To flush or not to flush (coolant), that is the question

TheHubbardBus · 01-19-2022, 10:37 AM

2003 IC, t444e. Getting ready to replace my heater & heater hoses, so I've decided to do a complete cooling system service (replacing all cooling system hoses, thermostat, degas tank cap). Also adding a cooling system filter (no additives) where before we didn't have one. Existing coolant is ELC, and so is what I'll be filing it with (Rotella ELC). I see no signs of anything dirty in the degas tank. It was an auction bus (school district) that saw regular maintenance. Also didn't see any significant nastiness when I pulled the heater. Have yet to drain the system so don't know what things will look like there.

I'm reading up on tons of references to flushing the system during service (either with just plain water, or an actual chemical flush). Is this really necessary for a well-maintained vehicle? Couldn't I essentially achieve the same results by changing out the coolant again in 6 months or a year down the road. I realize the coolant itself will last much longer than that, but despite the price - it's cheaper in my eyes to do another complete coolant change in the near future than to spend a day wallowing in coolant, as well as trying to find a place to dispose of the (gallons upon gallons) of refuse that will generate.

s2mikon · 01-19-2022, 12:28 PM

I would test the coolant in there now to see what the condition is. Freeze protection and ph. If it is in spec I would just drain and refill.

TheHubbardBus · 01-19-2022, 12:36 PM

Thank you sir.
Is this something I can use test strips for (the freeze protection)? Are those accurate enough for reliable results? Or something I need to send off to a lab?

s2mikon · 01-19-2022, 12:52 PM

I just use the test strips. NAPA, wix and Fleetguard all have them. I test twice a year. The test strips do have a shelf life so they will go stale before I can use them up.

s2mikon · 01-19-2022, 12:55 PM

If this never had a coolant filter you may want to change it out early because it will more than likely capture some sediment. At least that has been my experience in the past.

TheHubbardBus · 01-19-2022, 01:04 PM

Sounds great. Thanks so much for the advice. I'll do exactly that. Bought a couple (filters), so I'll put them to good use.

Booyah45828 · 01-19-2022, 02:29 PM

If there is no underlying problem requiring a flush(oil contamination, rust, sludge, etc.) general maintenance procedure is a drain and refill. No need to flush or add any chemicals, just drain as much as you can out and refill it back up. There are plugs in the block above the oil filter/cooler assembly, and behind the starter. Removing those will drain most coolant out of the engine, leaving the rest of the coolant left over negligible. Don't mess with the plugs if they look rusted siezed, as breaking one will just create more problems.

Wallowing in coolant an entire day is no fun. I don't blame you for trying to avoid that.

Test strips are pretty accurate, so long as you get the right ones and they're not expired. The test strips to use are coolant specific, these are the ones for rotella https://www.acustrip.com/cgi-bin/proddesc.cgi?s=480507. Use stuff from dealers and parts stores at your own risk, some aren't as picky about them, and some downright clueless.

TheHubbardBus · 01-19-2022, 02:47 PM

Sweet, Booyah. Thanks so much.
Appreciate the head-up on the test strips. I was already going down that path & with so many options to choose from (even among ELC-specific strips) it's good to have my choice narrowed down to what works.

Jolly Roger bus 223 · 01-19-2022, 05:32 PM

i say at a minimum to open up the drain valve on the bottom side of the radiator and see if you get any gunk out of it.
thats a sediment trap. filter or not that i think needs to be purged/bled periodically.
just my opinion

HamSkoolie · 01-19-2022, 06:45 PM

My 2002 F350 is a 7.3 Power Stroke (same as the DT444E) and my bus is a 1996 DT444E.

If your bus was well maintained and has ELC in it now then as long as you know the specific coolant that's in it I wouldn't worry about a complete drain and flush. I wouldn't even drain if it's spec. But definitely test the coolant as called for by the coolant and engine manufacturers. Not all ELC's are the same so if you can't determine the exact brand and type installed I would consider the flush.
My F350 was flushed, my bus hasn't but I may do that during the build. Flushing the F350 was pretty simple but I did go through a lot of distilled water.
If you decide to flush give me a yell and I'll send you the best flush procedure to use (tap water flush then a double distilled flush and finally the fill procedure). My F350 didn't take all that long but you will need to have collection buckets for two drainings in order to keep the coolant from entering the environment.

Dbacks2k4 · 01-19-2022, 07:55 PM

On my passenger fleet we've never done a full drain and refill of coolant. As long as it all looks and tests good we just top off. The only time we do a full drain, flush, and fill is when we acquire a new bus that comes with green in it (which is almost always pretty nasty). Then we drain and flush out several times with water before filling back up. We run Final Charge Red ELC in our entire fleet

HamSkoolie · 01-19-2022, 08:39 PM

Quote:

Originally Posted by Dbacks2k4

On my passenger fleet we've never done a full drain and refill of coolant. As long as it all looks and tests good we just top off. The only time we do a full drain, flush, and fill is when we acquire a new bus that comes with green in it (which is almost always pretty nasty). Then we drain and flush out several times with water before filling back up. We run Final Charge Red ELC in our entire fleet

The Ford Powerstroke 7.3 and DT444E (same block) are not like many other engines. They are extremely susceptible to "cavitation" that can destroy the engine and so more concern needs to be paid to them than many other engines. And if they come with "green stuff"..... they definitely need a tripple flush.

Dbacks2k4 · 01-19-2022, 09:12 PM

Quote:

Originally Posted by HamSkoolie

They are extremely susceptible to "cavitation" that can destroy the engine

That's a good reminder for everyone to not mix coolant types! Even the generic yellow and orange variants that are supposed to "work with any type of coolant" are a bad idea according to my mechanic.

