Engine/Transmission (1994 - 1998) +250 Degree Engine Coolant, Electric Fan?

[Canadian Cummins]

Try this as a temp fix before cutting hood

Instead of cutting up your hood, to see if opening the back of the hood area works just make a couple of hard wood blocks the same pattern as the hinge to hood mount about 3/4 thick, this will raise the back of the hood and let the air escape.

I did this to a TOJO FJ55 that we had put a Pontiac 400 v8 and 400auto had the same problems when wheeling in the interior of BC Canada, 100 F and using 4 low.

It worked a treat but looked weird.

CC

 

[wcjp]

Could remove the hood on the trail for the day. Leave it back at camp.

 

[MMcCallie]

One of the Jeep Cherokees was overheating so they removed their hood. I should have done the same. Another Cherokee bent both upper control arms so we went down to the flat land to get replacement parts.

On the way back up the mountains, with 5 of us in the truck, the engine temp went to about 220. It had never done this on pavement. However, i was flogging the truck at the request of my passengers. We also had both the front and rear a/c on.

We tried pulling the hood latch lever and let it draw more air in with the hood just propped loose, still caught on the last part of the latch so it wouldn't smack the windshield. Temps were still climbing. So, we put a cord on my swing down storage box on the front bumper to hold it open. The face of it is solid diamond plate, allowing very little airflow. I'd assumed that because it is all below the grill that it wouldn't interfere with airflow. Well, the engine coolant quickly dropped to about 195-200 for the rest of the long pull up the mountain.

I'm going to try keeping the diamond plate as a frame and filling in the middle with expanded metal. I'll see if the bumper modification maintains a consistent temperature drop. The electric fan mounted behind that space should now have far more air flow. If this doesn't maintain a major improvement, i'll again consider more drastic options.

 

[MMeier]

How about some pics of the front end and engine compartment of your rig?

 

[MMcCallie]

Bumper Pictures

Haven't taken any engine pics yet but here are some off road shots i have handy. I knew the storage box and skid plate would block more air than the stock bumper but i assumed the fan which is mounted just behind the bumper would make up for it. I hate to cut my bumper but i guess i need to.

BTW, the bumper is more squared up with the body lines than it looks. The frame has a bit of flex.

 

[fest3er]

This may be a dumb question, demanding a dumb look in response, but I have to ask. Is the electric fan between the lower skid plate and top of bumper, behind the diamond plate? It looks like air can't easily find its way in there. But the top half seems to be well open.

At a glance, it might be that the air that gets into the engine compartment can't get out because of the changed airflow where the stock bumper used to be. Remember, the stock bumper does aid and encourage proper air flow through the engine compartment. If you want to do some gule experimental sheet metal fabrication, try blocking off the visible parts of the frame, perhaps run some sheet from the skid plate up towards the headlights, and some vertical-ish line around the front of the pumpkin. That might create a vacuum of sorts on the engine compartment, thus encouraging positive air flow for cooling. Shoot, for a simple experiment, use some plastic tarp and duct tape it on, just to see if the idea has merit. Ugle, but proof-of-concept creations are rarely pretty.

I do like CC's idea to raise the rear of the hood. Heat likes to rise, so let it escape where it wants to. A rogue wheeler like you should have his windows closed with A/C blasting anyway, so that heat shouldn't be a problem for driver and passengers.

 

[MMcCallie]

I took some more pics today that will hopefully show more detail. You can just barely see the electric fan mounted in back of the storage box. There is space inside the box, over a foot deep, as well as the sides being fairly open beside the electric fan. The engine compartment gets much dirtier, sometimes on just one trail, than shown here. The space between the clutch fan and radiator is also visible. I think blocking more airflow would just make things worse.

 

[fest3er]

... I think blocking more airflow would just make things worse.

That's why I suggested tarp and duct tape. I'm thinking that, because the frame and engine are so open underneath, as you move forward, air is 'compressed' and directed into the spaces behind the radiator, thus inhibiting good air flow. If you closed off the under side just right, you might be able to encourage some venturi action that would help draw air through the radiator. Try to picture how the air might flow if the Excursion was in a wind tunnel.



The reason a lot of vehicles have an air dam under the bumper is to cause a certain amount of vacuum behind it, which helps draw air that's in the engine compartment down and under the vehicle. Granted, wheeling requires clearance, and air dams reduce that clearance. But the general idea is to ... encourage any frontal air that does not pass through the radiator to move to the sides of the vehicle, thus letting that heated air escape.



It may turn out that your only economical alternative is to raise the rear of the hood to allow the hot air to escape. (A non-economical, yet somewhat elegant, solution would be to install a second A/C system that puts an evaporator in front of the intercooler and radiator, and puts a condensor somewhere behind the vehicle, or on the roof. ) It's all about moving heat efficiently and effectively.

 

[MMcCallie]

Perhaps i should be more clear. The engine coolant climbs up to 250 when wheeling with the windows open, no a/c on in 100 degree F weather. There is no airflow when driving that slowly. Hence the electric fan to create some airflow.

