New Aluminum Radiator Running Warm

[Scouty]

So my new aluminum radiator (duel 1 1/4" rows) still can't keep the motor cool while crawling. On the freeway the motor runs at a constant 175 to 180, street driving the temp runs between 175 to 185, crawling the temp will go up to 200 or 210. At idle in the driveway the temp will stay around 190. So far I've flushed the system, run a direct 6 blade fan and stock shroud, had a robertshaw 180 thermostat but swapped to a napa 180 t-stat, have louvers cut into the hood, have a hood scoop facing towards the back, cut a bunch of the inner fenders out. The motor is a 345 with a mild isky cam, stock manifolds, pertronix ingition, and a edelbrock 1403 (500cfm). As suggested by Robert kenney I fatten up the primary mains to 92 and the secondary mains to 98. I checked the plugs after 2 75 mile trips, and they look brand new, no signs that the motor is running too Rich or too lean. I have the carter afb (625 cfm) at the local carb shop being rebuilt. In front of the radiator I have a fairly large tranny cooler and a small power steering cooler (see pic below) there is about 3 inches between them. The motor runs real smooth no missing or hesitations, the only hesitation is when you stomp on it, I'm thinking that might just be the smaller carb. I noticed that at idle and crawling my oil pressure drops to 5 to 7lbs, at freeway speeds pressure is about 40lbs. I'm also running an extra quart of oil.

I'm thinking the next step might be to move the tranny cooler away from the center of the radiator. Also I've seen some crawlers with an auxilary electric pusher fan that is used as a backup, but heard these are sometimes counter productive. I would also be concerned that the added plastic in front of the radiator would contribute to the heat issue. I know 210 isn't real hot, and it doesn't boil over, but when the ambient temps start to reach 100 plus I don't want any issues. Also I plan to drop the rebuilt carter back on and recheck the timing.

When I flushed the system I was unable to free up the water jacket plugs on the block, any suggestions for breaking these free without stripping or damaging them? Also any other suggestions regarding keeping this thing cool? And lastly if I do run an electric pusher fan, should it go right between the tranny cooler and radiator and right up against the radiator?

Thanks

 

[Greg R]

Not quite sure what you mean by "duel 1 1/4" rows".
I'll toss some ideas. The 6 bladed fan was an "increased cooling" option for a 345 equipped Scout. Airwise, the volume should be okay, but the radiators where a nominal 2" inches thick, and the fin count for the fins where a maximum of 12 fins/inch. What that means is that having a higher fin count or a thicker radiator May Reduce air volume because of the increased resistance. Normal driving or freeway ram air May not be affected by it; unless you're crawling whether on the trail or in a gridlock.
The transmission cooler is definitely blocking air, but enough to make it too hot is hard to say at this point. 200/210*f is not too hot, in fact my 1210/345 runs in that range regularly when hauling a load of green wood up a hill on a warm day.

Cutting your fenders May contribute some. The fan is going to pull air from the front, and the frontal area gets air from all over, not just straight in; and this is especially true at low gear high rev'in low speeds. Ever notice how a large farm truck going down a dirt/gravel road at low speed in granny seems to push a cloud of dust ahead of it?

The plugs can be a real beetch. The hard to turn ones get a good hammer tapping, some penetrating oil, and sometimes I twist clockwise and then counter-clockwise to get them to come out. If they snap off or round off, then it's time to do the drill and tap dance. One scenario that took a lot of time was to heat one with a torch, put some pb blaster on and let it set a day or two. Then, ever so slowly it came out. At least it didn't have to be drilled.

 

[Robert Kenney]

not quite sure what you mean by "duel 1 1/4" rows".

The radiator has 2 x 1 1/4" deep rows of tubes as opposed to 4 x 1/2" deep rows of tubes.


Scouty,
at low speeds your only friend is the air that the fan draws through the core of the radiator. You have the large fan and it is direct drive. That is the best you can do there.

1)
now where the shroud meets the radiator you May benifit from eliminating all gaps like where the top of the shroud goes over the top of the core and the sides if there is a gap for air to leak.
Use duct tape for the test. Seal all gaps and force all air the fan is able to move through the core.

