DAVESDAD

Hello all. I've been running a CRRC 50i for 2 years without many issues until the last couple of months when we had some backfire issues and couldn't get a good midrange. Got worse recently and today just quit while tuning it. Pulled the engine and found the cylinder had cracked right across at the base, just above the crankcase joint. Obviously well out of warranty but wondered if anyone else has had this problem and is it worth repairing or go for a new motor. I like this engine and spares are pretty cheap but worried the new cylinder might go the same way. I've yet to strip the engine to see if anything else is damaged. Any pointers what to look for?

Thanks

Tony

Tired Old Man

My Feedback: (1)

Buy a new jug. If you're a purist you could buy an entire top assembly and do it right. You've got a couple years on the ring inside what you have and it will never mate correctly to a new cylinder.

DAVESDAD

I think you might be right. Just pulled the cylinder, pictures below. Pretty catastrophic failure that looks like it started at the inlet.

Tired Old Man

My Feedback: (1)

The ring never matched up with the cylinder anyway. You should get an entire top. There's really nothing of the old top you want to re-use. If there is no obvious damage to the rod everything you need would be in a top assembly. If the rod was damaged (doubtful) it would be less work but slightly more expensive to buy the entire engine if it's still available.

A more important question is what caused the cylinder to break. Hopefully it wasn't from something suddenly catching an edge inside the cylinder.

DAVESDAD

Your last point is my concern. The rest of the engine seems fine. No damage to the piston, rod or bearings. Complete mystery to me why it failed, as it was running fine one minute and then just stopped. I've seen engines totalled from swallowing a stone or failed bearings but never one that just let go. Before this it was a great engine, pulled my Hangar 9 Extra 260 to unlimited vertical with ease. It is still a current engine and to rebuild is about £50 (say $75) a replacement engine is £240 (say $365) so its probably worth a rebuild and then fingers crossed. If I rebuild it will include new piston rings.

Thanks for the advice .

Tony

RTK

My Feedback: (1)

Was there a lot of carbon built up??

lou1947

I dont have a 50 but I have three CRRC Gf40"s. I have seen two broken crankshafts for no apparent reason. I just think that these engines are not the greatest motors coming from China.Its weird that your head would just crack. Keep us posted.

DAVESDAD

There was some carbon build up in the head but not excessive, no flakes or anything like that. Can't see any debris at all in the crankcase. This engine has always produced quite a lot of residue so I've probably been running it on the rich side from new. Only thing I can think is that I was ground running to tune it and it has been hot here (30 degrees), maybe it overheated, although it didn't smell hot, but I don't see why the cylinder would break where it did. Looking at the crack there are some shadowy marks which could be oil but it may be a weak part in the casting.

Tired Old Man

My Feedback: (1)

I would side with a defective casting for now. Try to avoid a rich condition on the next one. They can't break in correctly unless they get warm. 30 isn't all that hot for an ambient. Our little engines can easily handle double that for ambient if you have the usual cooling air ducks in a row.

STUKA BARRY

I hate when this happens.... But seriously, even though its out of warranty, I'd still send it back. This might start a recall or atleast have them investigate and locate the problem. Bar that you did'nt crash it, this is major structural failure. 3 years on an engine is nothing, these engines should last a lifetime, other than expendables ie gaskets, bearings, seals etc.

tryan02

I believe they are using inferior machining process's at CRRC I am done with them considering DLE. I have the 40CC here is a pic of my crank maybe 30 flights?

DAVESDAD

Thanks for the advice guys. Unfortunately I can't find the receipt but I know I bought the engine at a show in 2008 so I'll see what the importers have to say. Have to agree it looks like a failed casting rather than anything else as there is no damage to any other part of the engine. Yes your right elsewhere gets much hotter but in the UK this is heatstroke weather!!

Cheers

Tony

DAVESDAD

Looks like I'm nearer to understanding the failure of the cylinder as I've now pulled off the fractured part and can see inside the crack. I'm no engineer but if you look at the second picture in particular the machining for the inlet (appears as a smooth section) has almost broken through the casing itself. I estimate no more than a millimetre of metal left. At this same point there is a seam so very thin metal, a stress point, lots of heat and vibration a recipe for failure. So looks to me like a manufacturing fault.

Antique

My Feedback: (4)

When they cloned the G45 cylinder they didn't get it right....

DAVESDAD

Hi All

Final part of the saga. New parts turned up today, less than 2 days from ordering so pretty good going. All back together and now running well with a new cylinder and rings. Total cost £54 ($82) so not too bad. We'll see how long this one lasts.

craigpuckett

for tryan02

Looks like the crank was cracked 2/3 of the way for a long time, only 1/3 of the break is shiney

captinjohn

<hr />When they cloned the G45 the metal it was made from was notright for sure!<hr /> Capt,n

w8ye

My Feedback: (16)

There was a core shift in the casting process that caused a thin wall. They didn't follow through with sawn sectional evaluations. A lack of design completion and QC.

Tired Old Man

My Feedback: (1)

So what else is new

w8ye

My Feedback: (16)

S.O.S.

tryan02

thanks I noticed that also, I guess the CRRC engines are good for at least 2 flights.