Are you suggesting that "American iron" has the pump in the hot leg of the coolant circuit?



The image above is a Ford Windsor - shows the water pump in the cold leg - yes - it does pull the coolant out of the block (actually the head), but it pulls it through the radiator, and pushes it into the block - exactly the same way the J18/J20/J23 does.  I can go find you a diagram for an SBC V8, or even a G13 from a Samurai - it's all the same - hot from the head to the radiator, cold from the radiator back to the block, and the J series is no different in that regard.

Take a closer look at the J18/J20/J23 diagrams you have - do they have flow direction arrows - out the back of the head, through the outlet pipe over the exhaust, through the top hose in to the radiator down through the radiator tubes, out through the bottom hose to the thermostat, through the pump back to the block.

I'll admit to a 'senior moment' on my remembering of coolant flow direction.    My posting is incorrect.   

What  IS   correct is that coolant temps of 230 on average is unacceptable.

There is something wrong with my  coolant  configuration.  I feel confident I have eliminated obstruction.

I want to make a suggestion - remove the thermostat entirely - for diagnostic purposes only - see if the temperatures remain the same or if they drop.  If they drop, go back and look at my previous suggestion...

I want to make a suggestion - remove the thermostat entirely - for diagnostic purposes only - see if the temperatures remain the same or if they drop.  If they drop, go back and look at my previous suggestion...

I don't think I will be able to get a decent seal if I remove the thermostat and use just the rubber ring without using some sort of sealant.     

I tried a higher CFM fan and still have the same results.  The 3 row radiator is  in route.

I did notice while looking a the problem I have no idea how old the lower radiator hose is and while it feels OK but for $12 I will replace it with a new one
when I put in the radiator.

I don't think I will be able to get a decent seal if I remove the thermostat and use just the rubber ring without using some sort of sealant.     

I tried a higher CFM fan and still have the same results.  The 3 row radiator is  in route.

I did notice while looking a the problem I have no idea how old the lower radiator hose is and while it feels OK but for $12 I will replace it with a new one
when I put in the radiator.

Family members in the hospital and having to replace my tow vehicle after 17 years I finally got back to the problem.

3 row radiator and a 3mm hole in the thermostat and so far after a few short trips I have near normal temps. of around 212..   

Temps are +/- 20 degrees during the short trips I have taken.     I've dropped the BOSCH temp gauge and moved it to my Samurai because the temps
are not accurate given where readings are being taken.    I'm going to install an Ultragauge or a Scangauge so I can pull the temp numbers from the ECT.
Directly and display them so I can watch during the drive.

Thanks for the update, I was beginning to wonder where you had disappeared to.

Thanks for the update, I was beginning to wonder where you had disappeared to.

after about 1500 miles under my belt after the last post temps are very good.  Dead idle it at a stop light it will creep up to 221 but never go any higher. Stick it in neutral and 'blip' the accelerator and she'll drop to 210 so I'm happy
that I've gotten it to this point.  I'm also getting about 19MPg overall but I drive 70-80 on the Interstate and it'd probably be better if I dropped her down to a steady 60.

I haven't had real good luck with non-OEM thermostats. You might either try a new OEM thermostat or swap the old one back in, to see if that changes anything.

I have FINALLY found the overheating problems.

1.  I had  Air in the system. Bleeding a J23 is a royal pain in the ass. I finally figured out how to get it out by parking on an incline with a spill proof funnel. Bursting the throttle to 3K and eventually bled it out.

2. I had a partially plugged heater core. It was a pain to replace, I did it over several weekends. Biggest problem was getting the dash off. Finally found the right combination to get it out.  This is probably the biggest issue.

2. Motorad High Flow thermostat. Larger than OEM.

4. My Electric fan doesn't have enough overall  CFM at idle. its fine driving. These things need a Ford Taurus or Volvo 2 speed fan. I have one. Its higher CFM I'll be fine

i've been driving fine for over a month. 

I have transplanted a J23 motor from a 2005 Aerio into a 1998 Sidekick Sport w/Auto.   

I did a 'long block' swap, keeping everything Sport, (wiring intake, exhaust, and externals) to make the transverse mounted J23 fit. 

It runs very well.  I am pleased with the swap.  Much more power and a very good replacement for the 240,000 mile tired motor.

The problem I am having is that the engine runs about 30 degrees hotter than normal at idle and speeds up to 70MPH and I can't seem to
find out why. 

I've confirmed the temps of 230-240 with multiple scan tools, and resistance tests of the ECT according to the Service manual charts.

The motor has never overheated but the elevated temps are a real concern.

With the Swap I put in a V6 Grand Vitara Denso Radiator, 2 10 inch 800 CFM Fans (about 1600 CFM) with a shroud made out of an aluminum baking pan.   

During the Swap I also added a new thermostat (Car Quest Brand).  The water pump SHOULD be OK.  I have a cool rubber hose
running into the motor at the bottom ,  a hot radiator hose at the top so coolant is flowing.

I have parked the vehicle now until I can solve the problem.   

My calculations may have been wrong with planning the cooling capacity as I think the Aerio's radiator is about 20% larger
than a Grand Vitara but I would think that a radiator rated for a 2.5 V6, larger than the 2.3 would have been sufficient.

Thank you for your time.

I've returned after more than a year. 

I  finally solved my temp problems...   Turns out the issue was a 'low flow' heater core, additional 'air bubbles' in my cooling system as well as a 'cheap Amazon fan'.

I replaced the heater core in Feb of 2021 .  It seems that air was also being trapped in the cooling system.   I spent several weekends pulling the truck apart and replacing the heater core and a new Motorad thermostat.  I got the air bubbles out and its been workign well since replacement.

I also replaced the'Amazon Cheap' fan with a Volvo 850 OEM unit with a Volvo 2 speed fan controller and a BMW temp switch. This works very well

https://www.youtube.com/watch?v=zRKKyCy-x-s

Once this has been replaced the temps never get above 206 and easily drop back to 195 once the fan kicks on.  To my  knowledge it has never switched to the 2nd speed.  I went through the entire Virginia summer with several days above 90 degreees. Not Death Valley temps but still. Never an overheating issue.

Excellent news. I am still having occasional issues at idle. I might have to do the heater core swap. That will allow me to swap the evaporator coil also.