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Allan
Dodge Dakota
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10/04/2003
07:53:29
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 Subject: RE: 4.7liter Overheating - Case History
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There certainly is a difference between the old copper radiators of years gone by and the new alum. ones. Make sure that you are using a good thermostat (brand wise) and no air locks when you refill the system. If you wait till next summer before you look into it any more keep in touch to let us know how it finishes.
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varnuke
Dodge Dakota
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10/04/2003
10:23:12
| RE: 4.7liter Overheating - Case History
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Know I got a minimum total of over a Rem whole body dose of gammas while in the Navy. Not too keen on getting yearly X-rays just to see if I am dying or not. The way I figure it, I'm dying anyway, so at 54, I don't really care, just hope it is quick when it comes.
As far as the truck, the radiator is original. Yesterday I was driving and watching closely the temperature. It was fine for the whole trip until I got into slow stop-and-go traffic with some short stints between lights. The temp crept up to 210 with electric fan kicking in. My wife and I proceeded on to the grocery store. I dropped her off at the parking slot and left it idling the whole time she was in the store and it held steady at about 190 for 10 minutes not budging a fraction of an inch.
The water pump pulley still has the black paint on it, but I am noticing distinctly where the belt contacts it. Not sure if this is just smoothing down the high spots on the paint just due to contact, or if it is slipping and wearing it off.
I think the first thing I will do this next week is stop by the parts department and find out about the belt tensioner. Think I will replace that next and leave the radiator go until Spring with the temperatures down now.
I've never had a radiator go bad on me yet. This would be the first time I have ever witnessed a radiator go bad, with what I consider low mileage for a radiator core. Then again, the majority of my driving was interstate. I'd say about 70-80% of the miles are interstate driving. So, there has been a lot of constant flow going on in my coolant channels for long periods of time each trip, usually 1000 miles in a day.
It has me stumped as to what is going on. As far as the oil pressure going down at speed, I keep thinking about that one, and all I could guess at first is bad bearings causing too much gap in the internal pump clearances when the pump is at rpm, causing the pressure to drop. But that's a WAG. I don't even know what the design of the oil pump looks like on the Dakota.
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Dally
Dodge Dakota
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10/04/2003
10:43:05
| RE: 4.7liter Overheating - Case History
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I missed the part in your first post where you spoke of poor oil preassure. If you got poor oil preasure, that could be half of the battle, as oil does play a major roll in the reduction of heat creation to begin with. Don't rule out the rad though, I have had a few go to pot on me since these $hitty aluminum stuff got started. And yes, some rad shops will run the rods through, but you are better off with a recore job. If you end up recoring, go to a 4 core as a replacement; you won't be sorry.
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Kindig
Dodge Dakota
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10/05/2003
23:10:31
|  RE: 4.7liter Overheating - Case History
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Greetings Varnuke, Good luck with your rig. My truck is a 01 4.7 4x4 with no problems,except for those Dodge brakes. Albiet, I only have 28000 miles.
I am 51 and my hearing is terrible,I owe it all to the Engine room.Nobody back then was worried about ear problems. I remember one day we Lost the LOAD,in the middle of the Pacific.Dead in the water. We had to restart the main engines with battle latterns with NO ventilation.
It got to be 135 degress in the hole and we worked with 10 minute shifts. SO when I die I know I'm going to Heaven,cause I already did time in HELL.
Later Varnuke,
Kindig
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varnuke
Dodge Dakota
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10/06/2003
15:37:31
| RE: 4.7liter Overheating - Case History
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Stopped by the Dodge dealer this morning and ordered a belt tensioner. It apparently comes as an assembly. They are on back order. That was interesting in and of itself - wondering why so many are apparently being used. When I get the new one - $90.00 - I am going to take the old one apart and see if I can repair it with a new spring, or whatever, in our shop. Can't wait to see if this new tensioner does the trick since the radiator seems to be working okay at speed and in the parking lot while idling. The tensioner is the only thing left that could be causing the problem it seems to me.
