Cliff Chaffee

Hello all. I have been searching these forums for a while and have yet to find solid answers to my questions. Hopefully someone can lend a hand...

1996 Camaro Z28 (V8). Heater blows cold. Most all of the threads pertaining to this issue suggest flushing the heater core. I flushed the heater core AND the entire cooling system and bled it properly afterwards. The heater got "luke warm" but not hot. After a week or so of driving, the heater is back to blowing cold air. NOTED: heater core isn't leaking, engine is at correct operating temp.

Question #1:
Can I rip out all of the OEM lines and just put heater hose lines from the water pump connections strait to the heater core? Seems primitive, I know, but I'm an old school wrench and it just seems to make sense to get rid of that OEM cluster of hoses/connections, etc.

Question #2:
If I CAN replace OEM hoses with heater hoses from the auto parts store, is a restrictor absolutely necessary or can I just leave it out?

Thank you in advance!

Cliff

azmarkus

You did a thorough flush not just of the core but also of the hoses too?

Other possible items to check -

Ensure coolant is truly full

Thermostat, could restrict flow

Vacuum check valve, older car, could certainly get brittle
LT1 check valve, link courtesy shbox

Blend door

I'm not a mechanic in any sense of the word, just a few points I've seen associated with this problem in the past

Cliff Chaffee

Thank you for getting back to me!

Yessir...I flushed the hoses as well as the core. My flush was pretty thorough...by the time I was done, the water was crystal clear both ways. Coolant system is full and bled properly.

I forgot to mention on my earlier post I also installed a brand new thermostat.

I guess the part that concerns me is the fact the heater got "warm" after the flush...but after a week or so of driving, it is back to blowing cold air. Maybe that was a coincidence or maybe monkeying around under the hood bumped some kind of vacuum or something...I dunno.

The blend door...I can hear the "fwump" of the door moving and the change in the air volume when I switch the controls from cold to hot. I assume that means it's working

I have not looked at the check valve. Could that cause the problem I am seeing?

Man I miss the days of good ol' V8's and rebuilding Holley carbs (grin)

Thanks again,

Cliff

shbox

Feel your heater hoses and see if they are getting warm/hot. Did you install the correct and long LT1 thermostat? It is important for proper flow. The vacuum check valve does not have anything to do with heat.

Cliff Chaffee

Absolutely. I made sure it was the correct "long" LT1 thermostat and also went with the OEM recommended temp (160)

Both heater hose lines are hot!

fbody_brian

Quite a few people complain of not enough heat after a 160° stat.
And btw that's not the oem temp.

shbox

Right. 180 is the stock temp. 160 can make the heat a little low.

BoostedDSM

iTrader: (6)

I'm swapping my 160 stat out for a 180. I have **** heat compared to what I used to.

Safe assumption here, you nerd a 180 thermostat and it should fix your issue

bufmatmuslepants

iTrader: (3)

You need to feel the heater hose lines, and make sure that when the fan is OFF, the hoses are both warm, and when the fan is ON, the return is cooler. Feel it all the way back. If when the fan is on the return is still hot, your flapper "thump" may be lying to you.

steveo_

heater cores are made up of a series of thin ovalled pipes that are fed in parallel.

if the cooling system is neglected, years of dexcool sludge can clog most of a heater core so badly that flushing it doesn't solve anything.

on a friend's dexcool-era sonoma, for example, flushing it helped a bit, for a few days, but in the end we replaced it.

cutting it open after revealed the problem; the lower pipes (at least 2/3rds of the heater core) were so full of hardened sludge that there was no way cooling or flushing water could clear them.

when we flushed it, we were only flushing the top couple pipes out. since they're fed in parallel, water pressure won't easily clear a completely clogged pipe, it'll simply go through another pipe that's clear.

you might have another problem, just thought you should know.

BALLSS

^^^^

in 96 when GM made the 100k major service interval Dexcool was introduced as lasting that long vs conventional green coolant. Dexcool by itself was good but reacted to the stop leak pellets put in new vehicles. Over a short period (around 2 years) the pellets turned the DexCool into a brown sludge which quickly clogs the small passages in the heater core (and even the larger ones in radiator)

it is/was very hard to back flush the heater core to get it completely clear so many experienced poor/no heat. a 160 stat further exacerbated heat output.

The restrictor is needed as direct pressure from the WP is to much for the small heater core, especially at high RPM's as the WP flow increases with RPM.

Perhaps a "hot tank" can purge the passages of the heater core when you remove it...but at that point just put in a replacement