Coolant System Green Goo

[davidbrady]

Seems I have a green film inside my coolant system. Three years ago I had Prevost replace the coolant with ELC. I also had them renew the filter. Just to make sure I'm running as close to pure ELC as is reasonable this weekend I flushed many gallons of DD PowerCool ELC thru the system. The last thing I did was replace the coolant filter. When I took the old filter off and held it upside down some deposit fell out. When I cut the old filter apart I found a significant coating of green goo on the paper element to the point where the filter was clogged. I removed the sight glass from the deaeration tank and ran my finger along the inside of the tank, a green film transfered. I have a multi-thousand mile trip planned for this summer and I'm reluctant to run a caustic alkaline cleaner such as Fleetguard Restore through the system. I'm worried that this type of cleaner may cause problems during the trip; i.e., from loosening debris to eating away at seals and hoses. The manual has a lengthy description on what to do if coolant system contamination occurs resulting in engine overheating. Their remedy includes a fairly involved process of backflushing the radiators and the engine. In fact, any coolant system flush includes the recommendation of removing the transmission cooler for inspection, which I didn't do, and which I may do before the trip. My engine doesn't overheat. It runs beautifully just the way I would expect. On a 90 deg F day the coolant temperature runs around 190 to 195 deg F as does the oil temperature. The transmission temperature settles in around 205 to 210 degrees with occasional retarder use. Heavy retarder use on 6% grades sees transmission temps climb steadily to 230 where it stays for a duration as the fan kicks in full speed - the rate of temp climb from that point on is slower. Pulling long 6% grades out west in the summer sees the water temps climb to 200 to 205 deg F. I don't see any evidence of overheating, so according to the manual there are no grounds for backflushing. Any thoughts on what you would do knowing that a trip is planned in the near future?

[cmillsap]

David,

What type of coolant was in it before you had Prevost change to ELC? Was it the standard green ethylene glycol? Sounds like they didn't get it all flushed out when they changed it and there is a non-compatible issue between the old and new coolant. It's very difficult to change coolant types in these busses due to all the auxiliary coolant loops involved. I don't think the average tech at Prevost is totally aware of how best to flush a coolant system on a converted bus.

I believe( if the prior coolant was green) I would flush with plain water about 3 times while making sure all the aux coolant loops are open and flushable. Then I would fill the system with the same coolant (probably green ethylene glycol) that was in there before Prevost flushed it. Then I would go ahead on my trip and check it when I got back to see if any of the green goo was gone.

David, I run standard green ethylene glycol in both my S-60 and the generator engine. When I bought the bus from Marathon, I asked about what coolant was in it in case I needed to add coolant later on. They said the standard green ethylene glycol coolant is all they use in their coaches. They had installed new coolant earlier and topped it off with the green stuff before I left. I was a bit surprised but I have to say, I never have an issue with overheating. That coolant is now over two years old which I had Prevost test it recently to see if it needed changed. They said it's still good and all they needed to do was to change filters and the metered release filter.

[davidbrady]

Be very careful with Prevost Chuck. Prevost uses extended life coolant exclusively. If you ask them to top-up your cooling system the tech will probably pump ELC (OAT) coolant into your system screwing up your chemistry.

My bus had standard coolant in it when I purchased it. Prevost in Richmond, BC checked it and replaced the NalCool 3000 filter. During my 4500 mile trip home my DDEC coolant temperature sensor went bad. I stopped in Prevost (Nashville) for a new sensor. In the process they dumped probably 15 gallons of a 20 gallon system. They filled it with ELC (OAT). I thought nothing of it because I knew I'd be converting to ELC anyway. I asked them for a blank filter. They said they had none. I left it at that. I just now checked the receipt from 3 years and 15000 miles ago and I see they charged me for a new NalCool 3000 filter which I would not let them put on if I knew. Goes to show you need to watch these guys at every step.

Anyway, I know ELC coolant can tolerate 25% dilution by standard coolant, so I wasn't concerned about silicate dropout; frankly, I believe the silicate dropout occurred before I bought the bus when it was running standard coolant because ELC is silicate free. In reality, I have no idea what folks poured into it over the years, and I'm definitely remiss in not doing a total coolant system flush 3 years ago when I bought the bus.

Yesterday I pumped 45 gallons of fresh DD PowerCool ELC (OAT) through my system and renewed the filter with a blank: Wix: 24070. So I now have pure ELC but I also know there's a silicate dropout (green goo) film covering at least parts of the cooling system.

