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Discussion starter · #84 ·
Replaced the radiator cap again with a Stant with the locking lever, and no more mess in the engine bay. Seems the Mopar replacement wasn't up to the task either.

I've been checking the coolant level every day and I'm not losing anything else anymore, and the truck seems to be running fine again. I think it's just prone to run a little warmer when it's 105° outside as it's been for the last two weeks.

The overflow bottle cap decided it had enough and simply fell off, so I need to source a replacement to keep debris out of the overflow bottle. It has never really sat snug and was always kinda loose, since the truck was new.
 
Good news, all things being equal. It does take a little time to relax and trust the result after an ordeal like this.
Those yellow overflow caps are available everywhere. I broke mine at the hinge and had to replace it some time ago.

Dorman Part: 54201.

[ame]https://www.amazon.com/Dorman-54201-Engine-Coolant-Reservoir/dp/B00Z7MMSIS/ref=sr_1_3?crid=724MDTY15WPE&keywords=dodge+coolant+reservoir+cap&qid=1566330852&s=gateway&sprefix=dodge+collant+%2Caps%2C162&sr=8-3[/ame]
 
Discussion starter · #86 ·
Yeah, no kidding. I'm still paranoid, but starting to ease up.

I ordered a replacement cap yesterday, expecting it any minute thanks to Amazon Prime!

Now onto the next vehicle related project... a harmonic balancer that failed on my Mercedes which means serpentine belt doesn't spin because the rubber element just came apart :cussing: if it ain't one thing...
 
Discussion starter · #87 ·
Drove it today for an extended period of time myself, and it is still getting hot, far too hot.

Fuel economy is far worse than usual at 10.3mpg, whereas it's normally about 15mpg on average.

There's also a distinct "hot" or "burnt" metal smell when I get out of the truck, and it's coming from underneath. I'm suspecting it is the transmission... possibly the TC, or just the whole damn thing. Trans temp light never comes on, but it just flat out may not be registering anything.

Now that I think about it, I can let the truck cool and then let it idle for hours without ever moving it and the temps stay normal. It's after I've driven it around that the temps creep up and tend to rise up in stop and go traffic.

Letting it cool and then I'll check the radiator itself to see how the level looks; expansion tank still shows as being full.

If it is indeed a transmission issue, then I'm not going to opt for a rebuild or a replacement unit, I will do the manual swap. Part of me wants to pull the whole motor this time, and pull the heads to re-examine everything and have the block decked too. I'd hate for my heads to have warped yet again...

The saga continues!
 
Discussion starter · #88 ·
No noticeable drop in coolant levels in either the expansion tank or the radiator. I'm sure if I was still have head gasket issue even due to the block, I'd have missing coolant from burn-off.

Now, my dad says it never gets hot when he drives it, but he also drives super gently. No quick acceleration, no speeds above 65mph, etc.

I, on the other hand, am a fairly spirited driver when the mood suits me, and today was one of those days.

I'm further beginning to suspect the transmission.
 
Discussion starter · #89 ·
I must be going crazy...

It for sure runs toasty when I drive it, but here are photos my dad took when he drove it 30 miles (about an hour or so drive thanks to traffic) to work in stop and go traffic with 85° ambient temps. He also does not drive with the AC running either.





Now, I've always driven this truck more spirited than he does, and can't ever recall the temps creeping as they do.

I'm honestly at a loss.
 
How heavy is that foot?? There might be some clues in this. Drive the truck with the A/C off and check the gauge to see if it climbs. Then try driving as you normally do with the A/C on. When the temp begins to climb, shut off the A/C and see if the temp drops. I have a hunch that your A/C compressor has gone bad. Sometimes when they go bad, they can put a load on the engine which makes it work harder (which maybe why it begins to get hot) The other clue is the fuel economy. With the A/C off the truck is getting almost 20 mpg, almost twice what you've been reporting. Your dad maybe a slower driver but a 10 mpg difference can't be accounted for by slower driving. Ether the A/C is really dragging when it's on, (which is what I'm suspecting) or you enjoy stop light drag racing too much

Ed
 
Discussion starter · #91 ·
How heavy is that foot?? There might be some clues in this. Drive the truck with the A/C off and check the gauge to see if it climbs. Then try driving as you normally do with the A/C on. When the temp begins to climb, shut off the A/C and see if the temp drops. I have a hunch that your A/C compressor has gone bad. Sometimes when they go bad, they can put a load on the engine which makes it work harder (which maybe why it begins to get hot) The other clue is the fuel economy. With the A/C off the truck is getting almost 20 mpg, almost twice what you've been reporting. Your dad maybe a slower driver but a 10 mpg difference can't be accounted for by slower driving. Ether the A/C is really dragging when it's on, (which is what I'm suspecting) or you enjoy stop light drag racing too much

Ed
Not that heavy, mostly. I tend to move out occasionally and certainly travel at a higher speed, but I'm by no means burning rubber at intersections.

