Fj45 Engine Replacement with a 1hz

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Hello everyone
I replaced my fj45 engine (2f) with a 1hz and replaced the radiator with a bigger one.
The tempreture is OK in fall and winter but sometimes in summer, I have overheating problem specially when I use AC.
I have checked the water pump and it was OK.
I guess this problem causes by the exhaust.The old exhaust is for 2f engine and it might be small for 1hz because the exhaust gas comes out with a high pressure like a powerful hair dryer.
Should I replace my exhaust with a bigger one?
I would be happy to read your opinions.
 
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Definitely. Also, check fan and cowling fit. Presume your AC radiator is clean and not clogged?
Found this for you -
It has been a long time dream of mine to have a diesel version. I finally got my hands on one with only about 160,000 miles on it. It needs a bunch of work externally and electrically, but the engine itself is clean, especially on the inside.

One of the first issues that I had with the truck was that it was overheating. I spent countless hours tracking down and tracing down the problem. There were a few issues that were going on:

1. There was an undersized and wrong fan clutch installed. I replaced it with the Aisin FCT-025.

This was a huge improvement, and saw temperatures coming under much better control, but not sufficient to prevent overheating all together. An important and needed upgrade, but not the final cure.

2. I flushed the radiator and coolant system with Irontite. It took a couple of flushes to clean it out, the previous owner probably neglected this, or only ran water, but after three flushes, it started running clean.

This was also an additional improvement, and drastically reduced temperatures, but as with the fan clutch upgrade, it reduced normal engine temperatures, but anytime that I would start to climb a hill I would watch the temperature gauge rapidly rise.

Upon further investigation, we determined that the issue was the injection pump timing. The previous owner had done a timing belt and water pump change, but didn't calibrate the timing. I don't have the SST necessary to dial this in perfectly, so we eyeballed it and made slight adjustments to the orientation of the pump over the course of several days, and suddenly this thing was performing absolutely amazing. Tons more power, no more overheating, and much better gas mileage. I never realized what an effect timing had on engine temperatures, but now I know, and hopefully anyone out there searching for answers in their own projects can use this data that I've gathered. I'm waiting on the SST which I had to source from Japan so I can more accurately dial in the timing and improve the performance.
 
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The old exhaust is for 2f engine and it might be small for 1hz
The exhaust for a 2F 3F is the same diameter as the 1HZ (2 1/2 inch from memory). Do you know exactly what temps you are running in summer? Are you making black smoke?
Ive found 1HZ's tend to run a bit hotter in summer at high speeds. I always drop back to 4th gear and let them rev at about 2800 to 3000 to cool them down. I do this when the temps are above 35c
 
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The exhaust for a 2F 3F is the same diameter as the 1HZ (2 1/2 inch from memory). Do you know exactly what temps you are running in summer? Are you making black smoke?
Ive found 1HZ's tend to run a bit hotter in summer at high speeds. I always drop back to 4th gear and let them rev at about 2800 to 3000 to cool them down. I do this when the temps are above 35c
When the temp is over 37-38 this happens to me but it happens even in low revs not just in high speeds.
I have no black smoke but sometimes white smoke in low revs when I accelerate.
 
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Do your radiator hoses get hard after about 5-10 mins and stay hard when it gets hot?
A new radiator cap can do wonders as well as checking the radiator hose clamps.

What sort of radiator did you use and does it run at the same pressure as a 1HZ? The 1HZ is about 13 lbs psi
 

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