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Got the hose installed. It was not easy. I had to drain both halves of the reservoir so I could remove it to get access to long nipple where the hose attaches. The old hose seemed tight, no rub through or obvious hole. The ID size is 3/8 inch. The one O'Reily's sold me is not as thick walled and tends to kink easily if not routed exactly like the original. We will see in a few days if this was worth the trouble.
 

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Went into town and back, a 40 mile trip and nothing has changed. Coolant from the reservoir still needs to be added manually at the radiator cap after cooling down.
 

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1988 Dodge Dakota LWB RC 3.9V6 3 speed auto
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There's probably only three things there.

1) Radiator cap not sealing completely.

2) Hose still leaking at one end or the other (vacuum leak).

3) A pinhole leak somewhere else in the system, causing it to suck in air (again, one that leaks on vacuum but doesn't on pressure.)

You should have taken care of #2 (although I thought mine was done; turns out mine still leaks a bit somewhere. Or on #1 . I had just enough coolant to show up green when I ran it for a few minutes yesterday, before it was hot enough to help evaporate the coolant out before I could see it. Razzle frazzle ...)

#3 is the one that will drive you absolutely batty, because it requires a leak small enough that you don't see the coolant leaving; but big enough for it to suck air in when the system cools.

All I can suggest now is to pressure check the entire system, at about 24lbs or a bit more pressure, along the "A big enough fuse and smoke will show where it's broken" troubleshooting method.

Rwp
 

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Get a leakdown or at least a compression test done to check the headgaskets. Other than putting a fan clutch and fan back on it everything else is pretty much new.
 

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Discussion Starter #65
alpinegreenneon, is your coolant being pushed out while driving? and/or do you see it after you stop & park?
 

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Yes, it happens while I am driving. After it cools down, I check under the radiator cap and remove coolant from the reservoir and top up under the radiator cap. It can be as little as 2 ounces or as much as 24 ounces after a much longer trip. When I was only adding new coolant, it would eventually overflow from the reservoir so now I just transfer the coolant from the reservoir with the mityvac.
 

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Discussion Starter #67
oh ok. never pours out when you 1st park?
 

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Discussion Starter #70
alpinegreenneon, do you have the problem when the weather is colder?

it's weird since weather has been getting colder here in MD, i have not had to add coolant since i had it at the last shop (maybe 2-3 weeks ago), and no signs of it pouring out excessively or overheating.


that being said, a co worker asked if i had tried parking the truck with the "nose up" on an incline while at work. i told him i had not, but i would give it a shot. since parking on an incline facing up, i noticed that it has not poured out excessively. i have noticed a drip or two here and there. but nothing like it was doing previously. anyone have any feedback on that or is it just a coincidence.
 

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Discussion Starter #72
ok. update my part. since parking the truck on an incline with the nose up and since the weather has gotten cooler, i have had no problems what so ever. i even checked the coolant level @ the cap while doing the oil change yesterday and it was still full. guess i'm going to have to wait until spring/summer to see if i start having the problem again.
 

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ok. update my part. since parking the truck on an incline with the nose up and since the weather has gotten cooler, i have had no problems what so ever. i even checked the coolant level @ the cap while doing the oil change yesterday and it was still full. guess i'm going to have to wait until spring/summer to see if i start having the problem again.
I've been looking up several over heating issues related to the 4.7 and there seems to be tons of them and not just in Dakotas. This issue seems to equally effect Rams, and Jeeps too. The general consensus is, the 4.7 is known to have head gasket issues. There are a couple of probable reasons. By it's construction, the 4.7 has a cast iron block and uses aluminum heads. Many engines, and not just the 4.7 are built with cast iron blocks and aluminum heads, and not all of them are problematic, but they all share common concerns.

Aluminum and cast iron are very different materials which when heated, expand at different rates and at different amounts. Sometimes after numerous heat / cool cycles the head gaskets fail due to the difference in expansion and contraction of these two differing materials, moving against each other. Sometimes the head gasket leaks only when the engine is hot. In some cases the head is cracked or develops a large hole with an obvious coolant leak present.

Another problem with the use of aluminum heads and cast iron blocks is that the differing materials create a mild electrolysis which over time can cause a leak due to erosion. For these engines a coolant designed for "bi-metal" engines should be used.

The lack of evidence supporting a blown head gasket, makes this a difficult one to diagnose. You say that right now, your engine hasn't lost coolant since the weather has gotten cooler. And all of the tests to determine a blown head gasket has shown negative. The only things I can think of engine out of tune, your (aftermarket) fan isn't enough to cool the engine. Some other extra load.

Ed
 

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My Neons have aluminum heads on cast iron blocks and do not have leaking headgaskets with over 200k miles. My Dakota now seems to have fixed itself with the onset of really cold weather. When I look under the radiator cap, it's staying full.
 

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I was generalizing…… Plenty of engines come with aluminum heads and for the most part, many of those are apparently dependable and trouble-free……But it doesn't change the facts. Aluminum and cast steel do have different thermal expansion rates and issues with mild electrolysis. The Neon engine isn't excluded from the physics.

For some reason, it seems to be a bigger issue with the 4.7 and the only thing I can conclude is, the engine was probably not designed as well.


It's always great when problems fix themselves. OK, so now we can make some conclusions. You don't have a blown head gasket and other tests have also confirmed this. If there were a blown head gasket or crack in the head, you'd still be losing coolant, no matter how cold it got.

