Marciatelli

Hi there,

I am new to this forum and I tried to search similar threads but couldn't find anything so I decided to create this thread.

I run a Tamiya Nitrage 5.2 which comes with a Tamiya FR-32 FX engine. The FR-32 FX is basically a rebranded Ofna Force 32, there is no differentce in sleeves, pistons, cranks or carb, everything is the same.
While inspecting and maintaining the engine (I have noticed leaning out as well as fluids all over chassis coming from the flywheel), I have put some after-run oil into the engine. Five minutes later I had a puddle of oil coming out from the outside engine bearing. The bearing itself is a outside bearing 7X19X6 OFN52900.
I have few questions regarding nitro engine bearing change (I know how to replace them, just need to know more about the bearing that can be used).
1. What kind of bearing can be used? This particular part has rubber seals, can I use just metal shielded bearings or do they have a specific category?
2. The dimension of the bearing is 7X19x6, does that mean any 7X19X6 will fit and seal the engine good so there will be no air leaks or do they have specific engine and non-engine bearing with different tollerance?
3. I have inspected both inside and outside bearing, the outside bearing is leaking but inside seems fine and still holding smooth and strong, is it alright to replace only one engine bearing (which would be the outside bearing) or do they have to be replaced in pairs?

Thanks for your replies guys,
Mark

Sorry if my English is weird or has mistakes, its not my first language.

thailazer

Mark....Regarding your questions:

1. I have used both metal and plastic shielded bearings in glow engines on planes.

2. There are many different kinds of bearings of various quality out there. www.rcbearings.com is a good place to get glow engine bearings, and he ships world-wide. Maybe the engine experts can add more knowledge here on bearing types we need to use on glow engines.

3. Normally it is a good idea to replace both since you have the engine apart, but I recently just replaced a main bearing and left the front one in place as it was fine. No issues replacing just one.

Marciatelli

Thank you very much for your reply thailazer!

I have found this website which sells bearings in UK (where I am) and I have a question to the engine experts whether this bearing would be good enough quality to be used as outside bearing http://www.wychbearings.co.uk/607-2r...xr4aAg7C8P8HAQ

Thanks!

nitroexpress

Why do you seem reluctant to replace the bearing with the OFNA part? Although there are better bearings, for a RTR engine it should be fine and the price is good.

Anything that goes off road should have a rubber seal. The airplane guys and many on road vehicles can go metal or even no shield, but not off road where it's dirty conditions.

Marciatelli

Thank for the info!

I am not reluctant to replace it with OFNA bearings, I live in UK where the OFNA parts (even on eBay) arent too common, and if you find the parts you need, its usually pricey. Importing parts from asia/america to UK takes 1-2 week, and I forgot to mention that I am running on a slightly tight budget and need the parts quickly in.

I have seen Boca Bearings and Avid, they seem to have a great choice of bearings, do you guy know any other good brands that would offer quality product?

nitroexpress

Boca and Avid bearings are good, but you would still be importing them. Just go local.

http://www.bmmracing.co.uk/alpha-plu...x6-p-5232.html

supertib

this is normal...front bearings always wil lleak...no need to replace it...........

Marciatelli

Lots of glow fuel (not oil) used to be spit out of the bearing, creating puddles. I know that nitro engines should leak a little, but that was not healthy.

Marciatelli

Thank you very much for the info guys, it helped a lot!

supertib

because your tune was rich...bearings do not have anything to do ith sealing the engine.... but what would I know !

1QwkSport2.5r

The oil film between parts (crank, bearing race, etc) is what creates the seal. That same film of oil prevents the piston from contacting the cylinder wall while running.

Ive never seen a running engine spit liquid fuel from the front bearing; sealed bearing or open bearing. Oil sometimes sprays off when it fires up for the first time in awhile but I never see any oil leakage from any engine I own while running and rarely a drip after it's back on the shelf. I have a large collection of BB engines with every kind of seal/shield available (open, rubber seal, metal shield, etc) and they all perform perfectly. The idea one needs rubber seals is not a good one. The key is in the oil in the fuel.

But I'm a newb so YMMV.

supertib

these engines will piss fuel when they are pig rich... I have seen it hundreds of times......... no need to replace the front bearing, need to lean the dam needles...

1QwkSport2.5r

Hmm... Never seen it. Must be a new phenomenon.

