Heater Core

[alenstein]

Flushing the coolant and changing the thermostat did not help the heater siutation, its gets milddly warm on the highway but never hot, hot only after prolonged stop and go driving in the city.
Question. Anyway to flush the heater core at the firewal , before removing it completely, I looked under its kinda deep inside there hard to reach? Anyone done it. This would be the last resort before I get fed up and take it to my mechanic.

[Jeff_in_Atl]

I have a dumb question. Did you flush it in the reverse direction that it flows or the same direction it flows?

[alenstein]

I had it done by a mechanic they pumped it out under pressure .

[Jeff_in_Atl]

I had it done by a mechanic they pumped it out under pressure .

If they did not do it in the reverse direction, It isn't going to get the crap out of it.

One more dumb thing to ask. The outlet from the pump has a hose connected on it that is about 6 inches long. Then there is a plastic piece and another hose that goes on. That plastic piece has a necked down area inside it with about a 3/8" hole in it. I know it's a long shot, but could there be a piece of trash in there blocking the flow to the heater core. It's number 13 in the attached drawing.

[alenstein]

If it wasn't done in the reverse direction it wouldnt remove and slugde from the heater core you mean? One thing I did notice that the engine does stay cooler I had that done in October So i was able to observe it in warmer temperatures.
2nd. obsrevation that it does get hot only after the engine goes through few cycles above 210F. On the highway it stays dead even at 160F or so.
If a remove the piece under no. 13 when is the best to remove it while engine is cold? I don't want any coolant to be gushing out..

[Jeff_in_Atl]

If it wasn't done in the reverse direction it wouldnt remove and slugde from the heater core you mean? One thing I did notice that the engine does stay cooler I had that done in October So i was able to observe it in warmer temperatures.
2nd. obsrevation that it does get hot only after the engine goes through few cycles above 210F. On the highway it stays dead even at 160F or so.
If a remove the piece under no. 13 when is the best to remove it while engine is cold? I don't want any coolant to be gushing out..

No. If the heater core isn't reversed flushed, the crap won't come out.

What temperture thermostat is in it? Is it the correct thermostat for an LT1 or one for a SBC. I think if the SBC is used it will overheat. Somebody else can confirm that.

You can not remove that plastic piece in the assembly. You can disconnect the hose from the water pump, drain the fluid out of the line enough to bend the pipe and look down in it. You could also reverse flush that pipe (pump water into the end that connects to the firewall).

[alenstein]

The thermostat is 180F, ac delco I got it from gmpartsdirect.com .
Well I would have to wait until it gets warmer to reverse flush the core at work, no access to a driveway .
How hard is it to get to the heater core, and remove it?

[TraceZ]

You dont need to remove it unless it is leaking. Removing a f-body heater core is not a fun job... It's a HUGE job.

To properly flush it, You need to remove both the hoses from the motor... The one at the water pump and the one at the throttle body. Put a garden hose on it and flush it with pressure in both directions to really get it cleared out.

It will make a mess, there is no getting around that, but at least you will have heat in the car!

[alenstein]

Thanks Trace , Thanks jeff, Ill do the core flush as soon as the temp. goes above freezing.

[TraceZ]

I'd recommend going to a hardware store and combing through their garden hose/fittings section. Get a male hose end and then find a piece of tubing and a coupler that will fit onto the hoses under your hood. That way it will be quick and easy.

You will also want to get a section of garden hose to put on the "exit" line during the flush so it can hang down to the ground and not make a mess all over your car. Otherwise, you'll have the dirty flushed coolant going all over the place uncontrolled, maybe even on the opti.

[alenstein]

You're right Ill look into that. If I remove the hoses ,water pump and the one at the throttle body is there going to be a lot of coolant gushing out. Maybe i can try this today.

[TraceZ]

You're right Ill look into that. If I remove the hoses ,water pump and the one at the throttle body is there going to be a lot of coolant gushing out. Maybe i can try this today.

Make sure the car is cold, but you will lose some coolant. Not too bad. I'd be more concerned about the water freezing on the driveway and making it slick.

[alenstein]

No driveway,ill do this a work, am looking at 40 degree weather tomorrow it is still freezing today.

[Joe K. 99 Zeee!!]

I swear...I hear problems like these far too often. I'm really considering having regular coolent (the green stuff) put in next time and then have it flushed annually. The additives in the orange coolent have cost me a low coolent sensor and led to a couple reverse flushings for my heater core as well.

Is it just me or would it be cheaper/better to flush annually with the other type of coolent??

[96ws-6]

I am having the same problem, No heat.. it kind of works if the car sits for about 20 after the temp reached 180. I have flushed the radiator twice and the core and the water flowed just fine in and out of the core, i bought my thermostat at advance auto, would they give me the wrong one? I measured the stat and the hole in the water pump and they are the same, could it be vaccum lines or anything like that