Injuneer

Two possible things could come out of the bleeders - air or coolant vapor (steam). The 18 psi pressure in the cooling system is the only thing that keeps a 50/50 coolant mix from boiling at 260*F. When you open the vent the coolant boils as it exits to atmospheric pressure.

On the other hand, if the system is losing coolant, it's going to be replaced by air, and it will vent air, and boiling coolant.

Why is the system venting excessive coolant to the reservoir? If the cap was relieving at a lower than specified pressure, it would end up in the reservoir, and get pulled back into the radiator when the system cools down. But you indicate a new cap.

So.... what is building the pressure high enough to force the 18 psi cap to open up and dump coolant?. One explanation is combustion gasses, flowing through a tiny crack in the head gasket. Entirely possible for this to occur without putting coolant in the oil, as Bruce indicates above. There is no oil flow through the head other than gravity flow from the valve train.

Similarly, if the path between the combustion chamber and the coolant passage is small, you may not get much coolant flow from the passage to the combustion chamber, compared to the large flow of gasses from the combustion chamber to the coolant passage during the compression stroke and the huge pressures generated when the plug fires.

Get a kit to check the coolant for the presence of hydrocarbons.

Slayer

Thanks for the additional information. Fortunately, I work at Advance Auto, so I can use my employee discount to buy the combustion leak detector today. If it is a bad head gasket, I may just sell the car as is because I can't afford to fix it yet again.

Slayer

Okay, I need some more expert advice. Before I ran the combustion test, I let the car warm up. Once the temperature gauge approached 260 degrees (probably a false reading), I turned off the ca and let the fans cool it down while I removed the radiator cap to release enough coolant to lower the level in the radiator so as not to contaminate the liquid in the combustion tester tube. I inserted the nozzle into the radiator and started the car. It ran for maybe ninety seconds before the coolant in the radiator filled the tube, contaminating the liquid, and sprayed out of the radiator cap opening. Right before this happened, though, the blue liquid was bubbling and boiling like hot water on a stove, and the liquid remained blue. Was this enough of a test to confirm no combustion gasses in the coolant, or do I need to redo the test? If so, then how do I prevent the coolant from spraying out of the top of the radiator and contaminating the liquid in the combustion tester tube?

Injuneer

Didn't the kit have a funnel, or spacer for the fill neck, to keep the tester up out of splashing coolant?

Slayer

It just had a rubber cone on the end that connects to the radiator.

I just pulled the front cover off the water pump to check the impeller. Should it spin freely like a fan? Mine makes an audible click each time I move it, and it doesn't spin freely. Instead, it feels like it's clicking into a new "notch," for lack of a better description, each time I turn it. In other words, I can't spin it freely; I have to manually spin it, but I get a lot of resistance and an audible clicking when I spin it.

shoebox

It should not spin at all. It should only move when the cam does. Could be the pump, coupler, water pump drive or cam gear.

Slayer

So, I should definitely replace the water pump, right?

bw_hunter

You should remove it and check the coupler between the pump and the drive spline. Replace the coupler if it looks stripped or is shiny. Definately replace the pump.

I think the coupler is hard to find but I'm not certain as I have an electric water pump and haven't thought about thatsrt of things for a good longt ime.

Now would be an outstanding time to replace the opti. Or, at least, the cap and rotor...don't forget the red loctite on the rotor screws.

Slayer

Yeah, I'm definitely going to check the Opti cap and rotor because of all the coolant that's been pouring out from all this messing with the car. So far, though, the car still runs great, so the Opti should be good, but I'm going to try and cover it with a plastic bag before I pull the water pump to protect it.

bw_hunter

You'll be better served by changing it now rather than waiting. Antifreeze permeates the cap material and changes it's electrical properties. Why not save yourself a future headache by replacing this wear item now?

Slayer

With the luck I have, I'll probably get the car back together, and the Opti cap will take a dump on me, so I may as well get the new cap and rotor. I'm also going to replace the coupler because the teeth inside look okay, but the outside has a shiny ring around the middle. I may as well replace everything now instead of some now and some later.

bw_hunter

Don't forget to replace the seal in the timing cover as well as the two O-rings on the coupler. The coupler is part number 10128334, the O-rings are part number 12553792. Rock Auto has the seal, the O-rings and the water pump gaskets for $10...the coupler is going to be a dealer only part (I think)

shoebox

If investigation points to that being the culprit, then, yeah. You need to determine where the slippage and noise is coming from.

If the teeth on the coupler are ok, what it looks like on the outside does not matter. It is an expensive item. Grease the splines and use new o-rings when reinstalling.

pearlpurple

I'll second the no coolant in oil.

Both my 93 Z28 (in 2001) and my 2004 Impala when they blew head gaskets oil was clean.

With my Z28 it must have been a "pin" hole as coolant level dropped slowly and there was no sweet smelling smoke out of exhaust.

With my 2004 Impala the air in system symptoms having to bleed it out continuously and air bubbles coming through the coolant o/flow. Sounds a lot like what you are describing.

You may have stated this but I missed it but is the car blowing heat when it is over heating?

ASIDE: I too did not know (15+ years) that my 93 temp gauge was incorrect. I always thought that gauge was reading wrong but she had never over heated so never gave it any real thought.

Slayer

The one thing I never checked in all of this was to see if the heat was blowing hot when the car was overheating. I'm wondering if I should just cut my losses and sell the car instead of putting another $500 into it, and the problem still remain. I was somewhat confident that the head gaskets were okay because the combustion test fluid stayed blue as it was boiling shortly before it was contaminated with coolant, and being able to turn the impeller on the water pump by hand led me to believe the water pump was shot. Even my friend who worked on the car for a few hours the other day kept swearing the water pump had to be bad when he was constantly bleeding and topping off the system. When the car sat for almost one week without being started, the coolant level never dropped in the radiator. Right now, I'm torn as to what to do.

I found the water pump and the cap and rotor on Rock Auto for $437. Summit Racing has the coupler for $50.