oil cooler hookup

[skidookid]

Does it matter what line goes on top or bottom of oil cooler or what is best way for oil to flow into oil cooler, top or bottom?

[TX7A]

In at bottom; out from top.

[p51dplt]

Originally Posted by skidookid

Does it matter what line goes on top or bottom of oil cooler or what is best way for oil to flow into oil cooler, top or bottom?

Why? What is the theory behind this?

[noelf]

If flow is from the bottom to top, then the oil cooler rods will fill with oil and have an opportunity to spend some time cooling the oil.

If flow is from top to bottom, then the oil will "fall" through the rods, maybe not at the same rate through each rod, and not cool as effectively.

This will be somewhat dependent on the volume of oil flow through the cooler. If the flow / volume /pressure is great enough, it will not matter. If not, then there is an opportunity for air pockets to form in the cooler and those areas will not contribute to cooling the oil.

[BillL]

It depends. In application, if the HX is mounted on the baffles, the lower side is getting some second hand air that has passed through the head fins - or so it seems. In that case the air across the cooler is hotter there than at the top. In that case highest overall delta-T between the incoming air and oil is attained with hot oil coming into the bottom of the cooler and out the top.

Based on delta-T, if it is horizontal, or had external flow, I don't know how it makes much difference.

That is my theory.

[rv7charlie]

In general terms, it's better to flow up than down, simply to purge air from the exchanger. Oil pumps move so much fluid that it might not be an issue in your particular install, but there have been lots of cases where significant portions of heat exchangers were 'air locked' and doing nothing to cool the fluid going through them. In non-Lyc installations, if both inlet and outlet happen to be on the bottom of the HX as mounted, it's common to install a small air bleed from the top of the HX top tank back to the reservoir.

I haven't heard of many, if any, Lyc oil coolers being mounted with horizontal flow & both ports on the bottom, but if it's done, there's a risk of 'air locking' the exchanger, at least to some extent. If 20% of the HX just has air, then you lost 20% of your cooling.

Charlie

[rvbuilder2002]

Originally Posted by rv7charlie

In general terms, it's better to flow up than down, simply to purge air from the exchanger. Oil pumps move so much fluid that it might not be an issue in your particular install, but there have been lots of cases where significant portions of heat exchangers were 'air locked' and doing nothing to cool the fluid going through them. In non-Lyc installations, if both inlet and outlet happen to be on the bottom of the HX as mounted, it's common to install a small air bleed from the top of the HX top tank back to the reservoir.

I haven't heard of many, if any, Lyc oil coolers being mounted with horizontal flow & both ports on the bottom, but if it's done, there's a risk of 'air locking' the exchanger, at least to some extent. If 20% of the HX just has air, then you lost 20% of your cooling.

Charlie

This is exactly the reason I always configure in at the bottom and out at the top.
Since we can't see inside a cooler to confirm what is happening (make sure it purges all air), it is best to make sure that air can not stay in the cooler.