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Ls1 Miata overhears!! 250 degrees! Help please

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Old Sep 13, 2010 | 11:17 PM
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Unhappy Ls1 Miata overhears!! 250 degrees! Help please

Running a hugeee double pass radiator on my 01 Miata with an LS1. I have a pulled AND a pusher fan, the puller fan is located at the drivers side of the radiator covering a little over half the radiator while the pusher is located on the passengers side, so the 2 fans are not fighting eachother.

I have a 160 thermostat installed.
The radiator fill cap is located at the highest point of the system and I am having extremely odd cooling system issues. The PCM is set to turn on the puller at 160 degrees and the pusher is turned on by my command (switch)

City driving in 90 degree weather temps sometimes stay around 210 but most of the time see 220, never seen more than 225 according to aftermarket gauge.
On the highway, I saw temps of 220, no less than 215. Then it RANDOMLY climbed to 240, then back down to 220 on the highway, I tried turning the fan off and on when going 60 down the highway and it made no big difference.
Then I exited and temps skyrocketed to 250+, both fans full speed ahead!
I pulled over and the overflow began to SPRAY coolant for 15 minutes STRAIGHT!!!
I let it sit for 30 mins, added warm water to cooling system, started the car and started adding water while it was idling. Steady 200 degrees. While adding coolant it just started steaming and boiling EXTREMELY hot water and just kept coming out what seemed like endlessly!
I don't get it?!
I even tried parking with the front at an extreme incline!
Why is it boiling over with the cap off as im trying to fill it? Air pocket? I gave up and parked the car for the night.

I don't understand if I have an airflow issue or air pockets or what?!
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Old Sep 14, 2010 | 01:37 AM
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On initial fill, did you turn the heater on high for 10 minutes & only run the car for 10 minutes, let it cool, fill up & then repeat a second time? Do you have the front steam vents connected from the heads to a high point (top hose or filler neck)?
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Old Sep 14, 2010 | 02:01 AM
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Steam vent is connected to radiator.

No heater connected at this time.

I should let it run 10 mins then what?
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Old Sep 14, 2010 | 07:38 AM
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Before it overheats and all is well with both fans running, is there a lot of heat being removed by the fans?
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Old Sep 14, 2010 | 09:29 AM
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Kinda, they don't seem to blow enough CFM but why does it overheat on the highway?!
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Old Sep 14, 2010 | 09:41 AM
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Fans may want a shroud that makes all the air blow through
and not escape sideways.

Were the coolant crossover tubes preserved? Thermostat
have a proper bubble relief?
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Old Sep 14, 2010 | 10:09 AM
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The only way of bleeding the system is through the fill cap which does sit above the engine.

Yes the ls1 crossover tubes on top of the heads are being used, and the steam vent is installed on one of the radiator end tanks.
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Old Sep 14, 2010 | 11:04 AM
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Ok this is retarded.
How am I going to ever fill these engine up with coolant?

This morning, I went out to a COLD car, started it up, let it idle and obviously fluid maintained a proper fill level (full).
As soon as the thermostat opened up, the level went wayyy down, in which I added fluid and let it sit to allow any air bubbles to escape. Well, instead, it boils over (temp at this point on the gauge is 180)... It continues to keep COMING OUT! How do I fill this thing up?!
I am even using a funnel.
Even after shutting the engine off, it kept continously POURING out a steady stream through the filler without any obvious air bubbles coming up.
It kept coming out for a good 30 seconds before going down.

What the hell???
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Old Sep 14, 2010 | 12:31 PM
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As I stated. Turn on, run 10 minutes, turn off, cool down, open filler cap, fill. Then, turn on, run 10 minutes, turn off, cool down, open cap, fill...Then a third time. Make sure over flow tank is full before doing any of this. After third time, cool down & fill, then drive 5-10 miles, turn off, cool down fill (should be full).

Initial fill, you should fill the block through the hose running to the top of the water pump. Fill until coolant mix overflows out of the top of the radiator, then reconnect the water pump hose & fill remaining through radiator fill cap.

