Freddy

My Feedback: (3)

I have had this chronic problem lately with both my YS160/170DZ. Even after both enginese were checked out at YS Repair d to my leakage issue there is still a huge amount of burned black oil all over the inside of the nose cowling.
I had noticed that the header would slide fairly easy over the O-ring of the Hatori muffler. So I even bought a new set of both Hatori header and Hatori muffler and new O rings and the problem is still the same! I still noticed that the seal does not appear to be tight with the new parts.
I still think that it must be leaking at this interface so my next try is to add a narrow strip of aluminum tape to the inside of the muffler groove to see if I can get a tighter seal around the O ring by pushing it inward due to shrinking the groove inside diameter.
Any inputs?
Has anyone experienced this problem?
Thanks.

eddieC

My Feedback: (2)

I'd tape the I.D. of the interface for the O-ring. It's harder to make it smaller, much easier to make it bigger. You can get various O-rings at industrial supply shops.

bjr_93tz

The little graphite gasket the goes between the flange that screws into the head and the header is still there and in good condition?

I have seen what you describe and boy did his plane look a mess, a new o-ring fixed it up but if the new bits are too loose then??

I have also seen the spark plug washer a bit offset and not seal properly, but the residue wasn't black, it was a bit clearer.

kevenoco

My Feedback: (1)

I have had the same problem with one of my DZ 170's, but I'm not sure I've discovered the source. The other DZ170 is always clean (I keep the header attached to each so it could be a header issue still).

I recently removed the oily engine to clean everything up to try to solve this one. I tried taping the OD of the header stinger with silicone tape to tighten the seal (comes with YS Super Mount for nose ring) and replaced the o-ring. I ran the motor in the backyard for about 1 minute and the engine looked completely clean afterwards...

I have not flown yet so I'm not sure that this is the solution.

Dave Harmon

The area just above the threads on the supplied Chinese plug is a lot smaller than the i/d of the washer.
This washer can go off center and cause a sneaky leak that causes oil to blow out and some misfiring.
The only way I was able to find it was to remove the plug cap and put some alcohol around the plug then roll the engine by hand and saw a lot of bubbles from the leak.
In addition....my plug had egg shaped threads...I asked for a warrantee replacement but was denied...so I tossed it into the weeds next to some of Rene's Rossi carbs and got me some Rimfire plugs that are great quality.

Also...I had a huge problem that turned out to be a bad joint where the hall effect wire was connected to the backplate.
I could fly around and do a positive pull and it was ok....then do a negative push and the engine quit just like a rag was tossed in the prop.
I finally found it by running it on the test stand and moving the wire by hand.

There were so many quality control and design problems that I lost a year and a half of flying in spite of some of the most experienced help in the world both locally and on the phone.
Finally....I left the damn thing where it quit last...plane and all....done.
I've been flying something else now for 2 1/2 years with no maintainance.....I never thought I would get to that point but I did.

bjr_93tz

Hi Dave, I'll do a search for those rimfire plugs.

I "lost" about a season with my 170cdi as well while on the learning curve of it's funny little quirks and secret upgrades from YS. The pump is my favorite campfire story as I replaced the original pump with the revised unit with the hardened inserts after about 9 months. So far I've spotted 4 different regulator diaphram types with that latest one being a thin white teflon thing. I used a fibre reinforced silicone thermal transfer pad for a TO-3 transistor to get me out of trouble once and it held up well, before I did the right thing and replaced it with an OEM assembly.

Yep, the spark plug gasket took a while to figure out as I was blaming the intake tube o-rings. I still think I haven't got the intake tube in exactly the right spot as it's looking a little "damp" there after a couple of flights when usually the whole motor stays as dry as a bone.

I always lightly face the tappet cover and carb insulator when I pull it down, and nearly always use new o-rings and gaskets when I put it back together. O-ring and gasket kits are cheap enough.

apereira

Hello Freddy,

I haven't had that problem but one of my buddies did, I use the VITON O ring form Central Hobbies, VITON is far better than the Nitrile one from Hattori, and we found on my friend's that the header flange at the engine side distorted with time causing the problem, the latest Hattori header fixed this as the flanges are stiffer.

Hope this helps

Best regards

Alejandro

MTK

Freddy,
You can make your own seal ring and get a perfect fit. Get some ceramic cloth from McMaster Carr and a tube of Permatex Ultra Copper high temp sealant. Impregnate strands of ceramic with Ultra Copper and simply wind the thread onto the stem. Fit the header and let it cure overnight.

You can also make your own coupler with ceramic cloth and Ultra Copper. It's the best there is. If you decide to try it let me know and I'll walk you through the process.If any of you need the best coupler around, I don't charge much.Much better than Teflon because it seals the same as any silicone coupler, with about 600F temp rating

Thinn

I had the exact same problem with oil spill all over in the beginning of last season. I did not find the cause, but after using my engine more frequently (it had been hanging all winter), it just cleaned itself up after a while! I thought it was just cross being used to seldom! My guess was that the pump just needed some "break-in time" after a very long winter hibernation!

Audun

Freddy

My Feedback: (3)

Alejandro I am already using the Viton O-ring.

All - thanks for the pointers and I will check the suggestions step by step and try it out if and when the Seattle weather allows it.

Freddy

My Feedback: (3)

I think I answered my own question. The header O-ring I was using did not fit properly and was an aftermarket type. Ditto for the Viton O-ring, it may have been from a bad batch. I still had a brand new Hatori O-ring and it fits much tighter. I have not flown it yet as the highs of mid 30s F lately here are not appealing for me doing that.

Freddy

My Feedback: (3)

Finally test flew today. The new Hatori O ring solved it. Pretty simple no more leaks.

Don Szczur

My Feedback: (1)

Two things I found on my setup over the years. First make sure the pipe does not move forward and backward (a bit of rotation is OK but not too soft of a pipe mount). The forward and backward wear the o ring much faster. Second check your mount. The new Hyde mounts are much more efficient than older versions. I changed to one with a rotation limiter and have been running the same O ring since last August. Probably about 25 gallons through the setup and no leaking around the header. The engine compartment and pipe tunnel are clean.

Good luck,
Don