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  #1  
Old 08-18-2018, 11:07 AM
MED MED is offline
 
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Location: Aiken, SC
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Default Oil Cooler Fittings

The elbows provided in the kit for the oil cooler are aluminum, but the oil cooler box specifies these elbows be steel. I am planning to use steel, per the manufacturer’s requirement. I assume Van’s supplied aluminum for weight considerations, but wonder if I might be missing something.
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  #2  
Old 08-18-2018, 11:12 AM
jrs14855 jrs14855 is offline
 
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Default fittings

Aluminum fittings, especially in soft aluminum such as the oil cooler, are likely to gall the threads. This in turn may lead to the fitting seizing in the cooler before the proper torque is reached. Use the steel fittings with sealant such as titeseal on the threads.
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  #3  
Old 08-18-2018, 01:34 PM
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RV-14E RV-14E is offline
 
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I learned about "galling" during the install of the oil cooler with the AN822-8D aluminum fittings. As I was gently torquing them in, I could feel grinding. In fact, when I pulled the fittings out, it was clear the threads on the cooler were damaged.



So, I scrapped my oil cooler, bought a new one and went with steel fittings, AN822-8. They glided right in.

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Last edited by RV-14E : 08-18-2018 at 01:52 PM.
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  #4  
Old 08-18-2018, 02:06 PM
MED MED is offline
 
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Thanks for the responses. You guys are making me feel better about my decision to use steel.
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  #5  
Old 08-19-2018, 11:36 AM
Andrew Anunson Andrew Anunson is offline
 
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Quote:
Originally Posted by MED View Post
The elbows provided in the kit for the oil cooler are aluminum, but the oil cooler box specifies these elbows be steel. I am planning to use steel, per the manufacturer’s requirement. I assume Van’s supplied aluminum for weight considerations, but wonder if I might be missing something.
Yeah... can you call Vans about their mistake in your kit so that they make the change?
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  #6  
Old 08-19-2018, 11:55 AM
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G-force G-force is offline
 
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I'm curious what thread sealant you were using and ws the cooler anodize? I install thousands of aluminum on aluminum NPT fittings every year in the automotive world and never had one gall as long as I am using Loctite 567 that has PTFE in it. I suspect that welded assemblies such as that oil cooler leave you with a much softer thread than say the heat treated casting or billet 6061-T6 piece I typically deal with. I really doubt they are able to reheat treat such assemblies after welding leaving you with a dead soft thread material.

Quote:
Originally Posted by RV-14E View Post
I learned about "galling" during the install of the oil cooler with the AN822-8D aluminum fittings. As I was gently torquing them in, I could feel grinding. In fact, when I pulled the fittings out, it was clear the threads on the cooler were damaged.

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  #7  
Old 08-19-2018, 12:02 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by G-force View Post
I'm curious what thread sealant you were using and ws the cooler anodize?
I am curious as well.

Your second photo clearly shows use of a sealant similar to Loctite 567, but the first photo shows no indication of what thread sealant might have been used.
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  #8  
Old 08-19-2018, 12:34 PM
TS Flightlines TS Flightlines is offline
 
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whether aluminum or steel, you NEED a sealant for the NPT thread into the cooler. And, the sealer also acts as an anti-galling lubricant. PTFE is what we use most of the time.

Tom
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  #9  
Old 08-19-2018, 01:36 PM
Bavafa Bavafa is offline
 
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I used sealant and had no issues of course not flying yet so I can't say if I would have any leaks but considering how tight they got since they are 90 degree and clocking is critical, I am not expecting any leaking.
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  #10  
Old 08-19-2018, 04:34 PM
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RV-14E RV-14E is offline
 
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Quote:
Originally Posted by G-force View Post
I'm curious what thread sealant you were using and ws the cooler anodize? I install thousands of aluminum on aluminum NPT fittings every year in the automotive world and never had one gall as long as I am using Loctite 567 that has PTFE in it. I suspect that welded assemblies such as that oil cooler leave you with a much softer thread than say the heat treated casting or billet 6061-T6 piece I typically deal with. I really doubt they are able to reheat treat such assemblies after welding leaving you with a dead soft thread material.
Quote:
Originally Posted by rvbuilder2002 View Post
I am curious as well.

Your second photo clearly shows use of a sealant similar to Loctite 567, but the first photo shows no indication of what thread sealant might have been used.
Indeed. It was a learning experience for me and reflected my inexperience at the time...

When I installed the first fitting with thread sealant (not shown), I was concerned with how much torque was required to clock the fitting per plans. The fitting very quickly accumulated significant torque prior to reaching the desired clock.

Then I executed the mistake: I decided to "test fit" the second fitting in the other port (the one with the ruined threads in the picture above) without sealant (I didn't want to have to clean and reapply sealant if I had to back out the fitting with sealant initially) to gauge the torque. When the fitting started to grind (with surprisingly little torque), I backed it out to find the damage shown.

I returned to the oil cooler instructions to find the following delineated at bullet 5:



Note: "Use only steel hose fittings to connect to oil cooler ports."

I then searched online to learn why Airflow might direct to use only steel fittings. And thus the educational (and occasionally expensive) nature of building your own airplane took hold as I learned about "galling" for the first time.

Had I not foolishly attempted to temporarily position an aluminum fitting in an (very soft) aluminum port without sealant, I would not have learned about galling and might have missed Airflow's direction to use steel fittings.

Whilst I appreciate the RV-14's (and other models') plans stating to use aluminum fittings, and had personally seen three flying RVs with those fittings, I opted to follow Airflow's guidance and went with the steel fittings on my replacement oil cooler.
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Last edited by RV-14E : 08-19-2018 at 04:36 PM.
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