Water pump or Heater core?:banghead:

90sabre · #1 11-03-2008, 07:17 PM

I have a heat issue with my 99 Ram, I apologize in advance for the lengthy post, but I want to give you as much info as possible... I noticed my heat was very weak, at times non existent. Replaced thermostat (195 degree), replaced Radiator cap, flushed entire coolant system. Now at speeds over 40ish the heat gets warm, but at idle it blows cold. For highway driving it gets pretty warm but still not hot, and coming to a stop or decreasing the idle feels like flipping a switch to cold air. No leaking that I notice from the heater core, but a lot of gurgling and sloshing at idle and low speeds. I'm wondering if it is in fact the water pump not circulating properly as under load it gets warm. The engine runs at about 175 degrees in cool weather. Other than these symptoms the truck runs fine...I appreciate any thoughts/suggestions on this before I go ahead and replace the water pump...

Thanks,

Leo
99 Ram 318 4X4
getting cold here in New England...

Chris Stewart · #2 11-03-2008, 07:24 PM

Sounds like your thermostat is staying open or your temperature gauge is reading wrong.
You have a blend door in your AC/Heat ventilation system and it may be stuck or not shutting or opening fully. Try turning the temperature knob from full hot..wait a minute then turn it to full cold...ya know, exercise the thing and see if it'll loosen up and operate correctly.

Chris Stewart · #3 11-03-2008, 07:34 PM

With the motor cold, the radiator cap off and the coolant level low enough to see the tubes above the coolant, start the engine and see if there's coolant flow through the radiator with the coolant cold. As you can guess, there shouldn't be any flow until the coolant gets to operating temperature.

crazys182003 · #4 11-03-2008, 07:34 PM

to me it sounds either clogged or air got in the system if you are hearing gurgling and sloshing. Probably occured when you flushed the system if you did it yourself. Try burping the system and see what happens.

90sabre · #5 11-04-2008, 04:20 PM

[quote=Chris Stewart]With the motor cold, the radiator cap off and the coolant level low enough to see the tubes above the coolant, start the engine and see if there's coolant flow through the radiator with the coolant cold. As you can guess, there shouldn't be any flow until the coolant gets to operating temperature.[/QUOTE

Thanks,

Following your instructions I can clearly see a constant flow of coolant coming from the radiator going into the fill tube. I guess I am not sure what this means. Also, this morning after running at somewhat normal temps, I noticed that the temp gauge stayed near the bottom(130-140) for my entire 20 minute drive. Prior to this 20 minute drive the truck sat for about 15 minutes after running at a normal temp for about 20 minutes if that makes sense. My heat obviously was non existent. Thanks again for all the help! BTW, the gurgling was there prior to the flushing.

Leo

angus10 · #6 11-04-2008, 05:45 PM

I would replace the T-stat first,with a good one. Like OEM . Not junk from AutoZone for instance. If that doesn't cure it and you are sure you got all the air out, seeing how it's a 99, I bet the heater core is clogged. Common prob. And also how do you know the heater core is not leaking? If it's a small enough hole it will evaporate before you see a leak. But my bet is the core is clooged.

90sabre · #7 11-04-2008, 07:32 PM

Quote:

Originally Posted by angus10

I would replace the T-stat first,with a good one. Like OEM . Not junk from AutoZone for instance. If that doesn't cure it and you are sure you got all the air out, seeing how it's a 99, I bet the heater core is clogged. Common prob. And also how do you know the heater core is not leaking? If it's a small enough hole it will evaporate before you see a leak. But my bet is the core is clooged.

Yeah, its strange because as I rev the engine the heat gets warm, but now the engine isn't even getting as warm as it should...I did change the t-stat with a good one and also flushed the system thoroughly so I was thinking the heater core would have had to have been flushed?? Is it possible that the water pump isn't circulating enough causing this or do you all think that its my heater core. And you're right, I don't know if the core is leaking, just can't find it if it is...
thanks again!

90sabre · #8 11-05-2008, 10:10 AM

Just an update, it appears now that the water pump is leaking somewhere on the bottom, can't tell exactly where but I am definately loosing a small amount of coolant from that area. Still can't figure out why it is running so cold. 130 all the way to work today.

angus10 · #9 11-05-2008, 05:53 PM

There is a weep hole on the bottom side of the WP near the pulley, look there. You can also check the WP by removing the belt and grab the pulley and see if it wobbles up and down and sideways.Replace the T-stat and bypass hose if you change the WP. Don't use too much RTV on the WP or T-stat(just a thin coat on both sides of gaskets and let it dry a couple minutes), and make sure the round groove where the T-stat sits is clean and you get it centered properly.(And install it in the right direction).

The leak can be coming from above (T-stat housing not seated properly,upper hose to T-stat housing, temp sending unit, or bypass hose)and running down the side of the WP and making it look like it's coming from the bottom.So you really need to inspect it. And BTW, get atleast a Haynes manual because you will need to know all the tightening specs.

90sabre · #10 11-06-2008, 09:53 AM

Thanks for all the help, I do have the Haynes manual, but is there a better one to get?

angus10 · #11 11-06-2008, 05:21 PM

Well a factory service manual is better, but for what you are doing the Haynes is fine.

Chris Stewart · #12 11-09-2008, 08:45 PM

You shouldn't have any flow through the radiator with the motor cold.
That's what the thermostat does....it stops the flow of coolant through the radiator until it's at operating temperatures then it'll open slightly to keep the motor from overheating. If the motor continues to build excessive heat, the thermostat will open more in an effort to cool the hot motor.

Chris Stewart · #13 11-09-2008, 08:54 PM

The '99 gas burner wouldn't have a heater hose going into the drivers side radiator tank along with the top radiator hose would it?

90sabre · #14 11-10-2008, 08:55 AM

Quote:

Originally Posted by Chris Stewart

The '99 gas burner wouldn't have a heater hose going into the drivers side radiator tank along with the top radiator hose would it?

Not that I can see, I just see the top radiator hose. There are 2 heater hoses on the passenger side going from the firewall(heater core) to the motor. As far as the t stat, what your saying makes perfect sense, I have replaced it twice, most recently about a week ago with a 195 degree. Thanks!

Chris Stewart · #15 11-10-2008, 10:06 AM

Here's more to check...

Is there only 1 hole under the thermostat housing and the thermostat sets on it or is there a smaller hole next to the thermostat hole?

Is the thermostat wide enough that the thermostat housing holds it down in place or can the thermostat move vertically into the thermostat housing?

As you can see, the thermostat must be held in place by the thermostat housing and stay closed until the motor reaches operating temperatures then open just enough & even close back if necessary to maintain those operating temperatures to be effective.

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