010 head stops glowing

Hi Robert,

exactly the same thoughts here...either the thickness/mass of the glow filament, or its platinum/iridium cladding are not sufficient in the aftermarket heads to sustain continuous engine run........I did not want to add, but in addition to the filament issue,  the sealing of the aftermarket heads is also imperfect, even if you tighten them with a torque that one with 10+ years of COX engine experience would guess is the limit to prevent damage to the cylinder  .....I experienced that glow and sealing deficiency with all recently bought aftermarket 010 heads.

To mend the sealing problem, I add toothpaste on a flat smooth hard surface (flat glass or plastic sheet)  and press the head base against it, than rotate by hand a couple times , to make the seal smooth and perfect...then wash it in hot water to remove the remnant tooth paste.


But I cannot do anything with insufficient glow performance, with 30% nitro in my 010 fuel included..

I will  address it to Bernie and Matt, because these heads are not cheap, and are dead on arrival, at least as far as the filaments are concerned, whose deficiency cannot be doctored by the users, even if at least the sealing issue is repairable in my experience....they'd better check these quality issues with the current producer..

We are sorry to hear that there may be an issue with our Cox .010 glow heads.

The same vendor has been manufacturing these for the past 12 years and this is the first time that we have been made aware of any problems with them. Of course that in no way invalidates the claims that have been made. We simply have not heard of this before.

We just tested a multitude of them on a few different engines, and they seem to seal perfectly. This is not to say that there could not be the odd one with a defective thread, but three of such to the same customer seems like a statistical impossibility.

We have sold thousands of these glow heads without having heard of this issue before, and perhaps the sealing issue lies with the OPs cylinder. In any case, to resolve this, we have refunded the customer for the three .010 heads that he purchased.

In regards to the filament, since we are not in possession of the filament drawing (only the drawings for all the other components), we went with the drawing for the .049 version; which calls for a 0.015" thickness.

Upon testing today, we notice that they do require somewhat more amperage to glow brightly; which could possibly be an issue when using less than 30% Nitro and / or running the engine at less that full RPM. As we are now aware of this, we will use a slightly thinner wire in the next production run.

By the same token, if anyone has received defective .010 glow heads (or any other defective item) from us, we encourage them to contact us directly for a full refund.

Cox International wrote:
Upon testing today, we notice that they do require somewhat more amperage to glow brightly; which could possibly be an issue when using less than 30% Nitro and / or running the engine at less that full RPM.

I experienced this before with .010 after production glow heads. Used thicker gauge and shorter wires for glow plug clip to solve that problem.

Bernie,

I truly appreciate that you refunded me, but as I wrote you in my email, my concern is not so much with with the money I paid, but with the stock you have, which may show similar failures. If I lived near you, I would offer you to test run a few random heads on 010-s and see if they sustain constant engine run even if disconnected from the battery.
In my opinion the problem is not insufficient glow when electrified, but flame out when disconnected. Platina acts as a catalyser to burning methanol, and if present on the filament in insufficient amount, it will not sustain ignition of the fuel. If my reasoning is right, it is the vendor of the filament built in the head by your supplier, who may have deviated from genuine COX specs, and  not in terms of wire diameter, but regarding platinum or iridium cladding. I read here that similar issues occured with a production run of some standard plugs sold by others too, owing to insufficient platinum plating.

I by far did not want to discredit your business by posting about it here on CEF among your customers, I posted here just out of curiosity to see whether others share the same experience, and it looks like some others do.

We CEF members could help you on pushing the supplier to rectify this, with bench run videos of 010-s with and without the glow clip connected .

What is your opinion?

No worries but this is frankly the first time that we have heard of this issue in 12 years and thousands of sales later.

