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I need to do a re route
I looked at heaps of posts and it looks to me like I can just swap the front and back thermo around and then rearrange some new hoses etc
Sounds simple
IS IT ?

Yep.

do you have a heater?

Does your ecu turn the fans on?

Dann

Yes to both

Its slightly fiddly retaining the heater.

Essentially, you remove the front thermostat hoising and neck etc. And replace with a welsh plug.

Run a hose around the back of the head.

Take the front thermostat housing, remove the sensor, and cut off its boss and block the hole, weld to it a small fitting to feed the heater core.
If you lose the heater you dont have to weld this barb on.
Put the front thermostat houring at the back of the head, with a thermostat in it.

You are done.

Dann

thanks mate I'll have a look tomorow

na6.

Dann

These pictures might help.

Am I missing something
why go to all the trouble of finding spacer blocks etc is it for looks or what
why can't I just reverse the thurmo housings around and buy some length of hoses
It looks like the sensor on the back would hit on the firewall so why can't I just plug the hole and buy one of those adaptors from super cheap that goes inline
The heater hose can run around the front
I'll have a look at supercheap for a hose that might be the right shape

Everything you just said is right. The block is for the heater core feed.
This is why I mentioned welding one to the housing.

You mentioned the water temo sensor adaptor from supercheap, you dont need one, as your ecu turns the fans on, and that adaptor is only for people who need that front sensor to turn the fan on.

Dann

Looks like neither sensor will fit back in the housings
the back one hits the firewall and the front one hits the plastic cam belt cover
I think I need the one from the back as i think the temp gauge reads it
where does the ecu get its coolant temp signal from

olboy

This DIY coolant reroute on an NB8A might help:
viewtopic.php?f=76&t=40239

olboy wrote:where does the ecu get its coolant temp signal from

The green rear sensor - see pic just over half way down this page:
http://www.miata.net/garage/CoolingSystemProblems.html

There are 3 temp sensors.

The front one,
This is a thermoswitch, it is used to turn on the fans. If you have an ecu that controls the fans you can forget this completely.

The green larger rear one,
This is the temperature sendor for the ecu, it controls fueling and cold starts.

The small rear one, this is for the guage.

The small rear guage one is mounted on the head itself, however when you remove the rear housing to fit the front thermostat housing, you will remove the ecu temp sensor, this is why you need to either weld a fitting to the thermostat housing, or use the fitting from supercheap you mentioned.

Does that help?

Dann

Sorry to dig up old thread, but am likely to do (or get done) an engine swap in the next month in my NA8, gonna do oil filter relocation at same time, just wondering is it worth doing a coolant reroute? Are they really that necessary? For street use and the occasional 'spirited' drive?

No.

Sqeet