Green is out, Red is in

Volvo D12 Coolant Change

I decided to do the coolant drain and flush myself.  Not really all that hard, just messy!

 I bought 6 gallons of Volvo approved Zerex pre-charged diesel engine coolant at NAPA.  Expensive stuff at $17.95 a gallon.  I also got a filter and 6 gallons of distilled water.

 With the Volvo up on solid timber ramps and chocked wheels, I unscrewed the plugs with a 30mm socket and drained the old coolant from the block and radiator into a wash tub.

Once empty, I replaced the plugs and refilled with clean water, ran the engine to circulate and drained again.  I did this twice.

While the coolant was out, I added cut-off valves to the heater core, which has another small leak and will need removing and replacing later.  The valves will simplify that and in the mean time cut off flow to the sleeper heater.

 What blew my mind was the amount of crap inside the old coolant filter (yes,  I sawed it open).

I think I am going to run a few hundred miles and swap out the filter again.  I am sure there is still some suspended crap that the filter will pick up.

It ended up taking 10 gallons of 50/50 mix and one gallon of full strength.

I'm glad it's done.

I regularly cut open my oil filters, if you want to really know if you have a problem, the paper accordion element and place it in a press or vise to squeeze all the fluid out, the remainder will be the hard solids and possible parts like aluminum residue from the radiator corroding or water pump's hardened surfaces wearing like bearings etc.).

Most fleets that are large enough to have their own service terminals will install the heater core shut-off valves on the truck's 1st periodic inspection, good on you for doing so.  This not only allows you to bypass in the event of a leak, it prevents unwanted heat in the cab during the summer months when the bunk heater's valves don't close completely.  Make sure you install some form of isolators on the lines so the valves don't wobble around and cause rubber failure on the hoses.

I called the Volvo Tech Line and was told if I was using the red organic acid base antifreeze to install a blank filter with nothing in it.  So, that is what I did.

Lots of the stuff in the old filter was just plain old dirt!  The other junk shown in the picture I made appears to be from aluminum -- possibly the guts of my radiator.  In any event, the filter was effectively clogged.

No matter what, the cooling system is now clean and properly charged to prevent any further damage and liner pitting.  I've got a feeling that the condition of the coolant was what caused my rear heater core to start leaking.  The pH on the old coolant was above 9.5 according to the test strips I used.  It looked like swamp water with green algae growing in it!

In both the Tip of Texas and North Dakota, there is so much crap in the water that up grading the water is about the best upgrade you can make!

I did rinse twice with RO water.  The local store must have thought something was funny about a guy buying that much water three times in one morning.

Randy - Nice job - those look like normal rubber hoses.  You chose to not go with the extended life silicon hoses?

I retrieved the discarded coolant filter from the trash and scraped out the mixture in the bottom of the canister.  You can see it in the attached photo.  It is gritty, just like sand.  I am sure it is the type of stuff that keeps the diesel engine water pump folks employed.  I'm going to let it all dry and do some further examination on both the paper element stuff and the grit.

You know, I'm going to stop short of advising other HDT owners to check their coolant and filter if it has not been done lately.  But, if yours looks anything like mine...... well...... you know what's knocking at the door.