This means theres only one way to lose coolant in a perfectly sealed system. Thats for it to boil out. With everything having been replaced, and theres no confirmed clogs, I have to conclude that the culprit is in the only changed variables. Either you have the wrong temp thermostat, or your aftermarket fan isn't efficient enough. (Especially during the warm months)

In the last few years, the manufacturers have been using thermostats with a higher temp rating, for fuel economy and emissions reasons. Running a hotter thermostat means running warmer, which gives very little temp cushion, during the summer months, especially when you consider that an A/C may also be running at the same time. You could try a thermostat with a lower temp rating to open up that temp cushion….

What I mean by "aftermarket fan may not be efficient enough" is the factory fan is designed to draw a given amount of air thru the rad and also comes with a clutch to allow it to freewheel when not needed. Many aftermarket fans are not designed to meet the factory requirements and can differ greatly from the factory model, by diameter, number of blades, blade pitch, etc. Bottom line is, a different fan may not be pulling enough air thru the rad to keep the coolant cool, especially during the hot summer months. During winter, a fan is generally not needed because the air temp alone can be more than cold enough to prevent overheating, and I think thats why you haven't experienced any problems.

Let me touch on another related aspect. Air flow thru the radiator. You said you've replaced the radiator. Air flow is a funny thing. It likes to flow in the path of least resistance. A radiator has a lot of resistance, with all those tubes and fins in them. To force air to flow thru the radiator, manufacturers have to eliminate all the paths of least resistance, otherwise, air would naturally flow around the radiator, making it less efficient. When you replaced the radiator, on each side of the radiator are rubber skirts, curtains, shields, or whatever you want to call em. (Left side is behind over flow bottle) These "skirts" must be in place and should be intact. If the skirt either missing or have a big tear in them, or they aren't fastened down, a path of least resistance is created and less air will flow thru the radiator, making it less efficient.

On the other side of the radiator, your fan must have a shroud. Like the skirts, the shroud prevents a path of least resistance. Now you didn't mention if you've got a shroud in place. If you do have a fan shroud, it still maybe "inefficient" because of the aftermarket fan. The fan should fit just inside the shroud, and have very little space between the tips of the fan blades and the shroud opening. The fans shouldn't be too far inside or to far behind the shroud, and the diameter of the fan should not be too small in relation to the shroud opening. Too much space between the shroud and fan will create a path of least resistance and results in less efficiency.

Even after everything is said and done, you might still find that the truck overheats. It's always possible that the design itself fell short. Most manufacturers do not build for extremes. The basic design handles typical expected conditions but can't cope with extreme demands. For example, a police car will have greater demands on their electrical and cooling systems, because they tend to idle for long periods of time and use lights and computers. For those, the cars are equipped with improved systems. With traffic and weather conditions in your local area, it's possible that the design is not up to those conditions, in which case, you may have to consider upgrading the cooling system.

This might require a larger capacity radiator and perhaps an additional supplemental electric fan

Ed
 

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Wow, what a thread...well here I am. I have been having an issue with my 2001 4.7l Durango (I hope this is the right place). Now mine may be a simple solution. I am getting overheating, the bubbling and steam. However I have confirmed my electric fan is dead. I believe the clutch fan is in working order. Quick question before I go further. Would replacing the electric fan solve this issue? With it being cold outside I haven't had too many issues with it getting warm but a few months ago sitting in traffic the temperature was shooting up. Would the e-fan make that much of a difference? The main reason I am asking that is because if y'all believe it could be more I may stop toying with this thing. I just recently replaced 3 air sensors on it and there are some other non-mechanical things that need to be fixed. Thank you for any response!
 

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The electric fan will kick in under several circumstances, one being that the coolant is getting warm enough to justify it.

So, yes, I'd swap that fan out soonest.

And if that doesn't fix it, then I'd start looking at other choices.

(Logic: Fix what's obviously broken FIRST, then worry about the OTHER possible causes.)

RwP
 

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Thanks for the reply. I originally had replaced the thermostat. My father who is slightly more mechanically inclined suggested that. I did see an improvement such as the temp gauge stayed lower under normal circumstances but then it started overheating again. We drained all the fluid out and attempted to flush but we couldn't figure out how to get the pressure through so we added more fluid which I guess needs a burping now? I will also check the cap and for sure get that fan replaced. I'm assuming OEM is alright?
 

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Discussion Starter #79
I have to conclude that the culprit is in the only changed variables. Either you have the wrong temp thermostat, or your aftermarket fan isn't efficient enough. (Especially during the warm months) Ed
only thing is in my situation......i swapped to an OEM Mopar thermostat. the fan cools everything fine when the coolant is topped off to the correct level. if i top off the coolant prior to the drive home from work, and then get stuck in traffic, i can see the temp climb. but then i hear the fan turn on, and the temp gauge goes back down. the problem is when the coolant gets pushed out of the overflow. when the level gets low that's when things don't cool down.

and then to add another oddity to the mix, since i have been parking with the nose up on an incline, i do not notice the coolant coming out....maybe a few drips, but not pouring out like it has.
 

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Another thought.
A few years ago, I was losing coolant and couldn't track it down. I would sometimes see a wet spot or evidence of a wet stain around the end of the upper rad hose where it attached to the radiator. I was certain that there was coolant leaking out of the end of the hose and tightened the clamp as much as I dared. Still kept losing coolant. Not much, but noticeable over time. On a whim, after a drive, I opened up the hood and wiggled the upper hose and coolant bubbled out of the plastic radiator tank, near the hose….. I mean right thru the plastic! Well upon really close inspection, there was a very small crack in the tank and it was so small that I wasn't able to see it. Wiggling the hose opened the crack, it was so small that water sweated out of the crack and rapidly evaporated leaving the stain. It was so small a crack that it might not have shown with a pressure test…at least in a few minutes

I know you said you replaced the radiator, but make sure it is absolutely sealed. You could try adding some dye to the system, then see if you can find a possible leak by using a florescent light to spot any dye outside the system.

Ed
 
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