Taking my car into my friends shop in a few minutes along with a gallon of water and another of coolant (I used a mirror and checked, leaking coolant out of water-pump weep hole). Over the years and many different owners, this thing has blown water-pumps about 6 times. (installed by different mechanics too) The radiator has been replaced, and all of the cooling system in piecemeal, I even tried a new surge tank cap (maybe something with the pressure). What do you think or know can cause this? Looking for answers here. I’m assuming crappy parts (getting a quality one this time). Just want to get an idea. Mechanic thinks its a pressurization problem or because I use mostly aftermarket parts they may not be up to manufacturer specs like OEM, going to try and fix it up, but I am curious about other ideas if anyone else has experience with the issue.
2002 Chevy Cavalier. Failed pump 6 times thus far over the course of 10 years… I got it repaired, and yep it turns out, at least according to my mechanic that the pulley needed to be replaced, it was warped ever so slightly that over time it was wearing out the bearings in the pump with its wobble (seen it, even when attached perfect). Didn’t help that the belt was so damn old. Fixed it all up, new pulley, pump and belt, radiator flush and fill, for $303.00. The strange but great thing now, the temperature gauge is staying on 180 degrees, used to stick to around 200… I guess it more efficient now, or because I bought a pump that doesn’t have a plastic impeller. I always thought it was because the car is a frankenstein of aftermarket parts and the cooling system parts weren’t playing well with each other.
I had a similar problem with my Subaru Legacy. I had a minor front end collision. No, the fan and radiator never made contact, and neither the fan nor the radiator was visibly damaged. But I started going through water pumps monthly. They’d dribble or downright pour out coolant. They kept getting replaced on warranty, at $1100 per month, and the garage (a large and good local one) couldn’t figure it out.
The last time it happened, I noticed that the lower radiator supports appeared to have bent downward, so the radiator sat a little bit low. The radiator cap was wedged against something so that it wasn’t seated squarely. I wondered if its venting function was compromised, and perhaps the system spent significant amounts of time operating at a vacuum, causing the pump seal to run dry. I never found out, though.
I suspected the radiator surge tank myself myself, figuring I probably had it or a hose not seated properly since my old one cracked and I got another out of a pontiac sunfire at the junk yard and swapped it, but it seems good. I’m very suspicious of the cap on the surge tank, since it takes a little but more effort to get it on (almost as if the surge tank cap threads swell with heat or something) but mechanic suggests that the cap is fine. I got a waterpump with a lifetime warranty, so my mech. told me not to worry, if it craps out he’ll replace it and fix it up for free (no labor). Still bothers the hell out of me since I always want to know how things work. Not to mention the time hassle if it goes out. I have heard horror stories with this particular make/model of car ( chevy cavalier) and other models (sunfire, beretta, corsica) just burning through water pumps. I’m definitely going to take another look at those particular things just in case, thanks Napier.
I would venture to guess that that is pretty much impossible.
The vent cap in the overflow radiator is designed to release pressure into the overflow tank as the coolant heats up. If the cap can’t vent, the end result is a blown head gasket or burst radiator hose or burst radiator core. If the cap won’t seal, you will lose coolant, due to the reduced pressure in the system, and the commensurately reduced boiling point of the coolant. Remember that the radiator is pressurized - the only way for the system to have below atmospheric pressure would be to pull a vacuum on it externally, or for the radiator to be clogged and the water pump pulling a vacuum on the inlet side (in which case the car would overheat very quickly).
even with a faulty cap wouldn’t the overflow hose in a surge tank likely relieve pressure? A nitpick of mine is how my car has the hose designed where it would overflow right over the serpentine belt, So I angled it (not pinched) away, fearing contamination/coolant flowing onto the belt is somehow getting into the pump’s bearing behind it’s pulley. Pointless move on my part?
First of all, you shouldn’t be venting coolant. If you are, it means the engine is overheating. Coolant on the exterior of the pump isn’t going to hurt it, but it might cause the belt to slip, which could potentially damage the belt and cause poor charging, A/C operation, etc.
No overheating though, I mean more of a sharp turn or something causing a little to spill out of the overflow hose. The way its designed its only about half an inch above the tank FULL line. Little drops one the belt. It makes sense, belt was worn, occasionally heard squeaking from it, the one side of the belt was shiny so it makes sense it make have been slipping.
Could coolant potentially cause a bearing to fail? Just curious. Maybe it picks up soot/dirt and gathers with the drops over time.
I don’t see any way a small amount of coolant spilling on the pump or belt could make the pump fail. Pumps leak due to worn shaft seals or worn bearings. Both of those are caused by shaft vibration (bent pulley), too much side-load on the shaft (belt too tight) or too much thrust load (out-of-plane belt).
My thought was that the cap might be malfunctioning in that it would allow air and water vapor to escape while the system was hot and its pressure tried to go up, but would not allow air to come back in when the system cooled down again. Certainly, the temperature and therefore equilibrium pressure of the system would cycle up and down if the cap was completely sealed in both directions, and so a cap that vented pressure but blocked returning air (due to some hypothetical malfunction) could leave the system with a vacuum some of the time.
Thanks for the responses! I suppose getting a new cap with proper pressure rating can’t hurt, I’ll do that and see how it works out with this new water pump.