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mike stager
Dodge Dakota
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12/15/2007
21:37:28
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 Subject: No heat after flush
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This is a scenario I had to deal with before in a Chevy Van I owned. IT had a new water pump ( probably a rebuild ) and a new radiator and a replaced thermostat ( twice replaced ).
Scenario : No heat/low heat from heater after warming up truck @ idle. Engine heater plugged in all night long. Upper hose going into heater core hot, lower cold ( specifically, I can feel heat from the lower heater core hose, but cannot hold onto the upper for long ).
I flushed the heater core both ways ( reverse first ) and had excellent flow and no noticeable amount of debris. Plenty of coolant in the system, though it does use a small amount over a long period of time. Radiator cap replaced.
If I am up to operating temp by the gauge and am at idle, I get luke warm air at best. If I raise the rpms up I get a short burst of heat.
So, I can only assume that I'm not getting flow through the heater core. With the truck and the van, after a period of driving around town/highway...I get heat.
I could assume that the water pump is not supplying enough pressure to flow coolant through the heater core, but I don't believe that should be the case for two reasons. 1. It never gets hot, even in the summer pulling a trailer. 2. If I take the radiator cap off and rev the engine, it draws the coolant level down visibly.
So, the only other thing I can think of is that I've got a pressure problem. Could it be that I just simply have a slight leak in a head gasket that isn't so much of a problem that I dont' burn coolant, or ??? The only thing I know I need is an intake manifold gasket as the truck will surge the idle every once in a while.
Anyone have a suggestion? Being that it's been -14 the last couple of mornings, I'd like to figure out what gives! It'd be nice to go out to a warm vehicle instead of wasting all this gasoline.
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burpit
Dodge Dakota
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12/15/2007
21:50:56
| RE: No heat after flush
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on the back of the block theres a 1/2 inch plug to burp it.........get the air out eh......
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Mikey
Dodge Dakota
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12/16/2007
01:49:43
| RE: No heat after flush
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Exact same problem here. New pump and 3 thermostats.
I have a 99' 5.2 SLT.
Do I have the same 1/2 inch plug on the back of the engine?
Please help!!!
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mike stager
Dodge Dakota
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12/16/2007
03:01:23
| RE: No heat after flush
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I'm betting a pressure test of the cooling system would come back normal
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Mikey
Dodge Dakota
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12/16/2007
13:18:38
| RE: No heat after flush
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Mike Stager
If that is your bet, then I guess you know something that we don't.
Please share your thoughts.
Anything at all would be helpfull.
Thanx
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mike stager
Dodge Dakota
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12/16/2007
17:41:02
| RE: No heat after flush
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Well, the reason I say that is purely out of hope for some kind of air in the system, because if it ( the lack of pressure ) is the cause, then we've got some leaky gaskets somewhere.
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Mikey
Dodge Dakota
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12/16/2007
18:04:34
| RE: No heat after flush
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Does anybody think that I may have the same half inch plug on the back of my block(insert joke here!).
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Mikey
Dodge Dakota
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12/17/2007
12:51:42
| RE: No heat after flush
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Stager,
What brand of thermostat did you replace with.
You said that you plug it in, are you from Canada, cause I am, and I bought 4 thermostats from Partsource and Canadian tire in total. And they were all Motorad brand. If you can, buy one of the same brand that you have in there now and another brand, and check the spring to see how they compare as far as pressure. You should be able to return them after you check them, but maybe ask first.
I compared an old 180 that wasn't Motorad brand(I think it might have been Napa brand) to a Motorad 192 stat. The difference was pretty obvious. The 180 had a way stiffer spring than the 192, which it shouldn't. I bought a Napa 195 and I could hardly push it open with the tips of my thumbs.
I don't know if Napa exists in the states, but they have a pretty good stiff spring in there and that lets the pressure build more and makes quite a big difference. My gauge moved up about 2or3 needle widths. Although I'm still not sure what most engines are suppose to run at in the winter because I'm having a hard time getting an answer from anyone. Mine now runs at 85-90 maybe. It helped my heat quite a bit so I think you should check that out.
Kowalski
You have a plow so you must run in the cold of winter.
