The size of the radiator has nothing to do with it. The pump is going to move the same amount of water no matter the size of the radiator. The only difference is the system now holds more water and the water stays in the radiator a bit longer. In fact, my van has the rear climate control which adds over 20 extra feet of piping and an additional heater core (radiator). There's no special pump to go along with that option and it increases the capacity AND flow restriction way more than your larger radiator.

Factory radiators can fail even with good coolant. I just replaced mine earlier this year with around 200,000 on it. I caught the leak as nothing more than a damp spot on the bottom tank that hadn't started dripping yet so it would probably still be going now but still... 150,000 isn't out of the ball park. I know my van was well maintained by the utility company that owned it for the first 185,000 miles. An early failure doesn't mean they had the wrong coolant.

I paid $130 for a TYC radiator from RockAuto. I don't think it came with a cap but it uses the factory cap. I doubt the radiator for the 2500 is much different.

If there was a coolant mix causing corrosion it would be reflected in the condition of the fluid. If it came out clean you should be alright. The material being corroded has to go somewhere. It will also stain up your overflow reservoir.

I don't know about the higher PSI radiator cap. Higher PSI will put more stress on seals and make things like the weep hole leak earlier. That's just the facts on any system that holds pressure. How much of a difference it makes in the van I don't know.

I wouldn't stress over the head gaskets. There's nothing you can do about it. If you're concerned you can get a head gasket test kit from Amazon and test for it regularly.

 

Allright, The size of the radiator has nothing to do with it. GOT IT. you don't even need to INCREASE the pressure with your set up. Got it. And you use a 15 PSI cap for your van? it's probably the same. YEah I tried to get the old pump apart, but it's pressed in and I don't have a press. I would also need a three jaw puller for the pulley. IT's just too much effort. When I picked it up some dark red fluid came out from underneath the pulley(weep hole is there just like the old pumps likley). I guess that's just really old dex cool that got stuck in there. The rest of the system looks good. The reservoir looks mildly stained but so does every car no? I did see some floaters in my radiator after fill up, no idea what all that is. I saw one teeny tiny scrap of what looked like epoxy. the rest of it was like speckles, but not shiny. I'll have to run the system some more and see if the floaters are still there.

ALso I guess the dex is only good for 5 years or 150 k whichever comes first. I think it got changed after about 8 years. I guess it all makes sense now. Time to find a cap online and get that pressure down. Wish me luck, I am going to need it.

 

It took some searching but I found a radiator cap. The problem is that there is barely any spring tension when you screw it onto the filler neck of the radiator. Is that a big deal? I just popped the radiator cap and a little bit of fluid went into the reservoir, as if it were trapped and couldn't flow in. This didn't happen with the 19PSI cap which REALLY has spring tension in it.

The cap does seem to allow fluid into the reservoir when operating, and then let it fall back in. I guess I'll have to watch it. My motorcycle has a 16PSI cap on it and I took that off and felt the spring tension. IT's kind of the same for the new 16PSI cap on the van. I guess this is just normal and not a problem? let me know.