Coolant boiling in reserve tank

[CNAKitty]

Good news on the fans. With the cab blower fan on, they run. I had to run to the office for my check (wish they had direct deposit), and with the fan on high, temp dial straight up between cool and heat, and set at "normal" not Max or Heat, it didn't get near as hot. I checked the reservoir level when I got home, and it IS down again. But I'm going to wait until the car is cooled down to check it and add more coolant tonight when I get up for work again. Fortunately the majority of my driving is at night on way to work, and early morning on way home, and most of the 25 miles is on freeway going 75 mph. It's too hot here in Arizona already to run the heat in the car during day.. Meanwhile going to do some parts and tool ordering for curbside pickup from O'Reilly's when I get up tonight, before I have to leave for work.
I'd still appreciate any more advice you guys can leave here while i'm sleeping today. I'll check it when I get up. Right now it's a case of work/sleep, work/sleep, 6 nights on, 1 night off, 5 nights on, 1 off, rinse and repeat. Can anyone recommend a good bright worklight, preferably hang or magnet from hood, corded unless long lasting (4+ hours) rechargeable. I was considering some Performance Tool one's but hadn't settled yet. I need to get one since I don't have exterior light under the parking at my condo, and will be working on it at night when I get the time. Also a decent combustion tester from O'Reilly's, Auto Zone, or Pep Boy's, not Harbor Freight. Mid-range price should be ok.

Thanks!

 

[Lubener]

Originally Posted by CNAKitty
What's best way to check the water pump? Can it be done without taking off or needing to drain etc?

The water pump would not be high on my list as a probable cause unless it is leaking so badly that the coolant is very low. Head gasket or thermostat are more probable. When mine blew, the coolant bottle was overflowing because of the combustion pressure which was forced into the cooling system. The fan should be turning on during stop and go driving and especially at idle. You can test by turning on the A/C or unplugging the coolant temperature sensor used by the computer. The fan should turn on when you unplug the sensor.

 

[MCompact]

Originally Posted by eljefino

Running heat is a rudimentary, emergency way to get heat out of the engine.


Setting the heater to full hot and the heater fan to "Max" was SOP when driving a 2002 with a stock radiator in the mountains. We called it "Switching to auxiliary cooling."

 

[LDM]

Originally Posted by CNAKitty
What's best way to check the water pump? Can it be done without taking off or needing to drain etc?


Easiest test is usually to squeeze the upper radiator hose and see if you can feel water flowing through. Another would be to drain some coolant and then check if you can see the water pumping back into the radiator, although this is dependent on the radiator design.

You can also check to see if there is any coolant coming from the weep hole on the water pump. If there is, your water pump needs replaced and it may be the main source of why you keep losing coolant.

 

[DGXR]

Did you ever try a new radiator cap?

 

[Davejam]

I'm afraid if coolant is missing then it is either leaking coolant...or head gasket. No alternatives.

The boiling coolant spills out continuously because there is also exhaust gas under the cap. It also can pull coolant into the engine.

A leak somewhere or fans not working unfortunately would have been preferred, but its not sounding like that's the case. Sounds 100% like head gasket.

 

[bullwinkle]

If you have a bad enough radiator cap, a new one can slow it down a little. My brother picked up an old '97 Civic for his son, it had mysterious coolant disappearing issues & ran hot for no apparent reason, the new cap kept the pressure (mostly) in the engine & coolant loss slowed down. Excessive gas in the coolant can cause water pumping issues, but the cause of the leak will have to be addressed sooner or later.

 

[bullwinkle]

Originally Posted by Davejam
I'm afraid if coolant is missing then it is either leaking coolant...or head gasket. No alternatives.

The boiling coolant spills out continuously because there is also exhaust gas under the cap. It also can pull coolant into the engine.

A leak somewhere or fans not working unfortunately would have been preferred, but its not sounding like that's the case. Sounds 100% like head gasket.

Don't underestimate the chance of a cracked head or block too, I've had too many beaters that were abused by previous owners adding water to overheated engines, with resulting expensive repairs from cracked/warped heads to even warped block head surfaces. One of my best ones was a '90 Civic wagon, picked it up super cheap with a brand new radiator in it (first warning sign). It was fill the coolant, check the gas! One cylinder head & gasket later (incl. 2 new exhaust valves, valve job, resurfacing), put it together-my steam cloud turned blue! Off with the head again, rings coked up with carbon from overheating. Cleaned out the oil pan, new rings, hone, & rod bearings, put back together with another new HG-it was fine & ran for several years, still ran great when I sold it.

