TierAngst

I'm pretty sure my fans are kicking on properly but the car just doesn't seem to want to cool down at low speeds anymore. Noticed the temp jump waaay up in stop and go so I parked it for a few hours to let it cool, then jumped straight on the highway and came home, the temp stayed just fine at highway speeds but as soon as I slowed again it jumped right back up

xlwhellraiser

iTrader: (1)

Usually in stop an go traffic your fan is the primary source of cooling (and the radiator too). Once you get on the highway the air moves through your car without much aid of the fan. So, in stop and go traffic there is really no air movement and the fan sucks air in to keep you engine cool.
I am not sure of the set up on your car, but you might wanna check into getting a fan with more CFM and alower amp rating. A bigger CFM fan than yours will be a night and day difference on you cooling system.

Its also a good idea to check on the whole cooling system. Check for leaks, replace cap, check thermostat, flush the system. This way you would feel safe driving the car anywhere.

Good luck.

TierAngst

My fans push 4600cfm which is plenty. It started when I went to the drag strip the other day and isn't anything to do with my fans, radiator or thermostat as they were all replaced.

RBob

iTrader: (1)

Maybe double check the base timing. If the distributor moved it will retard the timing which dumps heat in the cooling system. With bringing up the strip, how did you do?

RBob.

TierAngst

I checked base timing the other day, its right at 6* advanced but I have it compensated for in the programming.

As for the strip, considering I was overheating it was 85* with a 10mph head wind, I ran a best of 16.95. My previous best with my old gears, when I had pulleys, and without the EBL was 16.81 but it was only like 75* and no wind. I think I should have ran much quicker, some of the other cars at the track I'm pretty sure were faster than what they ran, there was brand new LS2 GTO that was only running 14.4, and a new Hemi Charger running like a 14.9, a cammed/exhaust LS1 TA running mid 13s.

cheppibear

GM made these cooling systems very effective. Seems very odd that all of a sudden, the cooling system stopped functioning properly, especially since you checked/replaced various parts. Think about anything you replaced or changed, no matter how trivia. The "new" part could also be defective.

Is thermostat stuck closed? Test in boiling water.

Do you have enough coolant in? (#1 cause of increased temperatures at idle/stop and go traffic). I go through this all the time with my truck.

In your replacement process, what mix of antifreeze to water did you use, what thermostat rating? 50/50? Even with the transmission cooler lines running through the radiator, you should be ok.

Is water pump leaking?

Just some thinking out loud thoughts.

TierAngst

I double checked the fans today and they seem to be working just fine. I ordered a stage 2 waterpump from stewartcomponents.com hopefully it was worth the price of it. Will be flushing the system, replacing a worn out radiator hose, thermostat and the pump whenever it arrives.

I'm thinking there is maybe air in the system, I can't figure out why it would overheat only at low speeds like that with the fans working properly.

RBob

iTrader: (1)

It could be that the thermostat is not opening enough. Common failure mode. At higher engine speeds the water pump can force more water through. Are the fans blowing in over the engine? I've seen some setups where the connector isn't keyed. The fan(s) end up blowing out the front of the car.

RBob.

M1tch

when my car gets hot while driving i turn on the heat and it always cools the motor down because it throws the warm air into the interior

kdrolt

Some of the more common causes for overheating, besides bad water pump and/or bad serp belt/pullies, are:

1. stuck thermostat
2. collapsed metal coil spring inside the suction hose from the radiator (this pinches the water flow from the radiator to the water pump)
3. A bad radiator cap will cause overheating, because it won't allow a pressurized cooling system.
4. debris in the exterior cooling fins of the radiator

Check all these before you throw money at a water pump.

xlwhellraiser

iTrader: (1)

Ok, lets just analize this.
The car runs at normal temperature when its driven, lets say, over 50mph.
However in lower speed traffic, or stop and go traffic it overheats.

So one thing we know is that there is enough air coming thorough to cool it down. What we don't know is why it overheats when the car is moving slowly.

If its not the fans, than there must be something in the system that is not promoting optimal flow of coolant through the system.
Radiator cap could be the problem, but if it did not work properly the coolant would boil even at higher speeds. I'd replace it for the piece of mind.
You said that your hose was old, if its the bottom hose there is a chance that it might be sucked in due to the spring faliure or maybe the spring wasn't there at all.

The thermostat could be stuck somewhat open just enough to have the coolant flow through but not enough to cool the motor down. Than again if the thermostat was stuck like that it would be hard for the pump to push coolant through. Albeit at higher speeds there is more coolant flowing through the engine so its a possibility.

I would check the hoses, thermostat, cap, waterpump. Then I would flush the system. Make sure that your radiator is not stuffed up either, or its leaking. After this there should not be a problem.
Your motor seems to be runing right, from what you explain, however I would check the tune and see if, possibly, the closed loop, open loop temperatures were changed or tempered with. Probably not the case, but worth looking into.
If it still presists, I would take another look at the fans. Maybe they are, possibly blowing the wrong way, or not turning on right... I don't know you checked them and they seem alright.

Good luck, and let us know what happened.

TierAngst

Too late on buying the waterpump, I was getting it either way and figured now would be a good time to get it since its going to drain a bunch of coolant and this one needs a special t-stat anyways. So flushing it replacing t-stat and the higher flow water pump are going on next week. The radiator and cap are new as well as the upper hose and the fans are blowing the right direction.

I took it for a test drive today and all was well, it may have been that I started out when I first setup the fans to run from the ECM that I was running the new XDF with updated temp settings for the fans and had switched accidently since I didn't have the new XDF on my laptop I switched chips with the new programming and it hasn't overheated again that could have been the only thing.

TierAngst

Yep, I feel like an idiot... started overheating again, or shall I say never stopped. 2 or three of you had it right all along, the fans were pushing instead of pulling; they just happened to be so powerful that when I stuck my hand behind them while running I still got a good bit of air blowing at my hand though I should have remembered that hey used to push a ton more air than what I felt. The problem threw me off at first because I checked my wiring and it all looked okay, the problem was the +/- wires are blue and black coming from the fan motor, black being the +
Going to make a trip to radioshack and pick up a bunch of electrical connectors and rewire the buggers.

90RS305

Please post topics in the forum pertaining most to your PROBLEM, not your car...

xlwhellraiser

iTrader: (1)

It sounded like a fan problem cuz I couldn't have thought of anything else that would effect low speed cooling. I am glad you found it.
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Oh, don't return your water pump either. Put it on and you'll thank me later (unless you already have a new one). Nothing better than a new water pump. Piece of mind, and much more superior cooling than the stocker.

If you already replaced it, then disregard this comment.


Laters.

sogabe

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