this was a nice project...i'd really like to know how it went

Well, that engine is no longer in the car, but not because anything went wrong. Just....bigger plans.

As for the reroute, it worked too well actually and once my new engine goes in, I plan on modifying it. Having the coolant flow from the back of the head into the heater core and back to the rad instead of the mixing manifold is what I plan to change. Even with a temp sensor blocking off more than 1/2 the heater hose, the flow thru the heatercore and back to the radiator instead of the mixing manifold made it take FOREVER to get to operating temps in cooler ambient temps. Even worse, at speed with the GS rad, I couldn't get my coolant temps above ~120 on a cold day. Basically, it's like running without a thermostat b/c water bypasses the thermostat and goes rightback to the radiator.

I know that neogenesis and paul did very similar things and had similar resutls. IIRC, in the cold, paul blocked off 1/2 his rad so that he could keep his coolant temps up. I'm thinking about putting a inline valve into the heater lines so that at the track/summer, I can keep it wide open for the extra cooling and almost close it for better warmup in the cooler weather.

may i know what you did with the bypass lines?thanks

http://i57.photobucket.com/albums/g2...antrouting.jpg

those lines are trivial...

so i can just ignore them and perhaps just put in water plugs and simply concentrate on the coolant return line?

That might affect the IAC in its warm up idle up funtion.

BRG ...

Initial post, Pic 4.

What thermostat are you using? I find with a std (centered) Thermostat the ECU Thermosensor probe will contact the T-stat spring.


As far as heater return lines go, how about a heater control valve?

A heater control valve ( Honda Civics ) could prevent flow all together. No coolant flow = no mixing of rad outlet and hot heater core liquid. You can keep the factory heater core return line location as well.

Does it matter if the fan switch is before or after the t-stat? I looks like theres enough space next to where you tapped for the heater hose for it. Other wise I guess I could put it in the hard pipe going to the rad?
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Has anyone found the actual thread size & pitch for the 1.6 thermostat housing ? M14-1.5 (oil plug) seems to work but not quite exact. I too am doing a reroute (believe it or not, a bit different than all the ones I've seen) and I need to plug up the 1.6 t-stat housing (pipe plug preferably).

You can use the 1.6L housing with the original fan switch. Leaves about an 1" of clearance when modified like this....

1. Take original fan switch and cut plastic housing off that surrounds the sensor pin.
2. Carefully bend pin 90 degrees facing the passenger side. ( this is dependent on which side you route the return to radiator )
3. Take original plug, and remove plastic surrounding the female terminal.
4. Slightly compress female pin to increase tension. Then after connecting zip tie wire to T-stat housing. ( Important! You must have zero tension on pin or it will break off pin on sensor. This is accomplished with a decent sized pigtail when moving the original wiring.

Ill post a pic soon.

Olderguy can answer that

M14 x 1.5 is correct.

I have used the 3/8 npt tap (for drilling the oil pan)
And a 3/8 plug. Worked nice...

I am thinking about trying this as well. I have the basic BEGI reroute in right now that basically just circulates the coolant exiting the heater core back into the upper radiator hose (instead of the stock mixing manifold). It takes awhile for the car to heat up and will only get worse with the winter coming. I saw a link around here somewhere for a inline remote thermostat housing. Using something like that, and a hole drilled in the flange of the thermostat for constant circulation should do the trick?

Either that, or I was going to try teeing into the lower radiator hose, instead of the upper, though this is basically back to the stock arrangement. But, at least the tube running under the exhaust manifold is still removed which should help cooling a bit.

Ok this simple reroute is getting to be a PITA! I see why now there are 13489756 ways of doing this and none are 100%

Ok here my latest issue. Drill cursed water plug and tap it for ECU sensor, ok for drill and tap and I can't for the life of me see how is will NOT hit the thermostat? I have oriented the thermostat every way and it still looks like it will hit. Check it out.

Anyone actually done this and ran the car? Did the spring bind with the sensor?

a simple Male/Female adapter could fix that..

tap head for adapter, screw in. screw thermosensor into adapter. case closed.


something like this: http://www.mcmaster.com/itm/find.ASP...string=4822T42

https://www.miataturbo.net/forum/att...hermostat-.jpg

It definitely fits. Brian and one or two others have done this way as well without thermostat fit issues. FWIW, I was also able to rotate the thermostat so the little bleed valve was at the top as you are supposed to have it.

Sorry to bump this thread, but I'm in the process and have a question. What would be the negatives of having the fan switch (green one, correct?) in a different location like inline in a hose or in the front block of plate?

Reason I ask... I am doing this with the engine in the car and can't tap the head. I also want to use the current blocked port for my heater core feed with a 90* brass fitting to point it the right direction.

I have a MS1 so no need for the thermoswitch.

Bumping this for two reasons, thanks brg for the write up. Just finishing up doing mine.

The other reason is I was running into the same problem as icantdo55 with the t-stat spring hitting the clt probe. I starting looking at his pictures compared to what I had, and we had the same t-stat. Then I looked at brg pics and he had one of his t-stat. And it is defiantly different from the one I was trying to use.

So I went over to the local kragens and did some searching. The part I got is a "Murray Plus+ Thermostat" its 192* and I believe it came up on the computer for the 1994 to 1997 Miata's (probably wrong with the years). But the part number for that is 41492. I also got out there parts book and it says it fits Miatas and Kias.

Anyways heres a couple pics to show the difference. The thing is more off centered compared to the one I was using and the little bit helped get the thing to fit in there.

Again, thanks for the write up and hopefully this helps somebody out.