My coolant temp sensor is messing with me, but before I throw parts at it I need to change the coolant because it probably caused the problem in the first place. This coolant is old and RATCHET (not the kind of ratchet we like here). What kind of coolant do these trucks take? I am a DIYer as of one year ago and I have never messed with coolant in my life besides just looking at it and saying it's dirty and smells bad. I just need to know a kind that works and won't react with the ol' nasty that's in there.

Also, Dakota-specific tips on replacing the coolant are also welcome. I plan to take a hose out to drain it and not use the petcock on the radiator. I'm scared of breaking the old thing.

 

The regular green stuff. You want the heater on when you do it. Eric the car guy has a good coolant flush/fill vid. I bought that thing he uses and it never worked properly for me. There was not connector that would seal with my radiator top.
I have an old Ram 50 (mighty max with Chrysler name on it) and I was trying to fix an over heat problem. I ended up draining it, flushing it and drain it. Then added distilled water and a 1lb box of dry TSP from the Home Despot paint department. I ran it up to temp and let it cool several times. I think I even drove it a few miles. Then flushed it 3 or 4 more times with distilled water. Then finally filled it with coolant. I got heat for the first time since I had bought it. And now when I haul in summer it gets warm but not redline hot. (You pour out about a quart+ of the distilled water and with a funnel pour the dry TSP into that gallon of distilled water. Shake it up and pour in.)
If you don't want to use TSP which is pretty much he same thing as what you can buy as a flush just buy something you feel safe with. The distilled water is because we have hard water here and I wanted to eliminate any possible source of problem. I think that is what is recommended anyway.

 

Yes, your final product should have distilled water in it, not tap water. No minerals in distilled water to eat your internal cooling system. Also, flush the heater core while you have everything drained out. Plenty of vids showing how to flush your heater core (you flush it backwards from the way it normally flows). Important: Do not use high pressure to flush your heater core. You will smash the fins in it. Use only low pressure like your garden hose barely turned on.

 

The basic change is easy. Use regular coolant like Prestone or Peak. Since you don't do much work, get the premix. I would replace the thermostat while you're at it since crud can cause the unit to stick and maybe over heat your engine. (Bad mojo there!) There is a drain valve on the bottom of the radiator. It's a flat tab on the bottom of the tank on one side of the radiator. Set the heat control to hot to open the valve inside. Have a catch pan underneath and a garden hose handy as it gets messy.

Now, the way that "I" would do it is a little more complicated. You don't have to do this but it's a better change. If you can find a flush kit, they come with a garden hose connection you put in a heater hose. You cut the hose and use clamps to install it. Otherwise you can remove the hose from with the water pump or return line to the block. Stick a hose in and flush the block and heater core. I also like to remove the bottom radiator hose. This lets all the rust, mud, dead bugs or what ever flush out. Don't do this near the garden or pets area as anti-freeze is TOXIC. That's another reason you want a catch pan.With the bottom hose off, you can flush the radiator out too. Keep the water running until it runs clear.

Before you refill it, replace the thermostat with a 195 degree unit. DO NOT use a Failsafe brand. EVERY SINGLE ONE of those I've dealt with either was failed when I started working on it or failed soon after installation! Just a good old regular thermostat is fine, and cheaper. One tip though, if it doesn't have a little jiggle valve in it, drill a 1/64 hole to let air bubble through and it doesn't air lock. The jiggle valve is a itty bitty jiggly doo dad (<---------fancy technical term.) that jiggles. Air can pass but water can't.

 

I did notice driving it the other day that the heat is pretty weak. I'm not sure if the engine is having a hard time getting up to temp with the fan constantly running in safety mode, or if the heater core needs to be backflushed. While I am in there I'll go ahead and do it. What's the supposed risk of using TSP? Is it supposedly corrosive? I'm more worried about the coolant I have in there being corrosive so that's a risk I am willing to take. I have no idea how old this coolant is. I think I saw little pieces of rust in the bottom of the reservoir. The place I live has very mineral rich water too (along with vinyl chloride right now!) so I will definitely be using distilled. Oh and I keep forgetting I need a new radiator cap because the one that is on there is corroded absolutely to heck.

 

What year and engine are we talking about here. The first generation Dakotas had quite a few changes over the years.Anything that looks bad, like a corroded radiator cap, go ahead and replace it. It's amazing what a good flush with plaint water from the hose will get out.

 

Go easy on the core backflush. A mistake many people make is cranking up the water pressure as they backfill. It's a good way to flatten those thin fins in the core. Go very light on the backflush pressure. You're just trying to put enough backwards pressure to remove the trapped crap in there. Crank it up and you'll kill the heater core.

 

Glad you specified to not get the failsafe kind, that was one thing I was willing to splurge and extra $5 on, won't do it now! And I will do the premix because my garage is pretty dusty and I don't want to pour it more times than I have to. Good tip about removing the bottom radiator hose as well to get that junk out. Do you fully take it off and scrub the inside of the hose out?

I learned about the dangers of coolant around pets from the song "Bandit" by a band called Birdcloud. I have liked that song for years and now I am becoming the character in that song. XD

 

'89 with the LA-derived V6. Forget the exact name of it, it's the 3.9.

 

TSP tri sodium phosphate is a cleaner painters use to make sure walls etc are clean before they paint. They recommend you wear rubber gloves to deal with it. Other OTC flush stuff is a slightly different chemical formula of basically the same thing.
I did not and do not backflush. I just poured the water in normally via the radiator cap hole and ran the motor. Let it cool ran it again etc. That was enough to get whatever was blocking the heater core to dissolve. Another thing I was told is good to use instead of TSP is citric acid. I don't know where you'd buy that.