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.

The oil temperature sensor is in the pressure channels just off the oil filter. It is measuring oil temp of the oil that is entering the pressurized lubrication passages in the engine.

The only thing I cannot answer on the VHR specifically is if it is before or after the oil filter, because I have not taken the upper pan off and followed the oil passages in the upper pan casting. If it is before the oil filter, meaning just inline after the pump, then we are not able to see the immediate effects of the oil after leaving our aftermarket coolers. If it is after the oil filter, then we are seeing the immediate effects of our added coolers. I have an extra VHR engine sitting in my garage to use for my built engine project, sometime in the next few weeks when I take it apart to begin the build I can report back the answer to this.

But regardless of all that, the oil temperature sensor is definitely in the pressure channels after the pump.

Also, engines do not really have much of a return path for oil. The only passages for it are positioned near the cylinder head studs so that the oil can leave the cylinder heads and just drip back into the open crankcase down the sides. The upper oil pan itself, does not have any oil return passages.

Refer to service manual page LU-7. There you will read it instructing you to test engine oil pressure by removing the oil temp sensor and installing the nissan oil pressure test gauge hose. This is the only evidence I have at the moment of what I am saying... but it is clear evidence.

Hey guys, not sure if this will help, prior to the start of this thread I have read several other related oil cooler threads and combined several discussions into one post here: http://www.the370z.com/1435977-post21.html

I have re-posted it here. If its of no help and only boggles this discussion I will delete it. Let me know. Btw this is a great thread, subscribed.


Re-post:


Something to add to this thread (even if it's only for my own reference later when my memory has gone) since I have been reading through a lot forum threads lately on oil coolers, low oil temps, mocal thermostatic sandwich plates opening temp, the general oil temp we want to see coming OUT of the engine block, and block off plates. There a numbers of good threads on the topics. I have compiled the posts pertaining to the above mentioned topics and included the links to the threads for reference and further reading.

Here are some comments by Dustin from Z1 Motorsports who sells oil cooler kits.

http://www.the370z.com/815172-post115.html


http://www.the370z.com/engine-drivet...tml#post815915


http://www.the370z.com/drivetrain-en...ml#post1418647





Another good thread on the complete explanation on how the Mocal Thermostatic Sandwich Plate Operates:


http://www.the370z.com/drivetrain-en...tml#post990449


.

Well done ZForce. I was looking for that thread. :tiphat:

I think your wording is off... this isn't oil coming back to the pan, it is oil leaving the pan to the block.

All in all I wouldn't see this being a major issue anyhow... once the oil is at operating temperature, the oil in the pan/block/cooler are eventually going to meet some sort of equilibrium. Even without a cooler you have to beat on it pretty heavily to get an immediate and sharp climb in oil temperature and that is generally only 10-20 degrees.

Glad it was helpful :tup:

Opps, correct. Been a little sick.

The cover in the DIY by Speafish is so easy its not even funny. I did mine in 15 mins. Do it and be done with it. My temps are 180-200 now. Im in Germany and with it cooling off before the cover was on, I was seeing 160 for the oil temps.

You do realize the limp mode serves a purpose, yes? It took time to program, and time means money, and no corporation spends money without profit in mind, and what profit is there to be made with a limp mode unless warranty work were avoided by having it...

Glad the DIY link helped. :tup: I plan on installing my 25r oil cooler in the next few weeks and will testig out the correct plate coverage for ambient temps in the mid 30's plus. Will be starting with covering 80% of the cooler and go from there. Ideal dash gauge temps will be 170-190 with actual temps being 190-210.

I know I'm digging up an old thread but since, you know, "search the forum first..."

Thanks a lot ZForce and Dustin@Z1 for the info RE: post-OC temp readings. I used to feel a HUGE drop in power at about 225* (anyone else notice this?) before I got the OC. The OC install dropped my average temps LOADS so I thought the problem was over, but now I feel the power drop at around 205. It was baffling me for the longest time but that MUST mean the in-engine oil temps are basically about 20* hotter than the gauge says.

I just wish the car wouldn't pull so much power at 225*. I mean, it's terrible, even flooring it in first gear does near nothing until 4000rpm. :-/ Do you all get this lag at those temps?

Oh, on a side note, has anyone noticed turning on their AC ironically brings engine temps down about 10*? It's pretty consistent. I'm in Vegas, and I'd usually just bear the heat, but I actually HAVE to turn on AC just to kick in the fans to help cool my engine when it's lagging like hell.

:tiphat: No problem sir!

