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Anyone have any clue why a '96 Chevy Tahoe with a 350 would lose heat when driving?

Changed t-stat, water pump, heater core, nothing helped. Also changed heater box.

We only do transmission work here but I want to welcome you to the forum! Hang on and help will be forthcoming.

Does the coolant get up to temp? Are the heater hoses close to the same temp? It could be a blend door not moving...

Welcome aboard the good ship lolli pop. This place is great.

What was wrong with the t-stat, water pump and heater core ? Were they repalced chasing this problem? Rich is right on track.

3/4 hose gets hot/5/8 hose dose not even get warm/ even clean out heater core/

heater box was broken /and it had the prob with heat when it came in so its been a nightmare from day one / dose any one think it might be a intake gasget

took heater hose off and ran truck hardly any flow from 3/4 hose

I would check coolant flow next if one hose is hot and other is not thats the next step.

does this still have dexcool? sounds like the heater core is clogged. super flush, back flush the core and possible air flush.

Tina, the heater core is new. Wonder if it helped at all? Then shortly after even the new core was plugged?

3/4 hose has limited flow when disconnected.

wbuxton wrote:3/4 hose has limited flow when disconnected.

Yep, that put it over my head. I don't work on the stuff. I fold.

I would be looking for a flow restrictor in the heater hose being pluged up.

Does this have the quick disconnect on the back of the intake the heater hose connects to? If so I've seen those plugged not allowing flow.

or wp impeller(rare)

sbebenelli wrote:Does this have the quick disconnect on the back of the intake the heater hose connects to? If so I've seen those plugged not allowing flow.

Seen this already also.

i've seen more than a few times where over use of rtv has plugged the port in the back of the intake. be carefull with the connector. this is in the era where the intakes rot out. was the intake taken off recently? i've seen incorrect gasket replacement redirect the flow away from the heater core. the input hose should get so hot you can't hold on to it for more than a few seconds.

Ive repalced lots of the fiitings corroded and leaking but never blocked

brianp87 wrote:Ive repalced lots of the fiitings corroded and leaking but never blocked

I have seen t-stats completly blocked with "blue glue", around here people think you have to use an entire tube of the crap to do a simple t-stat, when most of the time you need none at all.

Wow i havent seen that. But thankfully 90% of the vehicles I see are worked on by just us. We used to do a ton of those heater fittings.