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1. 08:51 AM - Re: Re: Housai engine question: compression check (Justin Drafts)
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| Subject: | Re: Housai engine question: compression check |
Good morning all-
Update to the compression check, w/ good news.
Checking & resetting the valve clearances (0.3/0.4 mm) on all 9 cylinders
did the trick;
the lowest # I got on all compression checks was a comfortable 73/80 psi.
Latest takeoff
felt like I had a bit more giddyup as well, no surprise.
THANKS ALL for the good advice, much appreciated.
Justin
N280NC
On Sat, May 1, 2021 at 10:01 PM Walter Lannon <wlannon@shaw.ca> wrote:
> Justin et al;
>
> Having likely adjusted a few thousand radial engine valves over the past
> 70 years or so I can truthfully say I have never had occasion to use a
> torque wrench for this function.
>
> Just went through the torque specification sections of the P&W R985/R1340
> Overhaul Manual and found no recommendation whatsoever in this regard.
> Will check out the P&W Mtce. manual and corresponding FAA manuals next tr
ip
> to hangar.
>
> Not really surprised as this type of joint perfectly meets the definition
> of a =9Cjamb=9D nut lock! Will check out the FAA guidance an
d get back!
>
> Walt
>
> *From:* Justin Drafts <draftsjust417@gmail.com>
> *Sent:* Saturday, May 01, 2021 10:49 AM
> *To:* yak-list@matronics.com
> *Subject:* Re: Yak-List: Re: Housai engine question: compression check
>
> Good info, esp on open ended wrench caution...
> Stay tuned! J.
>
> On Fri, Apr 30, 2021, 6:57 PM Anthony Savarese <
> dsavarese0812@bellsouth.net> wrote:
>
>> No torque spec that I=99m aware of. Tighten securely using proper
17 mm
>> socket wrench or a properly fitted box end wrench. Don=99t use an
open end
>> wrench. Very likely you=99ll round off the corners of the hex nut.
>> Dennis .
>>
>> Sent from my iPhone
>>
>> On Apr 30, 2021, at 5:04 PM, Justin Drafts <draftsjust417@gmail.com>
>> wrote:
>>
>> =EF=BB
>> Fast question... what's the req'd torque in the rocker arms' jam nuts ?
>> What # has everyone used?
>>
>> Thanks again all--
>> Justin
>>
>> On Fri, Apr 30, 2021, 7:16 AM Justin Drafts <draftsjust417@gmail.com>
>> wrote:
>>
>>> All good info gents, thanks & very very much appreciated... stay tuned!
>>> J
>>>
>>> On Fri, Apr 30, 2021, 4:59 AM Mark Pennington <
>>> pennington.construction.inc.1@gmail.com> wrote:
>>>
>>>> Justin
>>>>
>>>> You are right about adjusting the valves. You photo is accurate.
>>>> I would talk to someone at length about the step by step procedure if
>>>> you haven=99t done that yet. How you use the feeler gauge is im
portant. As
>>>> taught to me by others.
>>>>
>>>> I would suggest fix the sticking valve before you adjust anything. I
>>>> am sure you are aware of that info.
>>>>
>>>> And Yes. MMO is a very wide and varied discussion for sure. Me, I
>>>> drink a pint before every flight. LOL.
>>>>
>>>> Mark
>>>> N621CJ.
>>>>
>>>> On Fri, Apr 30, 2021 at 7:48 AM Greg Wrobel <clouddog22@gmail.com>
>>>> wrote:
>>>>
>>>>> Sticking valves happen. We have all had them. The danger is when you
>>>>> let them go you may eventually burn the valve and then you have anoth
er
>>>>> issue to deal with. When you pull through in a perfect world you shou
ld not
>>>>> hear any air coming from exhaust or carb. Sometimes a small amount ma
y come
>>>>> through and after a flight it should normally go away if not, then yo
u need
>>>>> to address it with a rubber mallet, or spinning the valve (lapping).
We can
>>>>> get into discussing Marvel Mystery Oil in the fuel and/or oil but tha
t is
>>>>> another bag of opinions
>>>>>
>>>>> Greg "Clouddog" Wrobel
>>>>>
>>>>> On Thu, Apr 29, 2021, 21:34 Justin Drafts <draftsjust417@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Ok helpful gents and engine experts-
>>>>>> A fruitful sunny day spent @ hangar with the suspect cylinders.
>>>>>>
>>>>>> Checked the small starting air valve: definitely in good working
>>>>>> order and closing as appropriate.
