Problems with ZDZ 80
 

I have a ZDZ80 which is installed in a large plane which I purchased. It has a Bisson muffler attached and the engine is mounted upright. I have checked the ignition battery and it is plugged, and I appear to be getting gas to the carb (I choked it until it was wet), but I do not get any starting action at all. Engine does not appear to be firing. It does not seem to have a whole lot of compression. I am using a Sullivan starter because I have had no luck getting it to start by hand.
This is my first ZDZ, and am wondering where I should start in the troubleshooting of the engine. The spark plug has one of the Bosch-type resistor covers on it, and I have not removed it yet to make sure fire is ging to the plug, so that is my next step.
Are these engine notoriously hard to start? How much compression should I expect on it?
It is propped with a 26x10 prop, and am assuming this is the correct one for the appliaction.
Any suggestions?

RE: Problems with ZDZ 80
 

I ran a carbon 26x10 on mine, starting procedure was choke on, ignition off, full throttle position, approximately 5 flips....repeat with throttle at high idle position....then choke off, ignition on, high idle, and start it.

Check to be sure you have a full battery, and yes check your spark to be certain the hall sensor and ignition work. You can inspect the carb, checking the diaphragms for pliability, and get yourself a rebuilt kit if needed.

The lack of lubrication from sitting could be the low compression you experience, although these do have small cylinders on them, and proper cooling is a must. Pulling the muffler and reporting back with the condition of the piston side/skirt/top would be good to tell the story better.

RE: Problems with ZDZ 80
 

Doc is it used or new? They run on 93 octane so the engine is somewhat a high compression engine.

I would call RC Showcase for sure.

Ron

RE: Problems with ZDZ 80
 

Yeah, this engine is used, and I suspect that something is not right. I mean I expected an engine this large to have much more compression than what it has. I am afraid it was run hot, since the previous owner ran the plane with the exhaust vented directly into the cowling. Right now I am not too happy about what I have found on this engine, since I have a considerable amount of money sunk into this airplane.
If I remove the sparkplug and turn the engine thru, with the ignition turned "on" and the plugged grounded, will I be able to see a spark if the ignition module is working correctly?

RE: Problems with ZDZ 80
 

Unless things have changed since I last spoke with them....they have no spare parts for the 80rv, if your situation should require it.

RE: Problems with ZDZ 80
 

Yes you'll be able to see spark after grounding the plug. Sounds like your engine has been cooked. Pull the muffler and get us some pics.

RE: Problems with ZDZ 80
 

yup....ground the plug to the cylinder before turning on the ignition....then slowly rotate the hub till the magnet passes. That will confirm spark.

If you suspect poor cooling, I would seriously consider a peek at the piston...if you are so inclinded, pulling the cylinder off for a thorough inspection might be a good idea. Problem is, if it was run too hot, odds are good the the cylinder is no longer 'true', and even a new ring will do you no good at all.

If you get spark, lets get it some fuel....I;ve seen very low compression engines at least start, and further symptoms lead to further internal inspection.

RE: Problems with ZDZ 80
 

Yeah, I will do those things, prolly will be a few days before I can get to it, on call, and had too many late evenings this week.
This engine is on a 1/3 scale BUSA Fokker DVII. The way it is mounted, it hard to get to the carb, behind firewall, but I spent about an hour working this past weekend trying to get it to fire and it just would not do it. Gonna try getting the plug out and seeing what it looks like and if it is firing. Will let you guys know what I find from there. Sure I hope it can be fixed, it would be tough to find another engine to go in this bird, and it is too big and beautiful not to fly.

RE: Problems with ZDZ 80
 

How long had it been since it was run? Can you tell if attention was given to getting the airflow to move through the cylinder fins and out of the cowl? Perhaps we are jumping the gun here on disaster, and we're still looking at a routine maintenance issue with tank, filter, clunk, lines, diaphragms....etc.

If you do end up pulling the cylinder, go slow so as not to damage the base gasket, they currently don't have any and you'll be making your own. Not difficult at all, but you could save yourself the trouble by being careful and going slow.

RE: Problems with ZDZ 80
 

I know it was flown and or run just a few weeks before I purchased it. There is plenty of cooling in the cowl, with a big vent up front causing air to go around the fins and out the top of the fake engine.
What happened was somebody tried to make a scale type exhaust by cutting off the pipes on the Bisson muffler and gluing two rubber hoses in the holes, which they then routed out the side of the cowl. Well, I don't have to explain that the first time they ran it like that the heat burned thru those hoses and exhaust gases poured into the cowl. there was plenty of air going thru, BUT there was also a good amount of heat because I could see a little soot on the inside of the cowl and a place where the paint was starting to bubble up on the outside.
i took the muffler off and had it custom welded, filling in those holes and putting new pipes on it which route out the bottom of the fuse, effectively now there should be no hot exhaust gases in the cowl. I do remeber seeing a little soot at the exhaust outlet, but could not get a good look at the cylinder when I pulled off the muffler.
My guess is that if I do not get it running I will pull the engine off and let someone who is good with these take a look at it. I doubt I will break it down myself, especially if parts are at a minimum.