I may dump the coolant and save it so I can pour it back in, and remove the transmission cooler for inspection. This is the prudent thing to do. I'm going to try hard to do this before our trip.

[cmillsap]

David,

I don't allow anyone to add coolant to my system unless I see and approve it first. I don't understand why Prevost would install an SCA releasing filter when the system is full of ELC?? If they only use ELC, why would they install a filter that releases SCA into the system? Surely, they should know better?

The only reason that I suggested going back to the green ethylene glycol is that it may dissolve the green goo better than the ELC. But if you have already refilled with ELC, lets hope it will not exacerbate the growth of the green goo and maybe it will even dissolve it.

[davidbrady]

(07-02-2017 16:23)cmillsap Wrote:  David,

I don't allow anyone to add coolant to my system unless I see and approve it first. I don't understand why Prevost would install an SCA releasing filter when the system is full of ELC??

It's clear these guys don't understand the current crop of coolants on the market. Shame on them for not knowing, and shame on me for not checking. I was new to Prevost ownership and new to the Service Center experience and I pretty much put my fate into their hands. Big mistake.

(07-02-2017 16:23)cmillsap Wrote:  The only reason that I suggested going back to the green ethylene glycol is that it may dissolve the green goo better than the ELC. But if you have already refilled with ELC, lets hope it will not exacerbate the growth of the green goo and maybe it will even dissolve it.

As you know, I'm not a chemist but from what I've read silicate dropout (green goo) is very stable; i.e., inert, and is only produced by standard (green) coolant. ELC coolants have no silicates. It's not likely that any coolant will dissolve it. But, a harsh caustic alkaline rinse with something like Fleetguard's Restore will dissolve and remove it. The trouble I have with this is: in my case is the cure worse than the disease. Prevost's maintenance guide is very thorough. They only flush specific elements and they backflush; i.e., with reverse flowing water and bursts of air pressure. Check out the manual attached below. They backflush the heat exchangers and the engine, and that's it. Plus, they only do it if the engine is experiencing overheating! Mine isn't! These products like Restore need to be kept in the coolant system for a minimum of 2 hours and a maximum of 3. They attack soft metals and elastomers (silicon hoses) and who knows what else. I don't care if I have a film on my hoses, but I don't want a film on my radiators or inside my engine. I think the best I can hope for, as far as coolants sweeping it away, is the natural tendency of fluid flow erosion along with the loosening effects of heat and vibration, basically mechanical scrubbing. For instance, I can't imagine a microscopically thin film lasting long on an S60 cylinder liner! I think if I take it apart and find my transmission cooler to be absent of film, then I'm good to go.

[cmillsap]

David,

I'm not a chemists either but I think the green goo happened because Prevost (Richland) didn't flush enough of the green ethylene glycol out of the system before they added the ELC in. So you may have had significant amount of standard green ethylene glycol remaining in the system which got mixed with the ELC which caused the non-compatibility and consequently the green goo. But again, you know more about the make-up of coolants than I do.

I trust the Prevost tech (Louie) that always services my bus at Mira Loma. He's an old pro and would never mix coolants.

David, I changed from the standard green coolant to OAT in two of my Bluebirds. In both cases and ulterior to the claim that OAT cools better, I found no difference in the cooling ability of OAT as compared to the green ethylene glycol. If anything, it appeared to me that the coolant system heat rise was quicker with OAT than the standard green stuff when the engine was under load such as when climbing a steep grade. Maybe just my imagination tho.

[davidbrady]

