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Broken RCV 58 CD


Paul Marsh
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Was out flying my YT Taylorcraft, had quite a few flights, but on the last flight (obviously), the engine stopped and threw the spinner. The prop and nut were still on, but no compression/loose.

I took the engine apart (5 mins) and the con rod is U/S. Luckily no other damage, so will need a new one.

Has anyone got a knackered RCV58, which I can use the con rod off. Contacted RCV, requesting the cost of a new one, but might scrap the engine, although ran ok, has really no power compared to a OS 52FS, which am putting in later.

2015-08-22 16.46.37.jpg

2015-08-22 16.47.39.jpg

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Don't wish to teach you to suck eggs but have you checked all other parts for damage or found the cause of the rod failure ? I would definitely check the cylinder for varnish build up that can cause the piston to grab and twist the conrod causing the failure. The colour of the rod suggest it's got very hot ? Fitting a new rod will only treat the symtom not the cause. Good luck

Ps why not fit the other engine and save a tenner and have more power ?

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ED insteresting advice, I have one of these (in a box) thought it may one day "replace" an Os52 ... reading this and other bits on RCD; I do wonder!

OP - what fuel are you using with this motor? I guess with it being in a Taylorcraft your weren't prop hanging either!

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Was at full chat and running a 12x6. tried changing to a 12x7, but was not happy, and couldn't even take off. A 12x6 is ok, but due to lack of power needing full power and optimal setting to fly, any richer won't get off the ground. I'll repair the engine and put it back in it's box, as just put a OS52 in it and will now prop hang...

Fuel was Sport 5, which I use with all engines. Plenty of oil left in the crankcase, and no problems about lubrication.

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Just ordered a con rod from Weston. They were quite helpful and passed my on to the person who designed the RCV engine range and really wanted to know what version of engine it was and how/why it broke. Seems my engine is the later version, and it has been used alot, both as a YT demonstration model and my use for 10 years or so. Only was a broke con rod and for £10.87 a cheap repair.

He did ask what plug I was using - a OS F, but said they designed a special plug, which will help the top/bottom end and improve power - a hotter plug. A PP4T

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I think it is mostly down to castor oil (mineral) based fuels; I have a bagged a couple of bargain second hand engines, "varnished up", only to clean them and run on synthetic oil based fuels.. stayed clean, run very well and touching wood (my head) never had a problem!

But I stand to be corrected, perhaps ED can let us know more from his own considerable experience..

Cheers.

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Posted by Rob Tothill on 25/08/2015 08:44:41:
ED I was interested in what you said about varnish build up, what is the cause of this? Is there a solution if it occurs?

Hi Rob/ Area 51. The main cause of varnish build up is using a castor based fuel and the engine overheating.The Castor oil is vegetable based and cant withstand the heat that modern engines produce. Castor based fuel causes varnish especially when the engine gets hot . It sets like the castor oil skin on paint products . Synthetic based fuel prevents this and keeps an engines internals a lot cleaner. You may find some fuels that have a small percentage of castor oil added to the mix "to give added protection against a lean run " this can still cause gumming or varnish on internals and burnt on oil on the external casings and exhaust and eventual damage to the engine. Castor is fine on old diesel engines and similar that don't produce the power and subsequent heat that modern engine produce . Looking at the pic of the snapped con rod I would suspect that it has been run weak to get every last bit of power as they are not the most powerful of engines and the eventual build up of varnish has cased the piston to be grabbed / siezed by the rotating cylinder and bingo ..................snapped rod . It has obviously been run with a lean mixture and become very hot as the con rod should never get that discoloured with normal running. Only solution to varnish build up is to strip and clean the parts .I use cellulose thinners and a old tooth brush but be careful not to damage piston and liner .Best solution is to not let it build up in the first place . Many engines appear to  have been  run for years on castor fuel without problem but they are run by owners who obviously know how to set the engine a tad rich to prevent overheating . I now only use castor oil in my vintage diesels and cox engines everything else gets synthetic oil with no problems . JMO. I don't want any death threats from Castor oil enthusiasts smiley

