Mixing antifreeze = brown sludge

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Thank God this didn't happen to one of my cars. This is exactly why I like to do my own maintenance to my own cars. One of my co-workers asked me a question yesterday morning. She said her son took his 97 Ford F-150 to some repair shop to have the oil changed. They topped off the coolant with something that was NOT already in it. His truck started to overheat. She says now the cooling system is full of this brown sludge like in this photo: Apparently when you mix two different types of coolant they react and create a brown sludge. This is the first I've ever heard of this happening. I mean, logic would say if the coolant is green, use EG, if it's orange use Dex-Cool. How many times of coolant are there on the market? I only know of two , well three. 1) The "green stuff" which is ethylene glycol. Been around for ages. True and tested. 2) Then there is propylene glycol. This stuff was introduced as Sierra back in the 1980s. I had not seen it in years but apparently Peak still makes it. It's supposed to be 10 times less deadly than EG. I have no idea if this stuff can be mixed with ethylene glycol. Did you know it's found in food such as ice cream and those sauce packs that you mix separately in frozen dinners? I guess to prevent ice cream from freezing rock solid. The EPA says it's safe in small quantities. You know if you can believe what the government says... 3) Dex-Cool. This is the orange stuff that has been used in GM vehicles for quite some time. Some know-it-all I used to work with says it's corrosive to aluminum. My 98 Chevy van has it in it. I've never had any cooling issues with it and it's got about 150,000 miles on it. Is this stuff supposed to be better? Or is it something GM came up with like those stupid side battery terminals. So are there any other types of coolants besides EG, PG and Dex-Cool? I always thought Fords used EG (the green stuff). The question is, why would someone add Dex-Cool on top of EG or vice versa? Once this sludge develops how do you flush it out? She told me they have already changed out 4 thermostats and the truck has no heat so the heater core is clogged up. She asked me what would I do. I suggested taking the heater hoses loose from the engine and stick a water hose into each hose, turn it on and kink it back and fourth to see if it breaks loose. I've done this before on older cars like my 68 Ford. The heater core would occasionally clog up with rust scale. I guess from where the car has the original engine which is almost 50 years old. Install a flush tee in the heater hose and backwash the system for about 30 minutes Then add a couple of cups of Tide detergent and water and let the engine get hot, drain and backwash it again and repeat if necessary. I told her I hate to give advice on something I've never tried myself but if I had a car like this I might try filling the cooling system with something like diesel fuel or kerosene. But since the flash point is between 100 and 150F, I don't know if it would be safe to actually start the vehicle and let it get hot. I choice would be Tide detergent. If it were me, I'd be finding a lawyer or file a suite for small claims court and make the shop fix it or flush it out. Anybody ever had this happen?
 
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The first thing would be to contact the shop that did that! If it was a reputable shop they would own up to their mistake. If they don't do right, go to small claims court. She shouldn't have to fix a shops mistake! Thats why they get paid for their work, not to make more problems with the vehicle.
 

JC1

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I had an 84 tercel with brownish coolant. It was caused by the previous owners neglect of not maintaining the cooling system. I doubt the shop caused the coolant to go brown. Probably when they added new coolant it loosened up the crud in there and he's seeing the results. He should get it properly flushed out. There are more than two coolants out there besides Green and Dexcool. Toyota has a red and pink, Chrysler has HOAT and other variations. Honda has blue coolant. I'll have to find a list when I'm not on my phone and post it.
 
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Don't think diesel or kerosene are good ideas. I doubt this stuff is especially soluble in them, they don't mix with water, and they are likely to attack seals and rubber hoses. Flush with a hose, and the laundry detergent sound OK. The stuff has probably got scale mixed in with it, especially in the clogged heater, which might benefit from treatment with a mild acid like vinegar. I've also seen special products mentioned on here fairly recently. You could do a search. However, as pointed out above, this is the shops responsibility so they should fix it.
 
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Good luck to anyone tasked with cleaning that [censored] out. A lot of time and patience is going to be involved, a real lot. I've seen it and dealt with it over the years helping friends. I'd pressure test that cooling system just to rule out the <span style="text-decoration: underline">possibility</span> of a bad head gasket.
 
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What you call ethylene glycol you probably mean "classic green" 2 year antifreeze. This is actually pretty hard to "score" now; you have to try. Every antifreeze you can buy in town is EG except that Sierra you mention. Dexcool is EG with a different additive package, and generic all-makes all-models is dexcool with a slight twist, and a green color to avoid license fees. This is the stuff prominently on the shelves in walmart and the shop might buy it in bulk. Shops vary widely in the antifreeze they carry, but getting all-makes all-models is what usually happens if you show up with "already green". That said the all-makes promises to play nice with ford, so if you got that for a result, it's either the antifreeze's fault or the truck already has problems. Might be worth revisiting that shop and seeing what they say.
 
