Neglected vehicle - coolant looks like coffee and is broken down - what to do?

I have seen some nasty coolant in my day but I am working on another poor truck that has been neglected and the coolant is dead. I was replacing the power steering gear and changing the oil and happened to pop the cap off the coolant and it was NASTY! It was more brown like coffee or tea than anything. I had to give it a second look to make sure the oil wasn’t getting into the coolant. There is no oil in the coolant.

I would normally flush a system and replace with fresh coolant but am worried about what other problems flushing a system like this might cause. I told her that I insisted on putting in a new thermostat and radiator hoses when doing the coolant. I am concerned that the flush might result in the water pump or something else related going out. I have seen oil changes etc. expose serious problems with seriously neglected vehicles in the past as it is like all the crap is actually holding things together. It is a 1995 Dodge Ram V6 3.9L if this matters.

I changed the oil about 1000 miles ago and it was nasty. The oil I drained today didn’t look much better so I think it is cleaning gunk from the engine or something is wrong with the engine that is causing this. How long will it take for this sludge to clear out?

I have changed the manual transmission fluid as well as given it a tune-up which it needed as mice had chewed the wires.

I would not use a chemical flush. I would drain the system completely and refill it with a 2:1 concentration of antifreeze to distilled water. The extra antifreeze means extra corrosion inhibiters and that should take care of any pockets of brown coolant left in the system.

However, if you have some coolant laying around from previous coolant changes that is in pretty good shape, you could fill the system with this, drive for a week or two and then drain and refill using either the 2:1 or a 50/50 mix. I did this with an old van a couple years ago, it worked out pretty good, no leaks.

I had the same problem with my Grandmother’s car when I inherited it. I also did not use a chemical flush, but simply ran clean water through until it came out clear, then replaced it with a 60/40 mix of fresh coolant. I was doing a water pump, thermostat, and hoses at the same time. Kept the car for 2 more years without any new coolsnt problems or leaks.

I see you make reference to replacing the water pump at the same time. Do you think it is only a matter of time until it lets go, especially with the condition of this coolant? I seem to remember it having like 120-130k on the odometer. I think I might leave this for now as it looks like several other parts will likely need replacement at the same time. There is a metal coolant tube that is said to usually break during the work as well as the fan clutch which is suggested at the same time. I might just remove the belt and see how easily the water pump turns by hand. If VERY easy, I will consider doing this now or very soon.

I have been told that I should fill with vinegar and distilled water and drive it a few days as that will eat away at the rust and scale nicely. I would mainly be concerned about the radiator or water pump letting go from something like this, especially if there has been neglect.

The engine also has the timing set where the timing chain gets a little slack and begins hitting the timing cover, resulting in a clacking sound. All the Rams and Dakotas from this era seem to sound like this and I know it is a common problem. This isn’t really a problem but sounds bad and I see people solve this by replacing the timing set with the newer model that includes a tensioner. If the water pump has to come off, why not do it at the same time? Only Chrysler would come up with a design like that and use it for so many years until coming out with a revised design.

I am doing this for a friend and neighbor. Her husband has been in poor health for several years and although he used to be a maintenance man and mechanic, he just hasn’t been up to much lately so things just didn’t get done. I am actually amazed that the truck is doing as well as it has with it being a Chrysler and all. I have seen several Dodge/Chrysler products with MUCH better maintenance self-destruct with a lot less miles than this.

I refilled with synthetic oil this time so we will see what happens with the oil. I figure if the other oil was that nasty looking after like only 1000 miles, then I don’t want to use any kind of engine flush that would break all the crud loose at once, potentially clogging the oil pump and such.

The truck is sitting outside my house now if anyone wants me to go outside and look at anything.

I drained the nasty coolant today and refilled with a vinegar/water solution for a mild overnight type flush. The coolant looked like nasty tea with maybe a little greenish tint in it. There was a 1/2 inch layer of rusty colored sludge in the overflow tank. This just slides down and locks so I removed it and washed it out in the hose. This truck is still from the time when they used an iron block so I guess this isn’t a huge deal.

She is buying all the supplies today so I will flush the system with water and replace the hoses (this one has THREE (upper, lower, and short bypass hose), thermostat, and then a strong mix of coolant I may just stick the garden hose right down into the thermostat housing/fitting with the thermostat out to backflush the system.

It’s my guess water pump seal will give out. When I bought my '65 Cutlass last year, it had been sitting for a year or two. the owner’s wife wanted it GONE, so I got a pretty good deal. Anyway, I started driving it, and within 50 miles, the water pump seal started leaking. I’m expecting the same to happen to you, and would be pleasantly surprised if it didn’t.

