1991 3.0 4R

My truck had been getting a little hot up hills and in stop and go, so I thought I'd upgrade my cooling system. I bought a CSF 2056 triple core and a new Aisin fan clutch, installed them a few days ago.

I filled the coolant directly into the rad inlet hose going into the engine which has usually worked good for me to get the air out. Yesterday and today I pulled most of the upper hoses and filled them with water to make sure they weren't hiding bubbles. I even got the tiny hose running through the throttle body. My heater runs hot so I'm sure those hoses are burped. This morning I drove it up ramps and ran it nose up cap off for about 30 mins in an effort to burp it some more.

I have a digital gauge tapped into the rad inlet hose, so it should be the absolute hottest temp in there. I'm pretty sure it's fairly accurate, when just idling and warmed up it'll sit at 180-185 which is normal. Cruising at about 60mph it'll stay at 190-195. Once I start up a hill or even just start driving it harder, the temp will start climbing. At the top of hills it'll reach 220 and then have a hard time dropping back down unless I have a downhill I can coast it down. It generally won't go higher than that but it never went above about 205/210 uphill with the old rad.

Is this triple core just inefficient and cant handle the heat load of the 3vz? This is supposed to be one of the better rads to get for this truck but this one just doesn't seem to be able to handle it. I'm about ready to throw my old rad back in and return this one.

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What about the thermostat? If it's not opening all the way, it could be restricting flow through the radiator. Easy to check. Pull it out, and put it in a pan of water on the stove. Bring it up to a boil. You need a thermometer for this, really. It should start to open at 190°, and as the water heats up, it should open completely.

I had this trouble in my pickup. Wound up that no matter how many times I burped it, it would get hot. This is on the gauge on the instrument cluster. I replaced the radiator with a 3 core all metal one, hoses, thermostat, water pump, and the fan clutch. Finally, in desperation, and this was before the net, so no help there, I bought this stuff called Water Wetter. It lowers the surface tension of the water, very much like soap does. After a few days of driving it to work and back, an hour each way at highway speeds, the problem suddenly vanished, and LO! The recovery tank was almost empty after the truck cooled off out at work. Filled the recovery tank back up, and again when I got home that night, and I've never had a bit of trouble since. This was almost 30 years ago. I am going to have replace the radiator again, finally, but I think I got my money's worth after this long.

Point being, no matter how well you burp it, there are nooks and crannies that sometimes just will NOT give up their air bubble without some extra coaxing. The Water Wetter is readily available at most auto parts stores.

Hope this is some help...
Pat☺

 

The thermostat is relatively new and was working correctly when I installed it last summer. Worth rechecking though, I'll give it a shot. Ive seen water wetter at the store, never gave it a second look but on a recommendation I'll try it.

My dash gauge isn't working right. My last one was broken so I replaced it last year when I rebuilt, but I cheaped out and didn't get oem. It always reads above half once warmed up, even when my other gauge reads normal, and is completely maxed out by the time I hit 210. I think it's calibrated different from oem or something, I'm going to replace it.

​​​​​Thanks for the suggestion!

 

Hope it helps you out!
Good luck...
Pat☺

 

Did you install the fan backwards? What about the fan shroud

 

So I've been reading around about safe temps for engines, and apparently 220 is nothing to be worried about. Around 240 is when you might be having problems. I think the FSM mentions something about temps up to 230 being "normal". Does this sound right? Maybe I'm worrying about something that's not a big deal. My engines normally about 190, just hits 220 on hills and stop and go traffic when it's really hot out (we're hitting triple digits in Central CA right now)

BTW I put some water wetter in, I'll see if it makes a difference in the next couple days

 

All good. Fan oriented correctly and shroud in place

 

220 shouldn’t be a problem. with coolant mix, and pressure, boiling temp is quite a bit higher. if the system doesn’t hold pressure, or you only use water, 220 is much closer to boiling (and a problem).

fwiw, my ‘48 dodge 1.5-ton typically runs at 220. it is 50/50 mix and a no-pressure system, but the system holds 17 qts.

 

Ok. That makes me feel better. I've just never seen this engine get this hot so it concerned me. I still wish this triple core would be doing a bit better job. But it is all metal construction vs the plastic tanks on the last one so it should hold up to abuse better at least.

Thanks for the replies guys

 

If it were me, my next step would be to buy a no-spill funnel thingy from any auto parts store (Napa, O’Reillys, Autozone) and burp that motor really well. Hook up the funnel, fill it to about 1/3-1/2 full, fire if up, immediately turn the heater and fan on (to open the entire system), and let it
run for at least another 30-40 minutes. And it’s not a bad idea to park the vehicle on ramps or facing uphill on a steep grade (bubbles/air go up in liquid to escape the system out the funnel), and start squeezing the hoses to facilitate movement of air. Even after all of this I’ve had occasions when my system will burp and drink up some additional volume from the expansion tank in the first few days of driving.

Lastly, check the timing. Are you running different gears (4.88, 5.29) with small-ish tires (less than 33” for 4.88, and less than 35” for 5.29?), causing higher rpms? Just some ideas I’ve seen cause temp to wonder up.

 

If you solve this - please post an update. I’ve been chasing the same issue for about a year now. I’ve just resigned myself to having a truck that maxes out at 55mph.