» » »

Dodge Q&A

Ask Your Question

1993 Dodge Dakota Question: BRAND NEW cooling system and still only lukewarm air coming from the heater.

 

Question

Doughface1, 3.9L V6, Bridgeport, AL, January 25, 2014, 00:10
 Rookie

And I do MEAN brand NEW as in the entire cooling system,thermostat,(Safety type 190degree),Water pump,ALL hoses,heater core,blower motor,serpentine belt,everything and anything imaginable from stem to stern has been replaced.Also bled the system by elevating it about four feet in the air.One thing I might mention,originally it had a single core radiator,which was replaced with a dual or double core.If I sit parked and rev the engine it will in fact get REALLY HOT,but once I begin to drive it is as if there is not enough coolant passing thru the heater core?There is absolutely no restrictions in the system and this is about to set me to a looney bin.Any ideas would be greatly appreciated.It is constant too,once driving the air goes to tepid,but parked and revved it will get HOT!I have even placed a peice of wood in front of the radiator to block off 75 percent of the radiators ability to cool,and made sure the engine does not overheat,yet still cannot get the heater to blow HOT air when I am moving.

3 Answers
Flag This
  • Answer #1

    cardocIII from Gillespie's Auto Service, January 25, 2014, 01:07
    Profile_thumbnail
     Master

    Are both heater hoses too hot to hold onto? If not then you still have poor coolant flow through the core.

    Was the coolant very rusty? We have seen some engines that the cooling system was in such bad shape that the new heater cores quickly got restricted. Two things about that, you usually had some heat for a few days and they will flush out. There are aftermarket filters that can be installed inline with the heater core that will catch the debris, and yes you'll go through a few of them but they will do the job of getting that stuff out of the system while protecting the new heater core.

    In the shop we use a tool called "Air Lift" to refill the cooling system by first pulling it into a vacuum, which is the same way they are filled at the factory. Before we had that there were some cars that just refused to bleed air out easily. One way to do it is to loosen the heater hoses and us a pressure tester to build just a little pressure in the system at the radiator, and then we can "burp" the air out of the hoses and the heater core.

    Is the temperature blend door cable operated or is it electronic? If the hoses are too hot to touch then the blend door might not be sealing and directing all of the air through the heater core. Hang in there, these can be fixed. I always stress at a time like this, take a deep breath and then aproach it like its a completely different car and diagnose it like you never saw this one before. Doing that will lead you right to the problem.

    Flag This
  • Reply

    Doughface1, January 25, 2014, 15:17
     Rookie

    Appreciate all of the input.Especially the advice to step away and come back at it as if you never seen it before.Since I put in a new camshaft,lifers,redone the intake,etc.As well as a timing chain and gear set,oil pump and distributor gear with bushing,this obviously is not my first rodeo,and albeit I would not make a pimple on mechanics behind,I have plenty of experience thru the University of Hard Knocks,but this one is the first time I have ever ran into this much grief.
    As advised sadly I did not have one of those new fangled fancy non-contact infrared temp thingamabobs,thus I had to revert to old school,as in OUCH!)($(_$*YU%%))*%*DAGGUMIT,and a few more OWSSSSSSSSSS along the way,but I found that the upper radiator hose was HOT at the radiator and also at the thermostat,but in the center was quite cool.I surmised there had to still be air trapped in the system and have played some more,squeezing the hose,reving the engine and doing it some more.It appears that I have gotten even more out,confirmed by a seen a ton of bubbles while squeezing the hose.But it seems there is STILL air in the lines.I do have a pressure unit,can I use it,open the lower heater core hose,pressurize the system and let it bleed thru the loosened heater hose?BTW,flushed the engine when doing the camshaft,and the entire inside is clean as a whistle,coolant and sludge wise.Am rebuilding this thing and going to paint it soon,if I can ever get the air out of it that is.

    Flag This
  • Reply

    cardocIII, January 26, 2014, 04:52
    Profile_thumbnail
     Master

    "I have plenty of experience thru the University of Hard Knocks,but this one is the first time I have ever ran into this much grief."

    Welcome to our world. It doesn't matter how much experince someone has, every once in a while this job has a way of teaching us things we really didn't want to know. (VBG)

    Bleed it from each heater hose and the hoses themselves, then top the rad back off.

    Reply
    Flag This
  • Answer #2

    pushrod January 25, 2014, 04:29
    Profile_thumbnail
     Master

    While "driving down the road" and the heater output becomes cool, shift to neutral and rev the engine, will it warm back up? Do you have a non contact infared thermometer?

    Flag This
  • Reply

    Doughface1, January 25, 2014, 15:27
     Rookie

    Yes,while driving and it begins to get cool if I put it in nuetral and rev it,it will in fact get hot again.I don't have a non-contact infrared thermometer and had to wing it old school,finding out where I didn't get second degree burns grabbing a hose.I did find that the upper radiator hose was HOT at the radiator and also at the thermostat,but cool in the center? I squeezed the hoses and seen more air coming out,after raising the truck in the air,but STILL seem to have air trapped in the system.There is no rust in it at all,was cleaned thoroughly when I installed a new cam,lifters,etc. I was wondering however,since I do have a pressurizer,could I loosen the lower heater hose and pressurize the system and force out any remaining air via that method?

    Flag This
  • Reply

    pushrod, January 25, 2014, 17:34
    Profile_thumbnail
     Master

    Looses rad cap let it run and rev up every once and a while until heater gets hot several times on this engine it should purge itself. I have never had a problem with air in a cooling system that didn't take care of itself! Some are a royal pain in the a...neck but there you have it..
    Be SURE the system is FULL when finished.

    Flag This
  • Reply

    Doughface1, January 27, 2014, 04:05
     Rookie

    Appreciate your and Gilispies input.Am on the right track and getting hot air little by litte thanks to your advice.Good grief,I have never ran into this much of a headache on a cooling system in my life.If I had money to pay for a shop,I could probably drive something newer than a 93 Dakota and the 98 Silverado I do manage to keep on the road thanks to good folks like yourselves who took the time to point me in the right direction to resolve this issue.Again thank ya all.

    Flag This
  • Reply

    pushrod, January 27, 2014, 05:46
    Profile_thumbnail
     Master

    Sure thing! Keep'em running!!

    Reply
    Flag This
  • Answer #3

    asksteevies January 26, 2014, 10:41
    Profile_thumbnail
     Master

    just a shot in the dark , belt spinning water pump wrong way??
    if u google 3.9 belt routing, maybe its not on rite and your spinning the pump the wrong way....

    Flag This
  • Reply

    Doughface1, January 27, 2014, 04:10
     Rookie

    thanks for the input.Could have used this about three weeks ago,lol. I in fact had a friend lend a hand putting the water pump back on,and when we got to the point of re-installing the fan,I figured there was no way he could possibly screw that up and went inside to do something else.It took me almost two weeks to figure out what in the heck was going on,until I happened to be smoking a cigaretter and noticed the smoke was being blown away from the grill. I got this problem narrowed down,it is just a royal pain trying to get all of the air still trapped in the cooling system out after completely replacing the entire system.I am beginning to get hot air now.Thanks for taking the time to offer your help.Really appreciate it.

    Reply
    Flag This