For comparison, I mainly daily a '96 F350 with the 7.3 PSD and ZF5 manual and I average around 18mpg. I like the way the turbo sounds... but I'm not running a tune to smoke anyone from a stoplight.

It'll be some time before I get a chance to drive the truck myself, as my current work schedule has me getting home at odd hours, and I'm too tired to swing by my folks and grab it for a spin.

He's driving it daily and never reports high temps anymore since doing the head gaskets.
 
Not that heavy, mostly. I tend to move out occasionally and certainly travel at a higher speed, but I'm by no means burning rubber at intersections….
It's a joke…. Point being, your dad is showing 19+ mpg and it's not overheating on him, while you are getting about 10mpg and it seems to be overheating. The only real difference is, he isn't using the A/C and you are. You could drive slow and easy and improve your mileage, but not up to 10 mpg. The only explanation I can see is the A/C compressor is bad.


It'll be some time before I get a chance to drive the truck myself, as my current work schedule has me getting home at odd hours, and I'm too tired to swing by my folks and grab it for a spin.

He's driving it daily and never reports high temps anymore since doing the head gaskets.
Well, theres an easy solution. Ask your Dad to turn on the A/C when he drives it and watch the temp gauge to see if it climbs and check the fuel economy to see if it drops. Report the results back, before summer is over, otherwise you'll have to wait till next summer to deal with this.

Ed
 
Discussion starter · #93 ·
I understood that, I wish this thing was a little faster off the line when the mood strikes me, but that low-end torque is great for moving a load. Under normal driving circumstances (AC or not) in the past my personal average was usually 16-17mpg when driving.

I'll ask him to do just that and for him to record his results.

For some reason I'd be expecting to have AC issues if the compressor is in fact acting up, but AC seems to be fairly normal in terms of temps. However, things aren't always as they seem.
 
Discussion starter · #94 ·
An update, with no AC running, and driving with ambient temps in the high 90s in stop and go traffic, he sent me this:



No noticeable coolant loss; just checked. Looks normal, no signs of particulates, no cloudiness, nothing. Looks like normal coolant. No more signs of coolant leaking and being flung around by the fan since replacing the cap once more.
 
Have you confirmed that the gauge is accurate?? I know that many of the old Dodge trucks had terrible factory gauges. The Dakotas should have much better gauges, but gauges and sending units can still go bad and give an inaccurate reading.

Ed
 
Discussion starter · #96 ·
When the system was empty, I took the opportunity to replace the sending unit with a new OEM part. It hasn't gotten that hot over the last few days, so I haven't been able to take the infrared gun to it.

I suppose it's always possible it could have started misbehaving and giving inaccurate readings, but why now all of a sudden?

There's also been an intermittent Parking Brake and ABS light on, but not getting any codes, brake fluid levels are good, speedo works fine so don't think it's a speed sensor, and I can hear the ABS pump do it's thing on startup every time. There has been new anomaly where the fuel gauge will zero out and the low fuel light will come on, but then it springs back to life.

It's entirely possible there's some wonky electrical issue that's cropped up, but nothing looks out of the ordinary.
 
I suppose it's always possible it could have started misbehaving and giving inaccurate readings, but why now all of a sudden?
Because they do that, and usually at the most inopportune time….. It could be a number of things that could cause it, but the bottom line is, once you've eliminated everything else, it becomes time to question the source of your information…in this case, your temp gauge.