>>>>>>
>>>>>> Pulling off rocker covers and watching the rocker arm and valve
>>>>>> springs, I see there is
>>>>>> no gap at TDC between the rocker arm and top of the spring /stem for
>>>>>> cylinders #2 and #3.
>>>>>>
>>>>>> Just so I'm understanding valve lash / clearance correctly:
>>>>>> - the 0.010-0.014" clearance mentioned is supposed to be here at th
e
>>>>>> red circle in the
>>>>>> attached pic, correct? (While the stem is at its highest point of
>>>>>> travel/valve fully seated/TDC...)
>>>>>> -adjusting this clearance/lash requires turning the large adjustment
>>>>>> screw at the green arrow, correct?
>>>>>>
>>>>>> Based on the air I hear escaping the exhaust stack, I suspect the
>>>>>> exhaust valves are sticking or
>>>>>> otherwise remaining open.
>>>>>>
>>>>>> Not sure how I went from great compression #'s last year to 0/80 psi
>>>>>> this year, but very little surprises
>>>>>> me in maintenance anymore.
>>>>>>
>>>>>> Thoughts gents?
>>>>>> Thanks- Justin
>>>>>>
>>>>>> On Thu, Apr 29, 2021 at 5:09 AM A. Dennis Savarese <
>>>>>> dsavarese0812@bellsouth.net> wrote:
>>>>>>
>>>>>>> dsavarese0812@bellsouth.net>
>>>>>>>
>>>>>>> Also check the the air injector to make sure it is fully closed. I
t
>>>>>>> too
>>>>>>> has a very small valve inside of it about the size of a pencil
>>>>>>> eraser.
>>>>>>> If the little valve spring is broken or the valve remains open, it
>>>>>>> will
>>>>>>> of course affect the compression test.
>>>>>>> Dennis
>>>>>>>
>>>>>>> A. Dennis Savarese
>>>>>>> 334-546-8182
>>>>>>> www.yak-52.com
>>>>>>>
>>>>>>> On 4/28/2021 11:58 PM, Justin Drafts wrote:
>>>>>>> > Good evening all-
>>>>>>> >
>>>>>>> > A conundrum for you Housai engine experts; I need some advice to
>>>>>>> go fwd.
>>>>>>> > Doing the compression check today, I hit a weird wall.
>>>>>>> >
>>>>>>> > With a partner I was checking cylinders starting with #1 at top,
>>>>>>> going
>>>>>>> > CW when viewed from cockpit.
>>>>>>> > All #'s were good (avg 75/80 psi), until I got the last cylinder,
>>>>>>> #2.
>>>>>>> > We got 0 psi on the pressure gauge.
>>>>>>> >
>>>>>>> > Checking the pressure tester/gauges/fittings/hose, all are fine
>>>>>>> and
>>>>>>> > perfectly functional.
>>>>>>> >
>>>>>>> > So we double checked the previous cylinder, which had just 10 min
>>>>>>> > prior tested at 74/80 psi.... now it also
>>>>>>> > showed 0/80 psi. ??
>>>>>>> > No obvious air leaks from oil breather, carburetor, or exhaust
>>>>>>> stack;
>>>>>>> > no oil evident at bases of the cylinders;
>>>>>>> > the exhaust and intake stacks are good condition. I had flown the
>>>>>>> > plane earlier in the day w/o any negative
>>>>>>> > indications.
>>>>>>> >
>>>>>>> > Pulled the valve covers off to find the rocker arms, springs, etc
>>>>>>> in
>>>>>>> > great condition, doing their job when we
>>>>>>> > slowly turned the prop thru by hand.
>>>>>>> >
>>>>>>> > Stuck valves?
>>>>>>> >
>>>>>>> > We tried the "rope trick" to slip a nylon cord into the cylinder
>>>>>>> thru
>>>>>>> > the open sparkplug hole, then gently run
>>>>>>> > the piston up to TDC to try to reseat the possibly stuck-open
>>>>>>> valves.
>>>>>>> > As yet, no help.
>>>>>>> >
>>>>>>> > Fishing for advice & thoughts... what are we missing?
>>>>>>> > I've never seen a 0/80 psi reading... a bad piston ring or bad
>>>>>>> valve,
>>>>>>> > should have SOME psi indication 30~60psi.
>>>>>>> >
>>>>>>> > Thoughts? Pointers?
>>>>>>> > Thanks---
>>>>>>> >
>>>>>>> > Justin Drafts
>>>>>>> > N280NC
>>>>>>>
>>>>>>>
>>>>>>>
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