No water pump, 10 minute run time

[Caithness]

Situation:
Dead electric water pump, no coolant flow. 10 minute drive, after which we realized it. Temp gauge without water flow= completely inaccurate. General cooling setup of his car other than electric pump- mostly stock cooling system, straight water, 180 thermostat with 1/4" hole in it, 16 psi cap, only one fan (passenger fan).

What kind of damage are we looking at here? The car was cold at the start, not run for hours. 80 degree weather. When we looked at it after the drive the coolant reservoir was empty, the upper radiator hose still had water in it but it was steaming. There were sounds of bubbling right after it was shut off. The temp needle acted normally until the last 3-4 minutes of the drive, when it started going up and down but never reaching the H line- but there was no coolant flow so it's not a very good data point.

I think the problems could extend beyond the usual overheating stuff like blown headgasket, warped head, warped block- what would no coolant flow do to the head, especially around the exhaust ports? Obviously we're just going to figure out the pump problem, flush the system and see if it's running fine to start with, but what kind of damage should we be looking for?

 

[Old Mitsu Tech]

That, my friend is the million dollar question. Overheats come with so many variables as to actual temp in each location, duration of overheat etc. The head is usually the first to succumb to the extreme heat as it's aluminum. If you didn't warp the head you are indeed lucky. This can be exacerbated by influx of exhaust gas into the cooling passages which further block coolant and open air pockets at the high points which is where the ect sensor is.

First, fix the water pump problem. Then I would add water and run the engine to temp and see what happens. I would then do a hydrocarbon test of the cooling system to determine if exhaust fumes are indeed infiltrating the cooling system.

If all pans out,........ I'd just watch it for a few short trips to see what happens. If it got as hot as you said, then I'd be very dubious as to the health of the head.

That's about all you can do at this point. Unless you want to pull the head and have a good machine shop determine the extent of the damage if any.

Good Luck

 

[Caithness]

That hydrocarbon tester sounds like a nifty tool. I ran a search on it and it seems you should be able to get it at NAPA. We'll grab one of those once we figure out the pump issue. I was thinking he'd have to take it to a shop to get it leakdown tested to see if there was a headgasket issue if it wasn't immediately obvious on startup, just so he didn't find out by pushing all of his coolant on a 4th gear pull and making it worse.

 

[Old Mitsu Tech]

If coolant is getting to the pistons, then exhaust gas is getting to the coolant. Beaucoup engine compression psi as opposed to 16 cooling system psi under full load. That's what makes the hydrocarbon tester so nice.

If the blue liquid turns to pee yellow, you have hydrocarbons in your cooling system. Just follow the directions.

Good Luck