Yeah, I kinda figured the water pump seal will give it up too. We will see…

I have the hoses, thermostat, and new coolant on hand now. I also broke the news to her that I wouldn’t count on the water pump hanging together after this flush. It looks like I will need the fan clutch as well as the water pump outlet tube at the same time from what I have read.

I replaced the water pump because it started leaking as I was taking it home. Since the coolant was so bad, I decided to replace the hoses, too. I replace the thermostat and rad cap everytime I change out the coolant.

I convinced her to go ahead and get a water pump as I flushed coffee and rust colored water out of the cooling system for over half hour today. The water pump wasn’t showing any signs of leaking but I had to remove a ton of other things just to get at the thermostat. With it being a Chrysler product, I had to remove just about everything in the way of the water pump in order to replace the “bypass hose” which appeared to be on its last legs. While I think the upper and lower radiator hoses appear to have been replaced, the bypass hose is buried so deeply that no one had ever considered replacing this. Either way, I had to slide the AC compressor, alternator, and the bracket that holds all this out of the way in order to get to this. I told her I wasn’t going to be happy to repeat all this, especially if the water pump died in a month.

Chrysler seems to go out of their way to make products that are hard to work on OR they simply don’t care and just make something that is easy to assemble at the factory (engine out of vehicle) but impossible to repair (thermostat buried under something). I will never forget the time it took me 9 hours to change a thermostat on a Chrysler. These usually take less time that it takes to change the oil but not on a Chrysler! At least this is a 1995 and they hadn’t perfected the art of making cars almost impossible to work on!

How does the radiator look inside? Are the holes all corroded up? Is there leakage where the fins meet the end caps? If so, it will need replacing. And then when you get everything sealed and pressurized the heater core will blow. That’s what happened to me with my uncles truck that had the original fluid in it after 10 years. Sorry!

I don’t see any leaks from the heater core or radiator. The inside of the radiator is still kinda grungy looking but not like pictures of corroded radiators I have seen online. I am going to do everything attached directly to the engine and refill today. We will see how long the radiator holds together.

I THINK the old coolant was the standard green colored kind as I sometimes saw hints of green while flushing the rust-colored coffee out of the cooling system. I am going to replace with a very strong mix of the yellow long life variety. It is the AutoZone brand and supposed to be good for 5 years or 150,000 miles which is probably too long. This says it is universal and can mix with any color of antifreeze.

@cwatkin changing coolant every 5 years is pretty reasonable, in my opinion

Isn’t it 5 years/150K, “whichever comes first” ?

Yes, that is what I mean. I wouldn’t run it for 15 years, even if only 100k were put on during this time.

Either way, I am going to tear into this today and see what happens.

I am going to replace with a very strong mix of the yellow long life variety.

Would there be any value in initially replacing it with a weak mixture of antifreeze? Then in several weeks, if you don’t see any problems, replace the weak mixture with a normal 50/50 mix? There may be some sediment that loosens up in those several weeks of driving.

That is true. I did decide to proceed with a chemical flush (purchased) after doing the vinegar and water flush first. Both flushes released a lot of crud. I have the water pump removed and the mating surface cleaned off and ready for a new gasket. The old pump didn’t look horrible but it wasn’t great either. The interior aluminum body was coated with a thin film if rust and the impeller was coated in surface rust but still solid. The bearing didn’t feel like it was ready to give it up either but you never know. Either way, the water pump shouldn’t be an issue in the future.

I will consider using a “lite” mix and drain it again in a few weeks. One issue I don’t like is how to dispose of the old coolant and I have several jugs sitting here now. Our city has a way to dispose of it properly but you have to make an appointment and sometimes this isn’t very convenient. It doesn’t look like parts stores take it either. How is the best way to dispose of old coolant? I have some other haz-mat type stuff I am going to take in to the city on one of these appointments but coolant is always an issue when I don’t have a bunch of other things at the same time.

Ok, I got this truck back together. Something else I found was that it is mostly SAE with a few metric fasteners. It fired right up and began to circulate at the normal temp. I am going to let it set and make sure that I don’t need to add more coolant once it all sucks back in. Anyway, I went with a stronger than 50-50 mix as I figure this can be run a while with the cooling system flushed so well and changed in 6 months to a year or so without any major flushing.

Thanks for the followup. Glad to hear all it OK for now.

cwatkin, will you keep us posted when each hose in the cooling system fails, one at a time, over the next couple of months?

Drain and flush the radiator. Replace hoses too