Hello

me and my dad are a bit stumped on my 1989 ford ranger. (2.9l v6)
I just rebuilt the entire engine, including new heads, head gaskets, headers, head bolts.
the issue is that the truck runs great and drives great, the temp gauge says it’s running at normal operating temp but we think it might be broken. When we kill the engine it sits for about 30 seconds and it sounds like the water in the radiator is bubbling, after about 30 seconds the radiator launch’s all the water in the radiator into the reservoir and sometimes it’s so violent the radiator cap will be shooting water everywhere.
my dad thinks that I put the wrong head gaskets on it as the head gaskets I put in were missing some water jacket cut outs, although every head gaskets I’ve looked at for the truck has the same thing. The timing is also a little out I know this due to the fact that the truck is very under powered and could barely go up a hill in 1st and my timing light shows the 10 degrees it supposed to be at is actually 30-50.
I also took the thermostat out and it seems to have locked itself open which is strange as usually thermostats get stuck closed.
please help I really do not want to rebuild this motor I’ve spent way to much money and time on it and it don’t wanna have to put any more money into unless needed.

thank you
Joshua Kilgallon

 

What you describe is a "hot spot" in a head, air is trapped in a head and is not allowing coolant to circulate in that area, the flow from the water pump holds that air in place, an "air dam"
When you shut off the engine the water pump shuts off and coolant can then flow into that "hot spot", where it INSTANTLY EXPANDS to 3 or 4 times its volume, so pressure in the system exceeds Rad cap 15psi and forces it open which cause overflow tank to fill up and even overflow

Yes, you are correct not all water jackets have holes in the head gasket, all head gaskets are like that, its done to direct the coolant flow thru the engine block and heads from water pump and back to water pump on both sides of a V6 engine
If a head gasket has a "correct way" to be mounted it will have "top/front" on each gasket so no mistake can be made, if there are no "marks' then there is no left or right, or top or bottom, they can only go on one way and fit

It reads like you are getting a hot spot in a head, could be from an "air dam" if you don't get all the air out of the system when refilling
You should pull a heater hose off at the firewall and then refill the system, when coolant/water starts to come out of the hose AND heater core port the air is out, reconnect hose

Thermostat should fail open, its called "fail safe" mode, to prevent overheating, thermostat failing closed was a very very bad thermostat, lol

Is water pump spinning the right way, on some engines you can put on the fan belt so water pump spins backwards
Start engine and see if fan is blowing air back towards the engine, if not then its spinning backwards

After refilling the system, start engine and let it idle with rad cap off
There should be NO overflowing out of the cap, an initial "burp" is OK but thats it
Let it idle for a 2 minutes or so with no overflowing, you can top it up if the level drops
Watch for air bubbles, shouldn't be any
Put cap back on and drive until warmed up
Then shut it off and see if you still get/have the "hot spot"

If rad is overflowing with cap off then you have a blown head gasket(didn't seal) or cracked head, for sure, bummer
Air from a cylinder is being pushed into the cooling system and this creates the "hot spot"