Car in question is a 95 TA w/124K miles.

I have this kind of weird problem, or actually two problems, related to cooling/heating. Or something like that... Hopefully someone can shed some light...

Background: Car runs fine. According to the gauge, the temp stays about 210, or below, while driving and goes a bit over while idling. Water pump and radiator core have supposedly been changed a little while ago. Changed the thermostat today.

Problem #1: Cooling system creates a lot of pressure in the radiator. Or at least I think there shouldn't be that much of it. If the car is hot and I go try to open the radiator cap, the coolant just starts pouring out from underneath the cap. I know there should be some pressure while warm, but I don't think it should be that much. Would that be an indication of a blockage somewhere or...? After the car has cooled down, the coolant level in the radiator is so low you can't see it (even if the level was topped off so that it was visible before driving). There is no water mixed with oil.

Problem #2: Heater does not work. First flushed the heater core and then changed it about a week ago, but still no heat in the cabin. What's next?

Any and all help is greatly appreciated.

TS

 

#1: Sounds normal. Remove the cap to the radiator while the car was just running at operating temp and you should get coolant rushing out like a volcano. Thats 18 or so psi of pressure that the cooling system builds. The level should be up there unless you have a leak. If the low coolant sensor doesnt come on and you're not overheating...there shouldnt be a problem.

#2: Do all of your settings on your vents work (defrost, instrument panel, floor)? Is there any heat coming out of any of the vents? So long as the blower works, door to the temperature control and the heater core is fine...you should get heat.

 

#1- normal.

#2- the heat does not work because your coolant level is low enough so that coolant does not fill the heater core.

You need to find out where your coolant is going. It's either a leak, getting too hot and boiling out of the overflow tank, leaking through a headgasket or a crack in the block. Not being able to tell if the oil is a milky mix of oil and coolant is not always that easy to recognize. If you don't have white smoke out of the exhaust, and when you drain the oil if you let it sit and nothing separates and it doesn't look like chocolate milk you have most likely ruled out a head gasket/cracked block. Check under the passenger side dash, if it's wet then you have a heater core leaking. You'll probably want to remove the underdash to have a look. After you've checked these you need to check around the overflow tank to see if there are any signs of coolant, if that checks out ok start chasing down leaks.

 

Hmmm... Haven't thought about that coolant level thing. But if there is as much pressure as there is, there should at least some coolant reaching also the heater core. Or...?

The coolant level sensor is disconnected.

Haven't changed the oil, so can't tell anything by that. Oil on the dipstick looks fine and don't see any slush/foam when looking through the oil filler. No white smoke, either, so I'm assuming the block and/or head gaskets are fine.

All the settings on the dash work (defrost, floor etc.), but no heat out of the vents, just what ever the temperature outside might be. Or cold when the AC is on. While I swapped the heater core, I also checked the door in front of it and that opens and closes properly when the temp settings are changed.

 

Check the level in the radiator several mornings in a row (engine cold). If it is not full to the top, fill it up. Make sure the remote reservoir has the proper level. Also make sure there is no air in the system. Once the level stays full when you check it in the morning and any air is bled out (and you are sure the heater core and hoses are not clogged), you should have heat.
This assumes your temperature control mechanism is functioning normally inside the car.

 

Meaning? Is there some kind of controller behind the **** that could go bad?

As I mentioned above, the little door which controls the flow of air through the heater core is functioning properly when the **** is turned. I checked that while I had the heater core off.

Heater core should not be clogged, since it is brand new.

 

The temp control **** just has a cable attached to it that moves the door. If you have already checked that, then no problems there. Sorry, I missed that.

I know the core is new, but were the hoses flushed from the water pump end?

I am more apt to suspect no heat from your low coolant condition.

 

Let the engine get up to operating temperature with the radiator cap on (coolant system pressurized). Turn the bleeder screw to the hose that is routed to your heater core. If no coolant leaks out upon first turning the screw then your levels are too low. Why is the coolant level sensor disconnected?

 

The previous owner disconnected it. Most likely due to the usual malfunctioning of it.

I don't think I've seen a bleeder on the hose going to the core , but I'll check again...

 

The bleeder is right in front on the hose by the intake elbow with rubber line coming from the waterpump, the hard line portion with the bleeder screw and then back to rubber as it goes back to the heater core.

 

Got it. I actually tried to bleed through that yesterday when I changed the thermostat, but nothing came out.

Hmm...

 

I think you've found at least part your problem.

 

Guess so... But where the hell is the coolant going...?

At least I still haven't found any signs of it being mixed with oil.

 

Okay... A little update.

I guess the coolant was just low to begin with since it hasn't been low anymore and is not losing it anywhere. So I guess that issue is taken care of.

The other issue, still, is the heater. I did what SS RRR suggested and now that the coolant level is about where it should be, there was coolant coming out of the bleeder when I opened it.

But still no heat in the cabin.

Is it possible that the waterpump is not creating enough pressure to circle the coolant through the heater core? I have not checked the hoses whether there is a blockage somewhere or not, but I don't think so...

 

Get used to little or no heat. There are 2 things that kill the heat. One is the little plastic restrictor that holds back flow to the heater core. You'll see it in line to the heater core hose if it hasn't been removed. I had left mine off for a few days after doing what you need to do. Whew that heat coming from the vents was hot.

The other is particles sloughing off the engine block water jackets getting in either the restrictor or heater core and clogging the flow.

The first thing you do is check all the hoses for weapage. Usually around the factory crimps at the restrictor. Replace it or as I did, just repair it with a hacksaw and worm clamps. Now remove the 2 hoses to the heater core. If the restrictor is left on the hose the next step of washing out the heater core will be slow to impossible so remove it. You will probably find even water will not flow through the heater core with even a garden hose. I had to use compressed air to unclog mine.

Yeah I know, could have damaged the heater core. Well either it worked and I had heat or I had to replace the core anyway.

Oh BTW, unless you do a complete and thorough drain, flush and refill of the engine block, get used to doing this often.