1. LWR Hose Cold, UPR Hose Hot. 2. No overheat 3. New TStat 4. No improvement?

[andrewdoherty]

I've got 98k on my '03 GLS. The upper radiator hose gets hot, and the lower hose stays cold. The upper hose appears to be experiencing high pressure as even with screw hose clamps tightened down well and a new UPR radiator hose, coolant still leaks minutely as evidenced by the white reside. Not enough to drip, but just enough to get a whiff if I get my nose down to it. So I immediately think TStat. Pop a new one in with a drain and fill of new coolant and a few weeks later the same issue persists. The temp gauge moves normally, but never climbs above the midpoint of the gauge. No water in the oil or white smoke, and no loss of coolant or leaks (other than at the upper hose at the radiator junction as mentioned above). I've come up with a couple possibilities but would love to hear other suggestions.

1. Plug or reduction of coolant flow in radiator and/or coolant lines/passages
2. 2nd TStat was bad outta the box

[jayupark]

what you are experiencing is normal for our cars... at least for mine. Sometimes it takes up to 30 mins for the lower hose to get hot. I thought there was something wrong too, but the car never overheats and runs great... Try feeling the lower hose after driving for at least 45 mins.

[andrewdoherty]

Interesting. I've never timed it, but I am pretty sure I've run it 45 minutes+ and still had a cold lower hose. Thanks for the info!
I pulled the TStat today and bought a new TStat. Boiled both in water and and both behaved the same way. After the water boiled both opened the same amount and when removed simultaneously and allowed to air cool both closed at approximately the same rate.

[only1db]

3. there could also be an air bubble


but if the car is NOT over heating....i would drive it around...or even idle for 15 min...that lower hose should be warm.

[jayupark]

air bubble is possible too (I had one before... how could I forget, but the symptoms were a bit different, the car overheated).

To get rid of the air bubble, while the car is still cold, open the radiator cap and let it warm up for about 10-15 mins.

[andrewdoherty]

Only1, thanks for the 3rd idea. I have the car up on stands in the garage for new struts and drive shafts. I boiled the TStat that has been in the car and a new one and both performed the same so after 2 TStats I am going to eliminate that possibility. I am really leaning towards some type of plug in the radiator. With no offense to Jay, I have a hard time buying the idea that this is normal for our cars. Since the car is out of service anyway I am tempted to take the radiator to a shop and have it inspected and cleaned/rodded if necessary. Or I could just get it back together and try to make certain there's no bubbles, although as much as I have messed with the upper hose, checking fluid levels, and even installing the TStat with a drain and fill, it seems unlikely?

[andrewdoherty]

So a new radiator is about the same as a rod/cleaning. /eyeroll/

[songee623]

look in to a radiator from the junkyard find one off a elantra that was hit in the side or rear and look in to e-bay too.

[andrewdoherty]

Good idea. I am not too concerned about the cost as they are about 100-150. I just don't want to replace the radiator without knowing for certain it is the perpetrator. Are there any flow rate specifications for radiators? Even a rough idea of how quickly a clogged radiator drains compared to an unclogged radiator when water is run into the upper inlet and allowed to exit the lower outlet?

[songee623]

e-bay looks like $65 shipped is about the lowest then call the junkyard to see how much used to new is. as for the part two of your question sorry but i have no clue.
http://motors.shop.ebay.com/i.html?_...acat=0&bkBtn=1

[andrewdoherty]

WOW! Tempting . . .

[andrewdoherty]

I pulled the radiator today. No obvious exterior damage (a few slightly unstraight fins, but nothing to indicate damage made it to the tubes). I drained the radiator and ran a garden hose into the upper inlet pipe. Water flowed out the bottom as fast as the hose was pumping it in. I did the same with all the other possible combinations of outlet, inlet and filler neck. I didn't see anything that would lead me to believe that the radiator is clogged in any way. It sure seemed to drain quickly. I am beginning to wonder if a problem with the pump might be possible.The car has 98k with the original pump. I considered replacing it when I did the timing belt at 60k, but I figured if it aint broke don't fix it. I don't hear any squealing, and theres no leaking at all from the weep hole or anywhere else. No water in the oil or white smoke in the exhaust. Is it at all possible that the pump has just lost some circulation power? I'll double check the WP belt and make sure it is correct. I will stay up to date on this thread.

[andrewdoherty]

LOL, this has just turned into my own personal blog. haha. After some thought I am l; leaning away from the WP as the culprit. If low coolant flow were to blame I would expect an overheating problem and it would not make sense that there is excessive pressure at the UPR Radiator hose. I will get the car back on the ground in the next week or so and will post here as an update. I have left the TStat out to troubleshoot. If the problem disappears I am going to assume the after-market TStats I was using were causing the problem and I will install the factory TStat and consider it a lesson learned. I boiled a new after-market TStat and a factory Tstat together and noticed a significant difference in the speed (temperature indirectly) that the valve closed at. And since I had never done it I also replaced the radiator presssure cap and cleaned out the reservoir. I'll have fresh coolant in the car of course. Fingers crossed . . .

[andrewdoherty]

UPDATE:

The car went back together and has been driven daily since the last post. The car now has 125k miles on it and is now on its 3rd timing belt. Water pump stil appeared to be sealed and working properly so I left it alone as well as the tensioner. In the last 2k miles the top of the radiator developed a hairline crack and is now spewing coolant in the the rest of the engine bay. The car still never overheats. I bought a new radiator on ebay and will be replacing it in the next day or two. I'll replace the t-stat with an OEM and likely replace the u and l rad hoses just cuz I am in there. If anyone has any questions about this or needs any advice feel free to call. two one four two four five six six five one.

AWD