coolant change

[firefighter407]

was planning on changing the coolant in the expy and was what is the best way to drain the colant? and do I need to remove the block drain plug too?


Thanks

 

[tonydiv]

Just drain it from the radiator. Then fill it with water, run it until it's warmed up and then drain again. I do it a few times until the water looks clear when it comes out.

Just remember to have both the front and rear heat going, so that the heater cores get flushed out too.

 

[cdherman]

Depending on your local water, that might be OK or a real no-no. If the water has a lot of disolved solids, they can degrade the compunds in the antifreeze that protect water passages and radiator from corrosion from the inside.

tonydiv -- any idea how much comes out useing your approach? My HD towing coolant system is supposed to hold 24 quarts dry, according to the shop manual. Obviously, not all of that will come out, but depending on the proportions, if say 75% it is in the radiator, then its not so hard to get at least most of the old stuff out.

I was thinking of buying about 10 gal of distilled water, draining out the rad, refilling will distilled H20, running it till warm, draining again, replace with dist water again, repeat, then one last drain.

Then, based on how much came out, I would approximately know how much water is in the system still. I think I would pour in 3 gal of straight antifreeze, and then top back with more distilled water. If the shop manual is correct at 24 quarts (6 gal), then I should be OK.

I am also wondering about some of the flushes that are sold to clean out the system even better. I did that once on a old Buick and the water pump died 500 miles later. Sometimes its better not to mess with things too much I think.

 

[Racenut]

I have had good luck with the prestone cooling system cleaner. The only thing is make sure you flush it with a good flush kit for a long time with straight water while running to get out all the residue.

You should be about right at 3 gallons of straight antifreeze and then a top off with water.

 

[panda24619]

i drained mine from the radiator. my auto shop teacher told me not to even bother with the block plug in case of rust or it breaking. so i just drained what i could and then refilled it with coolant as it said in the haynes and the rest distilled water. dont remember how much it was but it seemed to work fine. i might wanna do it again with a full flush.

 

[cdherman]

Well, I drained mine today using the drain valve at the bottom of the radiator. Got only about 2.5 gal out, which is a far cry from the 6 gal in the system that that my expi is supposed to have (HD tow 2004 24 quarts according to the manual). And I drained it pretty good. I used my air compressor to pressurize the system from the fill tank so that the coolant really blew out of the drain.

Would take a serious number of drain and refills to flush out all of the old coolant this way......

As for splicing in a flush kit, I suppose one could do that. You put them into the heater lines (so as to bypass the thermostat). But even then, that's a lot of distilled water to throw into a truck.

If its going to retain 3.5 gal of coolant, then using tap water is not an option. Too much minerals (you have to use "demineralized water").

I bought a proper shop manual for the 2004 expy and navis --- it says you have to remove the thermostat to flush the system. I am not too keen on that. Dealer will do "flush" for $90, but I wonder if they are doing it RIGHT (as in removing the thermostat), or just draining what they can from the radiator petcock and then refilling....

It doesn't suprise me too much that so much coolant stays in the engine -- the bottom hose is large and goes downhill from the bottom of the radiator to clear under the oil filter. Then it hooks back up to the engine. I can imagine a lot of coolant being trapped in there.

I am one of those guys that likes to do his own maint, but this is a hassle, at least compared to my 65 F100 (smile...) I am calling the dealer to see what they really do for $90