cooling system spring cleaning

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319cssb

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I have looked in the direct support TM of the M809. There isn't much informati0on about the maintenance of the cooling system. Or I missed it.

On the way home, I had this brass pipe fly off. Probably due to age and fluid pressure. I saw a bit of rust sludge in the hose end. So this wants me to clean the system some.
IMG_5151.jpg

Is there any advise on what to do? Can I use the radiator flush products from the auto store?
I saw a bit about what fluid can ruin the engine. So I'll stick with green.
 

319cssb

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Im not really looking forward to doing rhis , but i have a bunch of rusty build ip in my cooling system. What is the proper way of cleaning and flyshing my m809. The TM is not very helpful here.
 

Scrounger

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Cleaning a cooling system is a balancing act. There is always going to be some stuff in the older systems, the question is how much to remove. If one gets to aggressive the normal oxidation on the wet liners can be removed, and that is certainly not desired. Also, large chunks can come loose and block passages.

My suggestion would be to start with draining the old coolant to see what it looks like, then go from there.

Fill the system with water, start the truck, then allow it to idle for 30 minutes.

If the system wasn’t to bad, with the engine running, I would open the petcock and add water till what come out is clear. Shut it down, finish draining, refill with standard green stuff, and SCA.

If the system has a lot of grime. After the 30-minute idle, drain and fill the cooling system with water and some Cascade dish washing soap. Allow to idle with the soap for 30 minutes. Do the same as above, open petcock and drain while adding water till clear. Then the standard refill.

If the system was bad, and only if it was bad then I would use a radiator flush like they sell at NAPA. The procedure is the same as with Cascade, just don’t idle with the stuff for more that 30 minutes.
 

74M35A2

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I've done the Cascade, love it. Water came out looking like it was from a 175 year old well pump. Stained the concrete and all. Very strong, for sure works. I followed it with vinegar and then CLR.
 

319cssb

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When I fixed the broken brass pipe on the road, the coolant reservoir return line had rusty sludge in it, so i am expecting the worst. The dish washer detergent idea sounds pretty good. Followed by vinegar and if needed the more aggressive flush. I read horror stories about the liners, so i am definetely goung to use the green stuff.

Not sure what the PO used, so that's another good reason for me to clean the system
 

Scrounger

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The rusty sludge is normal. The reason for using a dish washing soap like Cascade is because it doesn’t foam. It isn’t necessary to flush with anything other than water after the Cascade cleaning. Remember just enough cleaning to remove the trash and not hurt the liners and O-rings.

The petcocks on these trucks sometimes get clogged with sediment. When they are, I find it is easier to just remove it and allow the coolant to drain faster. If the petcock causes issues, I usually just break the tabs off the valve and remove it with a six-point socket, then install a new one.
 

74M35A2

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The vinegar and CLR flushed out completely clear, so I think the Cascade did all the dirty work itself. Just FYI.

I did it by yanking the lower hose off. I’m impatient.
 

URSATDX

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I drained my A3 into 5 gal buckets through petcock.
Removed lower/upper hose and T-Stat housing (replaced T-stat).
Flushed through upper hose T-Stat housing and any other orifice until clear.
Reassembled and ran just water up to temp.
Black again. Repeat til clear.
Filled with Peak FleetCharge with SCA.
Drove and it was still dirty. Drained the new dark coolant into clean buckets +/- 32 qts.
Most of the heavy black particles fell to the bucket bottom.
Installed an inline coolant filter and refilled with the used, now cleaner A/Freeze.
It's been a month and 3-400 miles and the coolant has cleared up dramatically.
I will do another drain/flush/fill at 1000 miles. I'll cut the coolant filter open to see what
I've caught.
 

319cssb

Member
726
7
18
Location
Easley SC
I drained my A3 into 5 gal buckets through petcock.
Removed lower/upper hose and T-Stat housing (replaced T-stat).
Flushed through upper hose T-Stat housing and any other orifice until clear.
Reassembled and ran just water up to temp.
Black again. Repeat til clear.
Filled with Peak FleetCharge with SCA.
Drove and it was still dirty. Drained the new dark coolant into clean buckets +/- 32 qts.
Most of the heavy black particles fell to the bucket bottom.
Installed an inline coolant filter and refilled with the used, now cleaner A/Freeze.
It's been a month and 3-400 miles and the coolant has cleared up dramatically.
I will do another drain/flush/fill at 1000 miles. I'll cut the coolant filter open to see what
I've caught.
There should be an interesting sight im that filter then. Getting results like that is half the joy of doing it, i guess.
 

juanprado

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Don't forget to turn the heater on and get the nasties from there also. I would recommend plumbing in a universal coolant filter spin on. Well worth the extra trouble in my opinion. It can have chemical or not. That is up to you if you want to test.
 

rivercreek

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Scrounger, I'm curious to know why the recommendation to not idle more than 30 min? Are you referring to oxidation removal from the liners or another reason? I'm on my 5th flush with dishwasher detergent after an oil cooler failure (M923A1) to remove oil from the system. I believe I have removed just about about all of the oil now, however now I've got MUD coming out. I mean a LOT of it. I've just switched to Red Devil Radiator Flush (3 bottles of it) and I've sent the old lady grocery shopping in it. I'm very interested to see if there is any difference. I had intended to let it sit and idle for a few hours when she got back but came across your post about extended idling. Thanks in advance for any input anyone may have regards removing all this mud. In the meantime, I reckon i'll be searching for some more posts on coolant system flushes - this is the first one I've come across so far. One other thing - does having completed 5 flushes with no clearing up sound unusual to any of you guys? It seems to me that there must be a really excessive amount of sediment in this particular cooling system to have produced no noticeable results (clearing up) after all these flushes. Anyone else have this experience?
 
