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Hey everyone. My girlfriend drives a 1993 chevy lumina . There is no heat coming from her vents. She said her low coolant light would come on sometimes. She went to the shop and they wanted to charge her $325 to replace a coolant bypass tube. I put coolant into her, and in the resevoir. She had heat for about two days. She ended up losing heat last night on her way to my house. I filled her coolant at my house, it took about a half a bottle. She was driving home and said she lost her heat again, and i just filled it before she left. The mechanic said she needs to replace the coolant bypass tube. What is the coolant bypass tube??? can i do this myself, like buy one from a junkyard and put it in. What is the purpose of the coolant bypass tube. thanks for all the help guys.

 
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Better make sure its not something else, like a leaky head gasket or make sure the coolant isnt leaking into the chamber. Could also be the water pump. And i know there will be idiots that post "well its because its domestic" but save it, you need heat so check the water pump and all the hoses. The car is old, could just have a reg. leak. $325 sounds high for that

 
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buy a chiltons manual for like 15 bucks on e-bay.

 
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that made me laugh.

 
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my g/f usually lasts about 2 hours then we take a break....

seriously get a second opinion BUT don't tell mechanic B what mecahnic A said, that way you get a totally unbiased opinion.....

 
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The bypass hose allows coolant to recirculate within the engine, without passing through the radiator, as it does when the engine is warmed up and the thermostat opens. The bypass hose connects the thermostat housing and the water pump. The water enters the bypass tube through the bypass valve, when such a valve is fitted.

The bypass valve is sometimes operated thermostatically; it closes off the bypass hose when a certain temperature is reached. This increases the circulation of the coolant within the engine. Many cars don't need a bypass valve, because there is plenty of coolant going through the radiator hoses due to the thermostat.



theres a few things to check that may be cheap and simple. to check if the heater core is blocked. disconnect the 2 black hoses going in to the fire wall and pour coolant in to one of the hoses going in to the firewall. If it comes out the other side your heater core isnt plugged. then take those hoses off and see if the hose that goes from the wall to engine is clogged. as far as the coolant bypass hose on a lumina goes i have no idea how it runs through the engine bay.

 
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Lol, i ment I put coolant into her car. hahaha

 
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You should be able to do the coolant bypass yourself. But look for a leak there first. If it is the 3.1 V6, the coolant runs across the front of the engine. It is a metal pipe. Look for leaks there due to corrosion.

 
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sounds like a heater core to me. they go on the 3.1s a lot, changed several in a grand am and berreta.

 
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but if it was the core why would it work again for a few minutes. it sounds odd.