Oil Cooler Failure

[DBentley]

How long should one expect an oil cooler to last without major failure? I have a flying RV6, 351 hours, and just completed my engine oil change as part of the condition inspection. I started the engine for the leak check and just got to idle when I heard a "pop" and oil came shooting out over the windshield and left wing. It's an Aero Classics 8000074, 9 row cooler, bought from Pacific Oil Cooler Service, and I've been flying for 5 years.

I'll call them on Monday and send it back I guess for repair. Looks like a separation at the top of one of the brazed rows, very clean. Glad it was on the ground, not in the air. Their web site recommends overhaul at 300 - 400 hrs. I always assumed they lasted considerably longer.

Duane Bentley
N515DB
West Chester, OH

[Geico266]

Welcome to VAF


What kind of oil pressure are you running? That seems pretty early to me for a oil cooler failure. Was it new or used?

[DBentley]

The cooler was new when installed five years ago. Oil Pressures - I don't recall specifically, but 60 -70 psi sounds about right. It was 75 degrees F and fresh 15W50 oil, so I don't think it was over presurred.

Duane

[Geico266]

Originally Posted by DBentley

The cooler was new when installed five years ago. Oil Pressures - I don't recall specifically, but 60 -70 psi sounds about right. It was 75 degrees F and fresh 15W50 oil, so I don't think it was over presurred.

Duane

Could have been a bad one from the start. Typically, an over presurized oil cooler will be "swollen". Sounds like you just got a "lemon".

Any unsual vibrations going on? It seems weird to be that it failed. Anyone else?


If it was gonna happen be glad it happened on the ground! We had a builder flying his Witman and a oil filter fitting broke pumping out all the oil in flight. He did a good job getting the plane on the ground, but there was some damage to the engine and he needed to tear it down.

[Bob Axsom]

I bought all of my original engine components from Van's including the oil cooler. I don't know the manufacturer but leaked early in my test flight period - someone pointed out the mass of oil on the belly when I refueled at Chino. I had discussions with the oil cooler service company in El Monte and because of cost decided to install a new one purchased from Aircraft Spruce instead. I installed it an in a move to prevent contamination while installing the unit I ran the oil line fittings on by hand. I neglected to tighten one of them. With a constant speed prop with normal start, taxi and run-up and a Vy climb out you can level out at 2,000 ft before the prop over speeds for lack of oil pressure and You can just make it back to the runway but not taxi off it before the engine seizes. The one installed after the crankshaft replacement and engine rebuild has served faithfully for 500 hours. The one I had in my Archer II had more than 4,000 hours of my time after 1,000 - 2,000 hours of other people's time with no problem. I agree with the opinion that your oil cooler had a latent defect and in no way reflects normal operational life expectancy. My normal in flight oil pressure is around 80.

Bob Axsom

[guccidude1]

Duane: Do you have a oil filter on the engine? An engine oil cooler failed at my airport recently, and the suspected cause was the oil screen being installed backwards. Dan.

[DBentley]

Yes, I do have an oil filter on the engine. The oil filter housing had a broken bolt prior to this event, so I removed the houseing replaced the bolt and reinstalled the filter housing and new filter. The gasget that goes on between the filter housing and accessory case has one side marked "towards the filter" and I installed that correctly.

What do you mean by filter screen in backwards?

Duane

[guccidude1]

Duane: Apparently, on engines without filters, a fine meshed cylindrical screen approximately 4" x 11/2" is used to filter the oil, it is designed to catch most particles with part numbers. My understanding is that it can be installed one of two ways, the correct way and the incorrect way. If installed incorrectly, backwards, the oil return flow is restricted and pressures high enough to blow oil cooler hoses or rupture oil coolers can be produced. Dan.

[DBentley]

Found the problem. It was me. When I removed the oil filter housing to replace the broken bolt, I put the housing back on with the new gasket on facing correctly - forward and aft. Unfortunately if was wrong, top to bottom. The oil pressure hole from the cooler back to the filter houseing was covered and apparently popped through coincidental with the oil cooler burst. Fortunately, the gasket material still had the "hanging chad" so no gasket material was lost into the oil system, or filter.

Thanks for the various suggestions. It got me to thinking and going back to the last changes in the oil system and working backwards.

Duane

[mannanj]

The oil pumps on Lycomings are capable of 400++psi depending on RPM, between the pump and the pressure relief valve. Most oil coolers can't withstand that pressure.