What does you engine temp usually run at in the winter(on the gauge). And what kind of stat do you have in there.
Thanx to all.
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mike stager
Dodge Dakota
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12/17/2007
15:42:32
| RE: No heat after flush
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Well, I ran the truck today ( much warmer out ) and noticed a couple of things. One, I plugged in my Actron scanner and watched the temp sensor. My reading maxed out at 172 degrees ( I have a 180 t stat ).
It sat out and idled for quite a while before the upper radiator hose even had any heat in it. I could feel the upper hose( inlet ) to the heater core warming up and by the time the t-stat finally opened, there was plenty of heat to that inlet line ( couldn't hold onto it for more than a couple of seconds ). The line coming out of the heater core was warm enough, but I could hold onto it much more comfortably.
So, I checked the upper radiator hose again. Near the T-stat housing it was hot, but the hose was cool at the top where it makes the bend to the radiator. Cup your hand and put it under the hose and you could feel heat, but the top of the hose was cool. Obviously there is some kind of flow problem, and the 180 T-stat is coming out and being replaced with a stock 195.
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mike stager
Dodge Dakota
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12/17/2007
15:44:50
| RE: No heat after flush
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Oh, and I had heat, but it was weak. If I revved the engine for a bit, I'd get real heat. So, it's obviously not a plugged heater core, it's a matter of flow THROUGH the heater core.
( oh, and I live in Minnesota and we do have NAPA auto stores here )
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Curly
Dodge Dakota
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12/17/2007
15:49:54
| RE: No heat after flush
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Theres been more problems with 180 Tstats then what its worth. Sounds like your running in open loop start by putting a 190-195 back in.
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dakota49
Dodge Dakota
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12/17/2007
18:48:00
| RE: No heat after flush
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I doubt if you are having a pressure problem, but as Mr. Stager said, a flow problem. I have found that sometimes if you get the heater hoses on backwards it can cause the same problem. That was with some older cars, I'm not sure about this newer stuff. I have the same problem with my 98 Chrysler Concord it only coold down if I have to let it idle for very long, like a few minutes. As soon as I take off it, or rev it up a little I get max heat again.
I also agree with Curly, put the 190-195 thermostat back in. I have a 190 in my Dakota, and it seems a little cool to me. But it does get hot after a couple of miles, and is great after that.
Good Luck
Dakota49
1988 3.9 4X4 5speed
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mike stager
Dodge Dakota
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12/17/2007
20:17:00
| RE: No heat after flush
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One would expect that if you let the truck idle, that you would come out to a defrosted windshield and a warm truck after 15 minutes of idling, no matter what temperature it is outside.
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Curly
Dodge Dakota
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12/18/2007
14:02:51
| RE: No heat after flush
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When I had a 180 in my truck and winter came around it could pretty much set at idle an hour. Then it never blew more then slightly warm air. Toes would freeze while driving and started tripping codes. I went to NAPA grabbed one of their Tsats cant remember if it was 190 or 195. But anyway problem solved. I went to a 180 in the summer of that year to help get rid of a ping issue. The 180 did do that but like I said no heat in winter and my truck became a total gas hog. The stock range NAPA tstat and NGK FR5's MPGs are back up. The heat is working great in winter and no more pinging. The only other thing I can think of is your Tstat is tuck open.
I hope all this is of some help for you.
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Curly
Dodge Dakota
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12/18/2007
14:05:29
| RE: No heat after flush
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Type O correction
The only other thing I can think of is your Tstat is stuck open.
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mike stager
Dodge Dakota
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12/18/2007
18:50:17
| RE: No heat after flush
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T stat isn't stuck open as I can feel when the stat opened by holding onto the upper radiator hose until it did, it was obvious when it started letting coolant flow through it.
I'm definitely picking up a new thermostat and replacing it. I'll be sure to post back the results here.
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mike stager
Dodge Dakota
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12/28/2007
17:11:36
| RE: No heat after flush
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Replaced the thermostat today. doesn't seem to warm up any quicker as I expected. It seems that I don't get the cooling system pressure build up as I would expect, so I am starting to wonder about that. I do get pressure after the truck has been driven long enough that it is warmed up for sure ( cannot collapse upper radiator hose with hand strength ).
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