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Dual oil cooler, answer to overcooling

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In doing research I come across how the dual oil coolers badly overcool the oil. The explanation is simple, the oil thermostat doesn't really shut off oil to the coolers, but provides a bypass and this is not sufficient. Shrug, TADT, cut out an oil cooler, switch to an expensive alternative.


So, in a thread on oil coolers, and low oil temps, someone linked to a mishimoto oil cooler sandwich plate. Nice looking piece. Slightly different layout. Looks like it not only provides a bypass, but restricts flow to the coolers. I dig the sandwich plate I purchased years ago for my twin cam, and sure enough, same thing, but not as nice as the Mishimoto.

Order one up on Amazon.
https://www.amazon.com/gp/product/B009AMOX48/ref=oh_aui_detailpage_o05_s02?ie=UTF8&psc=1

Nice

Ordered a pair of little gauges
https://www.amazon.com/gp/product/B001QJ9JX8/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B001QJBDJ6/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

Set up a little test.

conditions:
62-65 degrees [drops slightly from cracking garage door]
car idling, standstill
the oil temp gauge is too slow to react so the temp measurements are from a handheld non contact thermometer aimed at the oil pan. I have the gauge data, also.


results:

see for yourself. the stock thermostat is a POS, it is bleeding warming oil in just a few minutes, where the Mish. unit basically never does. While it is not that much different vertically, look at the time scale horizontally, there is nearly ten minutes for the stock setup to get across a given temp line, and that is without any air through the coolers. It will get worse when moving. The radiator fan comes on 10 minutes sooner.

At the end of the last test revved the engine up and measured again, the oil coolers do indeed get warm when pushed and hot with the mish unit. I will try it after it cools down again to see if the higher revs and force of the oil pump makes it flow more before the thermostat opens. It will still be far better than stock.

155 bucks all in[actually 136 , I used the stock sandwich plate adapter threaded piece, wasted 18 bucks on the mish piece]
oh, and two m20 to 5/8 BSP adapters and a couple of copper washers,

will use the 1/8 NPT port for the temp gauge

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2005 Ardent Red Elise, Touring Pack
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View attachment 1324802
In this picture you can see the oil tube that sprays oil onto the cam. The lobes on my intake cam that were wiped were the ones under the hole marked 1. When I blew air through the tube I found vary little flow coming through those holes. So I very carefully opened them ( a little at a time) till I had even flow. The part marked 2 goes down in to the head and has a seal on it, this was old and not sealing well. so I replaced it. I will find the part number later today. I found my cam was wiped 2 weeks after buying the car. Sense no one seems to be sure why they wipe I did several things to guard agents it happening agin; Mishimoto switch plate 200f tstat, MWR harden cams and their bigger rockers, oil temp gage, I don't have a cat so I run a zinc additive, and lastly never ever get on the happy cam till oil temp is 180+.
Hope this helps. There is a lot of knowledge here and some may disagree with me, thats fine listen to them too, they could be correct.
Sorry for the short highjack of the thread.
Thanks! That all makes sense. Thanks also for looking for the part number for the seal you mentioned
 

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2006 Lotus Exige
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478 Posts
Thanks! That all makes sense. Thanks also for looking for the part number for the seal you mentioned
I can’t find my seals. I will keep looking this weekend, I didn’t want you to think I was putting you off. I am sure you can take the old one to a parts store and find the right size. I bought several of them from the Toyota dealer. I’ll post when I find them

once agin sorry for the high Jack
 

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Discussion Starter · #783 ·
I think you should create a post about this. Not because I don't want this info here, but because some may not read it because they have become bored with this thread. I think this is potentially important information

View attachment 1324802
In this picture you can see the oil tube that sprays oil onto the cam. The lobes on my intake cam that were wiped were the ones under the hole marked 1. When I blew air through the tube I found vary little flow coming through those holes. So I very carefully opened them ( a little at a time) till I had even flow. The part marked 2 goes down in to the head and has a seal on it, this was old and not sealing well. so I replaced it. I will find the part number later today. I found my cam was wiped 2 weeks after buying the car. Sense no one seems to be sure why they wipe I did several things to guard agents it happening agin; Mishimoto switch plate 200f tstat, MWR harden cams and their bigger rockers, oil temp gage, I don't have a cat so I run a zinc additive, and lastly never ever get on the happy cam till oil temp is 180+.
Hope this helps. There is a lot of knowledge here and some may disagree with me, thats fine listen to them too, they could be correct.
Sorry for the short highjack of the thread.
 

