Coolant Flushing

[todds112]

Need some advice on a total cooling system flush.

I removed several of the small hoses and drained the coolant. Opened up the drain cock on the bottom of the radiator and drained all that. Pulled T-stat housing too. Put the hose with running water in every open hose and let the water run for a long time, until clear. Drained radiator totally. Left everything drain for a while and re-assembled hoses and T-stat.

Put in new Anti-Freeze, first straight (1.75 gallons), then 1:1 mix of anti-freeze and distilled water. I let the truck run with rad cap off for a bit. Buttoned it up and took it for a ride to open the T-stat (would never get hot enough idleing to do it). Removed the cap (after it cooled) and found the new coolant rusty and very weak. I figure there was some water hiding in the system somewhere and diluted it.

So I guess I'm draining the radiator again. It there any way to get all the water out of the system? Do I just fill it with water only, drive, drain and repeat until it stays clear?

I didn't know about the coolant drain on the rear right side of the engine until a few minutes ago. I'm assuming I should open that too and just run lots more clean water through it.

Any advice would be greatly appreciated.

 

[Warthog]

Per the -10 Operators manual the cooling system holds 28-32 qts or 7-8 gallons. The engine will hold at least half of that after draining. I would use straight coolant to refill.

Cleaning the system is an exercise. An old school trick is to use Cascade dishwasher detergent to clean the system. The new stuff doesn't work as well as the old stuff. See if you can find the commercial grade stuff.

Drain, fill, run and repeat is the best way to do it as there are many nooks and crannies where junk collects.

 

[todds112]

That seems about right, I only got about 4-5 gallons total in it.

I did run some CLR cleaner through. I'll flush it again and just add straight AF this time.

 

[todds112]

I drained the radiator tonight. Ran the truck with cardboard over the radiator and the throttle opened a bit. That was enough to get coolant flowing through the T-stat. I ran fresh water through it for about an hour and half before it got clear! Can't imagine how many gallons of water went through it! I didn't mess with the drain on the block, it didn't want to open and I wasn't pushing my luck. After it was good and clear for a bit, I shut everything down and let it drain out as much as possible. I added about 4 gallons of straight anti-freeze. That seems about right. I ran it some more with the cap off, but didn't get a chance to drive it.

I've read some of the posts about using distilled water (always did that in cars). I bought 4 gallons to use in my first attempt. I don't see how you could. You would have to have a tanker full to keep it flowing through! I guess I am over thinking it. The coolant looks much, much, better than it did before. Hope I am done with that chore for a looooooong time.

 

[Jeepsinker]

Drive it on a couple of moderate trips and you'll have to do it again. The best way to keep a cooling system clean is to never let it get rusty in the first place. Mine is not rusty but I flushed it a month or so ago anyway. I cut off the end of a water hose so I could connect it to the heater hose fittings. Backflushing it that way works fairly well. Just leave the cap off and let all the trash flow up and out. Flush through both fittings for best results.

 

[gimpyrobb]

There is also a drain under the intake manifold towards the front. After pulling the heads on my deuce, I have decided I am going to install a coolant filter. This will be after I get the radiator fixed(shroud came off) and flush the system real well.

 

[welldigger]

After running it hard for a while with coolant flush I stuck a hose in the rad cap and opened all of the coolant drains. Rad, block, and heater core. I let the truck idle with fresh water being fed in while leaving all ports open until clear water was coming out of all of them. I then shut the truck down and let it drain. Then added fresh water and coolant. Granted my cooling system wasn't really dirty to begin with.

 

[Larry Weibert]

M 35 flush. I just wanted to say thanks for the prior posts and info. ill add what i experianced if it helps anyone. I blew my lower hose so decided to do a flush at the same time. I took the advice of not using the NAPA hose and using one from a surplus supplier. I used one from Big Mikes. its shape was the same the lower leg appeared a tad longer. After test fitting I trimmed 1/2 inch off the lower leg to the rad so the back side didn't rub on the bracket behind the hose. I initially installed the hose without the inner spring from the old hose so I could easily pop it off several times when flushing it to drain it. I used irontite Thoro flush. It looked like powdered cherry cool aid. I filled it back up ran it 15 mins and dumped the water via lower hose. The mess was red and lots of rusty water. I refilled with water and ran it. I blocked the rad so it would heat up and drove two miles and got it up to 190 ish on the gauge. this time when dumping it it was even dirtier. I could still see a hint of the cleaner color so I did it again. I wound up filling running and dumping it 6 times to get clear water when draining. The last time I cracked the heater pet cock and let that piss until there was no trace of cleaner color, just clear water. I saw that it was posted that the capacity was 32 qts and several had problems getting over 20-22 qts when filling. so I figured I would start with 4 gals 16 qts of straight antifreeze first to make sure I got enough in. It took the 4 gals only. I had to run it shut it down for a while and re start it later to get one more gal in which makes 20 qts added similar to what others said. I hope the pics I added show up. Iam glad I added the antifreeze straight and not mixed or I wouldn't have been able to get the 50/50 mix in the end. Iam retired know so plan on driving and playing with the trucks. Thanks for all the good info from all here it really helped me.