It's either not full or you have a leaking head gasket. I'd say it's not full. Get it right; you're gonna flake some moly coating off of your piston rings if you keep it up. Then, you'll be pulling the engine.

As jimmyblue asked, are there air vent holes drilled into the thermostat housing?
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Old Sep 14, 2010 | 01:34 PM
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Will try that.

No air vent holes drilled, should I do this?







Last edited by 1SIKZ31; Sep 14, 2010 at 01:59 PM.
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Old Sep 14, 2010 | 02:10 PM
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Yes, add a top & bottom hole to the t-stat flange. Hole should be in the 3/32" diameter range.
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Old Sep 14, 2010 | 06:19 PM
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Here's a REALLY stupid question, don't get pissed I'm asking it: Is the water pump turning in the correct direction?
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Old Sep 14, 2010 | 06:20 PM
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Whats size thermo fans are u running?
Is this setup new asin the radiator and thermo fans?
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Old Sep 14, 2010 | 06:46 PM
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lmao
No idea if the water pump is going the correct direction??? Which way should it go standing in FRONT of the car?
lol

The radiator is a TIG welded "Double Pass" radiator, it is NEW, and am sure can handle a 1000whp+ application by looks alone, lol.

The E-Fan on the rad. one that came with the radiator, and you cant even feel the air coming out of the damn thing unless you put your hand like 1 foot or less away from it. Which is why I also installed that pusher fan on the AC condenser!
That thing flows "OK" at best, I can barely feel the air running through the radiator, so the conclusion is LOW air flow, EXCEPT the fact that even at highway speeds it gets very hot.

I have driven it in stop and go traffic and it has stayed at 220, so this all isn't making sense.

By the way I removed my Oil cap, looks good.
Checked my Oil, looks Good.
I also drilled those 2 holes in the thermostat, but had issues with the water running out of the "fill", so this is a really annoying thing to deal with.

Whats next?
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Old Sep 14, 2010 | 07:05 PM
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I ask about the rotation because I think something is very wrong with your setup. I'm pretty sure that GM had some installations of LS engines where the belt routing was different and the pump went the other way.

Where did this pump come from? Was it with the engine from the donor car it came from? What was the donor car? As I'm assuming you had to do some *interesting* mods to get it all to fit and work in a Miata, did you retain the same pump and belt routing?

When all is normal, the radiator and fans should be putting out a good amount of heat which would indicate everything is OK. If there is little heat being removed from the radiator by the fans, the heat is staying in the radiator and going back to the engine.
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Old Sep 14, 2010 | 07:12 PM
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Maybe your water pump is just shot. Perhaps the impeller is rotted and it's now just a spinning disc with no vanes left on it.

You can find out: With the radiator cap off, when the thermostat opens, you should be able to see coolant coursing through the radiator. If this doesn't happen, the pump is not pumping.
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Old Sep 14, 2010 | 08:33 PM
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I have no idea what you're talking about, water pouring out of the fill. If you fill the block & the radiator correctly & w/ a working water pump, the engine will cool properly. It's quite simple.

From the pics I see that the pump is running in the correct direction (belt from tensioner to under side of pump pulley) according to how the belt is routed. Also, see that it's a 98 & earlier pump. How many miles on the engine? Check the pump, as noted by others.
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Old Sep 14, 2010 | 08:54 PM
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Fixed!!!!

HA!!!

So like I said the filler does not take ANY more coolant, and is full.
I promptly removed the upper radiator hose, DRY!
Proceeded to add... wait for it... ONE POINT FIVE GALLONS of coolant to the system! ***>?!? lol

Anyway, holds 190 all day long!
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Old Sep 15, 2010 | 12:25 AM
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AHH that's great. I was just about to ask how hot the hoses were. Coulda been a few things but sometimes it's the simplest things.
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Old Sep 15, 2010 | 11:41 AM
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Your welcome
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