What do you think of this coolant reroute idea? - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 07-29-2007, 02:42 PM   #41
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lol basically what I said in different words.
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Old 07-30-2007, 11:19 PM   #42
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Don't forget about coolant flow to the turbo...nobody has talked about that here...

I have coolant coming out from the back of the head, after the t-stat (I've used the original OEM t-stat cap), using a J-shaped hose and going to the turbo. From the turbo, the coolant return goes back into the mixing manifold just before the water pump.

The rest of my reroute follows bbundy's: hole drilled in intake manifold, with fitting underneath -- goes to the heater core inlet. From the heater core, coolant goes to t-junction and returns to mixing manifold/water pump.
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Old 08-01-2007, 02:43 AM   #43
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Hey Jason, what do you think of these guys? They are saying that you can't do the reroute without a spacer. I am doubtful of their claims. Who is right?

http://forum.miata.net/vb/showthread.php?t=244148
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Old 08-01-2007, 01:11 PM   #44
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If the t-stat is closed and there is 0 flow past it, the coolant can flow out the front of the head, assuming you have the heater pickup point there.

If you're concerned about getting a bit of warmed coolant past the t-stat so it sees the coolant temp, there is a small, 3/8" pickup point in my head - I can't remember if factory used it, but I use it for the factory oil warmer, TB, and turbo.
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Old 08-01-2007, 05:14 PM   #45
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Yes, according to my engine, the 3/8" line pumps coolant through the intake manifold and then back to the water pump. You can see it join with the line just beneath the stock thermostat position.

I figure I can safely just run the 3/8" line straight from the intake back to the pump inlet and block off the connection with the thermostat stalk (presumably there for circulation past the otherwise isolated thermostat). This will actually ensure some amount of flow out the back of the head when the thermostat is closed. It is right next to the new thermostat location too.

One stupid question though, what do I do about the temperature sensor fitting that runs into the stock heater hose housing? I assume the TEC3 doesn't care, or it supplied it's own sensor for water temp that you have mounted elsewhere. I suppose I can run a wire to the front of the engine, though that will artificially reduce my coolant temp readings. Or if I can get the probe loose, I can just tee it in somewhere in the back of the head. I'm mostly curious what you did.
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Old 08-02-2007, 04:27 PM   #46
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I've done a reroute based on BBundy's diagrams and have put my CLT sensor (TEC3 setup) in-line using a T-fitting, just before the heater core inlet. That way, even when the t-stat is closed and coolant is still flowing to the heater core (fitting between #3 and #4 runner of ITM) and turbo (small fitting off back of head, on passenger's side of t-stat flange), you get a reading that (IMHO) is closest to actual coolant going through the block/head. I have the OEM temp sensor in a T-fitting from BEGi, and the fan temp sensor on the rear t-stat flange.
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Old 08-03-2007, 12:52 AM   #47
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Jason, I thought you said you didn't use a spacer. Where does that extra port beneath the thermostat housing come from? I have a 99 head and I dont have that port.

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Old 08-05-2007, 04:45 PM   #48
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Hey that kludgy job looks familiar!

I didn't use a spacer. The coolant source for the heater is from a hole I drilled and tapped in the head. This way I didn't need a spacer, I could keep the EGR tube, and didn't need to get it from all the way in front of the head.

see:



IIRC the temp sensor is screwed into an existing hole that has a plug from the factory. My memory could be wrong...

BTW because the heater supply is now a 1/2" hose instead of 5/8", heater is noticeably not as hot in the winter. Not really a problem in CA....
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Old 08-06-2007, 08:51 PM   #49
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Ok, so our setups are now exactly the same minus the drilled/tapped hole.

Oh here, look at what else I did to get moar flow from that 3/8" line-

It now flows straight from the intake to the pump inlet instead of providing flow for the stalk.
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Old 08-06-2007, 09:06 PM   #50
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The line from the front stalk is going to the heater core? Where is the flow from the back of the head going?
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Old 08-06-2007, 09:53 PM   #51
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To the radiator.

I ran a line up through where the coilpacks are usually bolted to the head, around the outside of the intake manifold, under the throttle and into the radiator inlet.
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Old 08-06-2007, 10:42 PM   #52
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Quote:
Originally Posted by beerslurpy View Post
To the radiator.

