Those of you that follow my build thread already know my motor, but for everyone else this is a fresh 408 I built for towing and wheeling in a 97 1500 with a full 98 2500 undercarriage with a nv4500. The radiator and related is all from the 97 with a new compressor and accumulator.

The problem I'm having is the temp wants to climb with the ac running. Cruising down the highway at 70 mph or just sitting still idling, no ac, it runs at about 182~186* (180 t-stat). Turn the air and it climbs to 200* fast. Running down the highway it won't go past that (yet), but if I idle for more than 5 minutes it will hit 230*.

I checked the flow on the radiator before dropping the engine in. I also blew out both radiator and condenser before installing (blowing dirt and bugs from fins), along with straightening fins.

I'm just looking for ideas from everyone on possible causes and solutions at this point. I haven't done any kind of troubleshooting on it yet to narrow down problems.
Thanks for reading.

 

Electric fans. At idle, the engine driven fan isn't moving enough air, apparently..... Going to a couple high-volume electrics might solve the issue. Either that, or a larger radiator. (is the v-10, or diesel radiator bigger??)

 

Yes the V10 and diesel are bigger but you need the core support or hack yours to make them fit. You can get a radiator with two rows that fits our trucks but it aint cheap.
http://www.griffinrad.com/load_detai...odge&model=Ram

All that's available is the single 1 1/4 row radiators. I have been searching for one with two rows and i found one that is a universal cheby style that is almost the same as ours. 100% aluminum but you need to fab the brackets and weld them on to make it work.

http://www.northernfactory.com/HIGH_...ACE_PRO/209615

 

Electric fans are in the plans. Just waiting for the money now. Maybe my fan clutch is going out finally. I don't have a clue how long it's been on there.

What is the difference in the mounts for the diesel and/or the 8.0 from the smaller engines? I've never looked at them in person and can't find much when searching. I noticed that both of those have bigger inlets and outlets.
I like the look of that first radiator even though it's pricey. It does come with electric fans, wiring, and shroud, and even claims to have a catch can on it. It wouldn't take much to setup the washer somewhere else I don't think.

 

The diesel and V10 radiators are wider.

 

Beyond the extra rows, the V10 radiator is wider (longer core)... the mounting bolt holes are there, maybe an 1" beyond the V8 mount holes.
You will need an adapter to neck down the hose size.

After fitting an all ali radiator with dual eFans, I saw more stable temps (not that my stock V8 had issues).
I can say that this setup is more than needed for a stock V8... I can disconnect one fan and there is no temp change... even in 90°F weather, standstill traffic, A/C blasting, it keeps up just fine... I haven't seen anything over 186°F (180°F Stant).

 

Thanks for the info about the differences in radiators.

With the stock motor, I never had issues either. I could pull 10 tons of hay on a heavy trailer through the mountains in this area (4% to 7% grades for ten or so miles) and never get above 205* with a 195* thermostat. I even tried to get it hot sometimes, and it wouldn't.
That is what lead me to ask this group about it. It's not enough to make me worry yet because I can cool it down, just making me curious why it's running so hot now.

 

Lot more cubes to generate heat, without added capacity to the cooling system to get rid of it.

 

Another thought... you could add an engine oil cooler, as a way to desperate more heat from the engine.

 

That's a good idea. Easy to implement too.