Oil Coolers and Over cooling
 

For those of us with oil coolers, I hope you know what I'm talking about. I know the simple solution is to build some sort of shroud. However, all these thermostatic plates state that they only open at 180+ but clearly that isn't the case. Is there any way to adjust the plates so that it doesn't slowly trickle oil to the cooler causing overcooling? I'm doing an oil change soon and the plate will be readily accessible, building a shroud just seems like another headache albeit a simple one.

The plates are never 100% closed for a reason. They only close to about 90% to prevent thermal shock by introducing cold oil kept in the lines/cooler to the engine once the engine oil temps reach a certain temperature.

The only real way to prevent over-cooling is to block a portion of the airflow to the cooler.

I figured...

The shroud is the simplest and most effective way anyways. Hard for a properly secured sheet of aluminum, cardboard, plastic, etc. to fail. :icon17:

You guys do realize that the oil Temp you see on your gauge is the Oil Temp of the oil temp returning to the Pan correct. This is the Temp coming from the return of the Oil cooler and not the Temp of the oil in the engine.

I'm pretty sure this is an impossible question to answer... but i'll put it out there anyways

Any idea what the temp of the oil entering the engine is based off what the gauge is reading.

ie: gauge reads 160, but b/c of some educated guesses, the oil entering the engine would be ...?

I did not know that but it makes sense. However, no matter how you break it down, I need an oil cooler for spirited drives in NY but it definitely leads to overcooling in NY winters. Anyways in the Long Island area want to make an extra shroud for me :)

You could do it in a few minutes. There's a DIY somewhere using some velcro and a sheet of aluminum (or plastic or anything else) that you could reach in and install/remove with ease.

Yeah I've seen the velcro DIY I'll have to get around to it, we're having a mild winter thus far in NY so I'll be driving the Z for a little longer than expected.

I'm still waiting to put my winter tires on... it's been so warm lately. :shakes head:

Not true... oil coolers (at least in the US) are aftermarket and there is no temp sensor anywhere inline on our cars (unless someone added one).

This should be the temp at the bottom of the block or oil rail and has nothing to do with the returning oil.

I never said it was "on" the return line from the oil cooler. I said

The FACTORY (OEM) sensor reads this Temp on the block on the return path to the oil pan. As seen in the attached Pic. Any more questions?

So what's a likely temp differential then?

Yea. Do you have an oil flow chart of the previous pick you posted. I already have a way to override the limp mode with the computer. The reason I ask is cause I have never heard of such a major problem on a car, and also have never heard of someone trashing a motor because of this situation. Unless someone proves otherwise I think this oil temp thing is nothing more than having a stupid guage on the dash. IF anyone has trashed an engine due to this please chime in. Thanks... (I know there are alot of debates on this subject and im not trying to start crap. Im just looking for facts on the situation)

Actually, with the standard Mocal thermo plate most people are using, the lines to the oil cooler are never closed even slightly. The thermostatic valve operates on the bypass flow that skips the cooler. When you're under 175-ish, the bypass is open and most of the flow bypasses the cooler because it's the shortest path (but the lines to the cooler are wide open and some flow goes through them, gradually warming up the cooler itself). From 175-185-ish, the valve gradually closes off the bypass passageway, forcing all flow through the cooler at 185+.

I only recently found out about this myself, but the general idea is that yes, the oil temp gauge is reading the coldest point in the cycle if you have an external cooler. The oil that's about to enter the cooler is probably significantly hotter. Still, the value on the gauge is the one you care about for overcooling. If it's too cold at the coldest point, that's right before it gets pushed to the top of your engine to lubricate the very critical stuff (your VVEL heads). Assuming it's even true, which I haven't seen any direct evidence of. But either way it's unimportant for the purpose of discussing overcooling.