Atreus21

Hi fellas.

Gonna give you the short version:

Car is coming perilously close to overheating. She's not leaking coolant. Multiple checks of the radiator and reservoir confirm this. Replaced the thermostat, thermostat gasket and housing gasket, no change. Removed the thermostat completely, no change. On the suggestion of some of the guys over at camarov6.com, I bled the air from the coolant using the bleeder screw over the T-stat housing. No change.

The water pump was replaced in September 2007. My brother had the idea of disconnecting the hose leading to the thermostat, and then starting the car; the point being that if coolant came pumping through the hose, then we could rule out a bad water pump.

I really, really don't want to change the water pump, because the last time I did, like an idiot, I put so much torque on one of the retaining screws that the screw head came off. Thankfully, the seal held, and hasn't leaked so far. But taking the pump off means dealing with a headless screw.

Any ideas apart from this?

MDTAHOE

When does it overheat? sitting still ? while driving?

Mike Sigmond

If it is your water pump, pull it off and the grip the broken stud with a pair of vise grips and unscrew it.

Hopefully its just a minor problem.

Torque wrenches are a good tool to have

tm4hammer

Is there any noticible bearing noise in the pump when runnnig, have you checked the belt and idler pulley for tension,and operation,pull belt spun the pump shaft and checked for free spin and or a rough uneven rotation , checked for side play,its not to common for a pump to loose its impeller and not make any noticable or signifiicant sign that it has, maybe a broken or worn out blades,,you can check your hoses for collapsing, then flow by starting engine grabbing the hose and squeezing it or substitute with duck bill vise grips , padding the hose with something, you will feel a press. surge when the thermostat opens (check for plugged vent hole on pump) also with cap off at op temp and running you should be able to see coolant flow in top of radiator at cap hole.check your radiator cap see its seating and if its holding pressure and venting coolant to catch tank when warm, then returning to and filling radiator when cooled, you can look at the gauge lines on the tank for hot and cold levels,if its not functioning it wil cause coolant to boil at lower temps., if it maintains correct or somewhat close temp.when driving then rises when you stop and idle or stop and go in heavy traffic you might check your fan clutch, if there is a rough gravely feel when rotated and or if you spin it by hand and get five or more revolutions you should replace the clutch check if fan shroud is intact, not broken or pulled away from radiator, dusty or areas that have alot of bugs can cause some buildup in cooling fins causing overheating problems depending how long its been installed, You can do a low pressure and i mean low pressure cleanse of all coolers flushing in the reverse direction of air flow, dont want to start bending fins , i use a spray nozzel from my hose at city water press. and not a pressure washer,check your radiator for blockage by bringing engine up to op. temp. and feeling the sides from hot left side to warm right side with even temp rise across , any cold spot inbetween would constitute scale build up or other blockage and it will need a chemical flush or replaced, thats a good start ,if all that fails anf thats alot check your timing that could also be a factor and on that broken bolt issue you could also double lock nut it or use a stud puller they work pretty good too! Time is my torque wrench and past mistakes and broken bolts my teacher!! good luck

Atreus21

It overheats regardless of motion. It overheats faster when the engine is revving, but it will eventually overheat sitting still.

You mean pull the pump over the broken screw? That didn't occur to me. I just hope there's sufficient clearance. Especially for the vice-grip.

Atreus21

I didn't notice any noise.

The belt was replaced in July 08. How do you check for tension? Pulley rotation seemed smooth.

Didn't notice any wiggling or anything.

Looked for collapsed hoses. I've already taken both of them off completely and inspected them, ran water through them, etc.

Pretty sure it's maintaining pressure. I took it off yesterday when I had to stop on the way to work, or risk further heating, and damn near scalded myself from the blast of coolant.

The fan is working with no obstruction. I hear it come on when the car reaches 210, and I've moved it by hand with smooth results. I haven't yet tried your test of the coolant level in the reservoir.

I've never tried this. I will run this past the camarov6 guys and see if I can get a procedure specific to my engine.

I'm praying that it's not a timing issue. Or anything else seriously wrong with the innards.

Thanks very much.

Atreus21

Would this be an adequate means of testing to see if the water pump still runs?

Mike Sigmond

Exactly, if you can get a grip on it to turn it.

tm4hammer

ya i hope its something simple to buddy! if its not any of the former then it could be in the timing cover or exhaust leaking into the coolant. but run through those first guy another thing do you hear any popping or crackling from the engine or even a gurgling sound from the heater hoses when the engine is hot and shut off and starting to cool down if so try to isolate it to a specific part of the engine use a probe if ya have one or simplifiy and use a long screwdriver hold it against the portion you think is doing it and the other end against your ear ! see what you can hear ! ha ha and no im not messing with ya ! no matter what you might hear from my lil bro Red ! it works sometimes, good luck and im pretty damn sure it will turn out to be something simple oh have you done any kind of mods, or upgrades or other maintance lately if so maybe back track also they make a left hand drill bit extractor that you might try on that bolt i have used them and they work pretty well it unscrews the bolt as you drill depending on how tight or buryed against something it is

Atreus21

Managed to get the water pump and the headless screw out with a vicegrip. Thanks for that good idea Mike Sigmond.

But the water pump looks fine. No wobbling, no corrosion or wobble on the impeller or the pulley, and no leaks either. Unless anyone else has any idea, I'm going to put it back on, as it doesn't look defective.

Question: Does a thermostat admit cool coolant to the engine, or hot coolant to the radiator?

If it's hot coolant to the radiator, then I wonder if I don't have a clog somewhere. Today, with the thermostat in place, I disconnected the hose connecting the thermostat housing to the radiator. Then I started the engine, and let it heat up. As it surpassed 195, which is what the thermostat is rated, faint smoke started coming from the block, and I saw an intermittent trickle coming from the thermostat housing. It never got any higher than a trickle, nor did it become a constant trickle.

I think the engine isn't getting coolant. And I don't know where the clog is.