Edited By Engine Doctor on 25/08/2015 11:51:29

Edited By Engine Doctor on 25/08/2015 11:53:54

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Posted by Area 51 on 25/08/2015 09:23:11:

I think it is mostly down to castor oil (mineral) based fuels; I have a bagged a couple of bargain second hand engines, "varnished up", only to clean them and run on synthetic oil based fuels.. stayed clean, run very well and touching wood (my head) never had a problem!

But I stand to be corrected, perhaps ED can let us know more from his own considerable experience..

Cheers.

I always thought Castor was a vegetable oil smiley

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It was run with the leanest mixture it would run with, any richer, the plane wouldn't fly, and had to be flown at full power the whole flight, as going to 90% throttle would not be sufficient for flight.

Got the new rod just now and the plug they recommend.

So good service, Weston, prompt delivery and product knowledge, and was more interested why I broke my engine, and fixing it, and wanted to learn from it and give advise. Putting it together now and give it test run...

dscf9300.jpg

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Posted by Rob Tothill on 25/08/2015 11:15:56:

Thanks Area 51. Did you clean the piston and liner too? If so is there a technique to remove the stuff without using elbow grease, as I assume that could affect tolerances if any abrasion occurred?

Rob, the best I have found for removing this gunk off the outside of the motor is Fairy power spray, in a green bottle for oven cleaning...leave it on the motor for around 15mins and toothbrush it in.. was with warm water and again still back..

As said above though Rob, a steer toward synthetic fuels is no bad thing.. I used coolpower for years, it was superb in 2 and 4 stroke.. but doesnt seem to be available in the UK now.. sad

As mentioned in the posting, Weston have been very helpful here, they also do fuel too!

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  • 6 years later...
On 22/08/2015 at 17:55, Paul Marsh said:

Was out flying my YT Taylorcraft, had quite a few flights, but on the last flight (obviously), the engine stopped and threw the spinner. The prop and nut were still on, but no compression/loose.

I took the engine apart (5 mins) and the con rod is U/S. Luckily no other damage, so will need a new one.

 

Has anyone got a knackered RCV58, which I can use the con rod off. Contacted RCV, requesting the cost of a new one, but might scrap the engine, although ran ok, has really no power compared to a OS 52FS, which am putting in later.

 

Another one broken!

 

I was flying my large twin yesterday which has a pair of RCV58s in it, when after 5 minutes or so in the air the model seemed to lose power. I managed to land just short of our patch, with no damage fortunately. On inspection, one of the engines had lost its alloy spinner cap, and the prop was loose (which is what fooled me into thinking both engines were still running, as the loose prop on the dead engine was windmilling). All evidence of a sudden stop in flight.

 

On removing the engine today, and splitting the crankcase, the big end has broken off and the crankpin appears damaged.

 

The engine which failed was bought cheap at a bring & buy sale a few years ago (unlike its twin which was bought new), and reading Engine Doctor's post above (August 25th 2015), it seems the piston may also have got grabbed by the rotating cylinder and twisted off. The other engine has always been run on sythetic, but unfortunately I don't know the fuel history of this one, although I remember having to clean a number of brown castor stains off when I first got it. Seems the previous owner may have known something I didn't 😕!

 

The decision has to be, do I try and repair it, or scrap it and turn to eBay?

 

IMG_5302.JPG

Edited by EvilC57
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Im with Martin on this one. The bush has picked up on the pin and overheated the aluminium rod to the point of failure. You can see the heat has blued the crank pin so that is the most likely issue. 

 

The reason for the pickup is not clear though as there is light surface corrosion staining on the crank but nothing major at all. There is no castor residue in there so the oil hole being blocked is unlikely too. 