 

[frank8003]

A filter can help, I used a mobile one because it won't break down.
Lots in here about coolant filters. I bought one new valve, hard to work down in generator area, was forced to cut out the original valve down there. Note this truck has no heater.
Pictures for the general too.

 

[cattlerepairman]

I drained the coolant, refilled with plain tap water, added CASCADE non sudsing detergent and ran the engine to operating temp. Then I drained again, unhooked the radiator hoses, put the garden hose into the upper radiator port on the block and ran the engine, water gushing out at the bottom until the water at the bottom came out clean.

The radiator I took to a shop to have it boiled, pressure tested and fixed.

Sent from my SM-G950W using Tapatalk

 

[Larry Weibert]

Cattlerepairman thanks for the info. I have many more 2.5 and 5 ton trucks that will need TLC so ill try the kitchen cleaner next truck. I bought trucks in 2005 thinking I would jump in and get playing with them. That took till retirement to do which is now. I started and drove three today it was a blast.

 

[frank8003]

That coolant stop valve, drain, down near the generator to be stock would be this one.

 

[aleigh]

I dunno that I would trust an oil filter to do the job of a coolant filter in general. There are purpose-built coolant filters (which are also cheap) and they have media designed for the application. Maybe that particular Mobil filter does work well as frank8003 noted but I'd be concerned about the media in the filter having some kind of problem in a water application... shedding the media or jamming up and bypassing / restricting.

 

[frank8003]

I dunno that I would trust an oil filter to do the job of a coolant filter in general. There are purpose-built coolant filters (which are also cheap) and they have media designed for the application. Maybe that particular Mobil filter does work well as frank8003 noted but I'd be concerned about the media in the filter having some kind of problem in a water application... shedding the media or jamming up and bypassing / restricting.

The Mobile one was used as Santa could afford only the head for it and the filters were free. Research indicated that particular Mobile flavor filter does not break down in coolant and subsequent filter cut-opens revealed no problems and lots of yuck trapped. Along with the 10 hours labor, valves, hoses and clamps, (my system valves were froze, had to cut them out), it is the cheapest it could be done. Still on the truck working fine. Original research was for the V6 Camaro oil filter whereas aftermarket China filters breakdown and plug the little holes that allow the variable DOHC system to function. It was a lot a research.
It is assembled so if I ever got a "real" coolant filter head it would be an easy changout.

 

[aleigh]

Implying the threads are different? I've never actually looked. A coolant filter is about 10 bucks, but I hear you, free is free. For others starting from scratch though I just wanted to let them know the option was available.

 

[russojap]

Dumb question,how critical is changing the coolant? My truck has the same stuff in from eight years ago. The coolant in the radiator filler neck looks fine but the thermostat probably hasn't opened in years.

 

[rustystud]

Dumb question,how critical is changing the coolant? My truck has the same stuff in from eight years ago. The coolant in the radiator filler neck looks fine but the thermostat probably hasn't opened in years.

Get a tester. What happens is the chemicals in the coolant breaks down and then it will no longer work as it should, ie: keeping the engine cool in summer and keeping it from freezing in winter. Also the additives help in stopping rust formations.
A cheap tester will work OK for this test. Or you can buy a $100.00 tester that will show you the actual working temp for the coolant.

 

[aleigh]

The little bulb tester things (which are just hydrometers) measure the specific gravity of the coolant. As the specific gravity rises the freezing point drops. What those don't measure for is how acidic the coolant is, and it can become so after time. Coolant ph is a whole thing in and of itself. If it's wrong, you can get galvanic corrosion, of all things. There are also other additives that get used up (like nitrite).

There are places that will test coolant just like oil. Someone else would have to chime in how important SCA additive packages are for the early deuce engines but they are indicated for the later engines like the cats. You want anything that meets ASTM D-6210.

 

[rustystud]

The little bulb tester things (which are just hydrometers) measure the specific gravity of the coolant. As the specific gravity rises the freezing point drops. What those don't measure for is how acidic the coolant is, and it can become so after time. Coolant ph is a whole thing in and of itself. If it's wrong, you can get galvanic corrosion, of all things. There are also other additives that get used up (like nitrite).

There are places that will test coolant just like oil. Someone else would have to chime in how important SCA additive packages are for the early deuce engines but they are indicated for the later engines like the cats. You want anything that meets ASTM D-6210.

You can buy the "test strips" that check for acidic, and nitrite levels. We tested all our vehicles at the transit agency every oil change. Most people don't need to be concerned with nitrite levels or really acidic levels if they change out their ant-freeze every two years like your suppose to. Our busses had over 40 gallons of coolant in them, so for us that meant a considerable amount of money to change out the coolant in over 4,000 busses ! We would add "Nalcool" and other additives to keep the coolant "fresh" throughout the years. Then every six years the coolant was changed out.