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Author Topic: My “new” MVVS 2cc Diesel went rogue today!  (Read 1281 times)

Offline frank mccune

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My “new” MVVS 2cc Diesel went rogue today!
« on: June 03, 2022, 07:26:21 PM »
     Hi All:

     While breaking in my MVVS today, the engine ran through the first tank of fuel with only one deviation from the norm.  This was that the compression screw backed almost the entire way out of the head.  After permitting the engine to cool and refueling the tank, I noticed that the prop could not be be moved but about 30 degrees each way from bdc. 

     After removing the backplate, I could see that the large end of the con rod was striking the case at about 8 and 4 o clock when viewed from the rear.

      I also noted that the exhaust port was blocked by the cylinder.  The exhaust port did not align. The cylinder must have turned. These above problems prevent the cylinder from being removed! Unless the piston is at tdc the cylinder can not be pushed out of the case.  This prohibits removal of the piston.

     I guess that the first item on the list, is to get the con rod to be able to rotate.

     Suggestions/comments?

     Tia,

     Frank


     

Offline frank mccune

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #1 on: June 03, 2022, 09:01:31 PM »
       One more look at the problem and I noticed something that made me go ahhhhhh.  There is about 1/8” opening in the right side of the exhaust port that shows the exhaust port in the sleeve  I will heat the case and attempt to rotate the sleeve to line up with the port in the case.

        I still have no idea a what may be preventing the crankshaft from turning 360 degrees.  Something may be hooking in a port, wrist pin, or part of the contra piston may have fallen into  the combustion chamber.  Until I can remove the cylinder, I m only speculating!

        Stay well,

        Frank

Offline Motorman

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #2 on: June 03, 2022, 09:52:14 PM »
Some sleeves have cut outs in the bottom on both sides to make clearance for the rod. If the liner is turned these slots will not line up with the travel of the rod.

You can make a locking lever for the compression screw from thin steel plate if you have the right tap. MVVS, I'll bet it's metric.

Motorman 8)

Offline frank mccune

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #3 on: June 04, 2022, 07:31:16 AM »
     Hi MM et al.:

     Thanks for the replies.  I will know more after I attempt to turn the cylinder.  But first, coffee!

      The engine really screamed on an 8-3 prop making me question when and how did the cylinder get turned!

       Stay well,

        Frank

       

       




Offline frank mccune

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #4 on: June 04, 2022, 01:49:57 PM »
     UPDATE

     The main problem has been solved via a blowtorch and a pot of coffee.  The only remaining problem is the refusal of the contra piston to back off.  Perhaps a night in an antifreeze bath will change its mind!

     I did learn a few things about the engine.  No, it does not have a snap ring.  The wrist pin is free floating and may hook on the cylinder upon assembly.  Due to the contra piston not moving, some type of lock must be fabricated to prevent the compression adjusting from backing out.

     Stay well,

     Frank

     

Offline Motorman

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #5 on: June 04, 2022, 02:06:21 PM »
Some contra pistons will only back off when the engine's cold. If it won't even do that, then it's fit too tight and should be taken out and polished. Set it up for the press then heat quickly and press before the heat transfers to the contra piston.

Motorman 8)

Offline john e. holliday

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #6 on: June 05, 2022, 07:43:15 PM »
When I was flying F2C all my diesels had Teflon tape on the compression screw.   You can also go to the hardware store (ACE) and find a locking nut for the compression screw.  Cause once set the compression was seldom moved.  We just opened the needle valve so many turns to wam up and then turned back in.  Is the contra piston a good tight fit I must also ask. D>K
John E. "DOC" Holliday
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Offline frank mccune

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #7 on: June 06, 2022, 08:45:19 AM »
     Hello All:

     Thanks for all of the replies!

     Here is the latest and perhaps the lat time that I will post re. the MVVS Diesel.

      I do believe that the cylinder did not rotate while the engine was running! It was more than likely installed incorrectly and I failed to notice that when I ran the engine.

     I did open the cylinder to permit the contra piston to be able to be moved to reduce compression.  It remains quite snug allowing fine tuning.

     Stay well,

     Frank

Online Dennis Toth

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #8 on: June 16, 2022, 03:59:50 PM »
Frank,
On most of the steel/iron diesels the cylinder has a tapper which tightens at the top. To remove the contra piston you push it down through the bore. Warming the cylinder will help. If you try to push it up it will jam tight, unless it is like the old OK Cub 0.049 & 0.074's that used an "O" ring seal these can come out the top.

