B5 A4: Oil Cooler DIY

Ok so after doing the DIY rear coolant flange, which was a bitch and took forever, I thought my coolant troubles were over. It turns out, however, that I was still loosing coolant but from where! I looked all over the motor but no bird shit stuff! Then that sad moment came where I pulled the dipstick... It bubbled on the end... BAD NEWS! So after consulting many people over here and searching, I found out what had happened. Basically it was either a bad head gasket or an oil cooler. Price? $1100 vs. $100.

So Oil Cooler it was. After talking to some shops they advised me that when the oil cooler goes, since coolant is more pressurized, youd lose coolant but your coolant reservoir wouldnt be that bad because no oil would really be comming back.

Also I read this from the Troubleshooting Guide on AF

"Oil Cooler - The Oild cooler on these cars uses a plate and plate heat exchanger. Oil on one side, coolant on the other side. Often the brazing on teh cooler can fail and oil and coolant mix together. This is often misdiagnosed as a bad head gasket. To test this remove the coolant hoses and apply air pressure to the oil cooler and watch for leaks. Oil cooler is located above the oil filter."

So to start my mission I ordered the OEM oil cooler from ECS tuning, along with a new magnetic drain plug and some oil filters.

I started off with a little ETKA Diagram



I jacked the car up and pulled the drain plug to drain my oil... when everything was out I put back in my new ECS magnetic drain plug and copper washer





Now onto the oil cooler... To get more room its a good idea to pull out the coolant reservoir... Its connected with a screw and 2 little clips. Be gentle with them you have to lift the reservoir at a weird angle but it comes out. Once its out pull the sensor out of the bottom and move it to the side. It should look like this.



Now I could get a good look at what I was dealing with...



You can see I boxed the oil cooler. Now, it has 2 coolant hoses connected to it as well as the oil filter... I proceeded by pulling off the first hose. There is a squeeze clamp on both, just move it to the side and start pulling on that hose. I had to use a flathead to move it a little because it had been on there for so long, just make sure you dont puncture the hose.

WARNING!!! MAKE SURE YOU GET SOMETHING UNDER THE CAR BECAUSE COOLANT WILL SPILL ALL OVER WHEN YOU TAKE THE HOSE OFF



Now onto the next hose, same thing. This one was a little harder but it came off eventually... When you have both off it should look like this



Now I skipped a little ahead on this pic ^ so you can see the oil filter is off.

This is the tool I used to take the old one off/put the new one in



Cost me like $4 for it... Make sure you take the oil filter with you when you get it so its the right size... So now everything is off and we just have to pull the oil cooler out.. There is a nut (#15) in the ETKA diagram, it should just come out real easy with your hand. Now, Take a flat head and pry the oil cooler out real slow... The oil cooler should start peeling away and eventually just slide off. Watch out because its a mess in there.

*Just in case you were wondering, the #13 gasket never came out when I did it so I assumed it was where it had to be and left it, if you see it come off with your oil cooler, make sure you replace it when u put the new one in*

Ok so now you got everything off... You got the nut, the old oil cooler, and the old oil filter.





So now its time to start fitting all your new stuff in.

Take the new oil cooler and slide it up exactly how the old one went. Connect the coolant hoses, it makes the oil cooler sit better when your trying to fit it up. Slide the squeeze clamps back over.



Now take your nut and thread it up tight. Make sure its got the oil cooler held pretty well. I tightened mine a little more with some pliars but not much. Now take your oil filter tool and get to work. The final product should look like this.



Now fill your oil with your choice oil, I do Mobil 1 Synthetic 0W-40...
Then fill your coolant with the OEM red G12 50/50 mix. Some may wonder why I didnt flush my coolant but since I caught this problem so early no oil ever got into it. you can see from this picture when I drained it it was still nice and red



Im not gonna lie my Rieger front made it a lot harder to find the drain for the coolant so that was part of the reason also...

Anyway I hoped this helped everyone. Crank her up and go for a drive! Hopefully your coolant in oil days are over!