cooling system conundrum

Morsetaper · 03-09-2010, 08:55 PM

I have a '96 Ram Van, 5.2L. It had developed a minor coolant leak, but since the weather had been so rotten, and it was such a minor leak-required topping off about every 1 1/2 weeks-I decided to just deal with it for awhile. Last week on my last day off, I realized that the leak was becoming more serious, and required attention.
Not having any free time for a couple of days, I dumped a bottle of Bar's Leaks into it to hold me temporarily. That worked, it held liquid, but...the van runs warm. Not to the point of overheating, but it's gettin' close. I'm only using it to and from work. 20 miles each way on the highway, and it gets close to overheating-but not quite.
I poked around a little yesterday and traced the leak to a heater hose. Replaced that and the leak is fixed. Refilled the radiator, eliminated all of the air that I could, and made sure the reservoir had the proper amount of coolant. Same condition. Runs warm almost to the point of overheating, but the system is full and not leaking at all.
Here are a few more details:

The engine comes up to just above normal operating temperature, then temp drops slightly, as it always has when everything is normal, so I think the thermostat is okay. It is after this point that the temp gradually creeps up.

Remanufactured water pump installed in October '09.

I can't detect any coolant flowing through the upper radiator hose, at any time, nor does the heater seem to be providing the heat it normally would.

It was suggested to me that there may be air trapped in the system, restricting flow. Especially since the hose was near the highest point in the system. Does this sound plausible? If so, what might be the best method for eliminating it?

I know a lot of the symptoms indicate an impeller problem with the pump, but I'd like to extinguish all of the easy possibilities before I pull that thing. Any help would be greatly appreciated.

alloro · 03-10-2010, 09:36 AM

Quote:

Originally Posted by Morsetaper

I dumped a bottle of Bar's Leaks into it to hold me temporarily. That worked, it held liquid, but...the van runs warm.

This is likely the cause of your new problem and not just a coincidence. First thing to try is back-flushing the heater core and radiator, as well as flushing the engine block. Replace the t-stat and fill the system back up and see how it goes. If that doesn't work, you might end up replacing both the radiator and heater core.

Morsetaper · 03-10-2010, 10:06 AM

Is there any "easy" way to access the thermostat on this thing?

alloro · 03-10-2010, 06:13 PM

Nope, you're stuck doing it the hard way.

Morsetaper · 03-11-2010, 08:22 AM

Oh well. FWIW, I did flush it yesterday, just to see if I could dislodge any air that might be trapped. It seems to be running a little cooler now, but not enough to consider it "normal". Don't know if I actually dislodged air or just freed up the T-stat some (or both), but it seemed like there was a lot of air bubbling out, and I now have coolant in the upper radiator hose, whereas I had none before. Guess I'll tear into it tomorrow.

Morsetaper · 03-11-2010, 08:27 AM

BTW, lemmee see if I got this straight. I gotta' drop the alternator and A/C compressor, and remove the mounting bracket in order to access the T-stat housing?

alloro · 03-11-2010, 04:49 PM

Quote:

Originally Posted by Morsetaper

BTW, lemmee see if I got this straight. I gotta' drop the alternator and A/C compressor, and remove the mounting bracket in order to access the T-stat housing?

Give that man a cigar!

Morsetaper · 03-19-2010, 02:28 PM

Well, I tore into it and replaced the T-stat. No change-still runs warm. Might even be running warmer than before. I suppose I'm looking at pulling the water pump again?

Also, after I test drove it, and found that I had corrected nothing, I parked it, and continued to let it run for a couple of minutes. Shortly after, it began to shudder, and then it stalled, and now it will not start. Any clues on that one? I'm letting it cool down right now, and I'll go out and see if it starts later.

alloro · 03-19-2010, 03:53 PM

Quote:

Originally Posted by Morsetaper

Shortly after, it began to shudder, and then it stalled

Maybe it overheated.

Morsetaper · 03-19-2010, 05:44 PM

I dunno. Seemed kind of unlikely to me, as the gauge hadn't been maxed out, and it wasn't boiling. I had driven it up to this point a number of times previously, without this happening. Any way, I'm getting ready to find out in just a minute.

Nope-won't start at all.

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