BTW, the filaments are not "cladded"; they are solid wire (Platinum/Rhodium I believe) Our vendor would not know what OEM specs are, and it is our responsibility to supply them with the correct specs. As of right now, we still don't know what the OEM wire diameter is but will make the filament thinner on the next production run, even though this issue has never been brought to our attention in over a decade.

balogh wrote:Bernie,

I truly appreciate that you refunded me, but as I wrote you in my email, my concern is not so much with with the money I paid, but with the stock you have, which may show similar failures. If I lived near you, I would offer you to test run a few random heads on 010-s and see if they sustain constant engine run even if disconnected from the battery.
In my opinion the problem is not insufficient glow when electrified, but flame out when disconnected. Platina acts as a catalyser to burning methanol, and if present on the filament in insufficient amount, it will not sustain ignition of the fuel. If my reasoning is right, it is the vendor of the filament built in the head by your supplier, who may have deviated from genuine COX specs, and  not in terms of wire diameter, but regarding platinum or iridium cladding. I read here that similar issues occured with a production run of some standard plugs sold by others too, owing to insufficient platinum plating.

I by far did not want to discredit your business by posting about it here on CEF among your customers, I posted here just out of curiosity to see whether others share the same experience, and it looks like some others do.

We CEF members could help you on pushing the supplier to rectify this, with bench run videos of 010-s with and without the glow clip connected .

What is your opinion?

Well Andras my friend, Thank you for your long distance diagnostics! ….I re-installed ….
The original head that came with it and it runs just fine with battery disconnected…. Started easy and tuned easy from rich to lean…. Only one tank full though due to time of day (noise)…. My stater pack is 4 “D” cells and fuel is Sig Champion 35…. Tested with two head gaskets…. Just glad the little rascal runs!!!

Bernie, First of all let me thank you for what you are doing in support of Cox engines…. If it were not for you and Matt it would be a sad story to try and keep these engines going… When I first re-looked at using them I was very happy to find out that even new parts were being made for them!

I ordered three heads and some other parts for the .010 but I’ll not ask for a refund…. I haven’t tried the other two, Maybe they’ll work …. I’d rather consider it a donation for the good work you’re doing…. In all fairness my engine was not that great of shape when I got it so we can’t really know its full potential until I run it some more, And like you say, Many heads have been sold with no problems coming back…. I do think it’s a good thing to really scrutinize that wire size in an OEM head to know for sure….. The run today encouraged me to find and order two NIP old stock new heads to try (Who knows, maybe they’ll have their own issues due to age)….But I would not hesitate to order more heads from you once they are tweaked a little….I finish flattening all my heads and backs of crankcases on a sheet of glass anyway so that doesn’t affect me much…

The .020 heads I have received from you are spot on…. Even using a throttle… That causes me to look more at the diameter of the wire for the .010 more than the plating if they are coming from the same shop….

Thank you again for your support of Cox engines…. So us old guys can enjoy them a few more years    

Robert

I checked electrical resistance of six 0.010 glowheads. Original Cox glowhead -I have only one- is 0.7 Ohms and current production glowheads -five glowheads- are 0.5 Ohms.

Thanks Robert and our offer of refunds for defective merchandise stands, as always

The odd part is that the current production run was made in 2021 and not a single complaint until today, and Matt from EX has said the same. Again, we can't rule out occasional defects and that is why we always offer to refund for something that does not work.

In retrospect, I concede that the filament thickness may not be optimal but, until today (first complaint), had no idea that this may be the case. In any case, we will make the filament thinner on the next production run; which may only be in 2-3 years.

rdw777 wrote:Well Andras my friend, Thank you for your long distance diagnostics! ….I re-installed ….
The original head that came with it and it runs just fine with battery disconnected…. Started easy and tuned easy from rich to lean…. Only one tank full though due to time of day (noise)…. My stater pack is 4 “D” cells and fuel is Sig Champion 35…. Tested with two head gaskets…. Just glad the little rascal runs!!!

Bernie, First of all let me thank you for what you are doing in support of Cox engines…. If it were not for you and Matt it would be a sad story to try and keep these engines going… When I first re-looked at using them I was very happy to find out that even new parts were being made for them!

I ordered three heads and some other parts for the .010 but I’ll not ask for a refund…. I haven’t tried the other two, Maybe they’ll work …. I’d rather consider it a donation for the good work you’re doing…. In all fairness my engine was not that great of shape when I got it so we can’t really know its full potential until I run it some more, And like you say, Many heads have been sold with no problems coming back…. I do think it’s a good thing to really scrutinize that wire size in an OEM head to know for sure….. The run today encouraged me to find and order two NIP old stock new heads to try (Who knows, maybe they’ll have their own issues due to age)….But I would not hesitate to order more heads from you once they are tweaked a little….I finish flattening all my heads and backs of crankcases on a sheet of glass anyway so that doesn’t affect me much…

The .020 heads I have received from you are spot on…. Even using a throttle… That causes me to look more at the diameter of the wire for the .010 more than the plating if they are coming from the same shop….