Marciatelli

Jeeeze, Im not questioning you knowledge... All Im saying is that when a bearing starts to act like "im gonna act like im not here" because of the rust and damage. I had to change it.
I am not firing shots at you...

supertib

That doesn't surprise me !

anyways I see it on every single engine I run on the breakin stand.....I may even have photos of the engine pissing fuel out the nose...........if the tune is rich they piss fuel, end of story.........

Marciatelli

+1

Thats how my engine performed before the bearing got corroded, and thats how it acts now as the bearing was replaced.

supertib

So if the bearing is damaged and spinning off center then it needs to be changed......your first post I read as the bearing was good, but leaking... now hearing its rusty and corroded changes things quite alot......

Marciatelli

What you saying is not wrong.
I like how you assume that it was "pig rich", matter of a fact it wasnt. Bashing tuning usually involves slight rich tuning but slight for the reason of safety.
I mean you saw it hundreds of times, you know what youre talking about.

Marciatelli

However I said that it was rusty and damaged, I do not understand what part you dont understand.
I did not measure with some fancy tools the existing/non-existing off center spin of the bearing.

Rusty and damaged bearing that pisses fuel all over the chassis means change the bearing.
If the problem continues (pissy bearing), youre right, its tooooo rich, but it stopped.
Now there are few drops here and there, good oil seal between the bearing and crank, thats it, new bearing, no problems.

Youre right, however youre trying to proove an unrelevant point.

Marciatelli

We are arguing about a solved issue now.

Yes, I didnt include that info in the first post that was slightly misleading and confuzing, I apologize.
Either way, I cannot look inside the bearing which is installed onto an engine (crank case), after taking the bearing apart and then looking upclose, I found that out.

supertib

nYour




Yeah... your first post didn''t say anything other then bearings felt good but were leaking...no mention of rust or corrosion..........

Your first argument there was no mention of rust or damage...only thing you said is it was leaking and spitting fuel ( which is a 100% sign of being tooo rich )

only today do you finally say bearing was damaged and rusty and corroded............. If your first post said that information we wouldn't be having this conversation

Remember your the guy posting on the forums asking for help with your engine... I tried to help you as best I could with the information you posted.....

.And yes since your posting asking for help on a forum I am going to trust my instincts over yours... ..

Over the years your about the 10 000 th person to post here with a leaking bearing...99% of them caused from being too rich.. hundreds of bearings changed needlessly because the guys didn't know any better and the people offering advice to them here didn't know any better either.....So I was trying to save you the hassles.

And yes..I have seen this hundreds of times.... that is no exaggeration...

in the end your the one asking advice on a forum not me..I am just the guy trying to take a few minutes to help a rookie out with his engine.....

supertib

so here is where I am at with Nitro engines...... this is one of my engines that I have modified setup and tuned......

http://www.youtube.com/watch?v=F4QpcI5PO2Q

Marciatelli

Thank you for quoting my reply to your post which later you edited...
I know you have a lot of experience when it comes to engines, your signature says it all.
I have also posted "Thank you very much for the info guys, it helped a lot! " which pretty much means thank you, the issue has been solved. After saying such thing, its not nessesary to comment further.
I am not perfect, I didnt include the info in the first post because I didnt really knew it myself. This lack of information has caused a confusion and for that I apologized already.
I know tlhat youre trying to help me, like you heped a loooooooot of other people (I can guess from your words and amounts of posts and activity).
I dont want to look like a dick, I am trying to be as competent as possible.

I will now explain what was wrong:
- The bearing was corroded and damaged, that lead to disformation on the metal surface of the bearing which did not allow formation of oil seal between crank and the bearing. This issue lead to leaking both side, progressively leaning out of the tuning (which I described in the first post) and leaking out fuel out of the crank case.
As I replaced the bearing, the problem went away.

Thank you very much for your help!

supertib

the seal , or as much as there is is formed between the crank and the crankcase..not the crank and the bearing.......... the bearings job is to keep the crank spinning smoothly on center...

1000's of RCU users have needlessly changed their front bearings over the years due to running too rich and their bearings leaking..... I was simply trying to help you...

Marciatelli

I know who you are, seen your website, products that you make and what you achieved.
I didnt doubt that you know what youre doing and that you have a lot of experience.
I didnt achieve any of that, the only thing I achieved (hobby wise) is puchasing few kits, building them and then enjyoing them.
I know youre great and all, but please stop rubbing it in.