source of coolant flow image
 

I am installing a thermostatic oil cooler sandwich plate, external cooler, and coolant reroute. I was going to remove the oem water fed oil cooler, and cap the nipple on the back of the head as well as the nipple on the water pump because i installed the plate to block the oem water neck at the head versus leaving half of the water neck.

essentially deleting the coolant line route from; the pump-the water neck-the throttle body-oil cooler-back of the head. I might be missing some in that route, i am going off of memory, im not by my car currently.

I was just curious if this would disrupt or hurt the cooling system?




I seen this posting;https://forum.miata.net/vb/showthread.php?t=243270

and was wondering where i can find this image?
https://forum.miata.net/vb/attachmen...7&d=1185310790

If you delete the whole coolant path from the back of the head to the bottom of the thermostat housing and then onto the mixing manifold (which is what I believe you mean by the "nipple on the pump",) you will defeat a mechanism which flows water across the thermostat element when the thermostat is closed. In theory, this will delay thermostat opening. In practice, people have done it and I haven't heard of any engines exploding. My advice would be to retain this path even if you delete the stock oil cooler, which I very strongly do not recommend in the first place for a street car.



I believe that specific drawing is from a 1.8 NA manual, which I don't have in PDF form. This is from a '90-'93, which is essentially the same except that you have an oil cooler instead of the intake-manifold thermal air control valve:

https://cimg8.ibsrv.net/gimg/www.mia...a3af8b783e.gif

The thermostat is at the rear of the head, because I am using the qmax reroute, so there is no longer a thermostat even in the path that I am looking to delete.

Doing this just removed the coolant hose from the rear of the head to the oil filter to the IAC valve on the throttle body to the water neck to the mixing manifold.

I am removing the one water oil cooler because I am running a thermostatic sandwich plate with an external cooler.

What ill effects will result from; running a thermostatic plate that will open at 180*F and then go to the 19 row derale external cooler. Versus. Leaving the oem water cooler inplace with 180*F coolant flowing through it with no external cooler?

All good on that subject, then. No negative impact on the cooling system.




The OEM unit is not merely an oil cooler, but also an oil pre-heater.

After startup, the coolant comes up to normal operating temperature much more quickly than the oil. By passing warm coolant and cold oil though the exchanger, the temperature of the oil is brought up to a reasonable level more quickly than without it.

Miatas don't tend to have oil temperature problems in street use, even when turbocharged, which is why I qualified the statement. If this is a pure track car, then the extra cooling of an external unit will be beneficial, and the loss of the pre-heating function of little consequence. But if this car is a daily driver in a region which experiences cool temperatures (Like, St. Paul, Minnesota, just to pick a city and state at random), then the OEM unit will provide increased longevity of the oil, greater efficiency, and all the other stuff that advertisements for Brand X oil promise to deliver.


https://cimg9.ibsrv.net/gimg/www.mia...e2f572c8d1.png

Mishimoto actually tested this and provided all of their data to show the results, read through part 3&4. Essentially they say to leave it in place for simplicity of the install of their kit but removing the oem cooler showed no ill impacts.

https://www.mishimoto.com/engineerin...rm-up-testing/

Well, there you go. A company which sells a kit that deletes the OEM heat-exchanger has proven that removing the OEM heat-exchanger is beneficial.


In all seriousness, you're 100% clear on removing the line which flows from the back of the head, through the cooler and throttle body, through the thermostat housing, and into the mixing manifold. With a rear-therm reroute, it has no function other than to service the oil-water heat exchanger (which you're dedicated to removing) and providing de-ice to the throttle body. Actual cooling performance will not be negatively impacted.

They actually recommend NOT removing it, but state that if you do there will be no negative impact, and have the data to prove it.