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O.S .46LA Head Gasket Help - 7/13/2012 4:56 AM   
garycarp


 

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From: abrams, WI, USA
Status: offline 		I have a  O.S .46LA its new with only 12-15 flights been having problems with it then noticed fuel forming on the head so i pulled it apart and there is no Head Gasket in it but they show one available
www3.towerhobbies.com/cgi-bin/WTI0001P is this a factory error anybody know?

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RE: O.S .46LA Head Gasket Help - 7/13/2012 5:05 AM   
SeamusG



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Status: offline 		The Tower pic shows the back plate gasket and the head gasket. There should be a head gasket. You need to contact the retail outlet where you bought the engine. Or, buy the gasket kit and replace it.

In the pic, is that the cylinder liner that looks like polished aluminum? You should be able to easily pull the liner up.


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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:27 AM   
JohnBuckner



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Status: offline 		I think you will find there is a head gasket already in place. Its in that recessed area on the cylinder that the head protrusion fits into.

Sometimes on some engines they can be quite hard to detect and are quite thin.

John

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RE: O.S .46LA Head Gasket Help - 7/13/2012 9:14 AM   
jaka


 

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Status: offline 		Hi!
I can see a head gasket in the picture. In the recesset area in the head. Just take a needle and pry and it out and it will come loose.


< Message edited by jaka -- 7/13/2012 7:40 PM >

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RE: O.S .46LA Head Gasket Help - 7/13/2012 2:38 PM   
SeamusG



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Status: offline 		Here's a parts explosion ...


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RE: O.S .46LA Head Gasket Help - 7/13/2012 5:15 PM   
JohnBuckner



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Status: offline 		Yup what jaka said on the removal. What I like to do on those is to use a #11 blade in your hobby knife and come from the piston side almost with the knife laying across the top of the cylinder and find that tiny demarcation line to work the blade in. Slowly walking the blade around the gasket as you raise it to top of the recess.

As for your running problems and apparent leakage from the head, well you said its a new engine and this occurred after 12 or 15 flights. Its only a four bolt head and any new engines head bolts should be retorqued after that period or at least just manually checked for tightness. A new engines head will always go through some loosening of the head initially.

I doubt there is any issue with your engine beyond just a loose head bolt or two, that is before you took it apart.

John

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RE: O.S .46LA Head Gasket Help - 7/13/2012 5:49 PM   
SeamusG



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Status: offline 		John - will you describe your technique for tightening head bolts? Thx.


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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:16 PM   
JohnBuckner



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Status: offline 		Not sure you could even call it a technique with a four bolt head like that, I just go to the opposing bolt each time as you go around the four. Actually the same for a six bolt head head criscrossing as you go around.

On a new engine I like to check for a loose bolts after the first few runs and agine after several flights. Just manually check each bolt using the crisscross and using some pressure, a loose bolt will become apparent. I also beleve the loosening of head bolt is not just caused by backing out of the bolt but also due to some actually stretching of the long bolt itself initially.

Thats all I do seems to work OK although I do have a nifty little torque wrench that I used in the past for some of my old racing engines, but can,t even remember the numbers anymore

John

Forgot to mention when reinstalling a head rather than just tightening each bolt individually even using the criss cross pattern its better to tighten each bolt a little at a time going around the crisscross pattern multible times.

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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:24 PM   
garycarp


 

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Status: offline 		exactly where is the paper gasket that goes around the bolt holes yes the one on the top of the cylinder is there but why is the other missing? this cant work like this can it I will order one but what a bunch of crap I hade to dead-stick 3 landings out of 12 and could of crashed my plane.

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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:34 PM   
RCKen



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Status: offline 		There is no other gasket that goes around the bolt holes. The one gasket is all that is needed for these engines. I would wager that your dead sticks are being caused by gaskets in the head of the engine. As others said above, it is common to have head bolts loosen a bit as an engine breaks in so you need to check them occasionally and tighten them as needed. An engine such as an OS really isn't fully broken in until it's had quite a few tanks of fuel ran through it (15-25 is a good estimate) so you need to keep checking the engine as it continues to break in. 

Do as was instructed above when you reassemble the engine, use a cross pattern on the head bolts as you tighten them back down and make sure they are all evenly tightened down. Then restart your engine and check for your fuel leaks again. 

Ken


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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:38 PM   
JohnBuckner



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Status: offline 		There is no paper gasket used on the cylinder head, None

That four bolt gasket you see in the part listing is the backplate gasket as Seamus pointed out. The photo in the tower add is deceptive because the two gaskets are shown over lapping, they are two different gaskets for two different locations on the engine.

This is not a bunch of crap' and you really likely do not need to order anything rather you may need some mentoring from an experianced flyer in handling your engine and perhaps flying. That may be your best solution. I am sorry if that sounds harsh but I see new folks mess up new (and old) engines all the time, heck I even see folks that have been around long enough to know better mess up new engines.

John

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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:42 PM   
garycarp


 

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Status: offline 		no look at the breakdown the are 2 gaskets for sure i also posted the link how there sold and called them on the phone there is 2-gaskets as shown on the breakdown diagram and 6-people at my rc club said where is the gasket? all bolts are as tight as you can go without causing damage it still leaks. thanks for the help i will order a gasket set witch comes with both gaskets.