Thank you again for your support of Cox engines…. So us old guys can enjoy them a few more years    

Robert

How do ohms relate to energy required to light and keep them lit? Lower number more or less energy required?

Levent Suberk wrote:I checked electrical resistance of six 0.010 glowheads. Original Cox glowhead -I have only one- is 0.7 Ohms and current production glowheads -five glowheads- are 0.5 Ohms.

Cox International wrote:How do ohms relate to energy required to light and keep them lit? Lower number more or less energy required?

Levent Suberk wrote:I checked electrical resistance of six 0.010 glowheads. Original Cox glowhead -I have only one- is 0.7 Ohms and current production glowheads -five glowheads- are 0.5 Ohms.

Trying to find amount of iridium or platinum used in coil. Wire element length are same with OEM coils as you already stated, but thickness of platinum wire may vary. Wire cross section area may be different in a given length. However because I checked only one OEM glowhead, so I can't say anything about it.

Cox International wrote:How do ohms relate to energy required to light and keep them lit? Lower number more or less energy required?

Levent Suberk wrote:I checked electrical resistance of six 0.010 glowheads. Original Cox glowhead -I have only one- is 0.7 Ohms and current production glowheads -five glowheads- are 0.5 Ohms.

P(power)=U(voltage)*I(current), and U = R(resistance)*I, so P=I*I*R..because Resistance is inversely proportional with wire cross section, the thinner the wire the more power is needed to pruduce the glow heat..

Thanks but would that not mean that a thicker filament needs less power? This would contradict that our (presumed) thicker filament needs more power?

balogh wrote:

Cox International wrote:How do ohms relate to energy required to light and keep them lit? Lower number more or less energy required?

Levent Suberk wrote:I checked electrical resistance of six 0.010 glowheads. Original Cox glowhead -I have only one- is 0.7 Ohms and current production glowheads -five glowheads- are 0.5 Ohms.

P(power)=U(voltage)*I(current), and U = R(resistance)*I, so P=I*I*R..because Resistance is inversely proportional with wire cross section, the thinner the wire the more power is needed to pruduce the glow heat..

Bernie, with the glow voltage being constant 1.5 Volts, the power that generates heat is P=U*I and with I =U/R, so
P=U*U/R, meaning that the lower the resistance, the higher the power that heats the filament...so thicker wire/lower resistance transforms more electric power into heat at constant voltage, as per your correct theory..

OK but then why does our filament for 010 require more power than our filament for 049; both having the same wire diameter of .007"? Because the 049 filament is bigger (more mass)?

balogh wrote:Bernie, with the glow voltage being constant 1.5 Volts, the power that generates heat I'd P=U*I and with I =U/R, so
P=U*U/R, meaning that the lower the resistance, the higher the power that heats the filament...so thicker wire/lower resistance transforms more electric power into heat at constant voltage..

Cox International wrote:OK but then why does our filament for 010 require more power than our filament for 049; both having the same wire diameter of .007"? Because the 049 filament is bigger (more mass)?

balogh wrote:Bernie, with the glow voltage being constant 1.5 Volts, the power that generates heat I'd P=U*I and with I =U/R, so P=U*U/R, meaning that the lower the resistance, the higher the power that heats the filament...so thicker wire/lower resistance transforms more electric power into heat at constant voltage..

If the wire has the same diameter and is of the same consistency (i.e. same alloy and iridium/platinum coating), to fit the .010 well, perhaps has a few less turns? If the glow heating element is slightly shorter may account for its higher current use given the same battery system. (Voltage is the same in both cases. The resistance element "R" is lower given it is shorter in length. I=V/R, then lower the resistance, the proportionately higher is the current.)