 

[samven]

Check your exhaust for white smoke (vapor) after it has run for a few min. If the white exhaust never stops you probably have a head gasket issue. After the engine is warmed up check the upper radiator hose to see if its hot. If the thermostat is not opening there will be no flow to that hose and it will stay mostly cool. If you are standing there with your hand on it when the thermostat opens you will feel it getting warmer. After its hot start looking for a leak, radiator hoses, heater hoses, smell around under the dash to see if you smell antifreeze, the heater core could be leaking, if it lets go it will flood the inside of the car. If you cant find a leak and the exhaust is clean you may have a clog in the radiator restricting but not stopping flow. A flush with a good cooling system cleaner may fix it. And replace the radiator cap too, if its gunked up it may have been leaking for a long time and not holding pressure. It could boil over into the overflow which overflows and then when cool it sucks what it can from the bottle leaving the bottle low.

 

[mk378]

You guys are all the reverse of the typical car owner who comes to a forum convinced up and down that there is no way my head gasket could be bad.

To review, as a doctor would say, the "presenting symptom" was overheating while idling for a long wait in a drive-thru line. If further questioning can differentiate it down to overheating only when the car is not moving, the radiator fan system is the primary suspect.

 

[super20dan]

blue devil time.

 

[caprice_2nv]

Fix the fans not coming on or leave the AC on time.

I recently realized the fans don't come on in my 05 Silverado unless I turn on the AC. The coolant temperature sensor connector is broken and needs replaced. For now, I remember to turn on AC if it will idle for a while.

 

[caprice_2nv]

I would monitor the coolant loss though. It could be some air pockets from when it got hot enough to boil over, or it could be leaking from the intake gaskets or water pump. One of my ex's had 3 cars with the 3.1 and I had to replace the water pump on every one of them as they all leaked. Once had 100k another had 120k, and one had 260k. Just my luck they all leaked.

 

[DzoG20]

Rent a pressure tester from some auto store and check if the cooling system holds the pressure. It is simple - when the car is cold, the tester is bolted at the place of the radiator cap and let it idle for a while - see instructions on the tool.
If it holds pressure ok - change the radiator cap - it's like $10 and burp properly the system (see manual)

 

[nwjones18]

Originally Posted by DzoG20
Rent a pressure tester from some auto store and check if the cooling system holds the pressure. It is simple - when the car is cold, the tester is bolted at the place of the radiator cap and let it idle for a while - see instructions on the tool.
If it holds pressure ok - change the radiator cap - it's like $10 and burp properly the system (see manual)


This is the right answer. the coolant will boil if the system isn't holding pressure. bad cap or a leak somewhere. My first thought wasn't head gasket when I read your post it was bad radiator cap.

 

[CNAKitty]

That's the first thing I'm getting asap. I just discovered it was gunked up last night when the parts stores were closed and haven't had a chance yet. I did clean it up, but still plan on getting a new one.

 

[CNAKitty]

Yeah, I was thinking along the same line about it boiling over into the reservoir then sucking back in. I know it's gunky, which is 1 reason I planned to flush it soon. And the reason I bought a replacement thermostat as well. Seems like I jinxed myself by planning this when there weren't these issues, and now they start up.

 

[clinebarger]

GM 3.1/3.4 engines are notorious for blowing head gaskets when overheated, You need to have a co2 test performed before firing the parts cannon.

 

[WyrTwister]

Also , check the engine oil & see if it looks like there is coolant in the oil . Will look milky , to some extent . Really bad , may look like a chocolate malt / milk shake .

If the radiator fans come on when the A/C is on , you will know the fan motors are working . In normal / no A/C operation , the computer monitors engine temperature . When that temperature exceeds a pre-set point , the computer sends a signal to the ran relay / relays . The relay / relays close and thus send 12 VDC to the fan motors .

When the engine temperature drops below a pre-set point , the computer turns off the signal to the relay / relays . The relay / relays no longer send 12 VDC to the fan motors .

 

[caprice_2nv]

Originally Posted by CNAKitty
Yeah, I was thinking along the same line about it boiling over into the reservoir then sucking back in. I know it's gunky, which is 1 reason I planned to flush it soon. And the reason I bought a replacement thermostat as well. Seems like I jinxed myself by planning this when there weren't these issues, and now they start up.


The coolant could also be gunky because someone added stop leak like gm crush tabs before you bought it, to seal up a leak. I added the crush tabs to my Caprice when I smelled a whiff of coolant from the heater core, the smell never came back but now I have chunkies all through the coolant and all over the rad cap.

Best case scenario would be leaking water pump. Worst case is head gasket, intake gaskets are not the end of the world either. Head gaskets were less common on the 3.1 than the 3.4 but still possible, especially if overheated. There is a 99% chance the intake gaskets were replaced before at that age and mileage. It's possible it needs them again though.