Speaking of dropping loads, we dumped both reactors in the Tasmanian Sea after leaving Perth. The Bainbridge did that on the line in the Gulf of Tonkin. I think I would have rather done it there too in the Gulf instead of the Tasmanian Sea. It took us 45 minutes to re-start #1RX and ER, and during that time it felt like we were in a typhoon the way the ship rolled in those waters down there. The good old days.
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DMSDAK
Dodge Dakota
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10/06/2003
21:42:56
|  RE: 4.7liter Overheating - Case History
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Man I had an overheating problem on my truck on my way back here to Kentucky from Wyoming and then again on my way back, all it was, was the Radiator Cap. A damn dealer Item 21 lbs. radiator cap, fixed it right off!
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outlaw17
Dodge Dakota
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10/06/2003
22:32:11
| RE: 4.7liter Overheating - Case History
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Do you happen to live in an area where there are lots of white poplar trees ? You know the ones that lose all that fuzz in spring ? I spent alot of time this spring and summer diagnosing overheating problems that seemed to stump most others and what I found to be the problem escpecially on highway vehicles was that the fuzz goes right through the A/C condensors and sticks to the rad , right where the fan is , so...... when the fan kicks in it has no effect at all and putting the A/C on makes it even worse with all the heat coming from the condensor . The only way you can tell if this is your problem , and I am betting that it is , is to pull the rad away from the condensor and look at the front side of it , there you will find a ton of fuzz stuck to it . Use a pressure washer or blow nozzle and get rid of it and your problem will be solved .
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WOW
Dodge Dakota
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10/07/2003
17:34:16
| RE: 4.7liter Overheating - Case History
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I'll bet you can tell how many fingers I'm holding up too !
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varnuke
Dodge Dakota
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10/07/2003
20:26:10
| RE: 4.7liter Overheating - Case History
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Summary as of today:
1.) Replaced water pump
2.) Flushed radiator
3.) Changed new thermostat (3 times)
4.) Filled and vented system with 50/50 antifreeze
5.) New fan belt
6.) New fan clutch
7.) Temp holds at 190-195 at idle for 10 minutes or more easily enough with radiator working well enough to cool engine
8.) Temp holds at 190-195 at speed on highway with radiator working well enough to cool engine
9.) Radiator sprayed for bugs and fuzz with high pressure washer
10.) Have NOT replaced radiator cap yet
11.) Have NOT replaced belt tensioner yet
12.) Truck heats up to over 210 when climbing even short steep hills or long drawn out hills then cools down immediately after leveling out and attaining steady speed, cools down fast then going down hill with foot off gas
13.) Not losing any anti-freeze coolant to engine through head gasket that I can see
14.) 173,000 miles, mostly 70-80% interstate highway miles still with original plugs, plug wires, etc.
15.) Oil changed every 3000 miles using Mobil 1 10W-30 synthetic up to 150,000, now changing it every 5000 miles
16.) Tends to heat up climbing relatively short hills or stop-and-go traffic on the level
I suspect the belt tensioner (on order), or the radiator per pervious reply posts, or radiator cap, or something else I am not putting together for lack of knowledge of the overall systems that may be interlocked with the coolant system that could be causing the problem - something I am not aware of.
I even ran the truck with an orifice that I made in the shop to replace the thermostat to act as if the thermostat was open all the way all the time. It took longer to warm up but acted the same way under the same conditions of hill climbing and stop-and-go traffic.
If the belt tensioner does not correct the problem, then I will do the radiator. If that does not correct the problem, then I'm going for a new truck, maybe the RAM with the diesel this next time.
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outlaw17
Dodge Dakota
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10/07/2003
22:21:42
| RE: 4.7liter Overheating - Case History
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Hey WOW , I'm gonna bet your holding up one , and I'm guessing its the middle finger on your right hand , now go look in the mirror .
varnuke , you say in the above post that it climbs to 210 , did someone tell you that is too hot ? 210 really is not 'too' hot , thats about when most electric fans kick in on most passenger cars to assist in the cooling , now if it was 250 , thats getting too hot . Just an opinion .
