Last post on Jul 24, 2003 at 9:15 AM
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Dodge Dakota, Engine, Truck
#1 of 6 Dakota 4.7 overheat
Jul 21, 2003 (4:29 pm)
This is the third time I've posted this, havent seen it displayed yet.
2000 Ext cab 4x4 4.7 auto without tow pkg. What is high end of operating temp. Is mine running too hot. In summer with 90+ ambient temp, A/C on, in city and stopping at red lights the gauge will go up to the right side of the "0" of the "210" reading. At this temp the fan will slow down, changed fan clutch , no difference. Can shut off ac and temp will drop to left side of the "1" at which time the electric fan will shut off and the mechanical fan will be turning faster than at the hotter temp. At constant 50MPH+ for a mile or more the temp also sarts dropping and will stay on top the "2" even at 80MPH. So it seems it is an air flow problem but radiator is not blocked.
#2 of 6 Re: Dakota 4.7 overheat
Jul 22, 2003 (3:57 pm)
The "normal" operating temperature range of the available engines in Dodge trucks is between 130 degrees F to 264 degrees F.
You don't state whether or not you get a "Check Gauges" or a malfuntion indicator illumination. The "Check Gauges" indicator illuminates at 252 degreees or higher and will not reset until the temperature has dropped below 246 degrees.
The malfuntion indicator (looks like a profile of an engine) will illuminate whenever the PCM records a diagnostic trouble code.
But the first question is whether or not there are other signs of actual overheating. Are you loosing coolant? Do you have any detonation? Can you verify the coolant temperature by using a service thermometer?
If you are not seeing a "Check Gauges" or malfuntion lamp, I would suspect that you either have a defective gauge, or more likely yet, a bad temperature sensor.
Because of the flucturating temperature readings, the second thing I would suspect is a bad thermostat.
Let us know how you make out.
#3 of 6 Dakoya 4.7 overheat
Jul 22, 2003 (7:45 pm)
Dusty, thanks for the response. No indicator lights, no boil over, no loss of coolant, no detonation, havent confirmed temp but the reading is consistent with the conditions in which they occur. Another usual thing is when it is this hot the AC will not blow cool. Your second suggestion seems most likely. Here is what happened to day, at the job site I was doing a job that just required me to be an observer, I just sat in my reuck w/AC on, at about noon and probably 90+ outside the temp started climbing onto the "0", I opened the hood about 10 inches, turned off the AC for 5 minutes it cooled down to the right side of the "2". I turned the AC back on with intake from the outside as I usually do. It was not cool so I switched to Max/recirculate, air got cool the cold, the temp stayed down at the right of the "2" for 1-1/2 hour till I shut off truck and got out. I'll change the thermostat this weekend, by the way where is it, on the bottom? Difficult job?
What do you think about the fan slowing down
Another problem I have is I had let the oil go too long, got thin, then I let it get low ( I think my 86' F-150 300/6 had spoiled me on this. it was so forgiving) Anyway thru my neglect it started tapping, I added oil but delayed changing it for a few weeks and I get a tapping at cold start up about 8 out of 10 times. I took it to Dodge dealer and they said change oil several times at about 1000 miles. It helped for the first 500 miles of each change. I did this three times, now back to about 4000 mile changes. Does this act like a bad hyd. lifter? I've never worked on the OHCam except a little bit on a Pinto, done a lot of work on Chev 350, would it be hard to identify which lifter, remove and replace?
#4 of 6 1tlynn...................
Jul 23, 2003 (2:38 pm)
>>I'll change the thermostat this weekend, by the way where is it, on the bottom? Difficult job?
What do you think about the fan slowing down<<
The thermostat is located very low on the right front of the engine block (left side if you're standing in front of the vehicle).
I'm not sure how difficult a job this is. You might explore accessing it from the underside of the vehicle.
I'd have to think about the fan slowing down. My gut feeling is that this is a normal reaction of the viscous fan.
>>Does this act like a bad hyd. lifter?<<
Well, assuming you have not lost oil pressure since you ran it with thin oil, I'd have to say the chances are pretty good that you lost the prime in one of the lifters. It may take a while for it to return, and may never. It is possible you lost a lobe on the camshsaft. I have seen this happen before.
You're sure its not a rod or main bearing knock?
Jul 23, 2003 (7:20 pm)
Oil pressure got a little low at idle, other than that it stayed up good. Bearing knock ? I suppose it could be but it the knock sounds high in engine though I havent had someone start it while I was at engine compartment listening. It won't knock any unless it has been sitting for more than two hours and the knock is for less than 2 seconds and then not every time, seems as if when cam stops at "lift" on suspect lifter, that the lifter leaks down. Guess I would need to mark crank pulley to identify where rotation stops that results in a knocking start up, then do a long duration shutdown at that same crank location/stroke giving time for possible leakdown then check for loose lifter. What do you think?
#6 of 6 Re:What do you think?
Jul 24, 2003 (9:15 am)
If it's still got some warranty left, report this to your dealer.
If out of warranty, keep changing oil and filter and drive it.