Maybe not a blown head gasket?

[Headnsouth]

I've got a 98 with 198K miles on it. Daily commuter - Ran great until the other day on the way home from work. AC was running with temps in the low 80's. Just get of the highway but still doing 45 mph and the engine runs rough and the I see the red temp light on the dash.
I pull over shut the engine down and coolant is flowing out of the overflow tank and no heat from the blower. From what I've read this points to a blown head gasket.

I manage to make it home and pull the water pump, thermostat and pump look new and the thermostat opens in a pot of water. I didn't measure the temp. No coolant in oil, no frothy goop in fill.

During the initial discovery of the overheat I did notice the rad fans were running.

A buddy mentioned maybe relays for the fans not hitting high speed

Thoughts? I hate to dig into this thing if its not a head gasket. what else can I check?
Thanks

I want to install a new thermostat and reinstall the pump and run it again before I either tear into it or trash it.

[Tech II]

Well, I would get a coolant pressure tester......the fact you had no heat from the heater core, means a huge air pocket was created, due to a loss of coolant....

I'm sure your coolant level was low BEFORE YOU REMOVED THE THERMOSTAT AND W/P......

With the engine warm, CAREFULLY remove the rad cap(cover with rag as you remove it).....now attach the pressure tester, and pressurize system.....see if pressure holds......if it drops, look for an EXTERNAL leak(especially lower intake gaskets).....

If no leak is seen externally, apply pressure to 12 psi, and leave pressurized overnight.....

Then remove the spark plugs and disable spark(remove two wire power supply to ICM on passenger side), and disable fuel(either f/p fuse or injector fuse).......Now watch the spark plug holes from the side of the vehicle as someone cranks the vehicle for the first time that morning......if coolant comes out of a spark plug hole(s), usually a head gasket(or rare, a crack).......

If I had to guess a cylinder, it would be #1(passenger side rear)

[Headnsouth]

Thanks for the advice. I've got a rad pressure tester. Got my fingers crossed.

[LMP]

Sorry for this, but head gasket failure is exactly the picture with all the exact symptoms. So common with this engine it is not an "if" but a "when". Try a few inexpensive fixes if you want hope but stop short of changing radiator, water pump, heater core...like several did stubbornly before finally accepting a head gasket was shot. No one wants a blown head gasket....normal....but the house is full...all around me in my place, and all across this and other GM 3.1/3.4 forums.

[Headnsouth]

Originally Posted by LMP

Sorry for this, but head gasket failure is exactly the picture with all the exact symptoms. So common with this engine it is not an "if" but a "when". Try a few inexpensive fixes if you want hope but stop short of changing radiator, water pump, heater core...like several did stubbornly before finally accepting a head gasket was shot. No one wants a blown head gasket....normal....but the house is full...all around me in my place, and all across this and other GM 3.1/3.4 forums.

Thanks, of course you hope for the best, least expensive repair. I will reinstall the water pump and thermostat and then pressure test anyway. It'll cost me nothing but time. Really can't complain nearly 200k miles 15 yo and I haven't put much into this van.

Doing a head gasket myself isn't something I will enjoy doing but for that kind of money it makes sense rather than buying some elses headache.