Hot, Hot, Hot

[mini_mull]

OK, I've exhausted all the possibilities I know of, and I'm taking it to my mechanic tomorrow, but I'm hoping you guys can shed some light on my problem before I do.

Here's the history. Over two years ago, right after I bought my burb I replaced the radiator and heater hoses. I had it flushed a year later. It ran at about 190* and life was good. Then in Feb I replaced the hoses, thermostat, t-stat housing and gasket, and flushed everything. Shortly after my heater core started leaking, so I replaced the heater core. It was still running about 190* and life was good. When the weather heated up it started running hotter than usual while idling, so in June I had the fan clutch replaced. It was still getting too hot at idle (220+) so I flushed the system again (which had gotten surprisingly rusty and corroded since Feb) and it still didn't help. I took the radiator to be rodded and repaired and they said it was too far gone, so I installed a new radiator, and also a water pump. It still runs too hot idling on hot days, so I replaced the t-stat again just in case it was sticking. That was yesterday, and today it ran even hotter and the temp climbed faster (230+). My oil pressure also drops when my temps rise, just in case that matters. I also pulled the crakcase cap today to check for bubbles and I couldn't see anything. My dipstick isn't milky either. Since I've replaced every part of the cooling system, I know of some time in the last 6 months and can't see any bubbles in the crankcase, I have no idea what else could be the problem. It runs fine while moving, but idling heat up quickly.

Sorry for the novel, but I wanted to include as many details as possible. Anyone think they can solve my puzzle?

 

[ryoken]

Shroud intact?

It certainly sounds like the clutch... try a box fan in front sitting in the driveway and see if the temp goes down...

You can cheat and lock the clutch too to check it...

 

[dyeager535]

Did you get the wrong waterpump at some point? You know, reverse rotation or vise-versa?

How about running with the radiator cap off, to try and get any air bubbles out. (never had that problem, but apparently it does happen, even though in stock setups the engine is lower than the radiator and it should self equalize)

At idle or cruise, or both? Not at cruise indicates an airflow issue, mainly the fan.

You running a decent antifreeze mix? I believe recommended change interval is 2 years for the green stuff, so it sounds like you were well within that range. I believe antifreeze makers state a typical minimum of 30% to 70% water, so if you were close to that, and didn't thoroughly drain the block, you might have gone under the recommended, which is recommended due to corrosion, both rust and galvanic.

IMO (and as you found it looks like) flushes are an absolute WASTE. You cannot get the corrosion out of a radiator, nor can the backyard mechanic even begin to diagnose a plugged radiator, especially since the majority of corrosion is below what you can see with your eye. BTDT, a flow test (or disassembly) is the only way to really know the internal condition of a radiator.

I'd run without a t-stat (it's free and easy) and see what happens if you are certain the water pump is up to snuff. If your cooling system is working, it will not overheat due to coolant "flowing too fast". The hotter water gets, the less heat it absorbs, therefore the colder the coolant entering the engine, the better its heat absorbtion properties. Likewise, keeping coolant in contact with the hot metal surfaces of an engine induces localized boiling, which is obviously terrible for cooling.

T-stats are a real crapshoot, although Delco's still have a good reputation for working every time, out of the box. I believe someone just recently had two bad non-delco 'stats brand new.

Edit: oil pressure drops as engine temps rise, pretty good indicator your engine is heating up if pressure drops as the indicated temp climbs.

 

[roadnotca]

I'd test the temp gauge system, and is the sensor in the T-stat hsg or the head. A product that really helps is RedLine Water Wetter.
AZ AZ AZ be hot hot hot.

 

[mini_mull]

Shroud intact?

It certainly sounds like the clutch... try a box fan in front sitting in the driveway and see if the temp goes down...

You can cheat and lock the clutch too to check it...

Shroud is perfect. I'll try my garage fan tomorrow, since I haven't been able to get it to overheat at night. How do I lock the clutch?

Did you get the wrong waterpump at some point? You know, reverse rotation or vise-versa?

It was labeled as a reverse rotation, which should be what I need with sepentine.

How about running with the radiator cap off, to try and get any air bubbles out. (never had that problem, but apparently it does happen, even though in stock setups the engine is lower than the radiator and it should self equalize)

Ran with it off yesterday after I installed the new t-stat, but I'll try it again tomorrow just in case.

At idle or cruise, or both? Not at cruise indicates an airflow issue, mainly the fan.

Idle only, cruise runs around 190* like it used to before I had problems.

