Team Camaro Tech banner

1 - 12 of 12 Posts

·
Registered
Joined
·
609 Posts
Discussion Starter #1
We have a 2003 Dodge Dakota 4WD that just started running on the hot side. If we let the truck sit in the driveway running, the temp switch will go to nearly the H level which is not normal for this vehicle . We have identified that both the electric and clutched fan are running and we have sufficient coolant available. When we drive the truck the temp reduces down back into the normal range ( it is 40 deg out) .

We are thinking either thermostat or possibly water pump.

Any thoughts on where to go next would be appreciated.
 

·
Registered
Joined
·
47 Posts
Sounds like a restriction of some kind. let it warm up to around operating temp, (sometime around when the thermostat should be open) then grab the top and bottom hoses to see if they're both hot. If it's overly warm on the gauge and one hose is still cold.. thar be a thermostat fault. If they're both warmish.. it may be a blockage in the radiator. or an airlock somewhere.
 

·
Registered
Joined
·
609 Posts
Discussion Starter #3
I was kind of thinking that as well. The top hose felt pressurized- almost bulging. I didnt feel the bottom, but while the top hose didnt feel hot , it was definitly under pressure.
 

·
Registered
Joined
·
13,326 Posts
Thermostat...and/or blocked cores...modern radiators are not as fogiving as the older models which where over built
Water pumps..if not seaping water thru seals and if have no play inthe shaft are very ralely at fault...thu its not unknow for an impaler to be slipping on the shaft.....but this usually shows as normal highway temps a biy higher than normal also... rare and unlikely.
If replacing thermost, check the new one in a jug of water before installing...and make sure u dont just buy any old thermostat in the correct heat range off the shelf...get the one for that model...thermosts open at different rates, have different flow rates etc.
 

·
Registered
Joined
·
8,349 Posts
If it's the 4.7L engine, those seem to have a lot of cooling issues. Thermostat is a big problem and many say there are some brands that just flat out don't work well. I think the Mopar one is supposed to be good. It's mounted down at the bottom of the engine which might explain the bulging top hose.

Another few things with that one are:
-Radiator gets buildup in it pretty easily.
-Head gaskets seem to have issues.
-Water pump uses a plastic impeller on a hex which can groove out which makes the engine cool fine at idle but then slips at running RPM.
 

·
Registered
Joined
·
609 Posts
Discussion Starter #6
May not be related but thought we should add this.

The truck had a engine light on- Codes read out previously that it was a vapor loss? suspected bad gas cap but code did not go away with new cap.

Yesterday son in law found hose that was cracked and damaged. He cut th ehose back and reattached. The hose runs out of the Canister purge valve into what looked like a connector to allow pressure release or ? ( looks like a tire valve, with a green cap)

Once he did this the check engine light is out, but now has noticed th etemp change....

Coincidence?
 

·
Registered
Joined
·
8,349 Posts
Well, an EVAP code is a soft code which will clear on its own but only after so many good cycles have occurred. So, correcting the problem doesn't always immediately correct the code. I get the "loose gas cap" (low vacuum) code all the time on my truck since it's got an aftermarket supercharger. Sometimes it'll clear in a couple of miles, sometimes it takes a couple of days, sometimes I'll just connect to the ECM and clear it myself. Disconnecting the battery and ECM fuse will also do it and if it was just a blip it'll stay gone.
 

·
Registered
Joined
·
609 Posts
Discussion Starter #8
We had cleared the code multiple times with an ECm tool , but the code would immediatly return . It has not returned after repairing the hose. I am assuming you feel this could have no impact on the cooling either way and is just a coincedent that one preceded the other?
 

·
Registered
Joined
·
8,349 Posts
Sounds like you fixed it. I can't imagine how correcting a vacuum leak would lead to overheating so I'd just call it coincidence. You may find some more places to look on the Dodge Forum and maybe Dodge Talk. That's where I went when helping a friend with a 4.7L. His issue was ultimately the radiator but it was the reverse of yours....ran fine at idle but hot going down the road. We have a 5.7L with no issues yet thankfully.
http://www.dodgeforum.com/forum/index.php
http://www.dodgetalk.com/forums/index.php


Unfortunately if you want to test out the thermostat on a 4.7L you wind up losing $30 worth of coolant if you don't catch it because of the location.
 

·
Registered
Joined
·
3,905 Posts
As to the notion that the upper hose felt "under pressure", remember, it can be pressurized from the lower hose thru the radiator, the cooling system is a closed vessel and will pressurize thruout. If the car "is at temp" and you have a cold hose, suspect a bad thermostat.

As was noted above, Chrysler water pump impellers are known to come loose which will manifest as good temp at idle, overheat at speed.

Just went thru all of this with my PT Cruiser and it turned out to be a bad radiator cap, of course, in my case, I was losing coolant. Pressure tested the cap and it failed, new cap=happy wife and car.

alan
 

·
Registered
Joined
·
609 Posts
Discussion Starter #12
So we prepared to change the thermostat out, went to drain the radiator and nothing came out. Removed the cap with a huge gush of air- Still nothing out of the bottom of the radiator, Noticed there was not a drop of coolant int he upper hose where we took the cap off. We added nearly a full gallon of coolant before this topped off. We started the truck with the cap off and tried to burp out the system. We continued to get burps as the truck came up to temp. The gauge showed the temp came up to normal range and held. we replaced the cap, drove the truck around and then let it sit in the driveway. The temp has been holding normal since.

On this truck you check the coolant level in the over flow tank and it showed full when we first started this whole deal, yet there was none in the hose and there was pressurized air instead when we pulled the cap. First thought was bad head gasket letting gases into the coolant and pressurizing the system. Im confused as the truck has now been running fine since the changes...Are we just on borrowed time as the head gasket is out and the pressure will eventually build and push out the coolant again??

Thoughts?
 
1 - 12 of 12 Posts
Top