1974 w200 with 1972 440/np435 trans.

Large 3 core aluminum radiator from "The Radiator Lady" probably Champion brand.
New hoses
New water pump
New thermostat
New radiator cap
Original shroud on aftermarket radiator so there are gaps here and there
No fan clutch. Direct mounted, and is a flex fan.

Cooling system was seriously neglected. Truck sat for over a decade non running. The coolant was muddy brown. Flushed about 6 times and finally came out clear. I bought the truck knowing it needed a radiator and shortly after the headgasket blew. I assume the mud was bars leaks dumped in there when the radiator blew.

Pre flush, truck ran 185*/190*.

Poured prestone flush in there and ran for a day, sat overnight. Pulled block drain plugs. Let drain, put plugs back in, and filled with distilled water. Ran until thermostat opened and then 10 minutes more. Cooled down, drained again, and repeat procedure. Finally pulled all hoses and flushed with garden hose in short bursts, even heater core.

After flush, truck ran 210*, idled in a drive through for about half an hour and she climbed to 220* or so. Once moving, came down to 200*

Water pump was replaced next day. Coolant overflow/return system installed the day after that.

With new radiator cap and overflow system on, cooling system didn't build pressure until after the second shutoff (ran for about 10 minutes, shut off for about 15 minutes, then ran another 10 minutes, then shutoff for 15 minutes, then ran another 10 minutes running errands.)

Truck runs 195* driving down the highway, but sit at a light will quickly jump to 210*-215* and takes a bit of driving to come back down.

Motor heat soaks to 230* but comes down fairly quick after started to about 210*.

Thermostat does work. Holding hand on cool hose until instant hot, and looking at the gauge shows the 180* thermostat opening around 175*

Cooling system was burped. I added very little at a time and waited for all gurgling sounds to stop, squeezed bottom hose as well as upper hose until no more bubbles or gurgling sound.

Everything was flushed and back flushed and then topped with 2 gallons of green concentrated conventional coolant and 2 gallons of distilled water. After running for a couple days, bright green coolant is dirty and coolant in overflow tank is brown. I'm thinking there's a pocket of crud somewhere, or it's the old freeze plugs that were pushed into the block, dissolving (previous owner).

What on earth am I missing? Do big blocks just run warm? I'm tempted to run an Efan but would rather correct this issue instead of doing a bandaid fix.

Old water pump next to new one.

Truck was warm, and I filled the radiator full full. Added coolant to the overflow tank, and it was drawn into the radiator.

I'd drain and flush with water until it's clear. Then fill with 2 gallon of vinegar and top off with water, runs for a few hours. If there is anything in there that shouldn't be the vinegar will loosen it up. Then flush with water several times until it's clear. I've learned the hard way that often the mixture of your antifreeze will cause the same problem you are having. So I will mix with about 35% antifreeze, 65% water. Unless it's winter.

A solid fan will move more air also at idle

Are you sure on the temps, aftermarket gauge?

It sounds like it runs 195 rolling which is good and then warms up at a stop. Usually, warm at stop is air flow related. I bet a factory style fan + thermal clutch would keep it cooler at a stop vs the flex fan.

Best would be the big 7 blade fan used on BB's with HD cooling and matching HD fan clutch. Also, some foam tape or similar to seal the shroud to the radiator would help so air is pulled through the radiator.

One other thing to check is pulley ratio. These cool best if the fan and WP is at least slightly over driven (crank pulley bigger than WP pulley). If you do change pulleys to speed it up suggest you wait until you have a regular fan + clutch... flex fans have been known to loose blades at speed with bad results.

PS: No need for a BB to run warm. Mine does not. That said, if the water jackets are plugged they will. Sounds like you flushed yours out really well. There can be crud that flushing won't touch however. With the past poor cooling maintenance that could be the situation you have. The fix is to pull the freeze plugs and use tools (screwdriver, coat hanger ect.) and a hose or pressure washer to loosen it up and flush it out. It can be done in chassis. I would work on the fan situation first however to see if that fixes it.

These are samples of each flush. Finally said to heck with it, and flushed with all hoses pulled. I have a pic of the final result but file is too large to upload, but this pic should give a sense of what I was working with.

Crank pulley and water pump pulley almost touch. I have to pull the water pump pulley to install power steering belt.

I may have a 7 blade fan around here off a 413 I think. I'll have to look.

I'm thinking of building a shroud but it'll have to wait till after the trip to Utah unfortunately. Also going to build a filler piece for in front of the radiator. Think an old floor mat would be ok to use? As in if it touches the radiator, will it melt?

Today ran cool. Sat in a drive through and she never went above 200*. Heat soaked to 200* when shut off at the gas station. But cooled down instantly once fired. Topped off the overflow tank to the "full" line after the truck was hot. Sat with hood open while I was cleaning up/out the rail to rail toolbox and after about 5 hours, the coolant level in the overflow is about 1/4 way down, so the radiator is pulling it in when cooling down.

Temps are from an aftermarket gauge that was in the truck when I bought it. I may actually buy a brand new one just for good cause.

Coolant is green but still looks dirty.

Gonna go for a drive tomorrow when it hits triple digits and see where I'm at. I'm also going to look for my fixed fans to see what I have.

Thanks for the tips guys!

my truck ran about 10* cooler all around with a large 7 or 8 blade flex fan on it, no clutch.
put a mopar fan and clutch on it for the hopes of more mpg's, but it still only runs around 190 so it's fine.
318/4 bbl intake/holley/headers

i had a freeze plug leaking, the one back by the starter, when i had it out i blasted the hose through the cooling system until it ran clear, so much rusty mud came out...

While looking at my different fans, I came across a fixed 4 blade that was on my 72. With it, the truck never ran hot.

Would it be better to run this fixed 4 blade, versus a 6 blade flex fan?

Scratch the last comment. I couldn't find my 7 blade and was getting desperate.

Anyway, found my 7 blade at my grandparents. The clutch was bad, but I have a new mopar performance clutch/5 blade fan combo I switched everything over.

Also found most of a core support filler piece that I put on there until I can figure out a better one.

Hopefully this is the magic ticket.

That's a nice big fan! It will want the matching HD fan clutch. The clutch with the 5 blade MP kit is lighter duty.

Good to know!

Hopefully it holds together long enough for the trip. Then I can get a new HD clutch. But so far, for the little I ran it, it is throwing MASSIVE air. I can feel the air being pulled through the radiator, AT THE GRILLE! If this don't fix something, I don't know.

Went for a spin. Short jaunt on the main road, hit 3 lights, came back home along a back road (25mph) and idled for 10 minutes. Never once got over 190*

Heat soaked to about 210* but came down quick once fired up.

I think I'll call it good besides getting an HD clutch in the near future. But as on now, should be good. Oh outside temps were mid 90's.