Oil cooler connections - VS

From my experience oil coolers are not in/out specific.

I second that.....Bruce

...you write: "There are two oil line connections on the bottom of the oil cooler"

the connections should always be on the top of the cooler. If one is in the lower position than the other, the lower one should be the "in" and the higher one should be the "out". Thats imbortant cause otherwise air will stay in the cooler. and this " air-bubble" will reduce the cooling effect significantly.

cheers Jan

Jan Peter Stahl posted:

...you write: "There are two oil line connections on the bottom of the oil cooler"

the connections should always be on the top of the cooler. If one is in the lower position than the other, the lower one should be the "in" and the higher one should be the "out". Thats imbortant cause otherwise air will stay in the cooler. and this " air-bubble" will reduce the cooling effect significantly.

cheers Jan

Interesting thought but isn't the tubing on those one way in and one way out? In other words as oil gets pumped in the air is forced out - there are no empty spaces.

Bob we are going to do our level best to get you completely confused.

Thank you, gentlemen.

Jan:

The cooler is mounted with both connectors at the bottom. That was another indicator to me that there is no difference in what lines go where. If there was a top connector and a bottom connector, I would be concerned. This system has worked fine since I have had the car, with no overheating. The fan seems to get the job done, even down here in steamy Florida.

Rusty, I started out confused. No harm, no foul, my friend!

As I think about Jan's comments, I think that when the engine is off the cooler must have air in it, as the sump, the external filler and the crank case all sit lower than the cooler, and gravity would cause the oil to drip down into them as the oiling system is not pressurized in the engine off condition. Is that correct?

Isn't the oil pump the only thing driving the oil through the system, there is no pump on the cooler and the engines internals are tossing the oil around that is made available by the oil pumps action?

If there's no leak and the pump doesn't let any oil bleed back into the sump (which it shouldn't) the cooler won't drain and fill up with air when you turn the engine off. And as everyone has said, it doesn't matter which end is in or out; if you think about it, oil just flows through and there's reason it can't run one way or the other. I do agree with Jan- If possible, both fittings should be at the top or intake at the bottom and out at the top (although if you think about it there shouldn't be any air pockets no matter how you position the cooler). Al

Al:

Thanks, I think you nailed it.

I think it really depends on the oil cooler type.

If it's a cooler like picture 1, it should not matter.

But if it's a cooler like picture 2 i think it matters a lot because if you mount these coolers with in- and outlet on the bottom, the oil will take the "easy way" and just flows through the lower part - the air stays in the upper part and will not go out. 

Jan

Jan,

I'm going to (in as friendly way as possible) disagree with the "air-pocket" hypothesis. Here's why:

Air pockets generally form in a closed system. If the system is open to atmosphere on the low side, and the pump is strong enough, it will push fluid through all of the piping and attendant what-nots on the "high-side" of the system. Any air in the system will be pushed along by the wall of fluid pressure building up behind it, because it has a place to escape to.

In a hydronic system, air-pockets form because the loop is closed and trapped air has nowhere to be vented. The air almost always moves to the "low side" of the system when they do air-lock. We put air-vents everywhere, but there's seldom air in the "high-side" of the system. The oil coolers are all part of the high-side-- taking 100% of the oil from the oil-pump.

The oil-pump itself is high-pressure/high-volume and self-priming. The suction side of it is at or near 0 psi, and always immersed in oil. The entire engine is an "open system" (is vented to atmosphere on the low side, which is the crankcase), so the thought that the "radiator-style" oil cooler would vapor-lock with a pump as big as a standard oil-pump is almost impossible.

In order for what you are saying to be a problem, the oil-pump capacity would have to be really, really tiny. It's not. That pump moves a lot of fluid, and is capable of generating a LOT of "head-pressure". With thick oil, it will generate enough pressure to explode a standard oil filter, and enough volume to empty the crankcase in seconds.

Anyhow, the "radiator style" micro-channels (the passageways between the "tanks") are pretty small. The oil-pump is going to fill the supply side of the radiator (cooler) first, because the oil-pump has way more capacity than the bottom couple of rows of channels. Once the tanks fills, the pump is going to push through all of the channels, fill the other tank (on the outlet side of the cooler), and then push through the galleys. There has to be a pressure drop across the sides of the cooler, but I'd bet it's small enough to be insignificant.

If the pump was lazy enough to not be filling the oil cooler, then the galleys would be seeing 0 psi of oil pressure. The fact that they see 40 psi+ tells me that the oil cooler is full.

As far as putting the fittings on the top-- I can see that there would be some advantage to that. The cooler could not drain down in the off-cycle (when the engine is not running), so it would remain full and able to supply oil to the galleys almost instantly on start-up. The disadvantage would be that the cooler would always be full of oil, and to do an oil change would require removing it and turning it upside down to get the oil out.

At least 75% of the people running oil coolers use the "radiator style" EMPI "Mesa"-style coolers. I'd be 95%+ have them mounted with the fittings down. They all work.