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Oil Cooler Fittings

MED

Well Known Member
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. :confused:
 
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.
 
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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Thanks for the responses. You guys are making me feel better about my decision to use steel.
 
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. :confused:

Yeah... can you call Vans about their mistake in your kit so that they make the change?
 
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.

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.

[
 
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.
 
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
 
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.
 
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.

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:

IMG_20170303_191229.jpg


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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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.

Thanks for adding the additional details.
They are important to understanding why your issue occurred and show that an aluminum fitting in an aluminum oil cooler isn't automatically a disaster waiting to happen.
(not arguing the fact that a steel fitting is a bit more forgiving)
 
Thanks for adding the additional details.
They are important to understanding why your issue occurred and show that an aluminum fitting in an aluminum oil cooler isn't automatically a disaster waiting to happen.
(not arguing the fact that a steel fitting is a bit more forgiving)

Fair. The additional details were critical and should have been included.

It's worth nothing from page 5-34 (bolded shown on that page):

"While the manual has been crafted in such a way as to minimize contradictions between the instructions provided by Van's and the instructions provided with a part/assembly that is included in the kit (wheels and brakes for example), should there be an instance where the instructions from Van's contradict the instructions provided with a particular kit component, those of the component manufacturer shall take precedence over those provided by Van's."
 
When torquing the hoses to these steel fittings what is the right torque? I think it is a lot higher according to my handbook but it seems very high compared to the aluminum torque values.
 
I'm adding this reply after randomly learning of the concern (googling what others have done fitting up oil cooler). This is exactly one day after installed aluminum fittings on my oil cooler.

I recently discovered Loctite "567" which has PTFE as mentioned by Tom and I now use it everywhere. The fittings went in "like butter" and clocking was not an issue, so I'm sticking with the aluminum fittings. (I did change the aft fitting of to a 45 as I routed my hoses a bit differently from standard).

I've also used Loctite 565 which works well but the 567 seems to have better lubricating qualities.
 
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