I ran a line up through where the coilpacks are usually bolted to the head, around the outside of the intake manifold, under the throttle and into the radiator inlet.
Call me crazy, but by your description you are starving the rear cylinders of cooling until the thermostat opens.
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Old 08-06-2007, 10:44 PM   #53
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The ideal situation is to have the cooling flow through the heater core, from the front of the engine to the rear until the thermostat opens, and then have the coolant still flow from front to rear, but then also coming forward to the radiator.
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Old 08-06-2007, 10:51 PM   #54
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But below 80C, how much cooling do the rear cylinders need? There is still that 3/8ths hose going out of the back of the head next to the thermostat housing.

I could put a 3/8ths inch or 1/2 inch restrictor in the heater hose so that the pump would draw more water out of the back of the head before the thermostat opens. If that fails, I can always order up a spacer and do the reroute that way.
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Old 08-07-2007, 09:16 AM   #55
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Quote:
Originally Posted by beerslurpy View Post
But below 80C, how much cooling do the rear cylinders need? There is still that 3/8ths hose going out of the back of the head next to the thermostat housing.

I could put a 3/8ths inch or 1/2 inch restrictor in the heater hose so that the pump would draw more water out of the back of the head before the thermostat opens. If that fails, I can always order up a spacer and do the reroute that way.
Where and how is the 3/8 out the back of the head going? Are you teeing it to the one in the front and putting them both to the heater?

Rather than doing that, I would say you would be better off not using the 3/8 line in the back, but drilling a 3/16 to 1/4" hole in the t/stat flange to allow initial back-of-the-head flow and the t/stat to see the temp rise.
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Old 08-07-2007, 10:00 AM   #56
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I'm currently in the process of a coolant re-route. There's a guy here who makes an aluminium pipe to go from the rear of the clock back to the top hose.

So I've swapped the thermostat housing and thermostat from the front of the block to the back, retaining the entire front 'stalk'. I've made a blanking plate for the front from 5mm aluminium plate, and have drilled and tapped for the water temp sensor to go in the blanking plate.

I use the exhaust side water line on the bottom of the front housing to feed coolant to the turbo - basically plumbing the turbo inline on that hose. The plumbing to the intake plenum is unchanged.

On the back of the block (in the rear thermostat housing) there is a 3/8"? outlet that sits before the relocated thermostat. A mate of mine fabricated up a brass inline hose join to step up from the small hose to the larger hose that enters the heater - that way the flow to the heater is essentially the same, and maintains flow while the thermostat is closed before it heats up.

I'll know if it's working once the replacement motor goes back in as of this weekend, as a result of a bent conrod a couple of weeks back.....
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Old 08-07-2007, 11:15 AM   #57
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I added two pics to my vb garage to show how I changed the coolant reroute thermostat to clean it up a little. It is the neck of a 1.8 thermostat cut off and sanded to fit inside the hose with the fan switch mounted in the original 1.6 thermostat cover.

The back of the motor has another 1.6 thermostat cover that I had a welder friend modify to give me the threaded hole for the temp sensor and the nipple for the heater line.

The thermostat has two 1/8" holes drilled into the flange so that the hot water flows to the thermostat so that it can see the temperature rise and open at the right time.

I have done the same without the heater core in the circuit to a friends 1.8, but drilled a larger hole in the thermostat flange for circulation before the thermostat opens.
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Old 08-07-2007, 03:21 PM   #58
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No, the 3/8th hose out the back of the head is going the stock route. When it gets to the front of the engine bay, instead of joining with the old thermostat location and then going to the pump inlet, it goes straight into the pump inlet from the intake manifold. The picture is above. That is the only mod I made.
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Old 08-07-2007, 04:35 PM   #59
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I don't think lack of cooling in the rear cylinders is an issue before the t-stat opens; you shouldn't be wailing on it anyway.
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Old 08-07-2007, 04:37 PM   #60
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Quote:
Originally Posted by beerslurpy View Post
No, the 3/8th hose out the back of the head is going the stock route. When it gets to the front of the engine bay, instead of joining with the old thermostat location and then going to the pump inlet, it goes straight into the pump inlet from the intake manifold. The picture is above. That is the only mod I made.
In my case it goes
back of head - oil warmer - TB - turbo - water pump inlet
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