I built the front box with about a 1/2" of space across the bottom hinges thinking that would be enough space to breath through but obviously not. I don't think i can create a vacuum when there is no airflow.

This is not about air conditioning, it is about making my engine run cooler. Air is escaping down low because i can see the dust blowing out the sides around my front tires when i'm going fast enough and both of my fans are engaged. Perhaps keeping air from escaping down there would help. My first step will simply be to decrease frontal blockage.

 

[MMcCallie]

Haven't been off road in a couple weeks so the hottest i've seen my coolant get is 210. When the temperature is only in the lower 90s and i'm in stop and go on the street, coolant stays under 190. Stays at 180 at speed.

Had my radiator drained and checked and it was "Clean as a whistle. " Put in just over 5 gallons of straight coolant to see if that helps prevent cavitation. I'm planning to add some DEI Radiator Relief to see if that keeps the temp from climbing so high.

If having a low water content doesn't help, i'll just drain a little and add water. Not sure which one boils faster, used the generic Napa antifreeze. What i had wasn't working so i'm trying something different. Was going to use Evans but would have cost a few times what this cost me.

My electric fan isn't pushing any air through the condensor. It is worthless. In addition to a custom shroud, i'm searching for electric fans that move at least 3,000 cfm and are no more than 3" thick. At idle, my clutch fan is at least drawing some air through as can be felt by hand from in front. Mechanic said one of the bearings in my Auto Zone clutch has already gone and that the blades on my fan are too few, too short, don't have enough pitch, and appear to have been straightened.

Just ordered a brand new 2007 Dodge HD fan and clutch. The clutch is electronically activated so i'll run a switch into the dash to lock it up. Possibly also wire it into the a/c and or a thermally activated switch. Might help with warm up in the winter and through water crossings too. The fan blades should be more numerous, longer, wider, plastic, and have more pitch. Cost $450 total, should be there for me to pick up tomorrow. I'm hoping this will be a great package.

PSD shroud was way, way too big. I'm realizing i absolutely have to have a fan shroud no matter how tough it will be to make one fit, even if it only sticks out an inch or two. Been searching salvage yards but haven't found a Dodge Cummins shroud. I'd prefer to modify a cheap plastic shroud but i'll probably have to fabricate one out of aluminum on Monday.

Put a thermometer in my a/c vents. 50 degrees in hot stop and go, 40 degrees when things are a little cooler with good airflow. I'm hoping that if i can lock my clutch in traffic even though coolant is at 180 that my a/c temperature will drop pleasantly. Custom shroud will probably make the biggest improvement. Hope my a/c compressor isn't toast already. Blows ice cold at night when it is in the 80s outside.

 

[MMeier]

Well, judging from the engine pics, that fan is worthless with out a shroud. And I would mix that coolant with some distilled water, straight anti has less cooling ability, sure someone here will come up with a more detailed explanation as to why. Since you have the new fan and clutch on the way, might as well get the appropriate shroud and get it mounted somehow in there. Just make sure it is sucked right up against the radiator so all air has to pass through it. If it were me ... . and I may still try it... on my '03 Ram I might try to make the earlier style shround, fan and clutch work, seeing as how my truck likes to through fan clutches at an alarming rate for whatever reason. Oh yeah, what is that covering up the top of the engine??

 

[MMcCallie]

Hmmm. I'm hoping these new electric clutches will be more like the Horton but for less than half the price. I'm told they became standard issue as of 2005. Are the fans the same on the Dodge Rams '03-'07. I'm thinking they all have 9 blades, is that right?

With the coolant, i'm trying what Evans does. They use no water because their product doesn't boil until a much higher temperature than water. Couldn't find a boiling point on the label of my Napa coolant. When the water gets hot enough to evaporate inside the engine, it creates a hot pocket that doesn't move. The hot vapor pocket doesn't allow coolant to contact the metal there so the heat isn't carried away to where it could be cooled through the radiator. Cavitation is supposedly more problematic on a diesel because of the shockwave sent through the block, especially during startup. If this doesn't work, it will be a simple fix to add water.

 

[MMeier]

Cavitation is not an issue with the Cummins engine. IIRC, in the 2004. 5 model year Dodge/Cummins, whomever you prefer, changed the way the fan and shroud work together, I believe the shroud is mounted to the engine on the newer models. The fan in my '03 is like 26" in diameter and the clutch has a 5 wire connector attached to it, who the brain behind that was I don't know. Boil/ freeze points should be on the back of the coolant jugs.

 

[WDixon27]

i think best cooling comes at around 70% water 30% green, i've seen cars with straight green and it grows some serious funk in the system, not sure if 70/30 is enough freeze protection for your area but 50/50 is generally a good all around mixture, i think once you get enough fan in there and clear the path for air to get to the radiator it will probably be happy, not only does that fan suck air in it blows out of the engine compartment along the block and transmission or down the front of the engine, that cummins is not as fat as the stroker that was in there air getting out shouldn't be much of a problem. evans coolant may be something to look at, i think the boiling point is something like 450 so you are not relying on pressure alone to keep the coolant from vaporizing around hot spots, which kinda self sustain and get worse as the coolant temp gets out of control