** that title should say "drained and refilled coolant" not "flushed". I did not flush.

Hi guys.

So I have been steadily working on my red z51 85.

I fired it up after sitting for 6 weeks and it is now overheating, and no heat is coming out the heater.

Here is the situation:

before doing any of this work, it never overheated, and always gave hot air from heater.

- water pump gasket was leaking, so i replaced them and no more leak. got new gaskets from local parts store and used the permatex aviation stuff. no more leaks.

- completely drained the coolant. drained the rad, pulled knock sensor (got very wet), pulled the oil cooler line on the driver side, pulled and cleaned the overflow.

- did not touch the thermostat.

- the car sat for 6 weeks empty of coolant and oil in my heated garage (i also did the oil pan gasket).

- got everything buttoned up, no more leaks anywhere.

- I filled the coolant up and followed the L98 "purge" instructions 5 times but couldn't get the car away from overheating.

- current condition is :

- upper rad hose gets freaking hot
- upper rad hose at no time is pressurized. when i squeeze it with my hand, simulating a blockage in this hose, pressure sslllooowwwlllyyy builds up. this is part of the reason why i am going to replace the thermostat first. its almost like the tstat isn't opening all the way.
- lower rad hose does not
- no heat comes from heater core
- popping sound is heard when it gets really hot
- gurgles after I turn it off

Note that during the re-fill process, i filled the rad, filled the overflow to the 'cold start' level, and turned it on with rad cap open. Eventually, the water level started to drop very quickly and filled it up with more 50/50 mix. eventually the system was filled, so i put the rad cap on. and the front end was raised during this hole time, with the heater on full blast in the car.

I have not been able to get the car operational without overheating and no heat comes from the heater after doing all of the above. today i bought a new 7$ thermostat hoping to god that somehow when the car sat for so long with no flud, it got stuck and thats all it is.

from what i have described, any thoughts guys?

VikingTrad3r

 

Something is plugged up in your cooling system. The heater core is connected all the time, even when the thermostat is closed, so that's a clue that something is wrong. Running the heater at "full blast" does not make a difference in how the water is circulated.

It does sound like the thermostat is stuck closed. Have you tried feeling the heater hoses where they go through the firewall? They should both be hot. If they are not then you might have a plugged heater core.

 

Sounds like an air lock. If your stat is stuck, you will never get all the air out.
Since you have a new one, replace it.

 

As agent said, this sounded to me like an air lock as well because of the correct function of the cooling system before the drain.

i pulled the tstat last night,drilled two holes in a new 7$ 180deg tstat, followed instructions in the fsm and away i went. no issues anymore.

one thing for sure, i need to FLUSH this car. even though its been drained from both sides of engine and refilled the water was still very rusty as i monitorred it in the rad topping it up throughout the refill procedure.

thnx for the help guys. VikingTrad3r

 

I said this in another thread; I hate when guys abandon the thread without posting a conclusion. Thank you for doing so.

 

i have another thread that is hanging open on a distributor install but i havnt had the time to do it. this forum has solved a gazillion problems on my 2 c4's and i want to pay that fwd by providing results that work for other noobs like me.

thanks for all your help

 

Viking...

If you want to do a good clean-out of the cooling system, get a jug of 'radiator CLEANER' and follow the directions. It will be next to the radiator FLUSH stuff.

Well worth doing. A little time consuming, but not troublesome. It will do a good job of getting the accumulated scale off the inside of the radiator. Gives you back cooling capacity that your car has 'lost' over the years.

 

After 4 years, I'm hoping he has already flushed the system - maybe twice!