Well, I finally lost my virginity... In terms of my water pump, that is.
I had the stock WP in my '98.0 SVT until yesterday. My philosophy was, given that any repair/replacement could cause its own problems, I wasn't going to do a "voluntary" pump replacement, but instead I'd be prepared in case mine crapped out. So, starting with about 50k miles on the clock, I'd take a spare WP, coolant catch pan, and extra coolant with me on road trips. I already keep a socket set and other basic tools in the car at all times.
Yesterday, I had a vehicle inspection in Rangely, Colorado, about 280 miles west of Denver. I could've flown to Grand Junction, but from there it was still a 100 mile drive, and for the return trip I'd be at the mercy of the airline schedule. So I told myself, screw it... I'll just drive, and in the end I'll get home sooner! Not to mention, essentially the entire trip is mountainous and/or twisty.
The trip was fun, but uneventful, until the return leg when I got on I-70 at Rifle. As I got up to cruising speed, the temperature gauge starts climbing... and climbing... M... A... L... and then stops between the L and the red zone. Immediately, I put the climate control on max fan, full hot, and I'm flooded with hot air. Hmmm... Some water's still circulating, bur I'll stop at the next exit to check. As I slow down on the ramp, the needle quickly drops to its typical location between "O" and "R". I get out to check the coolant reservoir. Level's OK, nothing has burped out past the pressure cap, no steam, no funny smells. Radiator hoses are properly warm.
At this point, I'm thinking either my temp. sender has gone bad, or my thermostat is sticking shut and only suddenly opening when it's way above its set point. Since it's Friday and I want to get home to see my family, I figure I'll limp on down the road but keep the cabin heat on high and watch the temp. gauge like a hawk.
For the next 25 miles or so, through Glenwood Springs, the heater's cranking out plenty of hot air, but the temp. gauge swung up to the edge of the red zone, then back down to normal, about every 2 minutes. All this time, I'm going 60 in a 75 zone and getting plenty of funny looks, but the evidence indicated I was still getting some cooling. I go through Glenwood Canyon, where thankfully the speed limit is only 55 anyway, walking on eggshells. Still, the behavior remains the same.
Finally, exiting Glenwood Canyon, it happened for real. The heat from the vents abruptly stopped, and I knew then and there the water pump impeller had breathed its last. I popped it out of gear, shut off the engine, and coasted to a stop. I just missed a freeway exit, but amazingly I came to a stop on an uphill just past the on-ramp, so I simply coasted backwards the wrong way on the on-ramp to get away from the high-speed traffic and find a wide spot on the shoulder. I called my wife, told here I'd be delayed coming home, and got to work.
I noticed right away that a small amount of coolant had burped out past the pressure cap, but the reservoir level has not dropped noticeably. While things were cooling down, I removed the air filter and intake accordion tube to make it easier to undo the rear battery clamp nut. I removed the bottom splash guard, battery, plastic water pump cover, and WP drive belt. I went ahead and jacked up the right-front corner of the car to give myself a tad more clearance to access the radiator drain. During all this, I could hear coolant burbling through the hoses, but I figure it was just convection currents within the cooling system.
From there, it was nothing special, except for breaking the impeller loose from the WP body, for which I used a screwdriver and hammer. Pulled off the old impeller, and thankfully, the entire impeller is still there, but cracked. This told me (a) that I didn't have chunks of plastic lodged in bad places throughout the system, and (b) that the WP was, indeed, the cause of my woes. Phew. There was a a fair bit of old gasket material still stuck to the WP body, but I simply torqued down the new impeller and gasket on top of it. Filled up the system, put everything back together, started it up... Got warm air!
I let it idle while I put my tools away. It burped a little bit of air, so I added a little more coolant. I then drove ~5 miles to the next town, the level had dropped in the reservoir, so I topped off the coolant again. The temp. gauge was right where it had always been, and I got hot air on demand. The car drove fine, although it idled a bit squirrelly at first (after all, I had disconnected the battery and it was re-learning how to idle at 7500' elevation).
When all was said and done, I figure the WP repair delayed me about 90 minutes. Not bad at all, considering the circumstances (probably would've waited that long for a tow from AAA). As of this morning, still no evidence of leaks. I win!
I'll post pictures when I get around to it.
In the final analysis, I was extremely lucky because I was prepared with the proper tools, I managed to get off the freeway, it was daylight, and the weather was typically beautiful (I love Colorado). While things certainly got hotter than normal, there's no evidence of catastrophic overheating. I believe that as the WP impeller finally started to let go, its performance degraded (impeller started slipping on the shaft) such that it couldn't move coolant past the thermostat unless it was cranked fully wide open. Coolant continued to go through the heater core, however, which explains how I was getting hot air. Eventually, the cracks in the impeller grew large enough that it didn't spin at all, and that's when I stopped getting hot air. Thankfully, I stopped quickly at that moment.
Here's the punch line... The odometer reading while I was stopped? 74,970. Didn't quite make it to 75 thousand.