It's entirely possible there's some wonky electrical issue that's cropped up, but nothing looks out of the ordinary.
There would be no way of knowing by visual inspection alone.
One of the things I know about these factory gauges is, they aren't always accurate and I kinda doubt if Chrysler ever calibrated them for accuracy. In the older D/W series trucks (and many cars, up to about the 90s) The face of these temp gauges were printed with a "C" and an "H" at each end of the needle swing, and the word "NORMAL" with a series of hash marks across it's face. Then someone would come along and say their truck was running very warm or hot because the needle was pointing to the letter "M" or "A" when it usually pointed to the letter "O" in NORMAL…. The question I would always ask is, what is the temp when the needle is pointed to the letter M or A? And they would usually say, I don't know, but the needle isn't where it's normally at, so they conclude there much be something wrong and that their truck is running hotter than normal. That maybe so, but without knowing the exact temp the engine is running at, theres no way to conclude if it's just running warm or it's overheating.

With our Dakotas, the design of the gauges are not much different, except that there are numbers printed on the face of the gauge, instead of the word "NORMAL". With the printed numbers indicating specific temperatures, it's easy to assume that it's accurate. But we can't always be certain because we can't be certain if the gauges were ever calibrated by the factory,,,, or if they were, somehow lost that calibration via malfunction, or if the gauge is working correctly at all.

The gauge functions much like a light bulb on a dimmer switch. When you turn down the dimmer, the light bulb goes dim and vise-versa, when you want to make the bulb bright. Temp gauges, fuel level gauges and modern speedos work about the same way. The sensor is basically a rheostat and the gauge reads the amount of resistance and translates it to usable info….and sometimes they can go bad.

So start from scratch. Assume that the gauge can't be trusted at all. One of the things you can try is install a known accurate gauge, -The installation doesn't have to be permanent, it just needs to be done to confirm the reading of the factory gauge. I personally prefer Autometers because they are calibrated for accuracy. For simplicity you can use a mechanical gauge. These do not require any wiring and are fully independent of the truck. If the factory gauge is accurate, this set up would tell you.

A temp gun might not work as well, it can only read radiated temp from the surface of whatever you are pointing it at. It doesn't actually read the coolant temp inside the engine, which happens to be flowing. And it can't be used when you are driving.

Ed
 
Discussion starter · #98 ·
I've got an ISSPro Trans Temp gauge out of my F350 that I used in the automatic transmission before I swapped it out. I've got a clip sense attachment I can use to mount it to the cooling line coming FROM the transmission to get the best possible reading of the trans temps, see if that has any bearing on what I'm dealing with.

Since the trans temp gauge is coming out of the F350, I was going to put the ISSPro coolant temp sensor I have in its place, but I forgot to install it in the truck when I replaced the radiator last month so I can use it in the D as well.

I will attempt to get both installed this week.
 
Discussion starter · #99 ·
Got the coolant temp sensor installed last night:


Let it warm up without driving. It hit between the 190 and 200 mark, before I could observe what seemed to be the T-stat opening and it settled here:


Ambient temps in the 50s.

After a quick drive and getting the trans warm, it got up to here before settling down just above the 190 mark:


This morning after turning onto the highway. You can see the IssPro gauge is near 200°, while the dash gauge is reporting cooler. Fast forward about 15 minutes and I arrive at the shop. Here are the readings on the trans and coolant gauges, and the dash gauge. Ambient temp about 57°:



Just returned home from the shop and recorded my results. Ambient temp 80° with AC running:



What I noticed is the hotter the trans got, the hotter the coolant temp liked to read and stay at. The highest it pegged on the IssPro was just a hair over 200°, and the electric fan or just driving would keep the temp down. The drive to the shop has a lot of hills going up and down, so that could also be a factor. I drove it just as I normally would.
 
Discussion starter · #100 ·
Here are some results from yesterday. These were taken when it was about 85° out, AC running.




This was the highest I ever saw the IssPro coolant temp gauge go, never any higher.

This was from after pulling into the driveway:




I expect the IssPro to show slightly hotter temps, because that's coolant that's going to the core as opposed to through the thermostat back to radiator to cool, but the temps have been reasonable. While the transmission is still cooler, the IssPro will usually sit at about 195°. It's when the trans starts to warm up beyond 180 where it seems cause the coolant temps to creep up slightly. Those were the hottest trans temps I've observed, and I'd basically done about 3 hours of town and highway driving yesterday. Otherwise, it seems the coolant temperature seems to spend most of its time around the 200° mark on the IssPro gauge.

Trans fluid level is still good, and the fluid looks healthy. Will just continue to keep an eye on it.
 
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