B2600 Still overheating after 3 autoshops and +600$

Hello, I've been having this serious problem with my car and maybe someone can help me figure it out.

My B2600 is randomly overheating, it can go perfectly for 2 hour drives full traffic, slopes, highway, etc but a few days ago it would heat up after I turn it off so I had to turn it on again to let it cool, and yesterday it heated up randomly on a hill in the way back home (had been driving it all morning with out any problems) so I let it sit for a while before turning it off and it cooled off to the regular temp.

I changed the oil pump a few month ago, the timing belt, checked the radiator wasn't blocked, radiator cap and flushed the system. I dont know what else to do, any ideas?.

Is the water pump weeping or howling? I has same problem with my b2200 and I changed the whole cooling system and turns out the water pump was bad and my heater core was partially clogged which was making it act funny after the water pump was replaced.

Don't know if it's the same on the b2600 but the water pump on the 2200 is right behind the timing belt and if you change one they recommend you change the other at the same time while the truck is all taken apart.

What work did you have done for the $600 bucks? We can't help, to avoid saying something you've already done.

First you have no way of knowing for sure if the radiatior is clean inside unless a radiator shop has taken it apart and ran the rod through all the tubes and cleaned it out. Or if you have a brand new one. Any other way is just guessing.

If it's the original one it needs to be rodded out. This may or may not be the issue. It also will not heat up after it has been shut off. No way to make heat after the engine stops. If the gauge is climbing after you turn the engine off it has an issue somewhere causing the gauge to act that way. But it is 100% for sure not hgeating up after it's shut off.

Ok the 600$ was for all the spare parts (the oil pump, timing belt), radiator flush, various engine tunnings (the thing with the special lamp) and service hours. I live outside the US so no worries about complains or anything like that.

I have read that it could be the water pump, I was planing on taking it to a Mazda shop but Im just graduating college and Im technically broke, is it necessary to take the truck apart again?

VSAWMike, Im sure its overheating because i can hear the coolant starting to boil just after I turn it off, even thou yesterday started heating randomly in while driving. The milage is 62.137 and its has the original radiator. Should I try replacing the water pump? radiator? heater core?

First, the radiator flush was a waste of money. All that does is get the loose stuff out. Take it to a radiator shop and have it rodded out. If it's cost effective then it's the best route. Contrary to what people think it's mostly brass and will last a very long time as long as the repairs are good.

But the quality and low price of aftermarket radiators is so good that only you can make that decision. But it needs to be rodded out or replaced. I'm not talking out of my ass on the cooling system. I did cooling system repairs for 14 years working at a radiator shop and I grew up around them as my dad owned one for 25 years and worked for other shops for many years before that.

Assuming the water pump is pumping and the head is not cracked or the head gasket is not leaking there are only a few other things that can cause it to heat up. I agree that it is overheating but not after you shut it off. That is just when the water is no longer moving and starts to boil in place.

The radiator shop can test with the blue fluid to see if you have a head gasket leak. Other than that the thermostat could be stuck closed or partially open. You also need the fan and shroud to get air through. However above about 40 mph they do nothing more than direct the air.

The heater core will have no effect on whether it overheats or not. The radiator will cool it without the heater core in the truck.

Also understand when filling the radiator you need to start and run the engine until the thermostat opens then add more coolant. If not you do not have enough in the system. Check the cap also. Yes they will almost always hold pressure but if they hold enough or not is the question. 13lbs should be what it has. Even a new cap can be bad or have a weak spring. Always check a new cap. Always check the thermostat by putting it in a pan of water on the stove to check that it opens all the way without sticking.

Perfect, thank you so much for your time. I'll begin checking the head gasket and have the radiator rodded out (tomorrow if possible), then try replacing the water pump + thermostat. Ill update as soon as I get some results (good ones hopefully).

Again, thanks for taking the time to reply.

Rodding out the radiator is a last ditch effort to save a dying radiator. Just buy a new one and be done with it.
Yes on the thermostat... I'd replace it too.

I'm in an area of several million people, and only in the downtown Phoenix area would you currently have a chance of even finding a radiator shop, figure two trips there.

So when my B2200 needed a new radiator, ordered through local O'Reilly (a 2-row all-metal radiator upgrade, by the way); when my 1998 Frontier started leaking at the crimped seal between the plastic top and the metal part, no way was I going to make two trips downtown to salvage that, O'Reilly again there.