93 chevy cavalier 3.1 over heating and heater blows cold, new water pump, thermostat, rad. cap, flushed the radiator, drilled a small hole in the edge of the thermostat, no water in oil and it doesnt smoke!!! what can it be?

Could be that the heater core is clogged... for the car to operate at optimal temperature (not to cold, not too hot) all cooking system had to be working properly, I had a '97 camaro, it had 2 previous owners and I had heater core issues and also the hose that goes to the expansion tank was clogged, causing the water to build enough pressure to escape trough radiator cap... anyways they're two totally different cars but seems to me you need a cooling system flush.

They sell a kit which includes a T fitting that goes in the hose flowing towards the heating core, and allows you to connect a garden hose to push water through the system with radiator cap off so all can circulate and clean up. Being careful (water pressure in houses is more than the system is designed to withstand, for instance a radiator cap can be 15 - 20 psi, depending on area, some homes have above 40 psi) is a great diy little project. Alternatively you can pay a mechanic shop to do it. After a flush, drain the radiator from bottom plug and refill with coolant always. Don't run your system with water and don't drive an overheating car, it will blow a gasket and that's when you kiss your car goodbye, repair is not only expensive but blown gasket might leave sequels on engine.

Possible trapped in system. Bleed system, should have two small screw bleeders, one in front of left valve cover on pipe behind water pump and the other on coolant pipe outlet as you follow upper rad. hose towards engine. Engine cool, remove rad cap, open both bleed screws and fill rad until coolant flows free out both bleed ports. close both bleed screws, rad cap off, start engine and let idle until upper hose is hot to touch , shut off, let it cool down for 20 minutes, top up rad and install cap. restart car ,drive and check.

If the coolant temp gauge is in it;s usual position when driving(at least 1/3 way up) then flush the heater core with a garden hose.Clamp off the heater hoses,remove them from the heater core and flush back and forth a few times until flow is good,reattach heater hoses and you should have heat as long as the heat/cold airflow door is in the heat position in the heater assembly under the dash.

To troubleshoot this types of problem,click the link below :----http://howtobyme.blogspot.in/2012/02/heater-blows-only-from-defrost.html
--------Go through the procedure to confirm the issue.

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Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Heat blows cold on drivers side and hot on passenger side?

http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

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This will help.Thanks.

change out your thermostat

YOU SHOULD FLUSH ENGINE BLOCK BEFORE INSTALLING NEW THERMOSTAT.YOU NEED RADIATOR FLUSHED AND ENGINE BLOCK FLUSHED.ALSO REPLACE THE RADIATOR PRESSURE CAP.

If you have flushed the heater, I assume you did this by removing the hoses from the thermostat housing. If there's still no heat, check

1. the thermostat is actually present. If not, put one in. If the radiator core is in bad shape, or blocked, replace the radiator.

2. the thermostat is not jammed open. If so, replace it and use a new gasket under the cap.

3. Verify that the water pump belt is not loose.

4. Remove some dash panels to get access to the heater core valve. Check that the valve is actually turning when you adjust the dash control.

could be waterpump?
i was going to say rad fan,but if so heater would be hot.
lack of coolant will make heater core to blow cold,if engine heats up with full coolant,usually means poor or no circulation.
water pump?
run engine with full coolant,at operating temp.with rad cap off and look in rad cap hole and see if there is movement of water inside rad.
[rad fan will not come on if water is not circulating through rad water pump?]

Remove and raise upper hose at thermostat end and remove lower rad hose.
Fill rad with a hose and watch for flow from bottom rad hose and/ or bottom rad hose connecton.......water should fall though rad easily.
Honda rads are cheap.....any restriction....replace rad.

Remove thermostat....fill thermostat housing with hose and watch for water flow at bottom rad hose.
Flush good.

Remove heater hoses.......flush back and forth until a good flow is present "With heater control set to hot" if no or poor flow....replace heater core.

Stop leak can plug everything.

Also.......not likely causing over heating....but ....at your mileage,if you do not know if the timing belt has been changed.....CHANGE IT NOW!
Water pump is optional at this mileage.

You probably never cleaned the cooling system out.

If you have not get it done by pros.

It seems something is blocking the flow. If the water pump went bad you will know. Rarely ever heard a impeller breaks off like you think. The bearings and the seal break first.

Check and see also if the heater valve is working.

As for the over heating even new thermostats fail. Reverse flush is needed or the procan measure the pressure in the radiator cooling system and edetermine if there is a engine pressure problem. Tools and experience is the key in the game of diagnosis.







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