RE: Problems with ZDZ 80
 

Well, do the steps you can to test components, and keep us posted. Though it might seem like a lot of work, if you are unfamiliar with the engine, it might not be a horrible idea for you to mount it on a stand, and run it just to familiarize yourself with it and its a great open view for inspection. Either way, good luck and let us know how it goes.

RE: Problems with ZDZ 80
 

Hi Doc, try an "instant engine starter" here in Australia we have a Nulon product called "Start ya *******" i know the name is a bit rude but that is what its called i think the name has a touch of Aussi humor. This product is in a spray can and has 25% ether in it
I had a bit of a problem starting with my 85 3W at first but take out the plug and spray it into the head and on the plug and replace and it should fire with all that either in it. or even better if you can get at the carb spray it into the carb. I guess there is an American product on simuler lines i bought mine at a mower shop. If it does not fire with that in it then there is another problem, if it fires you know that the ignition is working at least.
I found my problem to be the long distance between the tank and the engine about 12 inches and it took a lot of cranking before the gas was up to the carb, now i am experimenting with a small amount air pressure in the gas tank to make the carb drawer better once the engine has run its no problem as there is always gas left in the fuel line on the restart but the line dries out if you leave it for a few days.

RE: Problems with ZDZ 80
 

I've run a lot of engines at well over 400f and generally a ring will stick when and engine becomes too hot. I haven't seen any out of round cylinders yet. Rings are funny things even if they haven't stuck. One day they will be running just fine and suddenly the engine dies from a lack of compression when the ring loses it's tension. The lack of compression on a used engine makes me think ring.

Unless ZDZ changed pistons and rings in their 80's it's likely you will be able to obtain another one. Otherwise Frank Bowman in New Mexico is the place to go. Based upon ZDZ parts pricing you might want to try Bowman first. The replacement process is quite easy.

RE: Problems with ZDZ 80
 

The new 80RV-J has a 47mm bore and 46mm stroke, while the older 80RV had a 52mm bore and 38mm stroke. I would replace the ring. I think Frank Bowman has the dimensions for this engine and the cost is around $15 IIRC.

The ZDZ's have a higher compression ratio and consequently a higher compression pressure than most other engines on the market. My own ZDZ 80RV has so much compression that I can barely turn it over by grasping the hub, it requires a fair amount of force to pull it through. With a prop on it has a satisfying "snap" when pulling through compression. I have maybe 150 - 200 hours on the engine now and it still runs great.

RE: Problems with ZDZ 80
 

Frank is who fit a ring for my second hand 80rv, low compression, run too hot, and the cylinder was no longer true, as confirmed by frank himself, on the off chance it was just a very late night for me :) This was the only time I too have experienced an out of true cylinder...I should have included this info above. Hopefully you have better luck with your deal on a used one. At the time of my experience, late last fall...RCshowcase had no base gaskets, rings, pistons, cylinders or literally any parts for the discontinued 80rv. However their intent was to work with the manufacturer to get some parts in for those customers that still have em. Get Mike Dooley on the phone to confirm, as they may now have parts in stock if needed.

RE: Problems with ZDZ 80
 

Finally got home last nite at a decent hour and managed to spend a little more time frustrated over this enigma.
First I pullled thespark plu cable and found that I did not have a wrench capable of removing the plu, everything was too big to get in there and loosen it and the plug was in too tight. I did manage to check the EI unit, using another plug, and it sparks really nicely as the prop passes over the sensor, so the EI unit is working, so I can eliminate that.

I pulled the muffler and looked inside the chamber. Everything seems to be moving smoothly, and though there is a little soot, it does not appear to be excessive. The combustion chamber looked dry, even though I had choked the engine until the carb was dripping wet. I squirted a few drop on top of the cylinder and tried to get it to start. If the starter could keep it going pretty fast it seemed to act like it wanted to run, but the minute you removed the starter the combustion was not sustainable. The compression is not what I would suspect to be. For instance I have another large gasser and you can barely flip it thru, on this engine you meet a little resistance but it can be overcome fairly easily. The starter works fairly hard to turn it over, but it never stalls nor gets hot.

Next I am going to find a wrench to remove the plu and make sure the plug that is in it is working properly. The next step will be to remove the engine from the plane.
Can you guys tell me who to contact about servicing this engine? Someone mentioned Frank? Where can I find this guy? phone number? web site?
Thanks for the help
BTW if I wanted to replace this engine, what would e a good subsitute that would provide as much power and fit in a similar space?

