Crack in oil cooler mount

[jim skala]

RV9 with just over 1000 hours.
The aluminum piece that the oil cooler is mounted to was found to have developed a long vertical crack in the bend area, running the length of the oil cooler, and the oil cooler then had play where it could move a bit (maybe 1/16") where the crack could open. At the top end, the crack had not yet completed its run, and it was the only thing left holding the oil cooler. This crack is in the aluminum sheet angle that the oil cooler is mounted to.
Observing the crack: Push the oil cooler aft with a little pressure. If there is a crack in the mount, it will open the crack a bit and the oil cooler will move a bit.
Repair: First I stop drilled the crack at the top end. Then I riveted on two doublers across the crack, one at the center (0.40 aluminum, a couple inches from the top), and a heavy one at the lower end, where the crack probably started. The doubler at the lower end is 1/16" angle. This repair made the oil cooler mounting completely solid, very strong.
It might be good to install the lower doubler before the crack can start to form.

[vic syracuse]

This is a very common problem on RV's that have the cooler mounted to the aft cylinder. We probably see 75% of them cracked and needing a fix.

Check out my webinar for some pistures.

Vic

[RV8JD]

As others have pointed out, cracking of the baffle behind #4 cylinder with the oil cooler mounted there is pretty common. I purchased my first RV-8 with about 122 hours on it. The baffle cracked around 400 hours or so, IIRC. When we replaced the cracked sheet AL parts we also put in an extruded AL angle. The baffle has not cracked since, and that RV-8 now has 2,200+ hours on it.

I bought my current RV-8 with about 208 hours on it, and shortly after I bought it the baffle cracked on that one too. It has a brace between the engine case the baffle behind cylinder #4, but that didn't prevent the baffle from cracking. So we repaired it with the same AL angle fix, just as we did with my previous RV-8. So far so good, and I expect no cracking going forward.

Below are some pics from current RV-8.

Cracked:



Fixed:



Both RV-8s have parallel valve IO-360s, but my previous RV-8 has 10:1 high compression pistons. Both have Hartzell CS props.

I'm surprised Van's hasn't fixed that detail in the design yet (well, maybe not surprised since the RV-8s, 7s, 6s, 4s, and 9s are older models)!

(Oh, and "Skookum" is a technical term! )

[bjdecker]

In the for what it's worth department, at some point along the way - Van's changed the baffle material for Parts 4 & 5 in the IO-360 BAF kit from 2024-T3 to either 5052 or 6061 bare aluminium (unclad).

It's not reflected in the OP-04 drawing, but it's very apparent that it is now different material from the other pieces.

I don't know if they've changed this for the O-320, O-360, etc. baffles.

Cheers


B

[Scott Hersha]

On my latest RV8, I made a doubler angle at that corner that also went under the side baffle angle to tie them together. I made this angle piece out of steel, probably about .030-.040 thickness. Primed, painted, it looks like aluminum, but much stronger. No cracks.

[Ralph Inkster]

Also check for baffle cracking near the bottom inboard corner of the oil cooler. Pretty common to find cracks where the baffle starts curving under the lower half of #4 cylinder.