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  #1  
Old 05-12-2019, 07:00 AM
bsvantho bsvantho is offline
 
Join Date: Oct 2012
Location: Rochester Hills, MI
Posts: 58
Default Cylinder 4 High EGT/CHT on Ground

I am breaking in my new IO-540 and on the fourth flight I noticed a spike in Cylinder 4 EGT after landing. To a lesser extent the CHT also climbed.

This is what the temps looked like at cruise (25"/2500rpm). Pretty normal except maybe for CHT 1 & 2 being higher - need to trim the dams a bit more. Note Cyl 4 CHT is consistently the lowest temp and EGT spread is minimal.



After landing the Cyl 4 EGT crept up significantly in relation to other cylinders and Cyl 4 CHT is now the highest.



What might explain this spread at ground power settings? What to check? I am thinking ignition or fuel injector blockage but am still pretty new to this.

The data logs for flights 1-3 do not show this spread (EGT or CHT ) for cruise power or ground power settings.
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  #2  
Old 05-12-2019, 07:12 AM
Nova RV Nova RV is offline
 
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Location: Leesburg, VA
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Before you trim anything I would look for a partial blockage in an injector or the flow divider. I had this exact scenario (but in a 4 cyl) and it was something in the flow divider.
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RV-14A kit # 140243 (flying as of 11/18)

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  #3  
Old 05-12-2019, 07:27 AM
bsvantho bsvantho is offline
 
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Quote:
Originally Posted by Nova RV View Post
Before you trim anything I would look for a partial blockage in an injector or the flow divider. I had this exact scenario (but in a 4 cyl) and it was something in the flow divider.
Interesting. What did you end up doing to correct it?
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  #4  
Old 05-12-2019, 07:30 AM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by Nova RV View Post
Before you trim anything I would look for a partial blockage in an injector or the flow divider. I had this exact scenario (but in a 4 cyl) and it was something in the flow divider.
+1 to do this.
Suggest you first do the shot glass test to measure flow to each cylinder. Did this on an IO-360 with the same problem to find one cylinder getting much less flow at idle. The root problem was a tiny spec of crud in the spider.

Carl
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  #5  
Old 05-12-2019, 07:37 AM
bsvantho bsvantho is offline
 
Join Date: Oct 2012
Location: Rochester Hills, MI
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Quote:
Originally Posted by Carl Froehlich View Post
+1 to do this.
Suggest you first do the shot glass test to measure flow to each cylinder. Did this on an IO-360 with the same problem to find one cylinder getting much less flow at idle. The root problem was a tiny spec of crud in the spider.

Carl
Makes sense - will try that per the AFP manual.

Just out of curiosity did you see any issue while at cruise power?
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  #6  
Old 05-12-2019, 07:43 AM
Nova RV Nova RV is offline
 
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Location: Leesburg, VA
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Quote:
Originally Posted by bsvantho View Post
Interesting. What did you end up doing to correct it?
Flushed out the flow divider and it was good afterwards. Before you open the flow divider, do the flow test as Carl mentions and it will be clear if there is a partial blockage in that cylinder.
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CFI-I ASMEL, ATP

RV-14A kit # 140243 (flying as of 11/18)

www.mykitlog.com/chrismoon/
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  #7  
Old 05-12-2019, 07:50 AM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by bsvantho View Post
Makes sense - will try that per the AFP manual.

Just out of curiosity did you see any issue while at cruise power?
No - just at idle or low power. The symptoms were similar to a sticking valve.

Carl
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  #8  
Old 05-12-2019, 08:03 AM
bsvantho bsvantho is offline
 
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Location: Rochester Hills, MI
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Great, seems like the culprit, will do some testing. Thanks for the guidance guys.
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  #9  
Old 05-12-2019, 09:08 AM
amerkarim amerkarim is offline
 
Join Date: Nov 2017
Location: Houston Tx
Posts: 53
Question Flow test

Hi Guys,

Just out of interest

How do you do the flow test? What are the shot glasses for?

Best

Amer
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  #10  
Old 05-12-2019, 10:29 AM
Nova RV Nova RV is offline
 
Join Date: Aug 2015
Location: Leesburg, VA
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Check out pages 70-71
https://airflowperformance.com/wp-co...anual-9003.pdf
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CFI-I ASMEL, ATP

RV-14A kit # 140243 (flying as of 11/18)

www.mykitlog.com/chrismoon/
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