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It Finally Happened to ME! Update

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andynfultz(at)bellsouth.n
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Posted: Tue Nov 20, 2012 8:00 pm Post subject: It Finally Happened to ME! Update

Well  guys here's what I have found after pulling the head on the affected side this  afternoon.  The number 2 cyl exhaust valve stem broke just below the valve  head.  There is absolutely no sign of any problem with the guides.   Once that valve was loose in the cylinder much damage followed.  The  cylinder wall has an extra hole in it and I suspect that sent  metal into the water pump impellor causing damage there. The connecting rod  on the number 2 cylinder is bent 90 degrees just aft of the wrist pin connection  and that's when she stopped turning.  Inside the cylinder were two golf  ball size pieces of the piston and the wrist pin which looks good as new.  Amazing what did and did not get chewed up.  Now I wish I had an  answer to the big question.  What caused the valve to break?  May  never know, but I'd like to hear what yall may think might have caused a valve  to break.

  

 Andy  F.

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larrycmcfarland(at)gmail.
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Posted: Wed Nov 21, 2012 6:50 am Post subject: It Finally Happened to ME! Update

Hi Andy,

I failed to mention that Ron at Ram Performance, in the course of fixing the guides also put in a new, more robust set of exhaust valves and polished the ports.

and a better set of springs.  In reflection, it was a bargain.  Sounds like the valve slid into the piston which is possible if the upper retainer let  go.

Thanks for the update.

 

Larry McFarland

 

From: owner-stratus-list-server(at)matronics.com [mailto:owner-stratus-list-server(at)matronics.com] On Behalf Of Andy Fultz

Sent: Tuesday, November 20, 2012 10:00 PM

To: stratus-list(at)matronics.com

Subject: RE: It Finally Happened to ME! Update

 

Well guys here's what I have found after pulling the head on the affected side this afternoon.  The number 2 cyl exhaust valve stem broke just below the valve head.  There is absolutely no sign of any problem with the guides.  Once that valve was loose in the cylinder much damage followed.  The cylinder wall has an extra hole in it and I suspect that sent metal into the water pump impellor causing damage there. The connecting rod on the number 2 cylinder is bent 90 degrees just aft of the wrist pin connection and that's when she stopped turning.  Inside the cylinder were two golf ball size pieces of the piston and the wrist pin which looks good as new. Amazing what did and did not get chewed up.  Now I wish I had an answer to the big question.  What caused the valve to break?  May never know, but I'd like to hear what yall may think might have caused a valve to break.



 



Andy F.

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ronhansen123(at)gmail.com
Guest

Posted: Wed Nov 21, 2012 9:34 am Post subject: It Finally Happened to ME! Update

I have a Zenair 601HDS with a Stratus EA81 w/ Ram modified valves and re-jetted carbs.  I had water cooling problems from the start.  Never over-temped, but had to pull it back to keep from doing so many times as I tried different fixes to lower water temp.  

 

At about 50 hours just after landing and exiting the runway, a valve seat broke on #2 cylinder.  It broke the piston badly, but did not scratch the cylinder somehow and head damage was shallow and fixable.  Sort of embarrassing, but when it happened I thought I just had a fouled plug and ran it up trying to clear it as I taxied in.  I could get 3000 RPM and it was pretty smooth.  

 

Ron at Ram did the autopsy and rebuild.  His best guess was long-term minor head overtemp.  The valve seat had an old crack and a new one that was the last straw.  He said that since my EGT probe on the right side picked up sort of the average of the two cylinders, I could have one cylinder overheating and the other not.  Same story with water temp since it sort of averages all 4 cylinders.  His best guess was that due to the sharp bend in the intake right before the cylinders, the Stratus setup was putting more gas in the front cylinder (the bigger droplets don't make the corner well) and less in the rear, hence the rear was leaner and hotter, out of limits, but I didn't know it from my gauges.  He had discovered that issue years ago and made an adapter that evened out the fuel distribution.  He now is fuel injection only, but still had the parts and put the flow equalizers in during the rebuild.

 

On the dyno before he returned the engine, it was 103HP with good exhaust gas chemistry.  It has run fine since, though initially still warmer than Ron thought good for long term.  I finally got the water temp to a good place by fashioning sheet metal to go from the bottom cowl to the top of the radiator.  That keeps most of the hot air going by the muffler from entering the radiator.  Five dzus fasteners hold it on so it's a bit more work to remove the bottom cowl.  I didn't want to go thru the work to move the radiator back and use a scoop, etc. 

