8V71TI Coolant Drain Procedure?

[ThirdHatt]

I have searched this forum several times and cannot seem to locate the post that I read recently about several coolant drain points on the 8V71TI's. I plan on flushing the coolant in both mains soon and I would like to be fully aware of the procedure and prepared when I begin. Thanks again!

[Genesis]

There are several "low points".

One is on the water elbow at the inlet to the fresh water pump.
Another is on the bottm of each exhaust manifold.

The third "biggie" is on the bottom of the oil cooler housing.

There are also drains on the block itself, but in my experiience not much remains in the block if you open up the one on the bottom of the oil cooler housing - that's the low point in the system, along with the water elbow.

[REBrueckner]

What prompts you to change coolant? Any criteria you know of did you just decide now is the time??
The only specific test I know is via litmus paper which assures the coolant is alkaline, not acidic. This can also be checked with a voltmeter but I don't have the specified readings available. The other, of course is visual, if the coolant is oily, dirty, or has changed color, something is wrong.
Although not scientific, I installed drain cocks at the fresh water pump inlet and each winter drain a gallon and replace with fresh antifreeze and de ionized, distilled or (there is a third type I can't recall) water per Detroit. Be sure your new antifreeze, if used, meets DD (heavy duty) specs.

[ThirdHatt]

Genesis, Thank you for the specific drain points. That is precisely the information that I was looking for.

REBrueckner, I recently aquired a one-owner '73 58YF with fresh documented rebuilds (176hrs when I got her, 267 hrs to date). I have records of the heat exchangers being tested/replaced but I have noticed a color change in coolant since I have owned her (<100hrs) on both mains. Althought hey have performed perfectly, my instinct says to flush and refill both mains with a fresh mixture, and then watch for anything abnormal. I have no reson to suspect anything wrong, other than a color change in the coolant tanks of both engines. I tend to do routine/preventative maintenance more than most, and often just on a hunch. Who knows what, if anything will come of this coolant service but until I have personally changed every serviceable fluid/filter/impeller on these engines I cannot be satisfied that I have done everything possible to ensure maximum reliablility and longevity.

[Nonchalant1]

My 8V71TIs hold a little over 7 gal each. You'll get about 4.5 gal just by opening the petcock at the bottom of the big elbow under the thermostat that's on the starboard side of each engine. You get most ot the rest from the petcock at the extreme bottom of the oil cooler. The petcocks at the rear under the exhaust manifolds and and 2 front ones above the engine lower front cover are mostly to get the last passages dry for winter storage.

Doug Shuman

[Genesis]

I installed ball valves on the elbows and bottom of the oil cooler, along with hose barbs - I can now drain to 5 gallon buckets on centerline without getting coolant everywhere.

BEWARE if you do this; I had a brass hex nipple fail during inspection which, if it had failed underwater, would have cost me an engine. As a result I switched to hydraulic-rated SS fittings. They were not cheap (nothing Swagelok makes is) but they're tough as nails.... Remove the handles on the valves when not in use to prevent accidents!

[MikeP]

De-Ionized water is very corrosive to copper and copper-containing materials. It will destroy conventional copper radiators and is specifically warned against in a variety of automotive service bulletins. I believe all the DD coolers are nickel or other non-copper alloy. However, I still wouldn't use DI water because even if it's OK for the intercoolers, there are usually brass plugs/fittings or short copper pipes in the system.

Distilled water is safe in any application.

[DickB]

I last did this about three years ago. With my hazy recollection, I though I read somewhere that DD recommended changing the coolant every two years. Before changing, you might want to run a "flush" mixture through it for several hours to help clean it out.

Dick

[Genesis]

Yep - every 2 years is my schedule for coolant changes. Cheap insurance.

[REBrueckner]

What engine run procedures are used prior to draining all coolant? Does Detroit specify?
I've always run an engine until warm, not hot, before draining all coolant. I always wait a few hours before refilling just in case some component is hotter than I realize. And of course if you are going to change hoses, doing it during a coolant change is the right time.