Where to install Prestone flush kit?

[RnR]

I ran across an old Prestone Flush kit I picked up eons ago, and now wonder which hose I should be installing it on. Counter to the kit's instructions, both hoses coming from the firewall "appear" to go to my Grand Prix's water pump. There is a plastic T/garden hose adapter I am supposed to insert into one of these hoses.

The question is... which one should get the adapter?

 

[PhillyJoe]

Both lines do appear to go into the water pump area; going into the firewall, one is on top of the other. I haven't changed the a/f in my '01 GP, but the question is which hose is going into the heater core which I think is the hose you want to tie into. Someone gave me a tip that worked out well on another car. Go to the auto parts store and buy 1 foot of heater hose. Disconnect the hose at the water pump, add the hose "T", add the 1 foot hose and connect to the water pump. Flush, fill, remove the "T" and extra hose and reconnect. No cutting, and you have the "T" for the next car.

 

[Chris142]

I would have to follow the hoses myself to see. If this is on the 3.8 I "think" the upper hose is the pressure side.

 

[RnR]

Hmmm.. so what we're alluding to then is that the "pressure" side should be used, and that this is likely the upper firewall hose on my 3.8L?

Roger on a short, additional piece of hose & clamp in this case.

 

[Steve S]

It really won't matter. The water will go through both hoses equally. The flow will be from the water hose once you start the flush "turn the heater controls on as there is a flow valve" . Do you really need to flush out the system?

 

[RnR]

This engine just had it's suspect LIM gasket replaced and is temporarily running with a DexCool/Green coolant mix that I want to flush out. Will be switching to the green.

 

[mechanicx]

You could splice the T-fitting into either heater hose and it would fush the cooling system, but you should hook it into the heater inlet hose. The reason for this is because the inlet hose usually backs into the thermostat and will back flush the heater core while the heater outlet may just backflow into the engine and not through the heater as well.

You car should have top and bottom mounted heater hose on the firewall and should be the bottom one. http://parts.nalleygmc.com/showAssembly.aspx?ukey_product=2583622&ukey_assembly=401428

 

[RnR]

Excellent... the linked pic matches my setup and I appreciate the info.

Bottom hose it is.

Thanks!!!