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Slanty Shanty
Dodge Dakota
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10/08/2003
16:02:03
|  RE: 4.7liter Overheating - Case History
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I was having an overheating problem as well, and couldn't for the life of me figure out why. I take VERY good care of my 4.7QC w/78000 miles. Then I started having a rev problem? Wasn't sure what was causing that either. Figured my TPS was going out. But before I went and got a new one I took mine out and cleaned it (which I did about 4 months ago) just for poops and laughs. Cleaned the other sensor and the TB... put it all back together and boob, no more rev probs and no more overheating??? The TB, TPS, and that other thing wasn't that dirty? Maybe it was just loose or something?
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KEVIN
Dodge Dakota
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10/08/2003
16:25:17
|  RE: 4.7liter Overheating - Case History
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I HAD THE SAME PROBLEM WITH MY DAKODA OVERHEATING, I REPLACED THE THERMOSTAT TWICE WITH NO LUCK. IT WAS NOT USING ANY ANTIFREEZE SO IT WAS NOT THE WATER PUMP, A NEW RADIATOR CAP DID NOT HELP EITHER SO I TOOK IT TO A DEALERSHIP AND THEY SAID THAT A BYPASS HOSE WAS LEAKING, THEY FIXED IT AND I HAVE NOT HAD A PROBLEM SINCE
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varnuke
Dodge Dakota
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10/08/2003
17:10:32
| RE: 4.7liter Overheating - Case History
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outlaw17, I agree 210 is not that hot, and the fan does kick in at that temp on the gauge, but this is not typical of the way the truck has run for three years without heating up at all near 210.
The only time I had it heat up while new was when I drove I-15 between Las Vegas and LA. Driving up those mountains would make it heat up in the summer with the air conditioning on, but it would never overheat to the point where I had to turn off the air conditioner and turn on the heater full blast to pull those kind of hills.
I too keep a good eye on my machines after my years in the Navy, running all that equipment in the engine rooms. So, I notice when things are not right, or when the readings are starting to indicate that something is going wrong somewhere. That is what I have going on here with this cooling system on the truck right now. Something is not right and I can't figure it out. It has me stumped completely.
If I knew what the "TB" and "TPS" acronyms stand for, that Slanty Shanty mentioned, I'd check them out too.
What I'd like to know is what "bypass hose" Kevin had replaced on his truck. I think that is probably what is wrong with my truck. It is probably another system hose that uses the heat from the cooling system for some kind of an emissions system component or something like that which is screwing up the cooling system. Makes me think along these lines particularly when it heats up very quickly with heavy acceleration up hills.
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Hahahahahaha
Dodge Dakota
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10/08/2003
17:54:39
| RE: 4.7liter Overheating - Case History
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You have no idea how lost you are ! Bypass hose part of the emissions system ? Kevin has a leak but isn't losing any anti freeze ? You guys deserve each other. Hint - TB is throttle body, TPS is throttle position sensor (on the TB), and the bypass hose just takes some pressure off the system when the thermostat is closed. You guys are a panic !
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Dally
Dodge Dakota
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10/08/2003
19:02:35
| RE: 4.7liter Overheating - Case History
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TRUST ME, CHANGE THE RAD.... BEEN THERE, DONE THAT..... A FLUSH WILL GET YOU NO WHERE...
I had said before, that I have had this same problem, and solved it. And, like you, changed everything else first. It IS the rad.
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Jay
Dodge Dakota
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10/08/2003
22:57:54
| RE: 4.7liter Overheating - Case History
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A few of the guys posting here seem to be trying to spoil it for others without their "specialized knowledge." I'm glad to have found this board because I can ask questions about things I don't know about. Don't think it would be right for me to rub someone's nose in the dirt for asking something they DIDN'T know about. Beside, what would be the purpose of this board, in the first place? I could say to those few to chill-out, but I wonder if it would do any good. Instead, how about if the rest of us continue with the questions and answers and NOT be turned off by rude or juvenile behavior.
