Workhorse W-Series Cooling System Service

Of all the scheduled maintenance, changing the radiator coolant is one of those systems easy to neglect.  The thing is, if the cooling system is properly maintained, changing the coolant is a snap.

How to test your coolant:

To test your coolant, you will need a voltmeter, litmus paper and a refractometer.   These items are available on Amazon for under $20.

Use a refractometer to test your water/coolant ratio.  This device, available on Amazon for under $60, has rave reviews, it is affordable and easy to use.

The concern here is freeze/boil protection with the correct water to coolant ratio and the inhibitors in the coolant.  The water to coolant ratio is a bit like Goldilocks.  Water is excellent at heat dissipation, too much coolant and you cannot bleed off enough heat from the engine, too little coolant and you do not have sufficient freeze/boil -and- insufficient inhibitors.  The goal is 50/50 which is -34 Fahrenheit.  The glycol/water ratio remains constant overtime, this test does not indicate the health of the coolant.  With one drop of coolant, the alcohol bends the light rays differently from the water and you get clear reading for freeze protection.

For background on Dex-Cool check out this guy's post:  All About Dex-Cool   A veteran GM engineer told me besides the rust inhibitors, Dex-Cool also acts to prevent electrolysis occurring generating current as the coolant flows over the varying metals in the cooling system; Iron, AL, brass and the coolant acts like a battery.  I had to see this one for myself.  With your volt-meter set to DC,  put one prob in the coolant the other to ground with the motor running and the thermostat open.  Ideally you should have < .3 volts, as the voltage increases, electrolysis is occurring and eating away the soft metals in your cooling system namely AL heads, head gaskets and the heater core.  Be mindful of the coolant temp before you remove the radiator cap.   The second test is the pH of the coolant.  In time as the inhibitors degrade the pH of the coolant becomes acidic.  Think Flint, MI as the water in the cast-iron pipes became acidic instead of an alakaline, the pipes were destroyed, acids eat metal.  Your coolant should have a pH of 8 or 9.  It is the components, not just freeze and boil over protection which remains constant over time, we want to test and ensure the coolant is doing its job protecting the engine, radiator, seals, head-gasket, water-pump and heater core from electrolysis, corrosion and ultimately failure.  This service is cheap protection.

Regardless of the above tests, if  its been five years or 150k miles, it is time to service your cooling system.  Along with a coolant flush, this is an excellent time to replace the upper and lower radiator hoses, thermostat, serpentine belt, tensioner and idler-pulley as well.  Since I am doing this myself, I use ACDelco parts and reward myself with buying any tool I may need, like a refractometer.   The good news is Amazon sells ACDelco parts at a steep discount.  This is my rationale, a failure of any of these parts and not only is my journey interrupted, but I am now paying labor charges and full-retail for no-name parts, and arranging a tow; easily avoidable. Save your money, a trip to the shop and enjoy the satisfaction of doing your own work. 

The cooling system on a W-Series 8.1 liter holds 23.5 quarts, throw in the heater core and lets round up to 6 gallons, Winnebago owners with Motor-Aid need to add more capacity for the heat exchanger in the water heater.  The 8.1 holds over two gallons of coolant in the block.  The shops I have asked, tell me whatever comes out of the radiator is what gets replaced in a simple coolant change, that is just not enough coolant.   With nearly 1/2 the coolant in the block, you need to drain block as well as the radiator it to do this job.

Tools you will need:

1. Both a 5/16 or 8mm 1/4 socket with ratchet and nut driver. 
2. 3/8 Ratchet with 15mm socket
3. 1/2" or 13mm ratcheting wrench
4. 1/2 ratchet and extension
5. Flat screwdriver
6. Channel Locks (optional)

You will also need two specialty tools:

1. 1/2" 17mm hex socket (available on Amazon) to remove the engine block drain.
   
