bypass hose

[darylpreacher]

I have a 99 bravada, 4.3. There is no water in the heater hose to the heater core. There is hardly any water coming our of the intake manifold to the core. could the bypass hose be plugged? What is the purpose of the bypass hose?
thanks

[Chris Stewart]

Is the heater hose still dry on your Bravada?

[ericn1300]

The only bypass hose I know of is the heater supply hose. It bypasses the thermostat to bring you hot water to the heater core before the thermostat opens.

If the heater hose is empty it's probably not blocked. Anything big enough to block that hose would have caused far more serious problems in the smaller pasages in the engine block. You have either a low coolant problem or an air lock below the thermostat. An old trick my dad's farm mechanic showed me to avoid air blocks is to drill a 3/16th hole in the flange of the thermostat. This allows the air to pass while not signifiantly afecting warm up time.

If the coolant level is low, find the leak as soon as you can. Coolant leaks can be dangerous. Both to your engine, and possibly to your health.

By the way, Chris, my load leveler will be able to drive on her own again in about 20 days. I'll have to chauffer her shopping trip on black friday, the day after Thanksgiving, then she's on her own. Finaly.

[Chris Stewart]

Glad your wife is going to be back to normal. Sorry you have to do the Black Firday...at least you'll be able to stand guard to discourage the door dingers.

[darylpreacher]

Originally Posted by Chris Stewart

Glad your wife is going to be back to normal. Sorry you have to do the Black Firday...at least you'll be able to stand guard to discourage the door dingers.

Thanks for the information. The probelm turned out that the heater core was full of some really nasty looking dirt. I bought the car used, I have no idea what they put in it. But I reverse flushed the heater core, and flused the radiator, and it seems to be working fine.
Thanks Again,

[Chris Stewart]

The really nasty looking dirt is stopleak put in at the factory. That was an interesting episode of 4.3 V6 history although it was totally miserable for the poor folks that lost their engines due to clogged up radiators and cooling passages in the engine. It got covered up by GM saying the long life coolant had to be treated special...distilled water and no air allowed in the cooling system. Maybe the plastic intake manifold gaskets were leaking. I flushed mine in the normal fashion, added Prestone Long Life (orange stuff), used city water and had lots of air in the system with no problems...so much for the hype. I think the results speak for themselves...RIP Olds. Glad you're doing OK with it now.

[darylpreacher]

Chris, thanks for the info. That answers a lot of questions for me. But I'm with you, after all the air worked itself out of my system, it seems to doing great. Thanks again.