Engine/Transmission (1994 - 1998) No Thermostat Still Overheating, Water Pump?

[LMcCary]

Would like to know what the temp. is on the top hose vs. the bottom hose. It should be around 18 degrees different, it a lot more, your rad is partially restricted causeing the problem.

Two, do a bottle test, install a hose on the over flow tube and place the hose into a clear bottle with water to watch for bubbles cause by head leakage or Block.

Three, typ. temp is 200 degrees approx. If it boiling (not bubbling out from compression, then you need a higher press. cap esp. if you are running high elevations.

Four, if overheating while above 35 mph, then it is not the fan. Could be air flow or rad. or comp. leak.

Please give more details.

Thanks LMcCary

 

[Hammer]

One thing everyone seems to be overlooking also is his turbo... Garrett



If the charger is water cooled in the center section and its hooked up the demand on the cooling system is then having added stress placed on it. Couple that with the Ford radiator being smaller than the Dodge and you could believe what he is having issues with.



If the charger is cooled in the center section,I would remove the oil restrictor so it will get full oil feed for cooling the bearing and then remove the water cooling feed and try that to see if it eases the burden on the cooling system. On the water cooled turbos Garrett restricts the oil feed line and uses the water to help cool it. By removing the restrictor in the oil and taking the water off it will then be like any other turbo out there... ..... Andy

 

[ata]

If you don't have a SHROUD on the Radiator the fan is not pulling air through the Radiator it's pulling air from the sides and CAVITATING. Makes lots of noise and wind but not enough air through the Radiator. You will never get that rig to run cool without a SHROUD. Been there done that!

 

[Wingate]

I've seen water pump inpellers errode away. Since you've already changed the pump, this isn't a consideration. I'm sure that Cummins has a spec. for pump outlet pressure (for future reference)

The thermostat needs to be installed. Without it, the coolant can actually move too quickly thru the radiator not allowing enough cooling time before it returns to the engine.

Injection pump timing can play a role in coolant temperature, but realistically, I think yours is purely cooling system related.

Fan shrouds are a must, If you have a full sized pusher fan and a full sized puller fan, one of them needs to be able to handle the job on its own, and the other one needs to come off, they could possibly stall the air between them (if the pusher is moving more than the puller) or the pusher is just acting as another restriction for the puller.

As others have stated, you might shoot the inlet and outlet temps and check differential, this will give you an idea of restriction. Air trapped in the cooling system can give you fits... . If the outlet hose goes down in elevation from the engine outlet to the radiator, you might install a needle valve in the highest point to purge trapped air. Make sure your temp. probe/gauge is mounted as close to the thermostat (on the engine side) as possible, thats where the coolant should be the hottest. One other thing that comes to mind is to make sure youu use a good quality antifreeze mixed to the proper ratio. Redline makes a product called Wetter Water... or maybe its Water Wetter... that seems to help the coolant shed heat faster. I've used this product in ATV's for years and have had great luck with it. No more overheating when the radiator is plugged full of mud!!!. . I believe Royal Purple makes a similar product called Purple Ice.

One method I've used on N/G compressors to determine if there was adequate air flow across the cooler is a red shop rag should stay stuck to the cooler at idle, and a ball cap should stay at full speed!!!. . I know I know... REALLY technical huh... but it works.

 

[hsmith]

I did not read all the replys, but there is no way you can run cool without the t-stat. It keeps the coolant in the radiator long enough to cool a bit before opening and repeating the cycle.

 

[MMcCallie]

Overheating Update

It's been a year since I've addressed my engine overheating problem. Fortunately, I haven't reached boil in all this time. I am still running with no thermostat. I've received plenty of criticism for doing so but I can attest that in this manner is the only way I have ever been able to manage under hood temperatures of this beast.



