[Archived]

Gerald,

I have changed coolant on my coaches somewhere around 8 or 9 times now. I have never found a way to make the job easy.

I have learned a few tricks, but I am not suggesting you deviate from the service manual, but to know that I have not had coolant related issues. Maybe I have been lucky.

I leave the house and OTR valves open and drain the coach. My typical collection of old coolant by doing nothing more than opening the low point petcocks has been 18 gallons. If the paperwork is correct the total system including the heat exchangers and the OTR coolant heat exchanger amounts to 24 gallons so I have only drained 75%.

I refill with the correct coolant by alternating one gallon of coolant followed by one gallon of water (or you could use the pre-mix) until I replace the same amount as I removed. That is easier said than done because there is air trapped when the system is refilled. I start the Webasto and the Webasto circulating pump tends to purge the air from the system, so as the expansion tank goes down I keep adding coolant. After the Websto cycles “off” I start the engine and get it hot enough to open the thermostat and usually by then I have added the same amount I drained back in.

When I changed coolant types from the 2 year to the CAT EC-1 spec 6 year coolant I drained the system, refilled with water, brought everything up to temp and drained it. I repeated that about 3 times until the bright pink became pale pink. Then I did an engine flush and ran the engine for about 90 minutes, drained it and then refilled and drained it with water about 4 times. I assumed I had all but traces of the original coolant out, refilled with EC-1 coolant burping it by running the Webasto until it was full.

I hate changing coolant, which is why on the last coach I went with the 6 year coolant. I had to do my CAC replacement this past fall and since the radiator was out I replaced coolant with fresh 2 year. The next change I will repeat the process of going to 6 year which requires almost all trace of the 2 year to be removed.

The only time I drain everything (and I mean everything) is when I replace hoses. Fortunately there are bleeder valves at the Webasto heat exchangers to facilitate draining, but after doing that refilling is a much more involved process to insure the system is bubble free. So far the Webasto circulating pump has been the answer for that along with a lot of patience.

[Alvie]

The easiest way is to let Prevost or a shop do it but after having mine done, left shop and check engine light came on and I shut it down a ways down road. They didn’t let burp, and needed a couple more gallons of coolant. Glad I bought a few extra just in case. Hard to get good help nowadays even if you’re paying for it. Next time gonna do it myself.

[Archived]

Glen, I would not trust a typical truck or RV shop to get this right. I’d also not expect them to worry too much about mixing incompatible coolant types as the damage done will not be immediate. I have come to the conclusion, if you want to have stuff done right, you better do it yourself. A Prevost service center might be different.

Jon, thanks for the feedback. I think I’ll follow your procedure keeping the house lines open but not fooling around with the driver/OTR heat exchangers and valves but I’ll take a look at the coolant strainer in the OTR bay. Does that element need to be replaced or can it be cleaned?

Do you ever get an air lock in the Webasto doing this? The reason I’m asking is, when I got our bus someone had shorted the thermal fuse protection in the Webasto burner. I figured this was to prevent an airlock in the Webasto to cause overtemp at the burner. Of course, this is a great way to burn up your bus should the Webasto malfunction. It would be nice if there was a way to run the circulation pump without firing up the Webasto burner.

Thanks again for all the pointers, Gerald

[gary]

I cannot speak about the Websto circulating pump used by Marathon. I can only say the large one Liberty used on my last two coaches has not suffered from an air lock and has successfully been used to purge air.

I did want the Webasto to run because it was important to get the engine thermostate to open. So I was after getting heat into the engine and opening the thermostat to insure me that the engine is not suffering from an air lock.

The alternative to the methods I used is a cooling system vacuum. This is a device sold by all the principle tool companies such as Snap On and using shop air it will pull a vacuum on the cooling system. There is a hose attached that can be dropped into a tank or big pail of coolant and the system vacuum will literally pull coolant into the nooks and crannies. I have one, but using it on the coach takes forever to get a vacuum on a system that large.

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[Greg]

The OTR coolant screen can be cleaned and used. It’s a metal mesh filter.

[Peter]

My bad for forgetting to answer the question. I do strongly suggest all 8V92 owners with OTR to pay very close attention to that “filter”. I believe the 2 stroke engine cooling systems are susceptible to silicon dropout and far more plugged radiators are reported on the 2 stroke engines than on the Series 60.

One clue the coolant needs to be changed or its chemistry adjusted is if the sediment bowl located in the OTR evaporator bay has a sludge or slime in the bottom of it. I think the primary purpose of the filter is to trap any foreign materials such as small pieces of solder or debris that might have entered the coolant.

[Thomas]

Gerald on my earlier post on needing extra antifreeze added (burp job) it was Prevost Houston that had done the complete fluid change. Oil, antifreeze. a couple months ago. Prevost Ft Worth had done the Trans (Allison) back last year. Prevost is or has been the only one in the 3 years we have owned it that has touched my coach mechanically.

[Archived]

Due to my limited work space, and having to deal with a substantial amount of used coolant, I had my coolant changed out by both Prevost in Jacksonville and CoachWorx when required by my maintenance schedule.

I can recommend both based on my experience. In my opinion, CoachWorx did an especially thorough job.

It is both time consuming and messy, but critical to the longevity of everything the coolant touches.

[Archived]

Liberty did mine when I purchased the Coach and did the job by using a machine that vacummed out the old and then in with the new. No mess, no spills, very well done.

[Peter]

I had mine done at prevost in Mia Loma , I don’t like to do my own coolant changes because of all the animals around let somebody else deal with getting rid of it they did great job….

[Bryan]

Well, I bought the coolant and distilled water and ordered the blank coolant filter since the coolant is already pre-charged. Just waiting for a break in the weather to get it done.

It turns out Old World Industries makes Powercool for DD. They sell it as FleetCharge and NAPA resells the same coolant under their name ($14/gal with the Napa card). According to the manufacturer as long as one maintains the SCAs and pH, and avoids contaminations the coolant fill is good for life.

[Archived]

Don’t drink the Kool Aid. The coolant, including EC-1 spec coolant is not good for life.

All coolants have a life and depending on the technology it can be as little as 2 years or as much as 6 years.

Because diesels and wet liners require special coolants for the engines the proper maintenance needs to be followed because in worst cases “cavitation” can occur and the end result can be porosity in cylinder liners, a repair cost making coolant maintenance costs look like chump change.

[Chas]

I used Jon’s method of draining, flushing twice, pre-heating with the Webasto and then running the engine at high idle with max heating set on the OTR in between. Not hard to do but time consuming. The Parker filter in the OTR bay had quite a few paint chips and other small pieces. I don’t think it had been cleaned in a while.

The system is well designed. There are bleed valves on the main OTR heat exchanger and on the driver’s heat exchanger. They are easy to get to. The engine bleeds itself from the top of the thermostat housing to the expansion tank.

Thanks for everyone’s help. Much appreciated.

Gerald

[Robert]

I use Fleet Charge as well and it is a CAT-EC1 product which is SCA precharged. The life span says 8 years or 150,000 miles. I use it in all our heavy equipment and the few times we have had any engine work done the coolant passages looked really good.

Not sure who carrys it retail, we purchase from our Shell/Kendall distributor in Lakeland Fl. It is actually cheaper to purchase it in predeluted gallons from them. Very happy with this product.