My big question remains, "what causes the oil pressure gauge to read low, then go to zero while driving, up at idle?"
-- Jay
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Dally
Dodge Dakota
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10/08/2003
23:36:25
| RE: 4.7liter Overheating - Case History
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Jay, Sorry can't give any insight on that one aside from maybe an electrical thing.
If you are dissin me about my last post, I sometimes get frustrated when a question is asked, and someone says(me) "Yes, I have had that EXACT experience, here is what you need to do to fix it" then much later that same guy is still having the same problem and hasn't attempted to resolve it through what you have told him. Makes me think the guy just wants somthing to talk about and there is no problem at all.......
I find this site helpful too, keep on posting.
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Dally
Dodge Dakota
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10/08/2003
23:39:55
| RE: 4.7liter Overheating - Case History
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Hey, Maybe if the oil gets to hot, it thins out and causes a drop in preasure????????????
Just a stab in the dark
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varnuke
Dodge Dakota
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10/10/2003
20:26:24
| RE: 4.7liter Overheating - Case History
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Dally, I noted your and Allan's claim of the radiator being the culprit after having replaced just about everything there is to replace. The only thing I could not figure out was why it would work properly idling for 10-15 minutes in 80 degree weather as well as on the road, except for climbing hills and stop and go traffic.
Turns out there is probably just enough blockage present in the core leaving just enough heat transfer surface area left to essentially balance the overheating variables involved.
So I finally got around to getting down to the Dodge dealer again and talked to the main man in service. He checked out the radiator with his hand-held infrared temperature gauge and found that the top of the core is essentially blocked completely - as you suggested it was the radiator. The middle left side is working fine and the bottom left is partially blocked. The top left was reading about 77 degrees F; the middle left about 160; the bottom left about 132 the right inlet plenum side of the core was about 180.
Just within the last few weeks he said they had a brand new RAM in the shop with the same kind of heating problem. The temp would rise in his truck as he pulled hills with trailers attached. They checked his radiator with the gauge and found the middle of the core was blocked. Since that truck was still under warranty, he had to send that radiator back to Dodge, so he could not open it up to see how and why it failed.
So, I will have the new radiator tomorrow morning. I plan on replacing it tomorrow sometime. The service manager was interested in taking a look at the internals after I get it replaced, just to see how and why it failed. I can't wait to see what clogged it myself. I'll get some digital pictures of it once we get it apart.
Was looking over the installation tonight to see what kind of problems I may encounter in getting that thing out and replacing it with the new one. If anyone has done this and has produced a step-by-step procedure for doing it, or knows where one is on this site, I'd appreaciate knowing about it. It's always good to see one done or read about it prior to doing it the way I always approach it. I haven't gotten to the point yet where I know everything about everything there is to know. Know quite a bit about pressurized water nuclear reactors (PWR), steam plants, and machine tools, etc., but definitely little if any details about this 4.7L truck engine.
Looks like the AC condenser and transmission cooler are bolted and connected one way or another by supports to the radiatore core. Electric fan will have to be removed, and there is a diagonal support tube that runs down from the center of the front frame (two bolts there) on 45 degree angles down and outward from the center top. Not sure if this has to come off to get the radiator out or not. Once I get the new radiator I will be able to see where all the bolt holes are in it. Looks like it could be a little bit tricky getting it out the first time.
Got the new belt tensioner too today. Will replace it at the same time I do the radiator tomorrow. The old one is still tight but sticks a little in one position along its travel when you pull out on the belt by hand.
No bypass hose on the 4.7L associated with the cooling system according to parts guys at dealer.
Marshall Dodge in Covington, KY, located at Pike Street and I-75, is a very good place to do business in my opinion. They don't jack you around on parts pricing like the Dodge dealers in OH, and the people in parts and service have been very accommodating in answering all questions, etc.
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They
Dodge Dakota
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10/11/2003
06:07:18
| RE: 4.7liter Overheating - Case History
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are normally very acommodating to people who take the shotgun approach to mechanics, they get to sell a lot of parts that way !
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