Bernie. The resistance R is proportional with the length of the wire...longer wire means more resistance and more mass to be heated. At constant 1.5V glow voltage the electric power that transforms into heat is more if the Resistance is higher: P=U*I=I*I*R. So the 049 head generates more heat, to ignite a larger amount of fuel per cycle than in the smaller 010.

But is the 049 wire not thicker than the 010? At least visually judging, that would be my guess...

Thanks for the explanation

balogh wrote:Bernie. The resistance R is proportional with the length of the wire...longer wire means more resistance and more mass to be heated. At constant 1.5V glow voltage the electric power that transforms into heat is more if the Resistance is higher: P=U"I=I*I*R. So the 049 head generates more heat, to ignite a larger amount of fuel per cycle than in the smaller 010.

Bernie, could you sacrifice an original NOS Cox .010 head and carefully pull the wire element out, measure the length (factoring for the length taken up by the spot welds) and the gauge/diameter of the element?

I suppose you have to go with whatever wire is available for the element.

I could but that will likely not be necessary, as I have pursued this issue, have received clarity and will be posting an update in a few minutes.

Admin wrote:Bernie, could you sacrifice an original NOS Cox .010 head and carefully pull the wire element out, measure the length (factoring for the length taken up by the spot welds) and the gauge/diameter of the element?

I suppose you have to go with whatever wire is available for the element.

I checked with someone who is well-versed in glow plug / head manufacture, and what we use for our 010 head production is seemingly fine.

I just now re-tested the glow of the filaments for 010 - 020 and 049 (Regular and High Compression) on several dozen heads, because I realized that I had a battery-to-glow head connection issue this morning; hence obtained false readings.

All three sizes \ four types of our glow heads use the same filament (.007" diameter - 90% Platinum / 10% Rhodium). Recommended for all non RC use glow heads (not just Cox) is .006” to .008” wire diameter; so with .007”, we are right in the middle and thus the 010 version does have the correct filament diameter. It is also manufactured to correct coil #s and length.

Using a field box with a "dial", all 4 versions of our glow heads lit up brightly smack in the middle of the "green area" of the display, including the 010 version. Hence, the glow heads are manufactured to specs and we will not be changing anything on the next product run.

Very sorry for the misinformation earlier but, now that it has been established the 010 heads have the correct filament, this would explain the lack of issues during the preceding decade.

As to why OP and another user have experienced issues after removing the glow clip, we can only speculate, but really don’t know. Fuel could be an issue and we cannot rule out that the odd glow head is actually defective (loose solder joint); even though they all get tested when they arrive from the factory. Of course, the small mass / combustion chamber of the 010 head cools off more quickly than a bigger head, so not much wiggle-room for fuel issues or low RPM.

As always, just a quick note if someone receives a defective product and we will take care of it.

You may find this interesting -- the catalytic decomposition of methanol due to exposure to platinum.

Heating of platinum in methanol vapor.

Thanks Bernie for following it up so comprehensively..It is good to know the 010 heads in your current stock comply with requirements.

As to my and Robert's experience with sagging engine run after disconnection from battery, I am puzzled and would not have written about it without reason. My fuel is a fresh blend with 30% nitro. I am one of the not too many  010 owners here with active use of several 010 engines over 10+ years in a row in my RC planes, not just on bench tests stands, and my present experience with the aftermarket heads is indeed a very rare issue hitting these 010 gems. ( It is Brad, Mauricio, TeeBee, maybe  Robert, and I who most frequently posted on 010- s in real flight service)

Anyway, thanks again for standing behind your excellent COX products and having customer interest in focus..

The Tee Dee .010 was in production for a very long time, H.R. Warren evaluated it in 1961:

Sceptre Flight: Oct. 1961 Cox .010 Tee Dee Engine Review

Company changed hands with Estes 1996?, 35 years. Could it possible during that time, that a few minor changes to wire diameters and coatings were made, even for short periods?

That may explain some apparent inconsistencies. Also, a head that had been previously used, no telling of changes to reliable running being Castor coated and who knows what all "preservative" oils were used as after-runs.

At least am glad to see that users aren't orphaned due to lack of available new heads.

Also, I hope that those Cox .010 heads weren't at one time prior to our current owners, were not cleaned in leaded gasoline? That would poison the platinum, why cars went to unleaded fuel because of the platinum catalytic converters.