Oil cooler question

[joe_db]

Do any of you have oil coolers?
If so, do you have the water flow on the cold (inlet) side or the hot (exhaust) side of the cooling system?

[hanleyclifford]

Mine is on the "exhaust" side. I can see the value of cooling the oil right out of the pump before the coolant goes to the block but the plumbing could get complicated.

[joe_db]

What I meant was are you using hot or cold water. I think I explained it wrong. Normally I see oil coolers being cooled by cold raw water, but Indigo suggests using it on the hot side of the water circuit to heat the oil when cold and then cool it somewhat when it exceeds the hot water temperature. If IIRC, you want the oil to be at least 180 degrees F to boil off moisture. Airplanes have blocking plates to cover the oil coolers in winter for this reason.

[hanleyclifford]

I use hot water as Indigo suggests but I don't believe the A4 could ever have the problem of oil being "too cold". It might be interesting to measure coolant temperature just as it leaves the pump to see what temp differential the system is capable of.

[hanleyclifford]

When I first contemplated the idea of an oil cooler for the A4 I realized that the bled off oil from the relief valve was not going to deliver any meaningful quantity of oil to the cooler. Likewise tapping into the pressure side and then discharging cooled oil into the pan was bound to play havoc with the oil pressure. I ended up with an oil cooling/filtration loop totally independent of the engine's oiling system. In the picture you see the pickup (lower tube) and return (old fuel pump rod hole).

[romantic comedy]

I dont see that an oil cooler would be that useful. Seems most engines run cool anyway.
Also how can you have an oil cooler and not have an oil filter. How would it be plumbed?

[ndutton]

Hanley,
What type of pump are you using for the oil cooler loop?

[hanleyclifford]

Originally Posted by ndutton

Hanley,
What type of pump are you using for the oil cooler loop?

http://www.mcmaster.com/#4161k21/=qkfyml However, as you can see I did not pay attention to the mounting instuctions.

[ndutton]

Your answer raises more questions. 115VAC??

[hanleyclifford]

Originally Posted by ndutton

Your answer raises more questions. 115VAC??

Yes, the black box in the background is a 500w inverter. However, the pump is available in 12v. Edit: Looks like I lied; the catalogue no longer shows the 12v models (which I did not buy because they were considerably more expensive.

[ndutton]

the black box in the background is a 500w inverter

OK, that answers that. I commend leaving the oil pressure system alone and doing this in an auxiliary fashion.

You've gone quite a distance to cool the oil, what operational benefit have you realized as a result? Was filtration part of the installation or was it pure cooling? Was there something that indicated cooling the oil was necessary or did it seem like a good idea and you figured out a way? How much additional oil is required with the system?

WOW, one answer breeds four more questions.

[romantic comedy]

I just need to know why we would want to cool the oil.

Oil is a complicated fluid, and much different then water or anti freeze.

[hanleyclifford]

The original reason was to maintain viscosity and thus oil pressure. But there is also a heat dissipation payoff. Heat is the enemy of mechanical devices and shell bearings in particular. I have confirmed that simply by flipping the switch oil pressure rises by 5 psi. Remember, I use my boat very differently from most of the forum members - long trips with engine running 10-12 hours cruising at a stretch. A bonus was the incorporaton of a "full flow" oil filter just after the exchanger the benefits of which are known to all. The system requires very little additional oil, perhaps a pint. And just to anticipate Neil's next question ("How do you maintain prime on that non self-priming pump installed above the oil pan?"); the bleed-off from the pressure relief valve is directed into the pump supply side.

[joe_db]

Oil can be too hot or too cold.
Too cold - water and other contaminents never boil off. Thick oil is hard to pump and may result in excessive oil pressure.
Too hot - oil gets too thin and oil pressure falls. The oil will break down much quicker than usual.

[hanleyclifford]

That is a nice looking gauge; is it an aircraft gauge? The green range appears to coincide with what I think is acceptable for the A4 - does anyone have an oil temp gauge on their A4?