Oddjob

Installing additional oil cooling on a wet sump engine (specifically a 944 series engine, but this question probably applies to any wet sump motor).

Top of the additional oil cooler is a couple inches higher than where the lines return to the block (on the oil filter housing).

My concern is that when the engine is shut off, oil will drain out of the oil cooler until level w/ the filter housing. So there will be a couple inches of air volume in the cooler that will be pushed thru the oiling system each time the car is driven.

I believe the oil flow path goes thru the cooler, back thru the filter and then to the bearings. So I would think any air in the system would have to go out thru the bearings, which is a bad idea.

So, after I have all my AN lines/fittings cut and installed, I am thinking I need to drop the oil cooler lower to avoid it possibly draining back to the block.

Agree?

Van

I put a transmission cooler on my car, and I had that very issue. I ended up putting a check valve on one line, and a very light "pressure relief valve" on the other line. This keeps oil in the loop and prevents it from draining back.

Matt Romanowski

Get one of these https://www.cantonracingproducts.com...ion&key=24-280

jittsl

That's what I have on the output to cooler line of my tranny cooler and it seems to work perfectly. I also have the cooler, the pump and the filter all mounted with their nozzles facing upward so that they stay filled with oil. The only drain back I have is the small amount that resides above natural oil level and below the nipple of the filter. Van's suggestion of "a very light pressure relief valve" is probably the ultimate answer to all drain back.

stownsen914

Check valves can be restrictive even when open. You might want to consider this before putting one in your engine oiling system. Even putting the cooler higher than the block causes the oil pump to work harder than it otherwise would, which isn't ideal. (I wouldn't worry as much about either of these things for a for a tranny cooler.)

Scott

JoeMag

Not sure what cooler you have, but i've read to put the inlet into the bottom of the cooler and the outlet on the top. This way oil will push the air out where it naturally will go...

my trans cooler is way higher than trans oil level (probably 1 foot), and never had an issue. pump controlled based on trans temp.

stownsen914

Thought of one more thing ... since you're concerned about drainback of oil to the engine, make sure to mount the cooler with the fittings at the top of the cooler (i.e. facing up). This will ensure that the oil in the cooler cannot drain back to the engine. For a wet sump engine oil draining back to the engine between runs means that upon startup, the oil pump has to fill the cooler before your engine bearing get any oil pressure. I'd imagine this would take at least a few seconds, maybe longer. That kind of delay in getting oil to your bearings can't be good ...

Oddjob

Thanks for the thoughts/input guys.

Just to follow up w/ this:

I have spare engine parts and took a look at the flow channels in the oil filter housing. Took the thermostat out and filled it w/ water to see where the level sits before it would drain back into the block.

I did confirm that w/ the thermostat closed (cold start up), the oil coolers and lines will be back filled by oil flow underneath the oil filter, so they will fill on start up/idle. I did have the concern that they would sit w/ air in them until the thermostat opens, but that is not true.

After looking at all of it, I decided to re-route my oil lines (lower) and also lowered the oil cooler about 1" - so my system should stay filled w/ oil after shut down.

Gary R.

Looks good and you have the perfect avatar for a 944 motor!

Van

Ahhh, feel the love!