You running a decent antifreeze mix? I believe recommended change interval is 2 years for the green stuff, so it sounds like you were well within that range. I believe antifreeze makers state a typical minimum of 30% to 70% water, so if you were close to that, and didn't thoroughly drain the block, you might have gone under the recommended, which is recommended due to corrosion, both rust and galvanic.

I've always ran 50/50 and never had a problem before. I tested it yesterday with the little suction/pointer tester and it was right on.

IMO (and as you found it looks like) flushes are an absolute WASTE. You cannot get the corrosion out of a radiator, nor can the backyard mechanic even begin to diagnose a plugged radiator, especially since the majority of corrosion is below what you can see with your eye. BTDT, a flow test (or disassembly) is the only way to really know the internal condition of a radiator.

The flush was good for finishing off my core and staining my passenger carpet. It did take out a ton of crap with it.

I'd run without a t-stat (it's free and easy) and see what happens if you are certain the water pump is up to snuff. If your cooling system is working, it will not overheat due to coolant "flowing too fast". The hotter water gets, the less heat it absorbs, therefore the colder the coolant entering the engine, the better its heat absorbtion properties. Likewise, keeping coolant in contact with the hot metal surfaces of an engine induces localized boiling, which is obviously terrible for cooling.

T-stats are a real crapshoot, although Delco's still have a good reputation for working every time, out of the box. I believe someone just recently had two bad non-delco 'stats brand new.

I'll try without a t-stat tomorrow. The t-stat I put in last night was the Checker HD version, but the one I took out was a $20 nice one, I forget what brand. I guess I could buy a third.

Edit: oil pressure drops as engine temps rise, pretty good indicator your engine is heating up if pressure drops as the indicated temp climbs.

Is it possible there could be an oil blockage causing the overheating instead of a cooling problem?

I'd test the temp gauge system, and is the sensor in the T-stat hsg or the head. A product that really helps is RedLine Water Wetter.
AZ AZ AZ be hot hot hot.

The sensor for the gauge is in the head next to the spark plug, and the one for the computer is in the manifold. AZ is too hot, I haven't had a problem overheating at night, but add those oven temps and it's trouble. An all new cooling system should still be fine though. Can a bad sensor effect cooling? I didn't think our cooling systems were affected by any of that. I don't think my gauge is bad, since it starts out cold, heats to the right temp, but overheats at idle.

I'll try the fan and pulling the t-stat tomorrow when it's hot out, if anyone has any other ideas let me know. Thanks all.

 

[blazinzuk]

I have had an upper rad hose collapse on me before. See if yours has the wire reinforcements in it, if not see if you can find one that does. Also a coat hanger works pretty well

 

[AKbigsub]

Sounds like an airflow problem since it only heats up at an idle. Check the fan clutch by letting the engine warm up and then shutting it off. Turn the fan by hand - it should be VERY hard to turn. If it turns easily, the clutch is bad.

 

[doonjumper]

My $ is on the clutch fan. If it is, get a heavy duty brand name (non hayden) replacement.

 

[mosesburb]

If you didn't get an AC Delco fan clutch, get your money back and get a Delco unit. Usually they are a few more bucks (sometimes they are cheaper), but in quality, nothing is comparable.

 

[mini_mull]

I'll try out the warm it up, turn it off trick in the morning. It's almost brand new, so I'd love it to be the fan clutch, since it's under warranty. It's a Hayden HD from Checker.

 

[mosesburb]

I'll try out the warm it up, turn it off trick in the morning. It's almost brand new, so I'd love it to be the fan clutch, since it's under warranty. It's a Hayden HD from Checker.

No offense, but Hayden fan clutches suck. I sold them for about 15yrs and whenver someone had a problem (not an uncommon event), I'd warranty it, then when they continued having problems I'd get them a Delco and there would be no next time.
I actually used a Hayden on one of my vehicles years ago. All it would take was one trip to Flagstaff and it would be leaking. I changed it four times (once after each trip to Flag). Finally bought my first Delco and it has been on there for about 13-14 years now and it is still dry and still works (and has gone to Flag many times...).

 

[JEBSR]

It's ok to pull the thermostat just for troubleshooting purposes but do not leave it out. Running with the thermostat out will not allow an engine to run cooler unless the thermostat itself is bad. It can cause an engine to run warmer due to the water passing through the radiator too quickly and not being cooled down properly. This is why water restrictors are sold for performance engines that do not use thermostats. To allow enough flow restriction to regulate water flow as intended by the designers of the cooling system.