2. Hose clamp removal pliers, Sears may stock this item.
   

Parts list for 2005 W-Series:

1. Lower Hose ACDelco 24397L (Amazon)
2. Upper Hose ACDelco 26163X (Amazon)
3. Heater Bypass ACDelco 1255-8968 (Amazon)
4. 195 Degree Thermostat ACDelco 131-121 (Amazon)
5. Serpentine Belt ACDelco 6K1080 (Amazon)
6. Idler Pulley ACDelco 1258077 (Amazon)
7. Belt Tensioner ACDelco 39702  (eBay)
8. 3 Gallons DexCool ACDelco 10-101  (Jegs best price)
9. 8-10 Gallons distilled water. (Wolly World)
10. 2 1-1/4 - 2-1/4" Hose Clamps (parts house)
11. 2 1/2 - 1-1/4" Hose Clamps (parts house)
12. "Yellow" teflon tape (hardware store)

Down to business

All work is done from below, no mess inside.   I wear a beanie to insulate my noggin from all the sharp points and edges.   I have Gladys Kravitz for a neighbor, Brad, so I take extra care to collect all coolant, which is a challenge on this chassis and the right thing to do anyway.  Start by removing the serpentine belt, tensioner and idler pulley from the passenger side.  The belt pattern is fairly simple, so dont worry about it right now.  The tensioner has a 3/8 socket opening, use it to take the tension off the belt and remove from the idler, water-pump or alternator.  Keep the belt as a spare.  This belt with the oversized alternator and power steering takes a real beating.  This tensioner is not very strong, you can do it with your hand or use a 3/8 ratchet.  Now remove the tensioner and the idler pulley, both have a 15mm bolt.  Removing the belt and idler pulley makes changing the thermostat housing  easier opening up access to the three 13mm bolts holding the thermostat housing.  

You are now ready to drop the coolant.  Do not discount the need to remove coolant from the block.  Almost 1/2 of the system's coolant is in the engine.  Start by removing the radiator cap to allow air to come in.  If you have the factor clamps, use the specialty pliers to remove the lower radiator hose from the water pump.  Have buckets ready to catch coolant from the water pump and then bend the lower hose into another bucket.  I use a 2 and 5 gal bucket.  It is a good idea to have a tarp and towels down to catch and collect the inevitable coolant that misses your buckets.  There is no peatcock on the radiator, its the lower hose and drain plug on the block.  Next remove the 17mm hex drain plug from the left side of the motor.  You are going to repeat this two-step drain process two more times, experiment...

Coolant will rush out of this drain.  There is no great way to catch it all because of the frame.  

Now its time to remove the thermostat housing.  Unless you are a masochist, this part sucks.  You may find yourself exploring some dark thoughts directed to whomever decided these hose clamps were a good idea.  I believe it normal and healthy to let a few a expletives out during this part, it gets darker getting the heater bypass hose out.   Leave the upper hose attached to the housing, it is one less (sucky-factory) clamp to remove using the tool bloodying your knuckles.  Remove the upper clamp at the radiator, remove the three thermostat housing bolts, a 13mm or 1/2" ratcheting wrench makes this part easier.  Remove the upper hose from the housing using channel locks and keep the factory netting, this netting allows the upper hose to slide over the fan shroud instead of binding.

 With the three screws  out of the housing, using your hand break the housing free and pull the housing and hose out past the fan.  Remove the old thermostat and make sure you get the old rubber seal.   Now comes the hard part, removing the heater bypass hose.  You may be tempted at this point to skip-it, but you are this far and why risk it?  Think of the stress that little hose is subject to; extreme heat from the coolant and engine all those times you had to race to the top of the hill pulling your toad.  Your here, there is no hurry, have a beer and keep going.  I needed a ball-gag at this point to suppress the f-bombs I was dropping getting this little hose out.  Clean up the housing with 2000 wet dry, clean the gunk off the hosing and the water pump for the lower hose with a wire brush or some 600 wet dry.  The hard part is over.  You have just had an abject lesson on why a shop might be tempted not to change the thermostat or bypass hose, yet charge you anyway.

Its time to put it back together.  Replace the thermostat, ensure the rubber seal it came with is properly attached to the thermostat, housing is printed side up.  Drop it in.  Replace the hosing ensuring it easily goes against the block, this will confirm you have the thermostat seated properly.  Do not force anything.  Install the heater bypass hose using your new hose clamps.