RE: Problems with ZDZ 80
 

Frank Bowman is who you contact for aftermarket piston rings, very good at what he does. If you don't want to do any service work on the engine, and don't know anyone handy with engines in your club, I would recommend sending it to RCshowcase. The cylinder is only held on with 4 cap head screws, there is a thin base gasket there, and once off, you'll see that the ring groove has a locating pin for the ring gap. Unless you remove the piston you need not worry about which way this is oriented, however you will want to place the cylinder back on in the same orientation, which positions the ring locator pin opposite the exhaust port. I personally wouldn't recommend paying for shipping, and service charges to simply pull the cylinder, and inspect what you have going on. If your ring is obviously stuck, it is not too difficult to get it out, and certainly not too difficult to replace. And at that point you could work with Frank Bowman, and get a new ring in the mail. If at this point there are no signs of running extremely hot, you may just be ok with the new ring. YOu could take some good digital pictures and post them here for review. This could really save you some money, and get you back in the air quickly. Worst case, we don't want to see you pay for shipping and service charges, only to find out your upper end is shot, and there are currently no replacements.

Did you call Dooley? If so, and they do have parts....you COULD send it to them as an end all, it would come back to you running, but at a price I am sure. In the event you only need minor cleaning, a new ring, an reassembly, I would encourage you to post pictures, ask for help on here, and experience this yourself.

RE: Problems with ZDZ 80
 

I spoke to Mike at RCShowcase. He said parts are hard to come by, and might take a while to get them if I needed them. I am going to try and take it off the plane this weekend, and make sure the carb is working correctly. How do you get the four bolts off that hold on the cylinder head? They look like it requires a short allen wrench or something to get to them since they sit in the little recess about half way down the cylinder wall.
I feel comfortable replacing the ring, if I can make sure that is the issue. Especially if you guys are leading the way...LOL

RE: Problems with ZDZ 80
 

Yeah, there are no access holes in the cylinder fins, so you need to use a dremel and cutoff wheel to shorten an allen wrench to fit.

RE: Problems with ZDZ 80
 

If you do decide to pull the cylinder, please do take some pictures and post them. They will tell the whole story. If you want to check your inner cylinder bore to see if it is still true, a good way to do so, is to use your existing ring (if it comes off without breaking) or the new ring when you get it from Frank...and insert the ring into the cylinder bore maybe 1/2" from the bottom, as level as you can by eye, and eyeball the end gap at the ring ends. Then slide the ring half way down into the bore, recheck endgap, and finally getting close to the top of the cylinder bore, checking again. If you can tell that the gap is different as it progresses through the bore....uh oh.

RE: Problems with ZDZ 80
 

Sounds like a stuck ring to me...Before u take it apart, take the plu out and squirt some wd 40 into the cylinder, and put the plug back in. and see if it has compression then.. If it still doesnt, the ring is stuck or bad.. I have had luck with filling up the cylinder with this oil and letting is soak for a day or so and the ring will un stick if it's a carbon build up problem... I have an extra cylinder gasket if u need it, be glad to let u have it...

RE: Problems with ZDZ 80
 

Well I took it off the plane this weekend and got a good look at everything. Sorry no pics, but it was hard to get a pic of the things I thought were the problem. I checked the fuel supply. No kinks in the tubing, and tank is setup correctly. I opened the carb and found no trash, and the diaphragm looked OK. It draws some fuel when you rotate the engine. The cylinder walls looked dry, so I removed the spark ply and tried some WD40 in there and worked it around good. The compression did increase, but when you rotate the engine over you could see buuble coming around the cyliner where the ring is at, at the exhaust port. The spark plug is firing and it is a good stroong spark. After lubricating it, and checking everything, I reinstalled it, and it still would not fire. I think the ring is either bad or the piston is worn. I am sending it back in to Mike at RCShowcase, I spoke to him on Friday, and he is going to take a look at it. I am hoping it can be salvaged, and they can fix it. I will let you guys know what they find.
Thanks for all the help.
Tommy

RE: Problems with ZDZ 80
 

Please do let us know what RCS has to say....

RE: Problems with ZDZ 80
 

Got the call from RCS/TBM about my ZDZ which I sent in to them. The piston was the problem, the engine had been run hot, my suspicions about the open muffler in the cowl is probably what caused it. Since I had already found an engine and purchased it, I have had them send this one back to me, now way am I going to put several hundred dollars in the rebuild on this thing. If anyone needs parts, I will sell this one complete for you to rebuild or use however you wish. It includes the muffler and EI unit. The case, carb, muffler and stuff appears fine, but from what the guy said it needs a new piston, and probably a head.
Drop me a PM if you need it, I will get around to listing it on RCU Swap in a while.
Thanks
Tommy

RE: Problems with ZDZ 80