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Discussion Starter · #784 ·
Once I hit 180 I am all over the happy cam.
If everyone is worried about oil temp because of cam wipe I think we are making to big of a deal of oil temp. Oil temp may play a part but the big player is the way it oils the cams. That is the BIG problem. You best make sure you keep a good seal on that oil tube and check that it is flowing evenly and those last holes are getting oil. So yes oil temp is part of it but only part. I keep seals on hand so I can replace it after I pull the cam cover a few times.
I keep trying to convince people to not bother with the higher thermostat. For whatever reason, the failure rate seems high

I set out on this because people were like 'Oh, that is how it is, TADT, nothing to be done'

I never said[in fact noted that we do not know why cams wipe] but have proposed this as an improvement as cold oil is not in any way 'good' and this is a low dollar way to ensure that if it is causing a problem, it is less of a problem
 

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2006 Lotus Exige
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I keep trying to convince people to not bother with the higher thermostat. For whatever reason, the failure rate seems high

I set out on this because people were like 'Oh, that is how it is, TADT, nothing to be done'

I never said[in fact noted that we do not know why cams wipe] but have proposed this as an improvement as cold oil is not in any way 'good' and this is a low dollar way to ensure that if it is causing a problem, it is less of a problem
I do agree with you. I am sorry I should not have brought cam wipe into it. I was new to Lotus is why I went with the 200f thermostat, seemed like that was the one to use. Now I am not convinced it is any better than the 180.
 

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Less is Better
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I thought I'd check to see if my 200F thermostat was working as it should so I ran the car at idle and measured the oil cooler temperatures with an IR thermometer. What I found was that after 5 minutes the left cooler (the hotter one) quickly rose up from ambient to 25F over ambient (96F) at 10 minutes and then 59F over ambient (130F) at 15 minutes. This suggested to me that the thermostat was operating like the stock sandwitch plate in @exigegus's first plot, not his Mishimoto plot. I assumed the thermostat was bad so I replaced it with the 185F thermostat and reran the test. I made sure that the assembly matched Mishimoto's drawings. Big spring in first, then the collar taper towards the big spring, then the thermostat, then the cap, then the small spring, then the screw. All looked good coming out and going in. I was really surprised to find that the results were pretty much identical give or take 3 degrees.

I decided to see when the pin in the 200F thermostat popped on a bench test. I heated the base with a heat gun and measured the temperature with the IR thermometer. The pin popped up at about 90F. This actually makes sense when I look at the temperatures that I saw on the oil cooler of about 96F at 10 minutes. But certainly much less than 200F. I did verify that I'm measuring F, not C.

I'm kind of at a loss now. Maybe it's possible that both my thermostats are defective and open at 90F, but that seems really unlikely. Very odd. I've reached out to Mishimoto to see if they can help describe what I'm seeing, so we'll see.
 

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Not sure what the proper test is for thermostat pellets, but probably heating water is the best idea
Also not sure about the dynamics, whether the spring pressure is required etc
Melting wax heat flows pretty quickly so I doubt there's much to the method as long as you know what the case temp is. The bench test is secondary, however, to what I'm seeing with the oil cooler temperature. The sandwich plate is definitely not behaving as you observed.
 

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I explained that I found the pin popped at 90F to Mishimoto customer service. They said it must be defective and they'd refund my purchase. I haven't tested the 185F thermostat but I suspect it's also "defective" as it's behaving exactly the same way as the 200F. Now I have to find a thermostat that actually works as it's supposed to.
 

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2005 Ardent Red Elise, Touring Pack
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I am running the Mishimoto sandwich plate on my '05 NA Elise with dual oil coolers. Swapped from the 200F thermostat to the 185F and saw perhaps a bit shorter oil warmup time, and the same steady temperature range once up to temp (before getting on the fun cam) of around 180F-182F according to my particular gauge. Once I get on the second cam I can keep the oil temperature between 190F-200F.
Ambient temperature was between 70F-80F when comparing the two thermostats. Unfortunately I could not keep that variable exactly the same.
This tells me that the 200F thermostat was likely acting as if it were stuck open the whole time, so there is no harm in using the 185F thermostat. Worst case scenario, it's acting the same as the 200F and best case scenario it's doing its job and is giving me a little faster oil warmup time.

I'm now convinced to try completely bypassing the cooling system in my NA street car, retaining the Mishi sandwich plate in order to continue to measure oil temps at the plate.
 

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Off topic but related, whats the safest high temperature for stuck in gridlock with no airflowing over radiator?

I was stuck in LA rush hour for an hour and the temperature rose to 215. As soon as I was able to get moving again the temps dropped back down to 190. I think my only upgrade is the aftermarket aluminum radiator.

It was a 100 degree day, while I was watching it hit 215 I think I turned off the AC. In hindsight I think my truck midlines on 210 so this is probably acceptable.
 

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At 215F the fans switch to full speed.

Here is factory description of radiator fans operation:

The cooling fans are switched as a pair, and will operate at half speed (connected in series) when coolant temperature reaches 98°C on rise, and switch off at 94°C on fall.

If coolant temperature rises to 103°C, the fans will switch to full speed (connected in parallel), reverting to half speed at 98°C.

The fans will also run at half speed when the a.c. is switched on and the compressor is running, or if the engine management system detects a fault with the inlet air temperature or coolant temperature circuits.
 

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2005 Lotus Elise; 2007 Lotus Exige S; 2012 Porsche 991S
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Finally getting around to installing the mishimoto sandwich plate during my oil change this week.

Had a question though, does it matter which oil line goes to which connector on the new sandwich plate?
 
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