Seized OS 55

[Eckchaz]

I idled my new 55 on the ground for three tanks (went with 8sec backplate rule, misunderstood it!)!.. never siezed.. then took it for bed in flights with full power climb outs - this was my frst engine.. never gave me any problems dispite my novice hands

On my 91.. I couldnt do this as it seriously overheated after 1min. Then I learnt that its best to do a mix off both.. fly/hover whatever you want to do and then let is sit idling (reduced cooling from fan and blades) to let the heat build up in the engine for 30secs or so and then take off again to cool it down.

Both engines where brand new and had to be bedded in differently. FYI, I didnt have too any trouble with Ripmax.. fingers crossed for you Harry!

[Gixxer]

Every man and his dog knows a different way to run an engine in, and their way is always right.

I used to race karts when I was younger and I always rebuilt and tuned my own engines, and after trying loads of different running in methods, the one that always worked best was getting the engine under load as soon as possible. Not hammering it to death, but a good enough load so it knew it was being worked.

I personally wouldn't leave any engine ticking over for any longer than was absolutely necessary. I'd let it reach running temp on tickover then shut it down and let it cool. Next run I'd be putting a bit of load on the engine, because without load, the ring isn't going to be pushing hard enough against the bore to acheive what you're trying to achieve. I'd run the engine like that for about 5 minutes, then stop it and let it cool, and on the third run, I'd give it a bit more pain (again, not hammering it). That's the method I always use to run in a new or newly rebuilt engine, and it's always worked for me.

I'm not saying that leaving the engine idling is what caused it to sieze, because I don't know if overheating is what caused it, but idling the engine certainly isn't the right way to run it in.

[Boggy]

what a thread full of sloblocks! Just drive it gently with a piece of A4 on your back with this printed on it...


"RUNNING IN PLEASE PASS"

[electricsceadu]

what a thread full of sloblocks! Just drive it gently with a piece of A4 on your back with this printed on it...


"RUNNING IN PLEASE PASS"

i haven't seen that on a car in years
it made me smile

[Planehazza]

Sorry but this thread is just getting stupid now.

I really appreciate the help, but I think people are misunderstanding what I'm saying.

I never once said that I just leave it sat there idling and consider it run in. I like to let it idle for 1/2 a tank, just to get some fuel through it (as per several tuning/bnreading in vids I have watched) and lube it up effectively. THEN you go fly it, with governor off to vary the RPM and bed it in. Leaving it idling is simple the very first step of running in I like to do.

Idling for 6-7 mins on the ground should not cause a £200 engine to fail, ESPECIALLY when the needles are exactly on the recommended running settings (page 21 of the OS55 manual). If it does, it's poorly designed. There isn't a mark of damage on the piston, liner or head. There's just slight scoring on the back plate from the con rod.

not sure what they advise,but running an engine too rich will hinder the running in process.


cheers
andy k

Whilst that is true, if I have damaged the engine by running too rich by going off of their settings, then they are to blame not me.



Video links:

http://www.helifreak.com/showthread.php?t=276520

[Gixxer]

Sorry but this thread is just getting stupid now.

I really appreciate the help, but I think people are misunderstanding what I'm saying.

I never once said that I just leave it sat there idling and consider it run in. I like to let it idle for 1/2 a tank, just to get some fuel through it (as per several tuning/bnreading in vids I have watched) and lube it up effectively. THEN you go fly it, with governor off to vary the RPM and bed it in. Leaving it idling is simple the very first step of running in I like to do.

Idling for 6-7 mins on the ground should not cause a £200 engine to fail, ESPECIALLY when the needles are exactly on the recommended running settings (page 21 of the OS55 manual). If it does, it's poorly designed. There isn't a mark of damage on the piston, liner or head. There's just slight scoring on the back plate from the con rod.

If there's no sign that the piston siezed in the liner, then it's highly unlikely that it was overheating that caused the problem, as this would be the first thing to happen. It sounds like the problem lies elsewhere... maybe a bearing has failed?

Edit... I wasn't suggesting that you only intended to run it in on idle... I'd read your intentions, and you said you planned to load the engine shortly after. I was just pointing out how I'd run an engine in

[electricsceadu]

if there are no marks on the piston/liner/head
and i will assume the bearings spin ok
then this engine didn't seize
i would say it hydro locked
if it had seized there would be damage to the piston/liner or bearings

the scratching on the backplate is normal
unless they are deep grooves

[Planehazza]

if there are no marks on the piston/liner/head
and i will assume the bearings spin ok
then this engine didn't seize
i would say it hydro locked
if it had seized there would be damage to the piston/liner or bearings

the scratching on the backplate is normal
unless they are deep grooves

How would it be hydro locked? I have had the engine completely dissmantled. I can't see any damage to the piston, but I can't see the ring as it is below TDC.

And a failed bearing should not happen to a new engine that's had 1/3 of a tank through it. If it has, again more in my favour to have it replaced FOC.

[electricsceadu]

as you haven't said anything about the bearings has the cage broken up on the front or rear bearing?
the 55 has been known to have the odd rear bearing fail

[Mark_T]

So just for clarity, with the head off the piston is still locked in place and the crank will not turn?

[Planehazza]

So just for clarity, with the head off the piston is still locked in place and the crank will not turn?

Correct I've even tried (carefully) pushing on the piston, and that bugger aint moving. The rear bearing does look a bit rusty, worringly. I'm gonna take it apart again so I can post up some pics.

[electricsceadu]

How would it be hydro locked? I have had the engine completely dissmantled. I can't see any damage to the piston, but I can't see the ring as it is below TDC.

And a failed bearing should not happen to a new engine that's had 1/3 of a tank through it. If it has, again more in my favour to have it replaced FOC.

how far did you strip the engine?
was it stripped to its bare components?
did it come apart without any problems?

on re-assemble does the engine turn over ok without the plug in it?

[pgkevet]

.... I have had the engine completely dissmantled. I can't see any damage to the piston, but I can't see the ring as it is below TDC.....

....not completely dismantled then.

[electricsceadu]

Correct I've even tried (carefully) pushing on the piston, and that bugger aint moving. The rear bearing does look a bit rusty, worringly. I'm gonna take it apart again so I can post up some pics.

does the con rod move on the crank pin?
liner out will the piston move in the bore allowing the con rod to move?

if yes a crank bearing has failed
if no the big end bush has failed


my guess at the moment is the rear bearing has broken up

[electricsceadu]

thinking out loud
did anything drop into the carb whilst the engine was running
has a nut/washer bit of muck gone down the carb and jammed the crank up in the case?