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SC400 1JZ running hot

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Old 06-29-14, 09:39 AM   #1
LoveSCs
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Default SC400 1JZ running hot

Hi CL!

I picked up a 1JZ SC400 a couple months ago:

70mm single turbo (alot of underhood heat)
aluminum radiator with dual electric fans (no shroud)
Front mount intercooler
tranny cooler with fan mounted in front of radiator

The temp gauge on the dash never showed any signs of overheating (although the temp gauge is obviously for the 1uz). A couple weekends ago, I decided to put a digital AEM water temp gauge in just because I figured its a good to monitor with precision.

I seen it as high as 218F on the highway, and drives around 206-210 around town. As I understand it, the operating temp is 180-200? The heat works, but does not seem to be blowing 210F air. The top radiator tube is hot, and the bottom is warm-hot, so it seems as though coolant is being cooled and pumped through.

Yesterday, I removed the AC condenser thinking it may have been blocking airflow, but didn't help much. I then figured since the heat was not scorching hot, I might have air bubble in radiator and read to bleed 1JZ, just remove rad cap (while engine cold) and run car up to operating temp.

While car was running, coolant was tiny bit overflowing the radiator fill hole. Just enough that putting a rag around it would soak it up. Is this normal?

Thanks!
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Old 06-30-14, 08:53 PM   #2
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Fixed it. It was the thermostat. That water temp gauge was the best investment so far...

This time, I opened the hood after a drive and the lower radiator hose was still ambient temperature, even though my water temp gauge got up to 216. So I knew it had to either be a clogged radiator or thermostat (water pump was recently replaced). While draining the radiator, the coolant was rushing out, so I thought it couldn't be a clogged radiator. Then I bought the thermostat and put it in. Funny how a $20 part can ruin your whole engine...

After taking the old one out, I put it in boiling water and it was only cracking open.

Now with the new one in, it idles up to 195, and cruises at 190. Perfect. I might titanium wrap the downpipe and maybe it will bring it down a tad more.

Just wanted to give an update in case anyone comes across this thread.
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Old 07-01-14, 02:58 AM   #3
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Thanks for updating.
My car actually started running cooler once summer came in, its pretty strange. but i will go check my cooling system too!
-Loki
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Old 07-01-14, 06:56 PM   #4
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my car is the same set up and it keeps getting hot I keep getting air in my set up I got a new head gasket and put it on and still same **** I took out the t stat and still I put a new cap on my **** and still over heating could it be the water pump and how do you check it
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Old 07-02-14, 05:16 AM   #5
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Quote:
Originally Posted by soarer1988 View Post
my car is the same set up and it keeps getting hot I keep getting air in my set up I got a new head gasket and put it on and still same **** I took out the t stat and still I put a new cap on my **** and still over heating could it be the water pump and how do you check it
I don't think getting air in the system is a water pump issue. You may have done all of this already, but check for coolant leaks, check your oil and make sure it is not milky, and do a compression test to make sure that the new HG is holding up. Then (engine cold), make sure you have sufficient coolant in the radiator (enough to see but not all the way to the top). Then, with the engine cold and radiator cap off, turn on and run the engine until operating temp, and turn the heat on full blast. Once operating temp is reached, the thermostat should open and you should visually see the coolant flowing through the radiator. Also, put a glove on and squeeze on the bottom radiator hose. You should see the level of coolant rise in the radiator, indicating a good pump. You should also be able to feel the flow in the bottom radiator hose. Top off the coolant in the radiator and put the radiator cap on. Add coolant to proper level in reservoir. This procedure should make sure you have no air in the system.

Good Luck!
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Old 07-02-14, 05:16 AM
 
 
 
 
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