In the Alaskan winter the coldest temperatures I experienced were near -20 F. At highway speeds I experienced difficulty maintaining healthy coolant temperatures. In the coldest weather I was unable to maintain an engine temperature of three digits, not even making it up to 100 degrees. The worst of it was not being able to thaw the frosty ice from the inside of the windshield and windows. No fun having to chisel while driving. However, when 4 wheeling off road, getting stuck in 4 foot deep snow, my coolant would approach 220 F. I greatly improved highway temperature by shoving cardboard behind the grille. It usually took less than 5 minutes of driving to see over 100 degrees after being plugged in all night.



Highs most of this summer have been in the 50s though we've reached 80 degrees a few times. At speed my engine temperature naturally runs 100 degrees above ambient, as it should. When extended idling occurs the temperature rises. My fan has been able to bring my engine temperature below 180 degrees even when climbing mountains in low range off road to over 3,000 foot elevations.



I'm attaching an image of the fan and shroud setup I have been using the past few years. What you see is a stock Ford 7. 3 PSD fan shroud trimmed down for the custom plastic fan to clear. The fan is offset toward the driver's side, requiring that I relieved more material from the outer lip. On the passenger side in the upper right hand corner there is a huge gap of plastic that had to be removed for fitment because it was not flat and accommodating. Perhaps the biggest problem is the gap between the edge of the fan blades on the upper passenger side, which is similar at the bottom, which can't be seen in this photo.



I have acquired 4' deep strips of lexan. My plan is to fabricate a shroud that hugs closely to the outside edge of the fan blades and sits flush against the radiator. The sides and corners of the radiator will still be open on the engine side, but most of the pictures of other Ford Cummins conversions I've seen do the same and I'm the only one I know of who's experienced such drastic overheating issues.



I don't think I can move the radiator any closer to the fan because of the wiring and bracket in front of the fan for the Horton electromagnetic clutch. The fan itself is not a Horton product, only the clutch. I've also replaced the fan wiring with a 100% constant duty solenoid for both the engine fan and the 17" electric fan I have mounted down lower behind the bumper's skid plate. The electronics are now far more robust and reliable.



The distance from the surface of the radiator to the engine side edge of the fan blades is just over 4' so the lexan will nearly cover it. The way the fan currently blows extremely hard toward the ground and out the sides is indicative of improper circulation. I very much hope this will be the cure so that even though I'll be grossing 24,000 lbs that I won't have to pull over to cool off even when climbing through the Rocky Mountains. Maybe even with air conditioning on instead of heat!



I have a question before I fabricate. How much space do I need to leave between the enclosure of the shroud to the outer edge of the fan blades? I'm thinking an inch or less al the way around. I want to leave enough of a gap to allow for body and chassis flexing since this is a rock crawling vehicle that also catches high speed air on occasion. In other words, it needs to be as efficient as possible yet safe for the application.



I've determined that my heat and a/c problem is due to the hole burned in my heater core box thanks to Rob Watkin's faulty work. NAPA says they can patch the plastic while replacing the exhaust manifold to turbo gasket. This should improve the cooling of my a/c and keep hot engine air from blowing on my feet even when the air is turned off.



I'm considering leaving the lower portion of the Ford shroud in place for additional protection against branches and other debris that could damage the radiator. Any other fabrication oriented advice? I'm planning to get help during the project to have extra input.

 

[NIsaacs]

The fact that you can only run without a thermostat tells me that your water pump might be turning backwards. Are you sure the belt is on right? They can be a puzzle sometimes.



Nick

 

[THoltz]

My 2002 Dodge Service Manual says NOT to run engine with T-stat removed as it will allow coolant to bypass the radiator. I wonder if that by "gutting" your T-stat that you have inadvertantly done the same thing as removing your T-stat? Just a thought.

 

[Shadrach]

Where is your winch mounted? My buddy had an 18k Warn mounted above bumper height and had cooling issues. When he lowered it to below the top of the bumper it allowed more air through the rad. With your mods you are putting a lot of heat into the engine. Shadrach

 

[MMcCallie]

Bumper Pics

Wow, I didn't know Warn made an 18k off-road winch. Mine is mounted below the grille. The winch takes up a great deal of room in the box but there is room for air to flow above and around it. The electric fan is mounted behind the winch. There is a skid plate below that has a couple holes in it for more airflow.



