Water Pump Failure and Overheat
 

Driving home last night and it seems to me that the water pump failed. I started hearing some noise coming from the front of the engine yesterday, so I was keeping a close eye on everything. I also noticed a faint coolant smell. A few miles from my driveway the low coolant light started flashing. Then about 1/2 mile from my driveway the temp gauge went all the way up and the light went to steady red.

I instantly pulled the car over and shut her down. Lots of steam/smoke and coolant was pouring out from below the car towards the front of the engine. Towed it the rest of the way home and parked it.

Does this sound like a water pump failure? Do you think there would be any engine damage from overheating into the red, even if it was as brief as it was? I'd say the engine was only running at that high temp for 10-15 seconds or so before it was stopped and shut down.

When I got it home I swiftly put in an order from Pelican for a water pump, t-stat, and belt, with all new gaskets.

I am assuming the plastic impeller probably self destructed. Is there a good way to flush the debris from the impeller from the cooling system? I just got this thing back on the road, so I am hoping that there is no significant engine damage from this. Some encouraging words would help me feel a little better. Lol

2001 Boxster S 6M with 108k miles.

I read through some old threads today and see that there is a decent method to back flushing the coolant system to try to remove the plastic bits from the old impeller. It would seem that I am not the only one that has had a water pump go while driving and overheat. It seems most engines that have gone through this have been fine in the end as long as they were shut down fairly quickly. Fingers crossed, I guess.

Wishful thinking................

That's kind of scary coming from you. What are your thoughts on the chances of significant engine damage? Care to elaborate? I appreciate any insight here.

I think you could be fine, but once you put it back together, sell it on as you don't know when/if the damage will manifest itself, or not.

You should have switched the car off at the low coolant warning, topped it up with water or whatever and then driven it home. But if you were sure that the water pump was broken, got it towed home.

Good luck.

Simple: Overheating any engine entails risk of component failures, particularly an aluminum alloy engine, it is very risky business. We have had to replace multiple engines that suffered from that. Overheating can thermal expansion that can cause components to warp or lose structural integrity. Cylinder head cracking, and cylinder liner problems can result.

When we get one in that has been overheated, we typically run some extra diagnostics (pressure test the cooling system looking for signs of internal cracking, and run a leak down test on the cylinders) before returning the car to the customer, just to prevent any "come backs" from problems introduced by the thermal excursion.

Understood, and completely agree with everything you stated. I've owned a lot of different vehicles with different engine setups (iron block and heads, iron block aluminum heads, aluminum block and heads, etc.,) and understand what can happen when things get too hot. I have not completely familiarized myself with these engines.

I was more fishing for a response like "90% of these engines that I see, when overheated, result in cracked heads" or "if these engines see 250*F they are almost guaranteed to have cracked heads". Or better yet how about "nah, as long as it was shut down very quickly you should be fine", THAT was my wishful thinking. Lol

Some of the stories I have read on this forum have included drivers running their cars for extended times trying to make it home or to a dealership while the engine is overheating and the end results were not catastrophic. While in my case, it was shut down as quickly as possible and may have not even hit the 250 mark.

Either way, I am replacing the water pump and t-stat, flushing the coolant, adding the coolant under vacuum with the airlift tool, and then I will see how it ends up. The tank and cap have both been replaced. Fingers crossed.

Just an update:

Spent a few days last week, after work, replacing the Tstat, water pump, belt, and coolant. Everything went very smoothly, much to my surprise. A pretty easy task, even on Jack stands with a creeper. Flushed the cooling system a few times, didn't recover any plastic bits from the impeller, unfortunately.

The airlift tool is worth its weight in gold.

Got it all put back together and took it on a few hundred mile run up to a car show in Northern Michigan, in 90+ degree temps. Had to idle in traffic a few times and even sat at a coffee shop drive through with the wife for way to long 🙄🙄. Never budged above the 8 on the 180 mark.

Got home yesterday and let it sit for the night. When I got home from work today I pulled the oil filter (it was at the top mark on the dash when sitting from a recent oil change, so I wanted to recover a bit to get it down a notch or two). Inspected the oil to the best of my ability, and I see no signs of intermix in the oil.

I'm aware that it could take a bit to show up, but I see this as a good sign. I also know that there is going to forever be a risk of a plastic bit creating hotspots in the heads, as the impeller was chewed up a bit, but not a whole lot i can do about that aside from endless searching. Is there anything else I should be watching for over the next few hundred miles?

Overall, I'd say so far, so good.

I really wouldn't sweat it.
JFP notwithstanding, my 99 blew the coolant tank and dumped pretty much everything in the middle of a national park.
That was 10,000 miles ago and I just ran a track day with it last spring with no issues. It does tend to run warm at times but nothing outrageous. I did the wheel liner mod to let air through instead of all down and that seems to have helped some. But no pegging of the gauge or coolant loss.
There are so many possible failure points in the M96 that I don't even worry about them. I just enjoy the car and maintain it. If it blows, it isn't the end of the world.
Don't let worry negate the fun!