The drop in temp may be because the Aux fans kick may automatically kick on when the A/C is cycled on. I have honestly never paid any attenion to the 370Z and how this behaves. But I know most old school vehicles did this.

I would look at the IAT's that are coming in as well. Being in Vegas, the air is thinner, the pressure is lower, and it's much hotter. Did you notice it dropping power at 205 in the winter? I'm fairly certain the motor is pulling timing because it's sucking in air that's as hot as a hair dryer. An oil cooler does help maintain power, it's definitely not the cure all for maintaining it consistently through weather changes.

This is just an educated guess so please don't take this as word of God.

While we're on the topic of oil coolers, I have a stupid question. Are you guys using more than 5 quarts of oil? I might be 1 quart short (~ 10mm from H mark). I'm at 1,300 miles now since the last change.

I use exactly 5qts of oil and it puts me right at the high dot on my dipstick, and I too have a little bit of oil consumption. The service manager told me that it was normal

The behavior varies by vehicle design, but I too have definitely observed that a Z with normal ECU settings runs colder with the AC on. This seems counter-intuitive at first since the AC should be (a) adding engine load and (b) adding a little more heat back into the radiator via the condenser (the heat extracted from the hot air to make it blow cold). However, as noted by Dustin above, it's the fact that the ECU turns on the electric radiator fan(s) more often that makes up the difference and then some, due to increased airflow through the radiator (esp at lower speeds).

UpRev can now control this behavior: there are independent settings for AC-on vs AC-off which control fan duty cycle -vs- water temps. Aside from turning them on earlier in general, you can set the AC-on settings the same as AC-off and then you don't have to turn on the AC just to get the fans going.

Thread here: http://www.the370z.com/tuning/51935-...available.html

Just read through this and i have a question on this part:

If I am not misunderstanding the bolded part, it is saying the oil temp gauge in the car is reading the temp before the oil gets run through the engine correct?

So if I am seeing temps of 190* on the guage, that would mean the temps for the oil coming out of the engine is probably a bit higher than 200*?

Also if I am not misunderstanding, the oil temp we are predominantly concerned with is the temps leaving the engine?

Just wanting some clarification. :tiphat:

:tiphat:


I am not experiencing the lag your are experiencing at 225, then again I am located in a cooler region and we have not experienced yet this year any higher temps than 82 degrees. Looks like Dusting, SSFire and wstar covered the a /c fan. :tup:
_

The 25 row oil cooler takes an additional quart when filling up the belly pan which puts it at 6-6 1/8 quarts.

If you are at 10 mm then its about a little bit above 1/3 quart oil consumption.

OK Same topic (maybe different stupid queston) Just picked up a 2012 nismo (production date 11/11) and there is NO oil cooler on the Veh. My quess is Nissan installed on later productions. Any one Know if this is the case?

Don't take this the wrong way, but you do know that the stock cooler on the '12's is not a front mounted air to oil cooler right? All the stock one is, is a glorified sandwich plate to allow engine coolant to cool the oil.

which I might add is not nearly as effecient as the air to oil cooler. The warmer your oil gets the warmer the coolant gets and vice versa. I was extremely disappointed when I saw that nissan did this. They should have done it the right way.

So if I were to install My Z1 cooler, would it be better to tap in to the oil circuit and have both cooler's or remove the OE one. If it is water cooled then it is also warmed quicker in the winter right?

Don't know about adding a Z1 cooler to it but yes water-oil cooler is going to bring your oil temps up quicker in the winter versus a oil-air cooler.

Yeah this has been my assumption also since I got the car over a year ago. IAT's just getting too hot. Now that I have the oil cooler I never reach a high enough temp to feel the lag. In summer the air is hot, but the car still produces great power until about 20-25 minutes into a journey when that 205 (ergo 225) temp is hit, then it kicks on the lag. So it must be the already hot air coming in compounding with massive heat-soaking that's heating up my cold-air-intakes (Stillen G3s). I've flipped up the hood a couple of times when it's lagging and my intake pipes are too hot to touch. How do I check my IAT readings?

I have the Stillen 25-row. Mine takes about 5.5 quarts. But I don't drain the OC core when I oil change. Should I be?

That's exactly what I though, which is why I was surprised when I succumbed to the heat and turned on the AC and saw my engine actually cool down. :icon14:

This sounds good. I also read somewhere on the forum that Nissan's stock ECU maps are overly harsh on pulling timings in response to hot IAT readings, and I'm hoping that, with Uprev, the power-cut won't come so willingly.

if you keep a "dual" cooler setup you won't see much of a change because the oil and engine coolant are crossflowing. I woudn't thnk that it would be a reasonable setup to have, imho.