression but after three gaskets it didn't have much compression left at all. So I filed down the raised factory lip on top of the cylinder and got it seal with less gaskets (one)and more compression. you don't have to worry about filing it dead flat at the top of the cylinder because once it seals at the bottom with a copper gasket the top doesn't matter anymore. personally I think its a miss match of different cox manufacturers parts over time that just didn't match.
Basswood

balogh wrote:Thank you Greg for the advice. I sand the head by slightly pushing it down on the sand paper and rotating it around its centerline. Rather than sliding it to the left and right. This rotation may keep the surface perpendicular to the centerline, and as flat as the surface underneath.

If there is a a problem with perpendicularity, twisting the head like this won't help square up the head. You will have to slide it putting more pressure on the high spot to remove material there.

Basswood wrote:.....I noticed the cylinder had a high lip machined into top where the glow plug screws in.. I did some ink testing on the surfaces and noticed it wasn't sealing down at the bottom. it was sealing on the bottom fin of the glow plug......

Out of tolerance parts happen, probably more so back then. I've seen several because I was looking closely (measuring). I have a .09 cylinder that looks normal except it was only rough bored and never ground/honed on the inside.

I'd like to offer a few comments on the 010 heads, production, and general thoughts.

I can also confirm the heads are made to OEM specifications including the filament wire and thickness. OEM specifications in this case are from the later 90s and early 2000s. Note - it is not to say changes to parts might have happened over the years which is common when we are talking about a span of that long a time, improvements, etc.

I checked my stock, which was shared production with Bernie in this instance, and didn't find any issues with sealing or filament glow. It's not to say a bad head or two cannot find its way into the batch, but do not see anything widespread.

Cox varied the filament thickness throughout the years, generally in the .006 to .008 range some of which was driven by stock availability. Wire, to my knowledge, was always solid versus plated. Much smaller than that it will burn out quicker, a problem Fox 049 heads tended to have when they used .004 wire.

As usual, if anyone has any issues with products we sell, please reach out to fix the situation.

Matt

Well, really, what András says happened to me too.
A) The new generation glog plug loses compression in the center (cathode or anode), not against the cylinder.
B) the glow plug works fine at high rpm, wanting it to keep the rpm low (with restrictor ring), the engine stalls.
(I made several attempts with the fuel, finally I took a glow pluj from the old manufacture (in Cox bags), the engine works correctly, in high and low rpm.
This happened to me when I made the Micro P51 Mustang.
I can make a video for the case as soon as I have time showing the above.
I never made the claim, I took it as a fortuitous case of a product that does not meet 100% of its quality.

Gents,

As you may know I am an adamant  COX lover who likes to write success stories to raise the COX glory rather than complain about these gems. As the thread gets longer it turns out mine was not a distinct case of failure (compression loss by leaking , flame-out) but some of those who have 010 engines in use also met, infrequently, my issues or similar some day. The length of this thread is not proportional with the size of the problem, but shows the keen interest of our CEF community to interprete the behaviour and solve the  very rare irregular  issues we see with COX engines.

This isolated 010 head failure I and others with similar experience described does not mean any bad either about the engine or about our fantastic suppliers Bernie and Matt.

Simply put, as the knowledgeable Chinese thinker of the great medieval Xu dynasty also said,  "sh...t happens.."

I, as - a bit embarrassed -initiator of this thread thank you all for the valuable advice and shared experience, and especially thank Bernie and Matt for their professional businessman attitude in handling all, even very rare and hard-to-substantiate customer complaints. .

good. Here are the glow plugs I received. On the left is the one that loses compression through the (cathode or anode), it makes a micro bubble or balloon when it is in operation.
It doesn't hold the engine running at low rpm, probably due to pressure loss.
It is dated the day of the test in the plastic envelope: 08/04/2019, (April 4, 2019).
The other glow plug on the right came with this one, but I haven't used it yet, (I put a Cox Vintage glow plug on my engine).
I don't remember the exact supplier, but it is possible that they come from Mr. Bernie, since he buys some accessories through my importer, Mr. Ojeda.




Indicated with an oval and green arrow .010 that's original vendor handwriting, someone on the vendor's team might be able to recognize it.

I found that there is a gap between current production glowheads and top of cylinder about 0.3 mm. There is no gap with original glowhead.

Interesting observation, Levent...with no gap between the cylinder and lowermost head fin of old-stock heads, the sealing by the head bottom on the copper gasket could not be safely secured, because the fin could in principle bottom out on the cylinder top before the bottom of the head sits on the gasket?

Hi Andras. In fact there may be a very small gap with original glowhead, but I couldn't see it with 65 years old eyes

I tightened all of them equally as I can. Didn't tight too much to strip glowheads, only where it stops and a little more. I examined compression and all of them seem equal.

Realistically you can't get a seal between the top of the cylinder and the lower fin. The fin would just bend. If you are getting normal compression, it's sealing with the gasket.

Not sure where those heads are from, as we don't package them that way (not is it our handwriting). We also would not write "gaskets" in Spanish.

Although we did have some leaky 049 heads some years ago (they were not properly pressed), we did not come across any 010 versions like this so far. Which doesn't mean that it can't happen. Again, we warrant what we sell.

MauricioB wrote:good. Here are the glow plugs I received. On the left is the one that loses compression through the (cathode or anode), it makes a micro bubble or balloon when it is in operation.
It doesn't hold the engine running at low rpm, probably due to pressure loss.
It is dated the day of the test in the plastic envelope: 08/04/2019, (April 4, 2019).
The other glow plug on the right came with this one, but I haven't used it yet, (I put a Cox Vintage glow plug on my engine).
I don't remember the exact supplier, but it is possible that they come from Mr. Bernie, since he buys some accessories through my importer, Mr. Ojeda.




Indicated with an oval and green arrow .010 that's original vendor handwriting, someone on the vendor's team might be able to recognize it.

Cox International wrote:Not sure where those heads are from, as we don't package them that way (not is it our handwriting). We also would not write "gaskets" in Spanish.

Although we did have some leaky 049 heads some years ago (they were not properly pressed), we did not come across any 010 versions like this so far. Which doesn't mean that it can't happen. Again, we warrant what we sell.

MauricioB wrote:good. Here are the glow plugs I received. On the left is the one that loses compression through the (cathode or anode), it makes a micro bubble or balloon when it is in operation.
It doesn't hold the engine running at low rpm, probably due to pressure loss.
It is dated the day of the test in the plastic envelope: 08/04/2019, (April 4, 2019).
The other glow plug on the right came with this one, but I haven't used it yet, (I put a Cox Vintage glow plug on my engine).
I don't remember the exact supplier, but it is possible that they come from Mr. Bernie, since he buys some accessories through my importer, Mr. Ojeda.

Indicated with an oval and green arrow .010 that's original vendor handwriting, someone on the vendor's team might be able to recognize it.

Mr. Bernie only the letter marked in green is that of the supplier. everything else is my own handwriting, do you understand? In my comment I try to indicate that.
I can maybe trace the supplier, I have to contact the importer and see if he has the order, but I don't claim anything, I just share a personal experience.

Admin wrote:

MauricioB wrote: On the left is the one that loses compression through the (cathode or anode), it makes a micro bubble or balloon when it is in operation.

Might be able to carefully apply some high temperature RTV sealant or epoxy like JB Weld around the contact to seal it.

I've had old original Cox heads leak and blow bubbles around the contact post before.

thanks Jacob, look, I have sometimes solved this problem by enriching the fuel with castor oil, ie running the engine with high castor oil for a while, as it works, in some cases it has been sealed with the oil itself.