Radiator puzzle in Chicago

[TrentW]

My car overheated on me (just past 3/4 mark on gauge) driving on the expressway to meet a friend and I had to turn around and go home, shutting it down every once in awhile allow the engine to cool off.

I replaced the water pump (since I had seen drops of coolant under the car that seemed to have come from the pump area--now realize this may not necessarily mean a bad H2O pump) and t-stat, (yeah, including timing belt and tensioner--even though they only had 8k on them) flushed the system with the Prestone stuff, including draining the block. Refilled with 50/50 coolant and distilled H2O plus Water Wetter. I then attempted to first bleed the air from system without starting the engine, but couldn't get any coolant out of the bleed screw. Is this normal? Thought you should normally get an initial bleed? Had to run engine a few minutes before any coolant appeared thru bleeder screw. Bleeding the proper way--front off the ground foot and a half, heat set to full on, etc, thanks for that post jlevie! Had to repeatedly run the engine--bleed--shut the the engine down to keep it from overheating. Getting lots of hot air from the heater. Finally after a few bleeds, I noticed that the upper hoses were very warm, but the lower hose was practically cool to the touch. top Figuring my radiator was plugged, I called up my friend Ben and got another radiator and switched them out. Ran the engine, but still the lower hose is not even the slightest bit warm. The temp gauge seems to be at the halfway mark, but I haven't let it run long enough to see if it gets hotter or driven it yet cause I'm conderned about the cool lower hose. Oh yeah, both the fan clutch and gauge sensor are new also.

Okay guys, what's my next step?

[strad]

Have you checked to be sure the new thermostat you installed opens at the correct temperature?

[TrentW]

No. I'm so tired of trying to figure out what's happening I decided to see if someone could give me a solution. It's an 80 deg thermostat, wondering if I should go with a 70 or 75, as the car is always garaged and rarely driven in winter, but my tech friend said to use an 80. Besides, the hose off the thermo is hot...just not at the lower rad hose ...

[wodcutr]

The radiator is working properly if the water coming out is cooler than the water going in. That is what it is designed to do. If you are having trouble bleeding the system then you probably need a new radiator. I just had to figure out a similar problem and even though the radiator was letting fluid flow through it properly it had a small tube that was broken that connected to the bleed valve so it would not let the air out of the system. I tore my hair out trying to figure this out and finally figured it had to be the radiator and got a new one. Installed it and the system bled properly the first time, problem solved!

[TrentW]

I switched radiators and got the same result, so I don't see how that makes sense. Also, I'm not sure what you mean by the small tube that connects from the radiator to the bleed valve?

[TrentW]

Well I test drove it this morning and it's fine--temp gauge is between 1/4 & 1/2. I'll bleed the coolant one more time just to be safe.

[vr2jetta]

Usually if the in and out hoses on the radiator are significantly hotter/colder than the other it points to a thermostat. Reason being, the thermostat is not opening therefore not allowing the cooler water to flow through the engine. You may have gotten a bad thermostat. If it continues to happen, I would check there.

[TrentW]

That's exactly what my tech friend diagnosed originally, and I just happened to have a brand new spare t-stat and it did the same with either one. I find it hard to believe the very odd chance I could've gotten two bad ones. I'm gonna test the other one on the stove and see when it opens. They're Wahler btw. After I drove around for awhile today, I checked the lower hose and it was warm, along with the upper hose. Is it supposedly normal for the lower hose to be slightly cooler since it's cooled by the radiator or should it the same temp as the top?

[vr2jetta]

Finally after a few bleeds, I noticed that the upper hoses were very warm, but the lower hose was practically cool to the touch.

Thats why I brought it up. You could try gutting a t-stat and see what happens. Being in Chicago probably wouldnt be the best idea to leave it that way, but if it keeps happening you could rule out the t-stat. I agree on the little chance of getting 2 bad ones in a row though.

[vr2jetta]

Good radiator, good t-stat, good water pump, I hope the water jackets in the head/motor arent restricted.

[E30QUEST]

When i'm driving my car the temp needle goes down toward the blue area precisely btwn
1/4 and 1/2 but when i stop in traffic it goes to 3/4.What can be the problem?

[vr2jetta]

When i'm driving my car the temp needle goes down toward the blue area precisely btwn
1/4 and 1/2 but when i stop in traffic it goes to 3/4.What can be the problem?

From what I've heard E30's dont like traffic. They tend to get hot in traffic. Just what I heard though. I havent been in mine enough to know.

[TrentW]

Good radiator, good t-stat, good water pump, I hope the water jackets in the head/motor arent restricted.

Doubt that this is the culprit as the head was rebuilt and the jackets in the block looked clear.

[TrentW]

When i'm driving my car the temp needle goes down toward the blue area precisely btwn
1/4 and 1/2 but when i stop in traffic it goes to 3/4.What can be the problem?

You need to replace the fan clutch.

[vr2jetta]

Doubt that this is the culprit as the head was rebuilt and the jackets in the block looked clear.

IDK man, good luck though. If you figure it out be sure to post the solution in case someone else has a similar problem. That would sure piss me off if it happened to me!