I cussed a driver out pretty hard one night when he got back after a run and told me that he found a coolant leak while driving so just picked up a few gallons at an all-night convenience store to fill it back up instead of calling me to A) try to fix the leak B) determine if the bus was still safe to drive, and C) just brought more of the correct coolant out from our shop. I found the empty jugs, you guessed it, he added green conventional to our red ELC system because "it was better than nothing." No, adding distilled water on a warm night would've been better than nothing, we could've gotten that back in ratio later. Fortunately he only ran the bus for about an hour or two before his night was done and we immediately flushed the whole system to refill. What an expensive waste... that was a couple years ago and there appears to be no lasting damage to the engine, but wow was I madder than a hornet.

TheHubbardBus · 01-19-2022, 09:21 PM

Quote:

Originally Posted by HamSkoolie

My 2002 F350 is a 7.3 Power Stroke (same as the DT444E) and my bus is a 1996 DT444E.

If your bus was well maintained and has ELC in it now then as long as you know the specific coolant that's in it I wouldn't worry about a complete drain and flush. I wouldn't even drain if it's spec. But definitely test the coolant as called for by the coolant and engine manufacturers. Not all ELC's are the same so if you can't determine the exact brand and type installed I would consider the flush.

Fleetrite ELC is what was in it, and Rotella ELC is what's going in. I already reached out to International and they said they were compatible. I did not reach out to Rotella, but their online documentation lists compatability. Also looked up online specs and they meet the same EC1 standard and use the same OAT chemistry. Is there still cause for concern?

It's getting drained & refilled regardless, as I'm replacing all the hoses/valves/thermostat/cap/etc. I have to do the heater lines so I want to do everything else at once so I (hopefully) don't have to touch it for a while.

HamSkoolie · 01-19-2022, 09:41 PM

Quote:

Originally Posted by TheHubbardBus

Fleetrite ELC is what was in it, and Rotella ELC is what's going in. I already reached out to International and they said they were compatible. I did not reach out to Rotella, but their online documentation lists compatability. Also looked up online specs and they meet the same EC1 standard and use the same OAT chemistry. Is there still cause for concern?

It's getting drained & refilled regardless, as I'm replacing all the hoses/valves/thermostat/cap/etc. I have to do the heater lines so I want to do everything else at once so I (hopefully) don't have to touch it for a while.

If International said it's good then I'd take their word for it and just refill rather than doing the entire flush.....unless you find some other indicator calling for a flush.

TheHubbardBus · 01-19-2022, 09:47 PM

Cool, cool. Thanks again & thanks a million. If it looks questionable when I drain I'll change my plan back and flush (& hit you up for that routine).

HamSkoolie · 01-19-2022, 10:59 PM

Quote:

Originally Posted by TheHubbardBus

Cool, cool. Thanks again & thanks a million. If it looks questionable when I drain I'll change my plan back and flush (& hit you up for that routine).

No problem. Since you're running a DT444E I would suggest you join up with The Diesel Stop and PowerStroke Nation as the Ford Powerstroke 7.3 IS a DT444E with the exception of a few things. A lot of the maintenance, troubleshooting, and repair procedures are identical and these two sources have TONS of information useful for those with the DT444E.

https://www.thedieselstop.com/forums/
https://www.powerstrokenation.com/forums/

Booyah45828 · 01-20-2022, 08:17 AM

T444e isn't equipped with egr coolers, so it won't be real particular on the coolant used, so long as what you're filling is compatible with what you're draining. If it's not, a couple flushes and refills will be sufficient. Fleetpride to Rotella would require no extra steps or caution. Both are OAT chemistries with nitrites, so they shouldn't be combative to one another. Drain all that you can, refill it with the proper ratio, and go about your business.

Topping off with the universal stuff is okay if that's all you have available. Most stuff that's labeled universal is "compatible" with other coolants, as in it won't turn to jello if added. The reason they don't want you to use a bunch of it is because anytime you mix two different additive packages it results in neither of them working effectively.

Here's a neat article on coolants if you have some spare time. https://www.fleetequipmentmag.com/co...-thy-coolants/

FWIW I'm not aware of chronic cavitation problems with the t444e. The 7.3 idi that it replaced was known for it, but not the t444e.

I also didn't mention, but test strips will check the acidity of the coolant as well, which is another determining factor in flushes/drains. Also, every coolant has a "use life" that it should be changed out after as the inhibitors and additives will start to precipitate after that point, and that's why they recommend it to be changed. It's not that the coolant will freeze, and it's not a light switch on/off event. But the coolant will slowly degrade in it's performance after that point. Does that degradation matter? Maybe, maybe not. If you're overprotected it doesn't, but then again, it's better to be overprotected then under........

TheHubbardBus · 01-20-2022, 09:14 AM

Thanks again for all the great information & help.

That was a great article!

In a service environment, how often are you checking ELC coolants with test strips?

Booyah45828 · 01-20-2022, 09:33 AM

There's only 2 reasons that I'll check it.
1 If it's maintained by us, testing is part of the annual inspection, so it's tested once a year.
2a If I'm doing cooling system work on a vehicle that we don't maintain, I'll check it to make sure it didn't cause the issue, because the vehicle history is unknown.
2b If I'm doing cooling system work on a vehicle we do maintain, I might check it, but probably not, as vehicle history IS known.

Once it's in spec, it doesn't change all that quickly. So checking once a year is enough in my experience.

You may also like: