hairy46

My Feedback: (1)

Great thread! Thanks

purenitro33

Well that was the only thing I could think of after watching that video you sent me, that was a real head scratcher. I wonder if adding an ounce or two of benoil would help retain the seal on these leaky engines? I have some pure Sig castor oil that is super thick, it's been on the shelf for about 8 years lol.

SLAYERDUDE

Great discussion, keep it up boys!

How things are going my way with the MGT 8.0 -
Sealed carb, actually sealed and installed a #2 carb since a friend sent me one, my 8.0 was one of the first and came with the #1 carb that's supposed to be more problematic as far as tuning.
When I first got the 8.0 I ended up a total of 3 turns out on the bottom end from stock to get it to run right, Purenitro said that was the best running 8.0 he had seen when I posted this vid on another forum.
"Book" needle settings on this thing seemed way off.

[youtube]http://www.youtube.com/watch?v=lydywuDomjk[/youtube]

Anyways, it's just as erratic on the tune as it was before after I got it tuned in...
Ripps three rolling wheelies in a row one minute, richens itself up and is boggy, then 4 strokes and dies at idle.
Randomly runs good then bad, but no longer flames out after a WOT pass.

NOT asking for advice here, I'll figure it out myself, this thread is merely for info for others to read so don't bother posting a bunch of "you need to do this".[8D]

As far as spraying the engine with the flammable nitro wash, the 8.0 (TT .50 helicopter engine) seems to contradict what you guys are saying about the front brg sucking air...
If I spray at the carb it idles fine with no change, spray behind the flywheel and it idles down and spray longer and it dies.
If I block the front brg area with a piece of plastic and spray at the engine/carb there is no change.
No vids due to stormy weather and a short window to test today, once I get it sorted I'll post a vid of spraying just like I did in the first vid and we'll see if it was the "air cleaner sucking fumes" as the reason it died in that vid.

EDIT- OH! I also switched from Byrons 30% to OD Speed Blend today and it tuned the same, maybe I'll put some Benol in this gallon too and try that.
Original problem happened on Byrons gen 1 30%.

SLAYERDUDE

I know the front bearing is lubricated by engine oil, but do you guys see any problems with packing it with a grease such as Tri-Flow to possibly seal it?
I'm thinking about removing the seal and packing the brg so it will at least be fully sealed for a few minutes just for testing.
IMO it won't hurt anything, and I'm going to do it anyways, just wanted your thoughts.

nitroexpress

The grease won't last even a few minutes.If it gets sucked in, your engine won't behappy. If your going to remove the bearing seal, you'll never be able to reinstall it securely. Might as well just replace the bearing.

proanti1

My Feedback: (2)

As said, the grease will get sucked into the engine, and probably foul your plug. The bearings are lubricated by oil, not grease.

supertib

I t6ake bearing seal on and off all the time..... if your careful it is no issue

SLAYERDUDE

I'd been drinking all day when I thought about doing that lol, I wasn't going to pack alot in there mostly cover the seal and reinstall
but didn't think about grease getting into the oil return hole and clogging it up.

I've removed plenty of seals on bearings and reinstalled them without damage.

nitroexpress

Is it so simple that even a caveman can do it? Not everyone has your expertise. I really don't see the point of it. But for those that want to, go for it.

noginblue

millssniper007

If you put a 5 ABEC bearing in an engine that is turning 30,000 + it wouldnt last for a tank. RC engines are built specifically for high rpms, I have yet to to see a rc engine bearing with a metal bearing cage (retainer)

this is part of your statment from post 14

abec 1 is rated to 40000rpm max
abec 5 is rated to 56000rpm max

lots of rc engines have metal retainer on, the only reason why rc cars have them on is to stop or slow down dirt ingress as planes and the likes dont really spend any time in dirt so dont need them

SLAYERDUDE

Looks like the cage on the frt brg of the 8.0 is metal.
http://www.teamassociated.com/parts/details/25445/



Back when I was on the AE forums there were alot of guys that had frt brg issues with the 8.0, whether it was the brg seal causing the leak or just a bad brg, who knows...
They replaced the brg and it ran good again tho.
The brg's are pretty cheap so I might just order a set and see what happens.

proanti1

My Feedback: (2)

Well, the 8.0 is an airplane engine converted to a car engine, so it's not really designed for the load put on it by a drive train.

noginblue

what sort of load do you think is being put on the engine when its pushing a prop around and pulling a 10kg plane vertically, what the engine is used for has nothing to do with an air leak, way off topic

secondly can people please get off the front bearing creating a seal thing it doesnt, its the tolerence between the crank and the case that does that

taken off the os engine site

Some people believe that their engine is leaking air through the front bearing. This is not really possible. Almost all glow engines do not use the front bearing as a seal. Even if you see a metal shield on the front of the front bearing, this is not a seal, but a cover to keep dirt out. For years, many model engines had no shield on the front bearing at all.

SLAYERDUDE

I understand that the front brg isn't supposed to seal the engine at all, but!
I have old O.S. .12 CV engines that use a metal front brg "seal" so obviously those metal parts aren't creating a seal...
Could a worn brg cause enough slop to allow the crank to block seal to not seal?