 

[kwissman]

I would try two bottles of the redline water wetter and decrease the antifreeze percentage as it shows on the instructions.. The best heat transfer/cooling without the water wetter is 30% antifreeze. I did this on my BBC camaro and it made about a 20 degree difference. You dont need too much the freeze protection since you are in AZ.

 

[70jimmy]

I recently dumped my stock fan clutch and put on a flex a lite fan and spacer.

I don't have a temp guage that you can read in #'s but even at over 100degrees on a steady 10 mile climb I only reach the cold setting. First mark above where it starts.

 

[SUB602]

If its only getting hot at idle and not at cruise you have an airflow problem. Whether it be the the fan, fan clutch or shroud your probelms is airflow across the radiator. If everything is new than i would maybe get a larger radiator or add an electric fan in front of the radiator to draw in more air. Some of the Police cars i work on actually have a mechanical fan as well as an electric fan to help with the extreme heat here in AZ.

 

[dyeager535]

If its only getting hot at idle and not at cruise you have an airflow problem. Whether it be the the fan, fan clutch or shroud your probelms is airflow across the radiator.

Absolutely correct. You obviously do not have a coolant flow problem, since it cools at cruise ok. Forget all the other tests, your fan is the likely culprit. As I believe was mentioned before, put a large box fan in front of the radiator at idle and see if the problem gets better.


But if running fluid through the engine "too fast" makes an engine run hotter, how does it cool ok at cruise when engine RPM's (and thus coolant flow pushed by the water pump) are higher? Restriction creates pressure, more pressure=higher boiling point. Still doesn't mean you cool better with more pressure.

 

[mini_mull]

Ding, ding, ding. We have a winner. Fan clutch it is, or at least should be. I let it idle up over normal temp, turned it off, and my two year old could have turned the fan. I would have tried the box fan trick too, but I didn't get it to overheat by much. I'll try it again if I get a chance before I pull it. Thanks a ton guys. I'll be pulling it this afternoon if everything goes well. So, where do I get a delco clutch, dealer only? How about a Napa unit would it be a higher quality than the Hayden?

 

[ryoken]

Ding, ding, ding. We have a winner. Fan clutch it is, or at least should be. I let it idle up over normal temp, turned it off, and my two year old could have turned the fan. I would have tried the box fan trick too, but I didn't get it to overheat by much. I'll try it again if I get a chance before I pull it. Thanks a ton guys. I'll be pulling it this afternoon if everything goes well. So, where do I get a delco clutch, dealer only? How about a Napa unit would it be a higher quality than the Hayden?

Do I get a prize?

For the money they charge for those damn fan clutches, they should be gold plated... Think my guy wanted $90something for the Delco HD unit... Thus another reason I went electric...

Delco is not a "dealer only" line.. Any parts joint that deals with ACDelco can get ya one. They just might need to order it...

You can cheat and lock the clutch up by popping the coiled spring off the front, and turning the center pin all the way one way with a flatblade screwdriver till it locks up...

 

[dyeager535]

Get the part number from a dealer, then check out that part number at gmpartsdirect.com, see what they charge+ shipping.

 

[JEBSR]

But if running fluid through the engine "too fast" makes an engine run hotter, how does it cool ok at cruise when engine RPM's (and thus coolant flow pushed by the water pump) are higher? Restriction creates pressure, more pressure=higher boiling point. Still doesn't mean you cool better with more pressure.

Look, I'm not trying to get in a big conflict over this. Most of the info you are giving is right on. But you are looking at this from the standpoint of what the coolant is doing inside the engine.

The hotter water gets, the less heat it absorbs, therefore the colder the coolant entering the engine, the better its heat absorption properties. Likewise, keeping coolant in contact with the hot metal surfaces of an engine induces localized boiling, which is obviously terrible for cooling.

While what you are saying is true from how an engine operates, the same principles do not apply to how a radiator works. While a radiator will somewhat cool regardless of how much coolant moves, it will not cool efficiently or properly. This is why a larger radiator cools better than a small radiator. Because a larger amount of coolant stays in the radiator longer, allowing it to properly dissipate the heat. This is especially true at idle.

if running fluid through the engine "too fast" makes an engine run hotter, how does it cool ok at cruise when engine RPM's (and thus coolant flow pushed by the water pump) are higher?

Because at cruising speeds you have allot more air circulating than you do at idle. Like I said a radiator will cool regardless, just not as well if the coolant doesn't have time to properly cool down inside the radiator. keep in mind there are still the restrictions of the coolant passage sizes, water pump rpm's, etc. It can only flow so fast. It's not like it can flow uncontrollably.