I spoke with aftermarket radiator manufacturers a few months ago and they told me that the traditional belief that coolant needs to stay in the radiator long enough to be cooled is not true. They claim greater water pressure is more effective at cooling. They said keeping the water moving through the system faster means the heat is carried away and isn't allowed to get as hot. They also said all I need is a thicker radiator, no surprise they wanted to sell me their products.



In no way is coolant bypassing my radiator. I watched a '93 Cummins start up cold a few days ago. The thermostat wasn't warm enough to open and watching the coolant with the cap off for a few minutes the coolant didn't even start to flow. Mine is flowing through the radiator all the time, likely meaning it takes my engine longer to warm up, though my fan clutch is not engaged at startup so I'm also not pulling air through the radiator so perhaps that evens out the difference a bit.



Back on the subject of the thermostat being open and closed, if, say, a 180 thermostat is totally open at 180 degrees then how is it going to hold coolant for a greater duration in the radiator anyway? How is it any different from having a gutted thermostat that still has roughly the same amount of resistance over a certain temperature?



I've changed belts on this engine a couple times and I'm pretty sure the belt can go on only one way. Anyway, yes, even last week I had another mechanic looking it all over and specifically checking the direction of the water pump rotation. We looked at one he had in his shop and compared to verify. The coolant is visibly flowing through the fill/overflow tank.



I'm attaching recent pictures of my front bumper. It is large, heavy, strong, and obtrusive. I built it out of 1/4" steel, expanded metal, Schedule 80, and DOM as I recall. The only coolers possibly receiving less fresh air are the power steering and transmission coolers. Transmission usually runs down the road around 130 degrees, rarely gets over 150. I don't think the bumper is the problem.



Does anyone have input on how much space there should be between the shroud and the edge of the fan blades?

 

[NIsaacs]

Okay then, there has got to be a solution to this "no thermostat" issue.



Is your radiator factory gas or diesel model? Is the fan hub Dodge application as in 1. 35/1 speed or Cummins 1/1? Fan/shroud match should be 50% give or take a little. If you have done several mods since you pulled the goodies from the thermostat, I would re-install one and try it again.



Nick

 

[MMcCallie]

The radiator is a stock 2000 7. 3 diesel radiator. The fan hub is from a Dodge dealership for a Ram 3500. What do you mean by fan/shroud match 50%? Removing the thermostat is one of the most recent modifications to this engine. As best I can tell, the only benefit to having a thermostat would be faster warmups.

 

[NIsaacs]

The 50% thing was fan/shroud depth. I reread your post and you meant clearance between the shroud and edge of the fan, sorry. I would think anything from not touching to a couple inches would be fine.



The diesel radiator is huge on a Ford so that should be okay. I have done several Cummins conversions and this has never been a problem even with smaller radiators.



I hate to keep harping on this because you are obviously a good mechanic with your build up of this Ford, however sometimes I can't see the forest for the trees. Are you 100% sure the water pump is turning the right direction?



As cool as it is where you live, heat should never be an issue.



Nick

 

[MMcCallie]

I'm about to gross 24,000 lbs for near 3,000 miles to St. Louis so hot weather will be a major issue since it's been near 100 degrees most of this summer. Towing through the Rockies again is my biggest concern related to overheating.

 

[NIsaacs]

Dang, I am running out of ideas. That radiator should cool that truck. Is it clean on the inside? The early Dodge trucks with autos had an optional chassis mounted radiator/fan combo for cooling the transmission. Maybe something on that order fed by the heater hose flow could be installed?