Chuck,

Remember when we went through all this back on WOG with Gary Spires. He explained how OAT coolants can be mixed with standard coolants but you lose the benefits that OATs provide. What you don't want to use or mix in a DD S60 is an automotive style coolant because of their high silicate and phosphate content. I'm looking for pics but I think my coolant issues existed when I bought the bus. IIRC, my site glass on the overflow tank always had a film on it. It was always a little dirty. The silica gelation (green goo) can be caused by a ton of things from mixing with automotive coolants, to running at high temps, to adding too much SCA's, to not having enough SCA, to simply being plane old and used up (which is probably my case). This is why conventional coolants are such a pain in the ass! This weekend I flushed my system with DD PowerCool ELC which is Old World Industries Final Charge; aka, the stuff that Gary always raved about. I installed a new blank filter and I drove my normal 60 mile exercise trip. I then removed the filter and cut it apart. It was spotlessly clean. So at least I know I don't have any chunks of green goo floating around and I know I don't have any other types of precipitate floating around. Judging by how it runs I think I'm fine, but I may do a little disassembly to verify. When I return from our trip I'm going to remove the transmission cooler and take it apart. Turns out it has an outer shell and an inner removable tube assembly. There's a handful of o-rings that seal one fluid from the other. These seals should be replaced anyway. (Remember what I said about Fleetguard Restore attacking seals)? The manual says to replace these seals whenever the coolant is drained, which would be every two years if you're using conventional coolant. Those of us with retarders are all overdue for seal replacement inside our transmission coolers. That's one part, among many, of the "Zeroing-Out" philosophy that everyone misses.

Chuck, if I were you I'd get that conventional stuff out of there and replace it with ELC (OAT)!

[davidbrady]

From the attached DD document: "Cooling Requirements for Engine Cooling Systems":

"These types of coolants (OATs) should not be mixed with Standard Life Coolants. If an ELC antifreeze coolant and SLC antifreeze coolants are mixed, damage may not result, but the long-life advantages of the ELC antifreeze coolant will be lost. In this event, the coolant should be re-inhibited with OAT inhibitors and confirmed by analysis or else it must be maintained as an SLC antifreeze coolant."

So Prevost did the right thing by screwing on a NalCool 3000 needs release filter after partially filling my system with ELC (OAT). If you have a mixture then one option, as the above spells out, is to treat and maintain the fluid as a standard non-organic ethylene glycol fluid. The other is to retreat with new OAT inhibitors but who can do that and how is it done?

[cmillsap]

David,

Yes, I remember Gary Spires and a lot of other opinions from other “experts” especially on the subject of mixing coolant types. I went away more confused than before about coolants. Everyone had their own different opinion.

I don’t see anything wrong with running the green conventional low-silicate coolant (IAT) in our DD S-60 engines. The important thing is to make sure the coolant is maintained at the proper mixture, freeze point and PH level to protect the cooling systems of our heavy duty engines against corrosion, cavitation, liner pitting, freezing and boilover.

The pre-charged SCA timed release coolant filter sized properly for the system’s capacity works well to help maintain the proper SCAs for a certain period of use. But coolant condition needs to be checked regularly and changed periodically.

Until all these new-fangled coolants came on the market, the green stuff was what everybody used. The coolant system in both yours and my bus was probably filled with it from the factory. Every bus that I have owned had the green stuff in it when I bought it. I changed 2 of them over to OAT because I thought it would be better for my engine. But if it was, I didn’t see much advantage except it allowed a longer time between coolant changes.

My bus has probably run on the Green Stuff for over 154,000 miles with no issues (that I know of) related to or caused by the green coolant. It runs cool and the DDEC shows no codes of ever overheating. The coolant is clean with no discoloration. It’s been in there for two years and 12,000 miles. I’ll change it at 25,000 miles or next year. Obviously, I can’t check the cylinder liners for cavitation and pits but I’d bet there are no more than if it had been running with OAT for 154,000 miles.

While I appreciate the suggestion to change to OAT, I see no reason to change from the coolant type that’s probably been used in it for 14 years and 154,000 miles. Now, if you are saying that engine damage is more likely to occur if I continue to use the green stuff, I’m certainly willing to listen.

[davidbrady]

You're right Chuck, the standard life coolants will work and have worked for a long time. The advantages I see of an extended life coolant are ease of maintenance and elimination of silicate dropout. According to the DD doc I posted above, if you run SLC you need to renew the NalCool 3000 Needs Release filter every year, you need to use test strips to verify the Nitrite concentration and add supplements if the level is below 900ppm and dilute your coolant if the level is above 3200ppm, and you need to dump the coolant every two years, flush, and renew. With ELC your filter is a blank, you get to skip the Nitrite testing, you never add additives or dilute your coolant, and you can wait four years before dumping your entire coolant, flushing, and renewing. It's simply a matter of reducing the maintenance cost and effort of owning these machines. I'm all for simplifying.

Knowing what I now know about caustic flushing products, I wouldn't flush and neutralize without removing the transmission cooler, inspecting, and replacing seals. This is more work that I get to postpone for four years.