Hey all I'm finishing up a custom turbo build and the cooling system is my last hurdle.

Setup:
-MMR crossover delete with filler cap
-Thermostat housing modified to cap off all ports except inlet/outlet
-gutted t-stat
- head cooling mod routed to turbo coolant Port
- turbo coolant outlet to nipple on driver side of radiator.
-Aluminum fan shroud with 16" electric fan


Issue:
Car is running hot. As soon as I drive the car (under 40mph), temp climbs quickly. I will shut down and cool off at 220f.

Possible problems? :
- fan not moving enough air?
I had a 14" fan and upgraded to 16" with no improvement. I know that neither will perform like the stock fan but I feel like this should at least take the edge off, especially with a shroud.
- no expansion tank?
I am running the "puke hose" off of the filler cap to a tank that has the outlet on the bottom of the tank and it's vented. Is this enough or do I need to add an expansion tank to the system? If that's the case, do I just eliminate the t stat and go with the GT lower hoses?

Thanks in advance.
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Did the shroud help the ect's? What type of coolant are you running? I would suggest rmi-25 with 100% purified drinking water. What is the fan trigger set at?

 

Shroud did not help. I had just the 16"slim fan on the rad, then shroud from mishimoto with 14"fan, then modified shroud to fit 16" fan. At warmup or while bleeding ects are around 190. Fan comes on then. As soon as I drive (under 40mph), coolant temp rises quickly. I turn on the heat and pull over before 220f.

 

Also running about 60/40 water to coolant with MoCool additive.

 

Update: I received two 11" high output fans from mishimoto and installed them today. I re-bled the coolant and the fans actually cycled bringing the coolant temp below 185. (They turn on at 190).

Feeling much better I decided to go for a drive. The fans once again kicked on at 190 and the temperature stayed much more steady. However it consistently rose (driving under 35mph) and I pulled back into the driveway. The fans were running and held temp around 210 but wouldn't drop it.

I grabbed the rad hoses and the top one was definitely 210 but the lower hose was significantly cooler. I was able to grab hold and not have any discomfort.
Thoughts?

 

Pretty normal for the bottom hose to be a good bit cooler than the top with a good radiator. I've heard a lot of issues with aftermarket fans on these mod motors, which sucks because my stock fan isn't going to work with my turbo setup either.

 

check your not running retarded timing ?

 

Timing can definitely add more heat to the system.

The expansion tank is more about maintaining pressure and preventing cavitation than heat rejection. Personally I stuck with one for my build. It's possible if you start to lose pressure you can get cavitation, which will reduce flow, and cause more cooling issues. What is your pressure cap rating?

Do you have any numbers for the airflow on the fans you're using, and if applicable with what restriction? I switched to some Intrepid dual fans, which should have a better flow rate than the stock fan. The MKVIII and Taurus fans are other popular upgrades.

 

I can check timing however it's on a base file from a reputable tuner so I'd imagine the timing isn't too out of whack.

I am now running 2 mishimoto high output 11" fans. They are rated at 1700 cfm each so 3400 total cfm which tops the stock fan.

I've added a 180 thermostat just to dispell any concern that there isn't enough restriction. If I go start the car right now it will reach about 190, fans will kick on and within 45 seconds cycle the temp down to about 180.

I only have problems if I drive the car. I will cruise around and get it to 190, the fans kick on, but the temperature slowly rises. If I continue driving it will rise quickly, if I come to a stop it will slowly rise until I shut down. I don't let it pass 210.

 

your issue is on the Thermostat Housing setup

can you please post some pics ?
part number on the Thermostat ?

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I'll get better pics tomorrow. It's a stock unit that I capped off the auxiliary passages. It's still using the factory inlet and outlet. The t stat is I believe a 180 degree from advance auto. I tested it in a pot of water the other day and drilled two small holes to assist in bleeding

 

If you do a SEARCH you will find some of the issues that most people have with that setup.

Like others, I had the same issue that you are having..

The easiest way to fix your issue is putting the Thermostat Housing in the return hose on the top.<this is how I fix it>

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This will probably sound crazy, but I think you should try a higher temp thermostat. With the one you have it never closes, just pumping hot water on top of hot water in your radiator and it doesn't have time to cool off sufficiently. I don't know anything about mod motors, I know they are their own thing, but I've found this to work on gen 1 SBC's almost everytime.

 

I've searched 4 different forums lol. I didn't find anyone with a similar issue. Out of curiosity what is the advantage? Does it open sooner?

 

I'm open to try it, but the lower hose is definitely cooler than the upper so it would seem that the rad and fans are cooling the way they should.... Then again I wouldn't be posting if they were lol

 

the problem is that you modify the oem T housing & delete the by pass hose/return line from the oem cross over tube.


Take the oem Thermostat Housing setup out of the cooling system & run a strait hose.

Then go from there

I use a SBC IPSCO Thermostat Housing on the top

http://www.ipsco.org/Custom Services/Remote thermostat housing custom.htm


with a 180 degree sbc thermostat and drill at least 4 3/16" holes in it. Also make sure you put it in facing the correct direction.
Note the head cooling mod goes in front of the thermostat.

for your setup you are gonna need the 1 1/2" Hose to Two (2) -12 AN Ports
like this one

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Wow that makes a lot of sense. So what about this... If I weld a fitting on the t stat housing and run the line from the turbo to that. The turbo runs from the head cooling mod. As long as that's in front of the stat, it should work?