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There are over a dozen different types of antifreeze. There's "old fashioned green," Dexcool, G-05 (which is what newer Fords and Chryslers use), G11, G12, G48, FL-22, and a bunch of others I can't remember right now.
 
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A 1997 Ford truck that probably hasn't had its cooling system serviced in god knows how long, probably didn't get that way by just adding a different coolant. Yes coolants shouldn't be mixed, but by the looks of those pictures I'd say that entire system needs to be thoroughly flushed and changed. I'm surprised the heat is even working. There are several types of coolant on the market IAT -- inorganic acid technology...old school heavy silo can't and abrasive to modern water up seals. OAT- organic acid technology HOAT- hybrid organic acid technology POAT- I can't remember what he'll this stands for but Chrysler used it at one point before changing recently. And the colors? Oh my lord!!! Why? Just why do they do this to us? Ford actually has a green coolant that if course would lead one to believe it's the "old green stuff". When it's actually a special long life Green coolant. It supposedly replaced the GO5 Orange/yellow stuff that worked so well. Because if it works, replace it as soon as possible, right? GM uses their Dex Cool nightmare long life junk - I do find that this stuff doesn't play well with others. Honda and Nissan use a pretty blue coolant. Toyota uses long life and Suler long life pink stuff. Zerex Asian is a good cheaper alternative (made by Valvoline ), which supposedly you can mix or use into any Asian vehicle. VW and Audi use that Pentafrost...because they just have to be better than everybody. It's red. BMW uses this stuff that looks like Ford Go5, in fact I believe you can use the GO5 in the beemer. Ford has all sorts of stuff now though,mthey actually have an additive package that must be added to one of their coolants in their diesel pickup trucks. A light will come on the dash telling you when to put the additive in the coolant (around 70,000 miles). But out of all this just keep in mind that mixing is not ideal, and that IAT is not used in any modern applications that I know of - even the stuff that is now colored green. Most stuff is some sort of organic acid formula.
 
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Originally Posted By: demarpaint
Good luck to anyone tasked with cleaning that [censored] out. A lot of time and patience is going to be involved, a real lot. I've seen it and dealt with it over the years helping friends. I'd pressure test that cooling system just to rule out the possibility of a bad head gasket.
That's. What I was thinking. A leaking head gasket letting oil into the cooling jacket will do that too. I'd pressure test, if ok then rinse the goo out a couple timeswith hot water, then do a good cleaner treatment then drive it nice and warm dump and repeat until its coming out clear.. Then put in the right stuff and check it a couple times in the next month. You might want to change out the stat afterwards as cheap insurance for a few bucks. Do that before anything drastic like hot tanking the radiator. Better yet.......pressure test the head and if ok see if you can get the other shop to do all this. If it had been like that when they opened the cap they surely would have addressed it the issue then. Be nice and they will probably take care of it for her.
 
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Absolutely NO diesel or kerosene! The Ford was most likely neglected to begin with and the sludge was already there. Best course of action? Drain the coolant out, get a garden hose and flush the block and radiator, then remove the heater hoses and do the core separately. Being an F150, it'd be a good idea to buy some hose to extend the heater core fittings out some so as not to dump water on the rear ignition coils. Then refill with fresh coolant and change on an appropriate schedule.
 
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Ethylene glycol or propylene glycol doesent matter. What matters is the additives. Some addpacs react with some others.. That's why sludge can occur when mixing two different coolants - they might both be ethylene glycol but still develop sludge because of incompatible additive packs. I once came across a Propylene coolant with Vw approval. Vw coolant is usually always ethylene glycol. But this one, made by Texaco, had no color to it and mixed with G12plus without any issues at all.
 
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Generally a coolant reaction will cause a gel. That sludge doesn't look like anything I've seen from mixing coolant. Either rust or oil. Or someone really needed a toilet But seriously... Check for blown head gasket, also check that your oil cooler doesn't have an internal leak allowing oil to enter the cooling system
 

TurboFiat124

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Thanks guys for the explanation. The photo posted is not the actual photo but what she said looked like. I don't know the whole story on this truck. I was telling another co-worker and he said for all he knows, her son could have added the wrong coolant and had nothing to do with a shop to begin with! I would think if the truck had a blown head gasket, the coolant would look milky, not like mud. I'd have to see what it looked like myself. If I see green coolant in a radiator then I've always topped off with EG green and never though twice and never had any reactions in anything I've owned. If I see orange, I use Dex-cool. By the way, they say never to use tap water due to the calcium in the water. I've always just back flushed the old coolant out through the radiator snout with a flush tee in the heater hose hooked to a garden hose. Drain the radiator, poor in half the capacity of antifreeze then top off with water using my yellow no-spill funnel that connects to the radiator snout. Then start the engine, and once the fan kicks on, pull the funnel out and put the radiator cap back on. Then let the engine cycle to make sure all the air is out of the system. Otherwise if you want to get the tap water out, you have to drain the engine block and the drain plug is usually hard to get to. I've never had a problem using tap water in a cooling system and we have hard water around here.
 
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