Last edited:

URSATDX

Member
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So Jersey, NJ
From earlier post now with coolant filter pics.

I drained my A3 into 5 gal buckets through petcock.

Removed lower/upper hose and T-Stat housing (replaced T-stat).
Flushed through upper hose T-Stat housing and any other orifice until clear.
Reassembled and ran just water up to temp.
Black again. Repeat til clear.
Filled with Peak FleetCharge with SCA.
Drove and it was still dirty. Drained the new dark coolant into clean buckets +/- 32 qts.
Most of the heavy black particles fell to the bucket bottom.
Installed an inline coolant filter and refilled with the used, now cleaner A/Freeze.
It's been a month and 3-400 miles and the coolant has cleared up dramatically.
I will do another drain/flush/fill at 1000 miles. I'll cut the coolant filter open to see what
I've caught.
 

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Scrounger

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The caution about idling for only 30 minutes is when using radiator flushes. The stuff will over time remove the oxidation layer from the liners. How much or how fast is something only someone with a lab and test equipment can determine. So, to be on the safe side we always used the 30 minutes rule.

That “mud” is probably just thickened oil. Removing all the oil and gunk from a bad oil cooler is no fun. When the oil cooler on one of my M816s went south I removed the coolant lines from the engine and flushed the block. Then did the same with the radiator. Then put everything together and started flushing in earnest. I estimated that it took about 900 gals of water to “clean” the system. There was still stuff floating to the top of the coolant tank for some time.

The easiest way to remove the stuff that will float to the top of the coolant tank is with a shop rag. Every time you take the truck out, when you check the coolant, shove a rage into the tank. The oil will stick to the rag when removed.
 

rivercreek

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Thanks for the quick reply and explanation Scrounger. Wow - 900 gallons? I guess I'd better quit complaining about my 5 flushes... I've been using a vacuum pump to suck the floating oil in the overflow reservoir prior to draining. The rag idea may be easier though, i'll give it a try.
 

rivercreek

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Juan, i'm interested to know your thoughts on why it may be necessary to engage heater fan during the flush procedure. It is getting to be winter here (fairly cold out) and I don't produce much heat at all just idling (even with a big piece of cardboard covering about 80% of the rad) - I need to drive this truck fairly hard to build up enough heat to even release the thermostat, much less get the main engine fan to engage. My thought is that the coolant would circulate even through the heater core regardless of heater blower motor being on or off. Am I missing something in this regard that I should be aware of ? Also, do you or anyone else happen to have a good part # for an appropriate coolant filter and mount? Given my circumstances this sounds like a wise addition to this truck. Thanks for any advice/info that you or others could offer.
 

juanprado

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Juan, i'm interested to know your thoughts on why it may be necessary to engage heater fan during the flush procedure. It is getting to be winter here (fairly cold out) and I don't produce much heat at all just idling (even with a big piece of cardboard covering about 80% of the rad) - I need to drive this truck fairly hard to build up enough heat to even release the thermostat, much less get the main engine fan to engage. My thought is that the coolant would circulate even through the heater core regardless of heater blower motor being on or off. Am I missing something in this regard that I should be aware of ? Also, do you or anyone else happen to have a good part # for an appropriate coolant filter and mount? Given my circumstances this sounds like a wise addition to this truck. Thanks for any advice/info that you or others could offer.
On the M939 series, they have shut off valves in the heater hoses so this is an additional reason to flush as any sediment in the coolant would settle because of no circulation. My truck came from Louisiana so you would expect the heater got little use. I was shocked at how much "mud" drained out. I had disconnected the heater hoses and was just flushing the core separately. That mud might impede your heater core from giving you all the heat it could transfer normally.

I did not actually have the heater blower on but I also did the initial flush with the temp control cable on hot so the water would flow also through the core. I then flushed it separately On the 939 the cable control has to direct flow to the core and the shut off valves need to be open to get circulation.

Wix makes a coolant filter base with a universal mount. Same brand as Napa except they drop a digit. Check 4019 for the base. All the universal filters typically have the same base threads. Difference is the length of the filter and if it has chemical also in the medium. 4071 is widely used in hd market.

https://www.napaonline.com/en/p/FIL4019

Napa has the description wrong but this is the coolant filter mount. Note they list all the filters that work with it.
 

Redneck of Enon

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engine coolant question on my A3 ....ok, I had a fuel line leak due to it rubbing against the air line so while I was fixing them both I had to remove a line going to the air compressor turns out its a coolant line and the muddy coolant ran out ...the coolant in the reservoir looks clean ? anyway I need to flush so after reading many threads it seems pretty easy but the one thing I don't get is about using distilled water ? can't I just use the water hose ?
 
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