intermittent heating issue...

[koda2000]

if you still have your original radiator, it's probably leaking from where the plastic tanks attach to the aluminum core. look for greenish residue on the plastic tanks. you can also remove the front air deflector (4 10mm bolts) and look in there for wetness or signs of leaking. that may also explain why your not pulling fluid from the reservoir, as it will suck in air from the leak point.

 

[Steeda04SVT]

So what if both hoses are not hot that go to the heater core? Possible bad thermostat or still a possibility of a bad EATC?

 

[koda2000]

So what if both hoses are not hot that go to the heater core? Possible bad thermostat or still a possibility of a bad EATC?

if only one heater hose is hot it could mean several things.
- clogged heater core
- bad heater control valve
- bad EATC temp contorl solenoid

if you get some heat, but not much, it could mean a bad thermostat. where is your coolant temp indicator needle sitting. it should be in the middle. if it is then you could have a blend door problem. even a low coolant level

 

[RomeovilleIL]

Bad thermostat stuck open would have all the hoses cold and engine temp low. If both hoses are not hot but the engine shows normal temp (ie the other radiator hoses are hot) and radiator is full, it's either blocked heater core or malfuntion of heater control valve (valve broken/blocked, vac issue). Since it is easiest to reach and doesnt require any parts, test for blocked heater core first -- with engine cool pull hoses and see if water can flow through them. Should flow straight through, not trickle out. If it's clear move on the the heater control valve. Probably need to take out the airbox and the top radiator hose to reach it. Has a 9/16" bolt that mounts it to the block, 2 hose spring clips, and a vac line. Once removed hold up to the light. With no vaccuum it should be open and see clearly through it. Often the valve inside gets crap built up on it so even though the actuator arm moves ok on the outside the inside doesnt change. Leakstop likes to settle here and in the heater core. Usually you can just clean the gunk out. Test function of valve by applying vaccuum to ensure it closes before reassembly. If all this checks out, then test for vaccuum on the line. No vaccuum can be broken lines/poor fittings, hole in the vac ball, or problem with EATC. Best to trace from the line at the valve and work backwards checking for cracks or loose connections. Once you have exhausted all possibilities under the hood, then look inside at the EATC and its attached vac line.

 

[Steeda04SVT]

if only one heater hose is hot it could mean several things.
- clogged heater core
- bad heater control valve
- bad EATC temp contorl solenoid

if you get some heat, but not much, it could mean a bad thermostat. where is your coolant temp indicator needle sitting. it should be in the middle. if it is then you could have a blend door problem. even a low coolant level

Still reads normal, but both heater hoses are not hot at all. I was getting some heat yesterday but now I'm getting no heat at all. But yeah i just filled it with coolant and had some left over in the coolant overflow but now it's empty so where the hell is my coolant going? Almost went to go get a flush until i started to read this thread. Of all days too the high today is 36 with a low of 19 tonight. So def need to get this figured out.

I'm gonna go get more coolant and see if it fixes it and if so then I Just need to find my leak.

 

[RomeovilleIL]

#1 -- check your oil level & make sure it isnt filled with coolant
#2 -- get a pressure tester (rental tool) from any parts store. Fill the radiator then pressurize and look for leaks with engine off. A leak on hot exhaust might evaporate before leaving traces on the ground
#3 -- are you having hard starts when cold, or running a little rough until warmed up? if yes may have cracked heads leaking in to cylinders. After pressuring the cold system with the tester, pull your spark plugs and check for wetness

 

[koda2000]

#1 -- check your oil level & make sure it isnt filled with coolant
#2 -- get a pressure tester (rental tool) from any parts store. Fill the radiator then pressurize and look for leaks with engine off. A leak on hot exhaust might evaporate before leaving traces on the ground
#3 -- are you having hard starts when cold, or running a little rough until warmed up? if yes may have cracked heads leaking in to cylinders. After pressuring the cold system with the tester, pull your spark plugs and check for wetness

assuming the above tests are all negative, are you filling the radiator or the overflow tank? the reason i ask is that the hose that connects the reservoir to the radiator can become clogged or cracked (doesn't appear to be your problem). you may have a leaky radiator or heater core. is the floor wet on the passenger side? do you smell antifreeze in the cabin? do you see green residue on the radiator tanks? when the radiator is cool, remove the cap. fluid level should be right to the top. i always check this first before adding coolant to an empty reservoir. otherwise a low radiator will just empty the reservoir to fill itself. of course you shouldn't have to refill either unless there's a leak somewhere.

 

[Steeda04SVT]

Just put some coolant and the coolant temp needle is sitting a little lower than normal. Now with the coolant I put in. The top radiator hose is barely warm. Wondering if it's the thermostat. But no I don't smell coolant at all or see any on the garage floor at all.

But i'm letting it cool down before trying disconnecting the hoses to the heaters core to see if it's clogged or not then will check the heater control valve

 

[koda2000]

Just put some coolant and the coolant temp needle is sitting a little lower than normal. Now with the coolant I put in. The top radiator hose is barely warm. Wondering if it's the thermostat. But no I don't smell coolant at all or see any on the garage floor at all.

But i'm letting it cool down before trying disconnecting the hoses to the heaters core to see if it's clogged or not then will check the heater control valve

if you're disconnecting the heater hoses, you can back-flush your heater core to clean it out and make sure it's not clogged. if your coolant temp indicator is about in the middle, you should have adequate coolant temp. usually if the thermostat is bad the needle will be very low, or very high, but the only way to know for sure is to actually measure the coolant temp.

if it's been a while since you changed the thermostat put a new one it, but i'd be more concerned with where your coolant is going.

 

[Dono]

I didn't see the heater control valve mentioned. Its a valve that is in-line on one of the coolant hoses going to the heater core on the passenger side probably about a foot from the heater core. It should have a vacuum line going to it.

This valve is there for 'max ac' to shut off coolant flow to the heater core to make sure the cold air isn't being heated at all. If this valve is stuck closed for some reason you would not get any flow thru the heater core.

 

[Steeda04SVT]

Weirdest thing. Let the car sit for a bit to cool down so I could disconnect the heater core hoses and then I had to run to the store real quick and the heater was working fine again. So my uncle who is a mechanic is gonna check it all out when he gets home. I'm just like WTF over?!?!?!

 

[koda2000]

if only one heater hose is hot it could mean several things.
- clogged heater core
- bad heater control valve
- bad EATC temp contorl solenoid

if you get some heat, but not much, it could mean a bad thermostat. where is your coolant temp indicator needle sitting. it should be in the middle. if it is then you could have a blend door problem. even a low coolant level

I didn't see the heater control valve mentioned. Its a valve that is in-line on one of the coolant hoses going to the heater core on the passenger side probably about a foot from the heater core. It should have a vacuum line going to it.

This valve is there for 'max ac' to shut off coolant flow to the heater core to make sure the cold air isn't being heated at all. If this valve is stuck closed for some reason you would not get any flow thru the heater core.

you're right, you didn't see it mentioned...

 

[Dono]

oops....I was surprised I didn't see it.
That explains why. It was there all along.