 

Regarding my cooling fix experience on my 601/Stratus:

Data is difficult to interpret because no two flights are alike.
I did extensive testing of my water temp system to make sure it was accurate.

 
Larry's louvers helped by several degrees.
Putting small sheet metal "ears" on the sides of the rad inlet to funnel in more air did nothing to help cooling.

Wrapping the muffler with heat tape helped by several degrees.

 
Water Wetter I thought helped a tiny amount in temp, but really in the noise.  Hopefully there are greater benefits happening per their claims that don't show on the gauge.

Changing coolant from 50/50 to 75 water/25 coolant helped a bit.

 
Turning the heater on helped a bit when needed.  (Small heater core with coolant through it.)

Left and right EGTs helped sort out things such as carb balance and  helped monitor things overall, though don't sweat small differences between sides.  

I tested the Stratus gauge and probe in hot water and oil and they are not accurate.  I never used them in my plane, but got into testing this as I searched for solutions. 
Stratus gauge limit of 230 deg. seems very high to Ron, but it may be that Stratus was accounting for the crap gauge.  Ron said the engine should run at the thermostat setting of 190 deg. Period.  His red-line would be 220 deg. and would mean something isn't working right.

 
None of the things above got me to where I was comfortable.
Adding the sheet metal described above finally got me to a comfortable situation.  On most days even on long climbs water temp does not go above 205 deg.  Though when I climbed into a large inversion with 90 deg. OAT at 3000' it went to 215 and I thought still climbing so I pulled it back a bit.  Still plenty of power to climb.  On cooler days, say less than 75 degrees OAT, the water temp never goes past thermostat setting in full power climb and cycles around 190 deg. by a few degrees as the thermostat cycles.  In cruise, water temp is usually 189 deg.  

 
Ron at Ram is responsive, knows these engines, and does good work.  Stratus is not responsive, doesn't seem to have much interest in these engines, and I will only go there for parts that are harder to get elsewhere. 
I have about 50 hours since the Ram rebuild and so far so good.



I think I posted most of this in the past in multiple posts, but thought I'd put it together since there is current interest.  If there are other cooling ideas out there, I am still interested. 



Thanks,



Ron Hansen

Los Angeles



On Tue, Nov 20, 2012 at 8:00 PM, Andy Fultz <andynfultz(at)bellsouth.net (andynfultz(at)bellsouth.net)> wrote:

 [quote]       Well  guys here's what I have found after pulling the head on the affected side this  afternoon.  The number 2 cyl exhaust valve stem broke just below the valve  head.  There is absolutely no sign of any problem with the guides.   Once that valve was loose in the cylinder much damage followed.  The  cylinder wall has an extra hole in it and I suspect that sent  metal into the water pump impellor causing damage there. The connecting rod  on the number 2 cylinder is bent 90 degrees just aft of the wrist pin connection  and that's when she stopped turning.  Inside the cylinder were two golf  ball size pieces of the piston and the wrist pin which looks good as new.  Amazing what did and did not get chewed up.  Now I wish I had an  answer to the big question.  What caused the valve to break?  May  never know, but I'd like to hear what yall may think might have caused a valve  to break.

  

 Andy  F.

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andynfultz(at)bellsouth.n
Guest

Posted: Thu Nov 22, 2012 8:03 am Post subject: It Finally Happened to ME! Update

No  Larry,  the stem is still in place.  Just the valve head broke off the  stem. The stem is still secure in the guide, retainers and springs still in  place.

  

 Andy

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andynfultz(at)bellsouth.n
Guest

Posted: Thu Nov 22, 2012 8:09 am Post subject: It Finally Happened to ME! Update

Ron,  

  

    Thanks for your input.  Your situation sounds very much like  mine.

  

 Andy  F.

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jpkarnes

Joined: 03 Jul 2011
Posts: 19

Posted: Thu Nov 22, 2012 3:22 pm Post subject: It Finally Happened to ME! Update

Hi all, 

  

I also had engine cooling problem and led to blowing a head gasket a few years ago.  Anyway, I decided to go with dual motorcycle mufflers port and starboard with nothing impeding airflow to the radiator but the front gear strut.  My temps are much better now and will monitor those closely in the months to follow. 

  

John K. 

Bremerton, WA 

Zenith 601HDS / Stratus EA-81 with RAM heads

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