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YS 170 DZ CDI new problem

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Old 04-11-2010, 08:51 PM
  #1
pattratt
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Default YS 170 DZ CDI new problem

Hi All
Thanks to all who helped on my loose header problem. I am now having a huge oil down problem. By the end of a day of flying everthing from the prop back plate back is covered in a very thick clear oil! Even the wheel pants are covered! Unless the oil is coming from the front crankshaft bearing I don'y know how it would oil down the whole engine bay and cheek cowl. The oil is very clean and clear in color so I do not feel it is exhaust residue!! Any ideas welcome. I did notice in parts break down that there was a seperate oil seal behind the front bearing. Could a bad seal put out enough oil in five flights to completely cover the entire bottom of the fuse.?

Thanks
Dick
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Old 04-11-2010, 09:51 PM
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Default RE: YS 170 DZ CDI new problem

check the spark plug, it could be loose or broken, also change all fuel lines.

TUNY
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Old 04-11-2010, 11:16 PM
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Default RE: YS 170 DZ CDI new problem

Tuny
I will check both but engine is running very strong and has excellent compression.
Thanks for the reply as I had not checked either.
Dick
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Old 04-12-2010, 12:23 AM
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Default RE: YS 170 DZ CDI new problem

Dick,

Could this residue be coming from your vent line ?
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Old 04-12-2010, 12:42 AM
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Default RE: YS 170 DZ CDI new problem

Head Gasket.

Joe Dunnaway
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Old 04-12-2010, 03:15 AM
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Default RE: YS 170 DZ CDI new problem

Head gasket + 1 [8D]
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Old 04-12-2010, 07:50 AM
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Default RE: YS 170 DZ CDI new problem

Head gasket +2

Vicente "Vince" Bortone
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Old 04-12-2010, 08:14 AM
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Default RE: YS 170 DZ CDI new problem

I think if the engine is running well and the compression is good then I would be looking for leaks in the fuel system. I recently had a broken plug where the insulator had cracked and this sprayed loads of slightly coloured fuel / oil out. Took me ages to track; the fact that it was slightly discoloured suggested an exhaust related issue. I believe you say that this is not the case with your problem? Hence anything pre-injection would be suspect including the one way valve and the rocker box cover. Look also for missing / loose screws. Finally if you still can't track it then try siliconing up the joints for a quick test to see if you have poorly mating parts.

Hope this helps

Keith
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Old 04-12-2010, 10:14 AM
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Default RE: YS 170 DZ CDI new problem

Peter
The vent line exits at the landing gear area way back of the engine. Don't know how oil would get to engine from there?
Dick
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Old 04-12-2010, 10:19 AM
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Default RE: YS 170 DZ CDI new problem

Joe, Jon, & Vince

If it was the head gasket the oil residue should be discolored I would think? The engine runs very strong and has good compression. I have a compression gage so I will check to make sure compression is where it should be.

Thanks
Dick
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Old 04-12-2010, 10:30 AM
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Default RE: YS 170 DZ CDI new problem

Keith
This is a new engine and all new fuel tubing but good idea to replace all to be sure this is not the problem.
I have already checked the valve cover gasket for tightness and this engine does not use an external check valve. I will check the plug and head bolts.

Thanks
Dick
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Old 04-12-2010, 10:41 AM
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Default RE: YS 170 DZ CDI new problem

Hi Dick,

When I mention the one way valve, I'm referring to the black plastic valve that sits on top of the injector. This has a vent to atmosphere which sometimes leaks, but is unlikely to leak a lot unless faulty. Look also at the six backplate bolts.

Best wishes

Keith
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Old 04-12-2010, 11:02 AM
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Default RE: YS 170 DZ CDI new problem

In the non CDI version the oil residue is very clean. I am not sure about the CDI. Again the chances of head gasket is very high since we have seen it many times.

Good luck,

Vicente "Vince" Bortone
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Old 04-12-2010, 11:14 AM
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Default RE: YS 170 DZ CDI new problem

Hey Keith

Will do.

Thanks
Dick
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Old 04-12-2010, 11:16 AM
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Default RE: YS 170 DZ CDI new problem

OK Vince, I will check the head carefully. Did your engine run strong when you had this problem?

Dick
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Old 04-12-2010, 12:33 PM
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Default RE: YS 170 DZ CDI new problem

How about cleaning the entire area & surroundings thoroughly then running the engine (with belly pan of off) for a very short period. Then inspect closely for the first signs of a leak.

Glen
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Old 04-12-2010, 01:53 PM
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Default RE: YS 170 DZ CDI new problem

Dick.... With a head gasket leak, the engine will still run strong. Look at the head closely while turning the prop up against compression. You can usually see a few bubbles leaking around the head if you look closely.

Joe Dunnaway
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Old 04-12-2010, 02:55 PM
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Default RE: YS 170 DZ CDI new problem

Yes. It was difficult to notice any change in power.

Vicente "Vince" Bortone
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Old 04-12-2010, 05:19 PM
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Default RE: YS 170 DZ CDI new problem

Hey Glenn

Will do if I can not find any issues from what I have learned here. There is enough oil that I should be able to see where it is coming from!!
I talked to Richard Verano today and he feels pretty sure it's probably a loose head. I will check that and a number of other things people have suggested. I am sure I will find it as this is not a small problem. Richard also gave me some good advice on how to prime the engine on the first flight of the day. Much harder to prime this puppy than the old style 140's.
Thanks for the reply.

Dick
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Old 04-12-2010, 05:22 PM
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Default RE: YS 170 DZ CDI new problem

Will do Joe.
Thanks
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Old 04-12-2010, 05:43 PM
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Default RE: YS 170 DZ CDI new problem


Quote:
ORIGINAL: pattratt

Keith
This is a new engine and all new fuel tubing but good idea to replace all to be sure this is not the problem.
I have already checked the valve cover gasket for tightness and this engine does not use an external check valve. I will check the plug and head bolts.
Dick,

Even though your valve cover may be tight there may be a slight high spot on the surface thus allowing air/fuel to escape. Take the valve cover off and remove the gasket and sand it on some 600-800 sandpaper until you get it shiny all over - then clean it in alcohol and put it back with a new gasket.
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Old 04-12-2010, 09:35 PM
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Default RE: YS 170 DZ CDI new problem

Hey Derek
I took the cover off and it appeared to have imprinted the gasket pretty evenly.
I will remove it again and make sure it is even. I have done this before by laying the sand paper on glass and then moving the mating suface over it until it's all shinny.
Thanks
Dick

PS to all
Head bolts were tight but I turned the cap on the black plastic valve on top over a half turn in thr process of tighting it! It took an hour to get everything "clean." Next step will be to run the engine exposed to try and see the leak visually. Stay tuned!!
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Old 04-13-2010, 09:04 AM
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Default RE: YS 170 DZ CDI new problem

Check your front push rod cover O rings.
I had the same problem one of the top O rings broke.
Good luck.
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