2)
iirc some 266 sv and probably others had larger crank pulleys. You could see if they are larger than your existing ones. I would find a set if they will swap in to your setup. This would increase your fan rpm and increase the air flow. It will take some power away. ( this is a last resort type of deal)

3)
your idea of a pusher fan is a good idea. Run it only when you crawl.

4)
what is your initial timing? This is a place where you can reduce heat genaration by your engine. Take a few degrees out of it and retest. If it is the same add a few degrees and test.

5)
I don't think pulling the jacket plugs will help. The water is already taking heat from the motor at a rate higher than it can be removed an 190 degrees.

 

[chris142]

If it gets to 210 and you rev the engine up some does it cool off?

You May need to turn the idle up some so that the fan can move more air. 210f ain't hot. I wouldn't worry about it till 230f.

 

[ihpartsjeff]

Matt,

lots of great advice here. One thing that I would also consider a possibility is your not to stellar low range gearing. With a stock 727 and Dana 20(I believe this is what you are running) and 37's(?) with the 4.88 gears its just not enough and May be working the engine a little harder than normal. You might want to work on getting those lower transfer case gears in as that will at least help the situation.

 

[Robert Kenney]

I second what Jeff wrote. I was going to ask what rpm you are seeing while crawling. Low rpm high torque driving will make a lot of converter heat and engine heat while the fan is not turning fast enough to move the needed amount of air.

Lower the engine torque and increase fan speed by increasing your crawl ratio. That should fix it.

I suppose these scouts are being taken out of there intended operating regime and need some creative re-engineering.

One other thing. It seems like you are defiantly not fat so a bit more low speed fuel enrichment will help some. The 500 cfm carb is really plenty of capacity. Try moving the primary mains up .003-.005. This won't help mileage but will reduce heat a bit.

 

[ldo_marlin]

Here is what I would do:

- 195f thermostat . This keeps the coolant in the radiator longer to shed more heat. Your truck will run better with 195f thermostats too
- try to insulate between the radiator and the fan shroud to force the fan to pull air through the radiator. If there are gaps between the radiator and the shroud, the fan will pull air through the gaps and not through radiator.
- fan with more blades (not the fancy aluminum ones). Check the hayden website for sizes and # of blades. They are cheap.

 

[Robert Kenney]

195f thermostat . This keeps the coolant in the radiator longer to shed more heat. Your truck will run better with 195f thermostats too
.

Ido , at first glance this May sound correct but actualy laws of thermodynamics say the opposite. Pure miss information sorry to say.

An open t-stat is an open t-stat regardless of opening temp. Yes a larger delta t between the air and water increases the amount of heat that can be transfered at the ts opening temp. But at the temp scouty is having issues, the 195 ts will be less likely to be fully open restricting the flow through the radiator thus reducing the delta t between the radiator core and air thus reducing the amount of heat that can be transfered. Slowing the flow of water through the radiator does not increase the total heat transfer capacity actually the opposite is true.

The higher normal running temp will allow an already lean engine to run better with a resulting higher fuel economy. Scouty is not limited to emissions at the present time so he can and has jetted it up.

 

[Scouty]

Thanks for all the help guys. I think my next step is to play with the timing. If I remember correctly Jeff had mentioned some time ago that he thought the distributor might be off a tooth, so I'm going to bring the truck up to Jeff's and see if we can mess with the timing. Once I get the carter afb back from the shop I will put that back on. Lastly if I can find a low gear set for my 300 then I plan to swap in the 300 for my 20. Right now I'm running a 727 auto, Dana 20, and 5.13s, so the 4.1 should help the motor to work less.

Thanks again for all the help.

 

[Robert Kenney]

Lastly if I can find a low gear set for my 300 then I plan to swap in the 300 for my 20. Right now I'm running a 727 auto, Dana 20, and 5.13s, so the 4.1 should help the motor to work less.

Thanks again for all the help.

Iirc the d20 is 2-1 so the 4-1 will double your crawl rpm, move twice the air through the core and require 1/2 the torque. That will cure your issues for sure.