Changing Antifreeze

[dale farley]

I started draining my antifreeze this afternoon in preparation to switching to Extended Life. The Prevost manual says the system holds 24 gallons. I assumed the Webasto would hold a couple gallons more.

I have drained all 3 of the drain valves on the engine and lines, removed the plug from the bottom of the radiator, disconnected hoses from the Webasto and the heater lines, and I still have only 18 gallons of fluid. I opened the heater valve to let the heater lines drain, and that didn't seem to work, so I removed the lines in several places and that caused about another gallon to drain out the rear of the bus.

I have collected all I could so I would know how much I have drained. I don't know where the rest of the antifreeze can be. I placed 4" ramps under the front tires and lowered the rear of the bus to assist in the draining, but I don't see where I am going to get another 5 or more gallons. When I haved drained all I can, I intend to flush the system a couple times by filling with water and draining again after I run the bus until the thermostat opens.

Any suggestions as to how I can get any more antifreeze out of the bus? Has anyone else done this before?

[Jon Wehrenberg]

Dale, This is solely conjecture, but is it possible Prevost comes up with that quantity based on the bus air heat exchangers? I have gotten about 18 gallons out of mine, but that was when I was using and replacing the DD antifreeze. I have never made a substantial effort to drain every drop. Both buses, the 87 and this one seemed to drain about the same amount so I never chased what may have remained. In August I am switching to EC-1 so I have a real interest in finding where the extra coolant is hiding.

[ajducote]

When I had my antifreeze changed to long life, the mechanic disconnected both hoses in the engine compartment that go to the drivers heater. He then hooked a garden hose to one of the pipes and flushed it out until it ran clean from the second pipe. This completely flushed that whole heater loop. Then drained as much as possible by raising the front of the bus. He also turned on the "heat exchanger" switch for the AuqaHot and ran clean water thru that loop to flush it out. I don't know how much total old antifreeze was drained, but he went thru a lot of trouble to drain and flush as much as possible.

[truk4u]

Dale,

Assuming your going to buy your coolant at NAPA, please give me the NAPA part number when you make your purchase.

[dale farley]

Tom, I am changing to EC-1, and I got it at NAPA. I'm using the Zerex (P# ZXED-1 Concentrate). They also have the 50/50. I bought gallons of distilled water from Wal Mart to mix with it. Prevost says use distilled water. The antifreeze at NAPA is $16.72 plus tax. It was a little over $15 in January when oil was a little cheaper.

Jon, I think you may be right about Prevost's quantity being based on the bus air heat exchangers. I know the last time I changed the coolant (2 years ago), I just drained everything I could without disconnecting any lines, and I got a little over 16 gallons. This time, I poured 5 gallons of measured water in a 5 gallon bucket, marked where it came to in the bucket, drained it in the marked buckets, and allowed a little for spills, so I feel pretty confident about my quantity. When I had less than 5 gallons in the bucket, I poured it back in the gallon container to get an accurate measurement.

The worst problem I've had so far was removing the drain plug from the radiator. Because of its location and 5/16" square head, it is hard to get a grip on it and make it turn. It is brass. I used every socket, wrench and special tool I had to get it off. I heated it a little and gave up a couple times! I finally resorted to vice grips and was able to get it out, but I have to replace it with a new one before I reinstall it.

One thing I just noticed about the new software we are using, it is nice to be able to see the previous posts while posting a reply. We couldn't do that with the old software. A kudo for Jim Skiff.

[dale farley]

I was tied up a good portion of the day, but I did get time to drain and flush the system two times. The first time I filled and drained it today, there was still a significant amount of antifreeze and the solution was light green when it drained. The second time I did it there was no visible signs of antifreeze, and the solution was just a little yellow looking. I discovered yesterday that there is a 1" brass plug in the heating system that I can easily access when I lower my front bumper. When I remove that plug, it lets the heater lines drain quite freely. When I removed this plug after the second run today, the water in the heater lines was almost perfectly clear. Each time I filled, I let the engine warm up in the yard then drove a few miles with the Webasto running, the circulation pump engaged and the dash heater turned on. I was also running my OTR air and my dash air to neutralize some of the heat inside the bus and to help the engine warm up faster.

Just to be sure I have all the old antifreeze out of the system, I intend to attempt to flush water through the Webasto tomorrow, refill the system and take another short drive before draining the 4th time and refilling with the antifreeze. I was pleasantly surprised to see that the old antifreeze which was two years old, looked like new when I drained it out yesterday. I was also pleased that NAPA had the drain plug (that I messed up while removing) from the bottom of the radiator and a new radiator cap to fit the fill tank. They also had the drain cocks. One of mine was hard to turn, so I replaced it. In retrospect, I should have replaced all three of them. The brass radiator plug was $1.47, and the brass drain cocks are $2.47. I put lithium grease on the threads of the other drain cocks so hopefully, they will continue to turn easily.

[dale farley]

James, Sounds like a nightmare just to have your coolant changed. This is a significant part of the reason I do my own work. At least I know who to blame if it isn't done right. Your situation is another example of the importance of knowing what the shop should do before you leave your bus with them. Otherwise, you would be driving around with a horribly wrong mixture in your engine. Makes you wonder how many other buses the shop has done the same way? I'm glad you got yours straightened out even if it did take a week, two trips, and some arm twisting to get it accomplished.