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RE: O.S .46LA Head Gasket Help - 7/13/2012 6:49 PM   
garycarp


 

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Status: offline 		well on the website it dose say backplate ill just replace it anyway thanks for the help guys!!

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RE: O.S .46LA Head Gasket Help - 7/13/2012 7:33 PM   
JohnBuckner



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Status: offline 		Replaceing the gaskets are fine if you like but yes I did look at the brake down and it is quite obvious that there is only one gasket (alum shim type) and the backplate gasket is sold along with it in a single package. Paper gaskets an not used for head gaskets on modern engines.

Also if you order the two gasket set do not use two gaskets on the head that would be a mistake that will present even more running problems.

There is only one head gasket used on that engine and is an aluminum shim type and if the order talker said there are two then she or he is wrong. They are just order takers.

If the six people at your club said that engine has two head gaskets well then thats a bunch of "crap"

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RE: O.S .46LA Head Gasket Help - 7/13/2012 7:35 PM   
lfinney


 

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Status: offline 		if you take the point of a exacto blade, and push on the side of the shiney ring surrounding the squish band on the cylinder head it will lift up, i think you dont need anothe rhead gasket, a simple retorqueing after spraying off any goop with some carb cleaner will do the job. the headgasket is aluminum so its very easy to mistake as just part of the head

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RE: O.S .46LA Head Gasket Help - 7/13/2012 9:14 PM   
wildlifeguy


 

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Status: offline 		My guess, being a new engine, it is set too lean.  I would try richening the mixture a few clicks and trying again.  Again, just a thought and may be worth trying. 

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RE: O.S .46LA Head Gasket Help - 7/13/2012 9:22 PM   
SeamusG



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Status: offline 		Here's a couple of pics from an OS61FX rebuild. Differences include the head gasket is set in a recess in the head and there are 6 head bolts.

pic 1 - the loosen and tighten sequence for the head bolts (1 & 4, 2 & 5, 3 & 6)
pic 2 - the head gasket - very thin and easily "kinked".
pic 3 - I use a standard hex wrench - to torque but not over torque I apply pressure with my little finger only - keeps from buggering up cylinder head bolt threads
pic 4/5 - I use a length of fuel tubing to start threading the glow plug into the head - again, so as NOT to bugger the threads in the head.



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RE: O.S .46LA Head Gasket Help - 7/13/2012 9:29 PM   
pimmnz


 

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Status: offline 		Yep, that head gasket/shim is soft ally, and on disassembly can end up either stuck in the head recess, or lie on top of the liner. You need to look more carefully before deciding you don't have one. Fuel on the outside of the engine is common, most of it comes from the carb, choking, starting backwards, idling, all spit some fuel out and it ends up on the engine somewhere, so before insisting that you have a head leak, just be sure that you do...It will be visible when running on the ground and will show you where it is...
Evan, WB #12.

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RE: O.S .46LA Head Gasket Help - 7/13/2012 11:56 PM   
Mr Coffee



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Status: offline 		Good Afternoon,
This guy seems to be convinced that his engine needs two head gaskets.

Why do i have a feeling that Gary is going to install a second gasket?

- Allan


< Message edited by Mr Coffee -- 7/14/2012 2:22 AM >

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RE: O.S .46LA Head Gasket Help - 7/14/2012 1:57 AM   
dbacque


 

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Status: offline 		Gary,

Even with as many engines as I have rebuilt, I have been fooled by these metal shim type gaskets. Several times (including very recently) I've sworn that there was no gasket in an engine. But if you look closely you will see a slight color difference between the head and the recessed area where the cylinder sleeve seats into the head. That more silvery metal in the recessed area is the gasket. Trust us, it's visible in the photo.

The problem is that frequently the combination of fuel, oil and heat from running will glue pieces together. Sometimes the gasket likes to stick to the head. Sometimes it likes to stick to the top of the cylinder. Yours is stuck in the head.

If you really want to remove the gasket just to prove to yourself that it is there, notice that the bolt holes in the head cut into the outer circumference of the recessed area. That is where you need to go with your needle or hobby knife to try to pick the gasket out. Frequently the gasket is hard to remove if you try to pry it out from the edge of the seat but if you go at it from the bolt hole you can pop it loose.

Seriously, I've been rebuilding model engines for 40 years, that gasket is there. You should take the kind advice of all who have preceeded me and just reassemble the engine, torque things down and fly the snot out of it. If you must see the gasket, that's how to find it.

If you do order new gaskets, heed JohnBuckner's advice and be sure not to put the new head gasket on top of the one that is obviously already there. If you add a new gasket it is even more important that you pick away at things to get that old gasket out as two gaskets are going to cause you more problems than you have now.

The good news is that it's hard to hurt those aluminum gaskets. I discussed a top racing engine with the manufacturer recently, it had a crimped head gasket. I wanted to order a new one. He said that with the pressure that is applied to the gasket when the head is torqued, I shouldn't worry about anything short of it being torn it two. Bolt it down and fly it!

Dave

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RE: O.S .46LA Head Gasket Help - 7/16/2012 2:23 AM   
garycarp


 

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Status: offline 		Yup i got it the thin aluminum gasket is probably fine and  its there i was only talking about the paper gasket that dave said is not used so i will retork the bolts and if that don't fix the leak then i will order a new one and not use the paper one

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