Reuse the netting from the upper hose on the new hose,  Once the thermostat hosing is in and tight, install the upper hose, now install the new idler pulley and tensioner.   Remove, empty and clean the coolant overflow tank and re-install.  Time to install the new belt referring to the serpentine pattern below.  Start from the driver side.

Duct tape or an assistant will make this part easier.  Start by placing the belt over the AC pulley, then over the power steering pulley.  Go up and around the waterpump, the ribs will face out over the water pump.  Go around the crankshaft pulley.  To avoid another round of expletives, tape the belt in place over the AC and PS.  Time for you to switch to the passenger side.  Put your 3/8 ratchet into the tensioner, play with it a little bit to get a feel about how it works.  Gingerly place the belt around the alternator.  Your goal is to avoid a trip back to the driver side.  In one move, retract the tensioner, and pull the belt below the idler.  If you are not in all the groves, thats ok.  Take a little break and come back to it.  Remove any tape.  Adjust any pulleys where the belt is not fully in-place by removing tension with the ratchet on the tensioner.

Congratulations, you are almost ready to test, the rest of the job is easy.

Install the lower, replace the drain plug in the block hand-tight and no teflon tape yet.  Go back over everything, checking the five bolts and four hose clamps.  

The next step is to flush the system using distilled water repeating the drain process above.  It is all about pH and impurities; no tap water.  If you are keeping up with coolant changes, power-flushes and additive chemicals are not necessary.  With the motor off, you can get a couple gallons in the radiator.  But wait, you still need to confirm the serpentine belt without starting the motor.  Click the key a couple of times without starting the motor to move the belt and re-inspect.  If the belt gets thrown, oh well its not going far, try again.  The belt should now be fully seated in all pulleys and look good on the idler pulley and waterpump.   If you are satisfied, start the motor and be ready with 2-3 gallons distilled.  Keep adding distilled water.  Turn on heater inside, to speed things up, place cardboard over the radiator.  Using a scantool if you have one, bring the temp to 195 to open the thermostat.  The radiator should start "burping" and take another gallon distilled water.  The goal is to dilute the remaining illusive gallon of coolant still in the system with distilled water.  I do this flush twice, never using tap water.  You want to dilute the remaining old coolant as best you can.  Collect and dispose the discharged coolant as per your local requirements.    Measure what you get out of each flush.  You should have gotten 4.5-5 gallons from the radiator and block.  The system takes 6 gallons.  Assuming you are staring with a 50/50 concentration and drain 5 gallons out, your first flush you are at 8% concentration, second flush drops down to 4%.  Point is, there is still some old coolant in the system.  Dex-Cool is not to go above 70% concentration, target is 50%.  Assume there is still 2 quarts of old coolant in the system after two 5 gallon flushes.  For your last fill, use the teflon tape on the drain-plug and tighten, start by adding all 2.5 gallons or adjusted amount of Dex-Cool to the system and top off with two gallons or more of distilled water.  Adjust the amount of Dex-Cool based on what you removed in your flushes and dilution levers.  For 50/50 you would add 12 quarts.  Using all three gallons, with two 5 gallon flushes leaves a 58% concentration.  

Re-test your voltage and pH, you should at our around .3 volts and a pH of 8.

The final test, do you have the water/coolant ratio correct?  Too much bad, too little bad; 50/50 -34F freeze protection; just right.  I am about -32F, I could put straight dex-cool in the reserve bottle, but that might be a bit obsessive.

Pat yourself on the back, put on some bandaids, document your work for your records and know the work was done and done right.

SUMMARY:

Regardless of who does the work,  Trust, but VERIFY.  If a shop does the work, demand the shop prove to you they did the work, check your own work.  Demand, in a nice way, they show you the pH and the refractometer results.  You could be saving your motor.  

Correcting too little coolant.

On my Sierra Duramax I had freeze protection of -25F, target for 50/50 is -34F.  How to correct this:   The capacity for a Duramax pickup up with auto trans is 25.4 quarts, round up to 26 quarts, 50/50 is 13 quarts coolant.  Using the chart below, capacity 13quarts x2, I determined I had was missing two quarts of coolant and the ratio was roughly 46%, probably not a big deal.  To jump the missing one quart, I removed one gallon of coolant from the truck, then added a three quarts coolant and topped off with distilled.