Chevrolet Repair: Heater hoses, chevy lumina, heater hoses

Question
Hi, I have a 1993 chevy lumina van. I want to disconnect heater hoses to flush out heater core. One little problem, can't see the heater hoses. On most vehicles I have worked on, I can clearly see where they attach to fire wall but on this van, unless they run under engine block to fire wall, I can't see them at all. Would you possible have a diagram for this engine,3.1, showing where they are and where they go thru firewall. Thanks

Answer
Follow up:

Hi again Rick,

Thanks for the great rating.  I read the comment and want to add a few more things to check.  

The thermostat can cause this problem, also.  If your thermostat is stuck open, you will over cool the engine.  Your heater won't get hot enough because the engine is not hot enough.  The thermostat opens more or less to allow circulation, and a certain temperature range of the engine.  Many people think a bad thermostat will simply overheat the motor.  

Another thing to check is air in the system.  If you have topped off the coolant, you need to open the bleeder screws on the goose neck and the heater line.  If there is air in the system, the pressure range is wrong and the coolant temperature will be affected.  

Also check for low coolant.  Not enough of this can cause the heater core to not blow heat.  Is the coolant the right mixture?  Too watery will make the engine too cool.  

Is your fan stuck on?  If your engine cooling fan(s) are stuck on, you will over cool the engine, also.  

Hope this helps.

C J S



Hi Rick,

I don't have a diagram, but I know this van.  It has been a long time since I have seen one and my knowledge is a bit rusty.  But, if I remember right, the rubber part of the heater hoses are very short and are mostly an elbow.  They are low and toward the middle of the firewall.  Most of the heater hoses on this van are metal.  They bend around the engine.  You will see bleader screws on them.  One is inline and one is on top of the goose neck for the thermostat.  Follow this metal line around back of the engine.  You will see better with the car on ramps.  

Why do you suspect the heater core is plugged?  Does the heat seem weak?  It may not be the heater core, but a filter in your duct work.  Under the dash, in the middle, there is a square area.  This is actually an inline screen that filters the flow from the duct work, before it enters the cabin.  It gets gunked up.  You need to expose this and blow it out with compressed air.  It is large like a small furnace filter and shaped the same way.  It is designed like the radiator fins.  You will know this is bad if your blower motor seems to be weak.  It happens gradually, and you may not notice the weaker air flow.

Hope this helps.

C J S