The 8.0 "AE Pro 50 BK" Thunder Tiger engine is supposedly a converted Helicopter engine and is really starting to rub me the wrong way lol, maybe it's just this engine that has these issues.
http://www.tiger.com.tw/product/9445.html

I know alot of guys that have never run newer BB RTR engines think that air leaks are a myth, but I've dealt with plenty of air leaks on my HPI K5.9 and they were usually remedied easily by a little RTV, engine tuned like night and day after sealing so I KNOW that was the issue with that engine... more than once.
Never had any front bearing issues with the K5.9 or any engine for that matter, the 5.9 is in it's 13th gallon on all original parts except for the carb, never had the sleeve pinched, and is probably the most reliable engine I have out of many.

Anyways, back to this AE 8.0.
I tried adding Klotz Benol to the O'Donnells Speed Blend 30% tonight and same results.
Stomping rolling wheelies all over the yard with plenty of smoke and no lean jitters, random flameouts after WOT and it holds an idle sometimes, other times it won't.
No bubbles in the lines, set needles to factory, glow plug looks mint after at least 10 tanks of screwing around.
I gotta get a day where it's nice out and I have time to really mess with this thing before it gets dark.

noginblue

maybe but would have to be some serious wear on front bearing eg falling apart, if the engine eg the tt 50 pro heli engine, the older ones were known for being a complete nightmare to tune and keep tuned, just look it up on net

SLAYERDUDE

I know, I used to be the moderator of the MMGT, RC10, RC10GT and MGT sections of AE Forums... there was a new member with an 8.0 turd almost every week for months.[&:]
This one ran great (after I went waay off from stock needle settings) until recently.

SLAYERDUDE

So, I finally got a length of rubber hose to disprove the theory that the brake/nitro cleaner was being sucked into the air cleaner and not actually going in the front bearing.
I know there's a new thread on the same subject and Neil agrees that this is fact, but I still wanted to put it on film for everyone to see.

There's no arguing with this vid.

[youtube]http://www.youtube.com/watch?v=Le1yvGyduQc[/youtube]

Mclovin350z

I don't get what your problem is. It idles nice, why not just run it? If you think there's a bearing problem then change the bearing, they're cheap.

SLAYERDUDE

This was started as a thread to help others diagnose a tuning issue and learn, and it still is... I don't have "a problem"
(I do have issues tho..)

I have random flameouts for no reason, at WOT, just after WOT, sometimes has nasty lean jitters once warmed up.
Anytime I've had weird tuning issues it's been an air leak (usually at the carb), everything is sealed and it still happens so I suspected the frt bearing and just wanted to show how to check it.

When I get some spare cash I may buy a new bearing, in the meantime I'm going to attempt to fix it for free like I usually do.
I own 23 RC's so it may not be soon, but I will update on any progress.

nitroexpress

Seems like your tune is off. Just curious, what is the idle gap set at?

SLAYERDUDE

Lol, again, this is NOT a - "Hey guys, I don't know what I'm doing so can you help me" thread.

Idle gap is at 1mm just like it's been since I initially tuned it 3 turns out total on the bottom end from stock "book" specs that were wrong.

And the idle gap has nothing to do with random flameouts AT WOT, maybe the rear bearing is worn and that's why that happens, I haven't torn it apart yet, but now that I have a vid of it dying when spraying a flammable substance at the frt brg I will soon tear it apart and start looking at the bearings.


Not yelling at you Nitroexpress, but I can in fact tune my way out of a wet paper bag.
I'm the only guy at the track (I race a D8T truggy with an ERCM JL .21) that can start at the pits and hand my pit guy a fuel bottle... and that's ALL he needs.

nitroexpress

Gee, I didn't know any tracks allowed ERCM pipes, but whatever. Your JL .21 might be the bomb, I'm just saying that MGT doesn't look quite right. 1mm gap is too much. But if it works for you, then fine.

SLAYERDUDE

I started racing a year ago at "club level" so they allow anything for the most part, my JL .21 is ERCM modded and piped and gets a sweet 12 minute runtime.
Alot of guys say 1mm is too large of a gap, but it's kind of funny that those are the same guys at the track that flame all the time and have starterboxes mounted in pit lane...
I ran an Axial .28 in the D8T last year due to no money, and I beat 1/2 of those guys half the time even tho I had to make a pitstop every 5 minutes, in a 20 minute A-Main I took 3 pitstops for fuel while they took one or two....
That crappy Axial ran all day long with no flameouts, had a 1mm gap on that too.
Sorry, but I'm a 1mm kind of guy, especially after seeing friends time after time running back to the pits to restart while I go round and round making laps.

As for the MGT 8.0, it ripps wheelies across the yard and does backflips with ease when it was running good with the same 1mm gap.

3 gallons, there shouldn't be some random reason that I should run a closer gap...

[youtube]http://www.youtube.com/watch?v=Uc7UtlvwdzU[/youtube]

[youtube]http://www.youtube.com/watch?v=fXhqgodBPIc[/youtube]

[youtube]http://www.youtube.com/watch?v=lydywuDomjk[/youtube]

nitroexpress

If you're happy, then that's all that counts. But I think, from the vids, it could be a bit crisper

.

Mclovin350z

Most engines can be tuned to less than a 1mm gap, but it is a .50, so I'm not gonna harrass you about it.