Nick

 

[MMcCallie]

New Lexan Fan Shroud

Today I fabricated my first fan shroud. I used 4' wide 1/4" thick lexan. The largest sheet available was about 64" which just barely encapsulated the diameter of the shroud but without enough room to allow it spin. I used another strip several inches long to create the necessary length and bolted them together.



It didn't turn out perfect but looks fairly sharp and seems to be very effective. The bottom got as much as a 2" gap between the edge of the blades and the shroud. The bolt heads have just a finger's thickness between the fan and shroud. I was hoping for a little more clearance but I've tested the fan engaged on a very rough road and had no issues.



I sliced open some fuel lines and slipped them around the edge of the shroud to help seal against the radiator and protect against rubbing. Had to notch a large area to clear the harmonic balancer, the upper radiator cap, and the bracket and wires for the fan clutch. Ended up clearing a bit more than needed for the harmonic balancer, which might aid in belt changes, and the top turned out really close.



The top is mounted to the 2 bolts at the top of the radiator. The bottom is zip tied out to the radiator core support brackets. The bolts on the driver's side were hitting so I removed one of the 4 bolts and ran a zip tie from that outer hole to around the frame and that tugged just enough to clear the bolts.



I left the stock lower shroud section in place to protect against debris. The top is open around the new shroud because the Ford top wouldn't fit over the new one. Initial tests showed tremendous improvement in suction power. I had an empty soda can laying on it's side at the front of my bumper that was pulled up to the grill when the engine was revved with the fan engaged. Same with an empty water bottle. Empty plastic bags were flattened and held against the grill. At least I am certainly pulling air through from the front. In the engine bay the air is no longer blowing out the sides. It now blows out at an angle, directing the main flow of air straight toward the engine.



During a test drive it was late at night with temps in the 50s so I had a hard time getting the engine temperature up. Climbing a hill my coolant was up to 188 but in less than a minute long climb it only dropped to 186. Coolant hovered at 160 the rest of the ride home without the fan on.



I won't know how much more efficient this shroud will be until I'm either towing heavy up long, steep grades or I'm driving in hot weather. I'm attaching a picture taken after completed. Perhaps in the daylight I can get a better photo.

 

[DonTX]

Not sure about a Cummins, but back in the old days, taking the thermostat out would generally cause overheating. Without the restriction of the thermostat, the coolant would pass thru the radiator too fast to dissipate much heat. This may not be your only problem, but I would strongly suggest doing the trouble shooting with a proper thermostat in place. Also, a diesel needs the thermostat to insure it operates at the proper temperature as well. The fast warmup is mostly a by product of the thermostat, not the sole purpose. .

I did not read all the replys, but there is no way you can run cool without the t-stat. It keeps the coolant in the radiator long enough to cool a bit before opening and repeating the cycle.

 

[JTHUSKINS]

Been there, done that. See my post in 911 arhcives about heating while towing. I found my problem to be a busted wastegate diaphram combined with a NAPA thermostat. Just a thought. The fan shroud issue can cause poor air flow. When my stock fan is engaged it sounds like a jet engine under the hood moving air

 

[NIsaacs]

Nice looking work, very clean. However, I wonder if the flow will only be fan sized? I can see a large amount of radiator volume bypassed. I wonder if a square shroud might flow less but over the complete volume available?



just thinking out loud... .....



Nick

 

[cerberusiam]

You need a functioning thermostat, thats a given. The engine will not circulate and warm correctly without it. Use a Cummins one for the best results.



The cooling system has to hold at least 15 lbs of pressure, maybe more. Not usre what those caps are rated at but it won't boil even at 280 degrees under the correct pressure. They just relieve enough to keep things from blowing up which may be why you think you are loosing coolant becuase there is no coolant recovery system.



You have the temp sensor at the absolute hottest part of the engine that suffers from poor flow and heat transfer. You may see 230 there and 180 at the thermostat and thing there is a problem. There is a coolant bypass kit just for this problem that relieves the pressure and adds flow to the rear cylinders to mitigate the issues. Pretty sure that will address a lot of your problems.