 

My concern is the 'modification' to the carb intake. Makes me think someone in the past thought themselves an engineer and has been playing around with it so goodness knows what they have been upto

 

Looking at the scoring i am also not completely sure it has not spun its crank bearings as well 😕 

Edited by Jon - Laser Engines
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Well an update on my RCV 58. a few days after it happened, contacted Weston UK, and they had them in stock, think it was around £8. Put it back in, and the engine runs fine. Put it back in it's box, where it still is now.

Reckon if you give Weston UK a call, they might still have them, and damage is probably only your con rod.

I actually updated 7 years ago, and video of it running, don't believe it was long ago.

Edited by Paul Marsh
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17 minutes ago, Jon - Laser Engines said:

Im with Martin on this one. The bush has picked up on the pin and overheated the aluminium rod to the point of failure. You can see the heat has blued the crank pin so that is the most likely issue. 

 

The reason for the pickup is not clear though as there is light surface corrosion staining on the crank but nothing major at all. There is no castor residue in there so the oil hole being blocked is unlikely too. 

 

My concern is the 'modification' to the carb intake. Makes me think someone in the past thought themselves an engineer and has been playing around with it so goodness knows what they have been upto

 

Looking at the scoring i am also not completely sure it has not spun its crank bearings as well 😕 

Some interesting points there thanks Martin, Jon & all. I’d observed that the crank pin looked dry, but (stupidly) dismissed it. Is it possible for the pin to be dry? If so, I guess it might also explain why the crank case bearings appear to have been spun. Yes the piston moves OK In the cylinder, so presumably we’re looking at lack of lower end lubrication - the engine is inverted when installed in the model, but they’re designed to run at any angle aren’t they.

 

Well done for spotting the mod to the carb inlet, it appears to have been drilled and tapped for some reason. Buy hey, I only paid £10 for the engine as I say, at a bring & buy. But as they say, buy cheap, buy twice.

 

So, if I get in touch with Weston to try and get a new con rod and crank shaft, bearing in mind the apparent lack of lower end lubrication, what’s to say it won’t seize again?

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The pin will be dry of oil now as it got bloomin hot (250-350'c) and burnt it all off. The issue with the rod will not make the bearings spin (if they actually have) but could point to other issues historically. That crankcase design lends itself to a weak hold on the bearings and if the bolts came loose at one point they could have spun. 

 

In terms of repairing the damage you will need to change the cylinder base and rear crankshaft bearing as they are likely going to be full of debris. You could try washing them out but i have not had much success with that. The crank pin will have bronze welded to it and this needs to be cleaned off. I use 400 grit wet and dry with some oil. Its quite a long job and even when you think its clean you need to check with a magnifying glass to make sure not a scrap of bronze remains. If it does, it will pickup again on that spot. 

 

Beyond that the whole engine will need to be stripped and cleaned to remove debris. if you have access to an ultrasonic cleaner then i would buzz each part in there and then rebuild from fresh. 

 

If the engine only cost a tenner than its up to you how much time/effort/cash you want to put into its repair but i personally would do all the bearings and the rod if i was going to fix it and not bin it. If you change the rod but skimp on the bearings by only washing them you may wreck the piston/liner if some debris remains and contaminates the engine. Changing the crank is an option but i dont know how fussy the RCV's are on the fit of the gears. A new crank may not mesh as well so i would leave it alone. Its also likely a crank would not be cheap so there is that to consider as well. 

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OK thanks for your suggestions Jon.

 

The crankshaft bearings seem free enough at the moment, but as you say, they really need cleaning out to make sure. I don't have an ultrasonic bath, maybe I should treat myself to one sometime.

 

As you say, it was only a tenner so I'm not sure it's worth all the effort of trying to get it going again. By the time I've bought all the bits that may be required (with no guarantee that they'll actually fix it), I'm inclined to wait and see what comes up on eBay in terms of what looks likely to be a good runner.

 

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