I'm trying to install one of those flush and fill kits into the heater inlet hose, but I'm a bit fuzzy as to which one is the inlet. There of course are two heater hoses side by side that come out of the firewall. One hose connects from the firewall to the rear of the engine (which is towards the passenger side-right of car), and the other hose is on the driver's side (left) which connects to the thermostat housing. I am thinking that the hose on the rightmost (passenger) side that goes from the engine block to the firewall should be the inlet heater hose, correct?

 

Don't do it! There is a block drain on the water pump and a radiator drain on the radiator. You just do not need a "flush kit".

 

X 2

Don't do it, return the flush kit and get your money back.

Unless you are very familiar with working on HHR cooling systems, have it done by a professional, the chance of getting air trapped in the system and blowing a head gasket/cracking the head due to overheating is pretty high.

 

I've installed one of these kits on every car I've owned for the last 15 years, and I have always seen very noticeable results in the resultant decrease in temps. Just draining and refilling does little for getting crud out of the heatercore and block. This includes my HHR that I had for the last 1 1/2 years that got totaled a few weeks ago. We just bought another HHR, and I just wanted to double check to make sure I'm remembering which hose is the inlet correctly.

As for the overheating thing, you simply put the car up on ramps so that the front is elevated, fill it back up after draining, run the car with the cap off, and top it off. Any trapped air will work itself out rather quickly.

 

My idea was that if you open both drains you can flush the system through the pressure cap. No kit required. I won't even get into how often you should change coolant (GM recommends 150K) or what color the coolant should be. Do as you like, your car is yours . I am not trying to argue any point, just trying to help.

I just looked at my service manual, it does not want to be helpful, the sketches are real sketchy. GMpartsdirect does not show the hoses. I give up. But, wait... NalleyGMC.com shows the inlet as the one on the bottom at the firewall, the one with extra insulation.

 

I do appreciate the input. No argument here. I prefer though to use the flush/fill kit as with a garden hose attached, it really force flushes out the system. I've never trusted just draining and refilling like most people do.

After some looking around online, I did conclude that the line coming from the engine going to the firewall has to be the heater inlet (which has the insulation on it), while the line coming from the firewall to the thermostat is the outlet. I thought that was the case, but I just wanted to make sure.

I got the flush "T" put in today, which was no small feat given the placement of the inlet hose. It was a pain in the neck. I put the car up on ramps, drained out the rad, loosened up the engine block drain screw, put in the "T", turned the heater on full, and cranked up the connected garden hose with the car running for about 5-10 minutes. I then drained everything out, tightened everything, and filled her back up while still raised on the ramps. The car should be good to go for a while.

Just my 2cents worth on the coolant issue. 150,000 miles is a bunch of bunk . The cheapest insurance to the well being of a car is keeping fluids changed. I usually flush mine out every year at the start of summer before it gets hot. After I flushed and changed the antifreeze on my last HHR, I saw a clear consistent 10 degree improvement on the average engine temp. We'll see how this one does.

Some of the maintenance intervals that GM recommends are just off. For instance, the serpentine belt is supposed to last 120,000 miles. The belt on my last one was cracking at 75k, and this one is cracking at 87k. GM claims that you never have to change the trans fluid with normal use. I have a hard time swallowing that one.

Thanks for the link to the NalleyGMC site. I've been looking for another site beside compnine that has schematics on it.

 

When I was young my dad was a certified master mechanic at the local Ford Lincoln Mercury dealership where we lived.

In those days if you managed to get around 50,000 miles on a car it usually meant you had rebuilt at least the engine once.

My dad was sent off to darkest Michigan to become the goto guru on these strange, brand new, cutting edge, Ford automatic transmissions. He always thought you should change the automatic transmission fluid and filter every 25,000 miles unless you had to have the automatic transmission rebuilt before that.

I started out working in a body shop that also did general repair and radiator work. Hell we would do anything anyone wanted,... to their car, for a price.

We would remove the block drain plugs in an engine then attach a water hose with a special air injector to really blast the water jackets clean. Sometimes there was enough gack in the water jackets that it just plugged the block drains.

When this would happen we would remove the frost plugs and do it again. Sometimes we had to do that several times and even add caustic soda and let the engine run for a really long time to boil the crap out.

Once we were pretty sure we had the water jackets in the block cleaned out we would put the frost plugs back in and remove the heater core because it would be full of junk

We had a awesome machine called a flometer that would tell you how many gallons per minute/second were able to flow in your heating system. There were books that told you what to expect to see in gallons per minute/second.

Most of the tests required the thermostat to be fully open. If you got real low readings that would be the first thing to replace.

Then next would be the water pump. The machine had its own pump built in so you could test a radiator or heater core that someone had already removed.

 

Very interesting. I guess in many respects cars have come a long way compared to that.

 

A properly functioning thermostat also serves as a regulator. It opens when coolant temperature reaches the design setpoint (180 degrees in the case of the HHR). It also closes again if the coolant gets cooled below 180 degrees. There is lag time involved due to design elements and the speed at which the aperture opens and closes.
Ecotec engines are designed to operate best at 180 degrees F or more. Cooler is definitely not better. You would be wasting fuel, and the BCM will shut off the coolant temperature reading, zero out the analog temperature gauge, and disable the air conditioning, if the engine operates below 180 degrees F for a pre-programmed period of time.
Not much chance of that happening in warmer months even with a stuck open thermostat. The cooling system is not efficient enough to get the coolant temperature under 180 if the ambient air temperature is over about 70 degrees.

 

A properly functioning thermostat also serves as a regulator. It opens when coolant temperature reaches the design setpoint (180 degrees in the case of the HHR). It also closes again if the coolant gets cooled below 180 degrees. There is lag time involved due to design elements and the speed at which the aperture opens and closes.
Ecotec engines are designed to operate best at 180 degrees F or more. Cooler is definitely not better. You would be wasting fuel, and the BCM will shut off the coolant temperature reading, zero out the analog temperature gauge, and disable the air conditioning, if the engine operates below 180 degrees F for a pre-programmed period of time.
Not much chance of that happening in warmer months even with a stuck open thermostat. The cooling system is not efficient enough to get the coolant temperature under 180 if the ambient air temperature is over about 70 degrees.