Best,    DennisT

Offline Steve Helmick

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #9 on: July 06, 2022, 03:58:39 PM »
https://5.allegroimg.com/s1024/0c3bc7/f5b0b8734128ba9b792bb8dc1a75

Is this it? I googled for "MVVS 2.0 cc images" to get the link. This was the only picture. It appears that the head bolts down like most, leading me to speculate that the cylinder was misaligned and/or the head screws were loose. When you buy stuff on eBay, this is apparently pretty common...usually Fox or McCoy engines with the cylinder in backwards or piston or rod in backwards. How did you come by this one?  H^^ Steve 
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline frank mccune

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #10 on: July 06, 2022, 05:44:09 PM »
     Hi Steve:

     Thanks for the reply.

     My engine is a bit different than the one you posted.  Mine is a Diesel with a
rectangular exhaust port and has muffler lugs on the side of the case.  The head is smooth with three screws holding it onto the engine.

      I think that I bought if off E Bay for very little money.  Another one came up NIB for twice as much and I had to purchase it as the only bidder.  I wanted a new Diesel engine to start from the beginning now that I learned a bit about breaking in engines.  I am on a quest to learn how to hand start a Diesel engine. Lol  A new purpose built Diesel may be the answer to my quest.

      I have no idea as to why I am attracted to Diesel engine but a friend of mine also flies Diesels.  He has a a stash of old Diesels that include ED Racer, a Russian Mills .33 cc, and Oliver Tigre 2.5 and 3.2 cc.  They all hand start very easily!  What am I doing wrong?

      I also have a collection of DDD heads that can only be started via an electric starter. 

     Have you played with Diesels? I like the idea of not having to fuss with a glow plug!

Offline Motorman

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #11 on: July 06, 2022, 06:27:22 PM »
When it's cold, back off the compression a little, set the needle a little rich, give it a good prime in the exhaust and flip the prop until it fires.

Offline Dave Hull

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #12 on: July 07, 2022, 01:44:37 AM »
If you have trouble still after following the MM suggestions, put a heavy prop on it. Something plastic, and bigger than you really want to run. It will give you enough inertia to make starting easier. After you get your settings into the ball park, you can switch to a realistic flight prop.

If, when you flip, you find it gets stuck at TDC or doesn't rotate thru, you likely have one of several issues:

--the engine is dry. Give it an exhaust port prime, but don't hydro-lock the thing and bend the rod or wrist pin--or break off your finger!
--the contrapiston is backed way out. Usually, the bottom of the contrapiston should be near-flush with the inside of the head as a good starting point. On an engine that you just received, you will have no idea where the contrapiston is, unless you buy it from a diesel guy that you trust. And, once you get it set, you rarely move it much--only backing it out for cold starts, or if you change prop size.
--the engine has lost its compression seal. Look at the piston and check for scuffing and scarring. It should be shiny near the top and brown down the rest of the way. If it has been cleaned, it might not have any varnish on it and that can make it harder to start. If it was improperly cleaned you can lose the fit, and therefore the compression. And it will be hard to start.
--the prop inertia is too low to allow easy starting with any combination of the above problems

Remember, when running diesels, take your shirt and pants off on the back porch before you come into the house. And, when you want to get the diesel stains out of your clothes, you use scissors.....

Dave



Offline GERALD WIMMER

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #13 on: July 07, 2022, 05:21:42 AM »


Remember, when running diesels, take your shirt and pants off on the back porch before you come into the house. And, when you want to get the diesel stains out of your clothes, you use scissors.....

Dave

Hello I must be sick as I love the smell of diesels and that fuel is like perfume to me. Too much nostalgia I suppose.
My sons enjoy the challenge, particularly the younger 13 year who is good at starting and tuning them.
After the first start of the day they are usually easy to restart and ball raced diesels are easier to get that first start out of , like the TBR PAW engines. A diesel with a poor fit whether too tight or too loose is going to be more difficult then a glow.

Regards Gerald

Offline Steve Helmick

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Re: My “new” MVVS 2cc Diesel went rogue today!
« Reply #14 on: July 22, 2022, 11:48:21 AM »
     Hi Steve:

    Have you played with Diesels? I like the idea of not having to fuss with a glow plug!

Yes, I have. First one was a Taifun Tornado 2.5 (when I was 15). Next a Rivers 2.5. Later, some PAW's, a John .3cc, a Pfeffer ?cc, an Indian Mills 1.3cc, an Eta MkII or III, and a ST G.20 coverted to diesel. Some were very easy to get running. I did not like the smell of OUR diesel fuel, but have read that diesel fuel in the UK and elsewhere smells much less offensive. If I was to give any words of wisdom, it's that you need to break them in on the bench, because it's pretty near impossible to put them in the air with a rich setting...they quit very shortly after launch.

Glow plugs are zero problem, at least if you buy a good one (not a Fox!) of the correct length and heat range. I'm a fan of Thunderbolts, but they're made by Ohlsson Corp., and they make many brands here in the USA...including K&B. I had problems with the seals on Fireball glowplugs, and Fox glowplugs were always crap.  y1 Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.


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