The stock oil cooler in all FCs has a small thermostat located in the end tank of the cooler. At 140F the thermostat begins to open. This thermostat is located in the oil OUT part of the endtank.

Here is a picture of the thermostat:

The thermostat goes into this hole along with the heavy black spring.

In that picture you are looking at the bottom of the cooler. If you look closely at that picture you will notice a very small hole in the bottom of the cavity the thermostat goes into.

In order to understand flushing the oil cooler you need to look at the way the oil flows.

If you notice in the picture as the oil comes IN to the cooler it has two ways to go. One way is thru the end tank and out the OUT line back the engine (Bypassing the cooler ). The oil bypassed the cooler by flowing thru the small hole in this picture.

The second place the oil can go is THRU the cooler. The ONLY way this will happen is when the oil is hotter than 140F. At this temp the thermostat starts to extend and it blocks the small hole pictured above. So, the oil only has one choice on where to go....thru the cooler to be cooled.

So, why does all this matter when you are flushing out your oil cooler?

In order to flush the oil cooler and actually flush out the cooler and not just the end tank you need to PLUG the small hole the thermostat plugs. Why? Because the thermostat is at a temp lower than 140F so that by pass hole is OPEN.

This is just temporary while you are flushing the cooler.

You can use what ever plugs that hole...and is long enough for you to screw the large bolt back on it to secure it. This is just temporary while you are flushing the cooler.

I decided to use my center punch

Notice its pointy end. This will go in the same small hole the thermostat plugs.


There it is in the hole. Next you would screw that large 29MM nut head on it...don't crush it in there. Just enough to seal up that hole. You can see the 29mm bolt sitting on the ground.

I think the best material to use would be a wooden dowel rod with a pointy end.

You might think that it is just good enough to not plug this hole....but what ever you flush thru the cooler...and if the hole is still open....your flushing solution is going to do the same thing the oil does when it is cold. Bypass the oil cooler. Not a good thing if you are trying to get crap out of the cooler.

Hope this helps!

James

 

Nice job, and thanks for the pics

 

i smell an archive

 

what do u guys use to flush the cooler?

kerosene? gasoline? (for the cheap and dangerous)

do u get much particulate matter comin out of the cooler? or just old oil...

 

werd

 

I just ran water thru it first. Then started with the Simple Green and ran that till it was coming out clean. And then water until it came out clean.

Then ran compressed air thru it for a while.

Then let it sit in the sun to hopfully get all the water out of it. A little water still in there should not be bad. I should come out of the oil when it gets up to full temp.

I got dirty oil out of mine too. But I think this procedure would be really important if you had a bearing failure or something that could put anything into the oil like bearing material.

James

 

and what did the stuff comin out look like? anything different then a regular oil change would?

 

Just send it to a properly equipped facility that will hot flush it. Mine was cleaned, leak checked, tested and hot flushed by an FAA certified Facility that does nothing but clean oil coolers.

https://www.rx7club.com/showthread.p...ghlight=cooler

https://www.rx7club.com/showthread.p...ghlight=cooler

 

where be the pics?

 

I could not agree with you more man...there are a lot of oil coolers running around in the air since most small plane engines are air cooled.

However, if your trying to do it on the cheap....this will help you get a lot better flush than not doing this.

However, if your engine did spin a bearing or put metal in the oil. The expense of going to a FAA repair shop....could be worth it.

And at first it was a water / black oil mess.
James

 

nice! thanks =)

 

sweet thanks for the pic. this will help with my duel FC oil cooler setup I am going to try to get my fmic temps down.

 

Archive.