1987 B2000 overheating

my B2000 is overheating and i havent been able to fix the issue, driving or at idle. i have only replaced the fan clutch so far. (im sure that was bad) when i shut the truck down i can hear it boiling over. im not sure what to look at next any help would be great. also i was having issues with the EGR valve so i fabricated a plate to cover where the valve went. not sure if that could be an issue.

Thermostat, or water pump.

Any way to check them? Would rather get it right the first time lol

Verify cooling system is full of coolant, and has no air bubbles. If temperature is reading normal operating temperature (1/2 way up the gauge) the upper radiator hose should be warm. If it is, check to see if the entire radiator is getting warm to check for blocked radiator (blocked areas will stay cool where blocked).

To check water pump, I would turn heater to full hot, and make sure the heater core hoses are getting warm, you do not need the fan on for this. However, if they don't get warm, it could also be a faulty coolant control valve for the heater (a valve shuts off coolant flow when temp knob on cold), or a blocked heater core. You could also check to make sure the coolant bypass hoses that run behind the motor, under the intake are getting warm. The end is the 180 degree small hose that comes from under the intake manifold to the thermostat housing, the water pump pumps water from the thermostat through that small hose under the intake, around the motor, and meets up with the heater core return hose under the exhaust manifold. The hose near the thermostat could get warm with no water pump pumping due to hot water rising, but if the pump is not pumping, theoretically it should stay cold on the pipe behind the exhaust manifold, which returns coolant back to the pump.

I should add, if you drain the coolant, you may as well replace the thermostat, it is easy to get to and cheap. If you replace the water pump, replace the timing belt at the same time, it has to be removed, and if you don't know when it was changed last now you will know.

Does your truck still have the original radiator? I got my '88 B2200 in 1994, and was real good at changing coolant every two years, but that radiator still wouldn't do its job when it got like 20 years old. I ended up installing a brand-new 2-row radiator from O'Reilly (didn't use the ATF part), and that has worked great for me here in Arizona.

The automatic trucks came factory with 2-row radiator, and it works great with 5-speeds. I think a lot of suppliers don't make the 1-row anymore, to consolidate inventory.

With the heater on I get only cool air, so could the heater core be cloged? Cusser I'm assuming the radiator is original ill look into a new one also. I'm in Tucson and need to have the issue fixed soon. That heat is on its way. Thanks for the help guys!

Thinking about your issue, and re-reading, after any coolant-related service on these (such as thermostat replacement, coolange change), it's VERY IMPORTANT (note the capitals) to bleed out ALL the air from the cooling system, and sometimes tricky on these trucks. I jack up the front end, unscrew the radiator cap, and run the engine like that for 20 minutes, topping off with 50/50 as necessary. Very important on these trucks, and that can affect both coolant temperature and your heater operation.




OK, that's a real clue. See above. Also, drive the engine like 15 minutes with the heat switched "on" even if no heat comes out. Open the hood and feel both the input line and the output line of the heater core at center of engine firewall. Both should be hot if hot coolant is circulating through the heater core. Since you're in Tucson, you may find it easier to "not have heat" than to dismantle the dash if the HC is bad, but others like Dan Woodland have written good tutorials how to do that.

It's also possible that a cable end has slipped off a control (under the dash, look up and to the center as someone moves the levers/controls) and one of the flaps (doors) is inoperative, like letting in cool outside air.

The first thing you should do is pull the thermostat. While the housing is off, start the engine and see if the water pump pushes any water out of the head. After that, check the rest of the stuff!
Fundamentals, guys. Don't steer him off of that yet.

hey guys sorry to get back so late been crazy busy, so far ive replaced fan clutch, thermostat, and now the water pump. still overheating... the only other thing i can think is left is the radiator, am i right in assuming this is the issue? havent had the time to check if it is clogged but think its safe to say it is. what do y'all think? again thanks for all the help.