Car Question

P

Patrick

Guest
I was hoping someone on here knows a thing or two about cars. Can anyone explain to me what a water pump is in a way that makes more sense than google?

Specifically, my car notified me that I need to "fill coolant liquid" shortly after purchasing it (its used) and this was while under warranty. The guy at the shop said no problem, just fill it up a bit because its just under the line. filled it up. a month later it ran out again (indicating a leak, which I suspected all along) but this time it was after warranty. Brought it in, said it needed some part that would take a week to come in. took a month. could still drive the car but it needed fixing. finally got it "fixed" and had a what I was going to say all planned out if he tried to charge me (since the issue dated to the in-warranty period. No charge. I was thrilled to have this over with. But it wasn't. Get home. park. sleep. wake up. turn car on and see check engine light and something that illuminates to read "TCS" on dash. bring it back to shop. told it is ok don't worry about it. Then drive car, works fine, bring it home. next day, car doesn't start. Or more precisely it turns on but when I stepped on the pedal it shut off immediately. I live two blocks away from the dealership/shop but had to have it towed there. Next day says it was simply a matter of having moved something out of the way when he fixed the thing that he had to order the part for and not moving it back to the right place so that it was getting electrical shortage or something. fine. a little annoyed but said fine. drove it the next day and it shut off while driving. lost power steering AND breaks. had to come to a stop by rolling. turned car back on and it worked. later that day, it did NOT work. had to bring dealer guy to the site instead of having towed. he reset the computer and said it "should be" fine to drive. he "thinks so." whatever. next day i drove it a mile and parked it. wouldn;t turn on again. now really frustrated. gave guy the keys and had to walk to work today. he picked it up and brought it to the shop and had it "fixed" again. SO here is my question - now he claims I need a "WATER PUMP" which will cost $250....this sounds like it has a pretty good chance of being related to what I FIRST BROUGHT THE CAR IN FOR MONTHS AGO and my question is, for anyone who knows about this stuff: is a water pump related to a coolant system? specifically, if it says fill coolant liquid, is the water pump the cause of this? I feel like charging the guy $250 and driving over his foot on my way out of the dealership. anyhelp would be appreciated
 
Funny, my 2003 Saab just had a problem with a crack in the water pump, and it needed to be replaced. Paid about $250. The dealership in Missouri claimed that there wasn't a single part in the entire USA, then, when we called up Herb Chambers, they had it waiting for us on a trip back to Boston. I think the water pump is related to interior climate, whereas coolant is related to engine temperature. But that's a total guess.
 
An automotive water pump circulates coolant in your engine. Link.

Toby is our resident auto enthusiast. Perhaps he'll weigh in.
 
Toby doesn't care about any car that is not worth at least $100,000.
 
well, my car is a 2000 Saab 9-5, so that is interesting, Kennedy. I don't know if the electrical issues have been caused by the water pump issue, but I strongly suspect the coolant issue was. Its like I brought it in to have it fixed and the guy fucked it up more. I can't very well complain to the person who is fixing my car, or they may be the like the waiter who "fixes" the undercooked burger by slipping in a booger.
 
Weird, mine is a 9-3, but both were built during the GM era. When the water pump cracked, it was very small and leaked only a tiny amount. The Missouri dealership just patched it and it ran fine, until we could get the replacement part. The car never once seemed to have trouble driving. Then again, this all occurred during a cold snap when it was never above 20 degrees.

Nonetheless, Saabs rock. I can't wait to see what they start rolling out under Spyker, starting with that new 9-5 (even if it is a GM model).
 
I owned a SAAB 30 years ago. It was a nice car.

OK. To business. Every internal combustion engine requires cooling. This is because the engine is a device for controlling and converting a series of explosions into motion. Heat is a consequence. Failure to regulate the thermal energy created may result in the expansion and/or meltdown of the engine's constituent components. This results in distortion, cracking, excessive friction and/or loss of compression. In other words, failure.

There are two types of common cooling methods: air and liquid. Air cooling is simpler, as it requires no plumbing. The engine is cooled by the passage of air over it, generated by the motion of the object that it propels, or a fan or propeller. Since we are not discussing aviation radial engines like in a B 17 of P 47, or Porsche 356's or 911's, we will end the discussion of aircooling right here.

Most automobiles are liquid cooled. This is because, unlike an aircooled engine, which is somewhat dependent on vehicle motion for proper cooling, a liquid cooled engine does not primarily depend upon vehicular motion to do its job.

The liquid cooled engine has nine constituent elements: the engine, the plumbing (hoses), the heat exchanger, more commonly known as the radiator, thermal sensors (the thermostat), fan, fan belt, the fluid pump (water pump), the pump drive belt (or sometimes a chain) and of course, the coolant fluid.

Here is how it works. The water pump draws fluid out of the radiator through a hose, and pumps it into cooling galleries inside the engine (little tunnels that run through the engine block). In a properly designed engine, these "water" passages go through the parts of the block that suffer from the greatest thermal shock, for example, around the cylinders and around the combustion chambers. The coolant fluid soaks up the combustion byproduct-heat. The now hot fluid flows out of the engine via hose and back into the radiator. The thousands of little fins on the surface of the radiator cause a heat exchange with the air, and the now cooled fluid is ready for its return trip back to the engine.

Overheating is due to a failure of one or more of the nine elements. Let's look at a few common problems.

Water pump: if it fails, fluid won't circulate and the engine will over heat. Causes of failure: shaft bearing loses lubrication; the pump seal that fits between the pump and the engine (to which the pump is bolted by 3 or 4 bolts) deteriorates and fluid leaks out instead of going into the engine cooling galleries.

Belt (or chain) failure: the impeller inside the pump is connected to a shaft that sticks out the front of the pump. The end of the shaft will have a pulley wheel (or in ancient cars a sprocket). That pulley wheel is driven by a belt that is connected to a pulley wheel on the end of the crank shaft. If the belt is worn out, it will slip, and the pump will work less well. If it breaks, the pump won't work at all. Over heat.

Deteriorated or poorly secured hoses will leak fluid. Failure looms.

Bad coolant: tap water contains minerals that will oxidize the inside of the radiator and engine cooling galleries. This creates silt, which leads to blockage and less efficient heat exchange. It is the equivalent of a heart attack for your car. Use purified water, mixed with a proper anti-freeze. The glycol in the anti-freeze has the beneficial effect of not only reducing the freezing point of the coolant, but of raising the boiling point above 212 deg. F.
If you don't do this, with either a freeze or a boil, the best you can hope for are burst hoses. Just as likely you will have a cracked engine block. Oh, by the way, make sure you top up your coolant now and then. Too little doesn't work. One more. Glycol is sweet to the taste. Don't use it around your pets; they will drink it and die. Keep that in mind if you spill, or over fill the radiator...the overflow will run out a little overflow pipe and make a nice green puddle in your driveway. Looks like Midori to Toby and his pals.

Thermostat: this is a little device that sits inside one of the coolant hoses. It is thermally activated valve that costs ten bucks. When your car is cold, it sits in a closed position. That stops the flow of coolant through the hoses, and lets your engine heat up quicker. When the coolant in the now non-circulating system hits about 180 degrees, it opens and the coolant begins to circulate. Why have it? It lets your engine warm up faster to its most efficient operating temperature. In cold weather regions, it means you will get heat faster. If this little sucker fails in the closed position, your car will overheat. If it fails in an open position, you will notice that the engine runs cool (less efficiently), and that your cabin heat isn't as good.

Fan and fan belt: wait a minute you say. This sounds like air cooling! You are right. The liquid cooled auto engine usually needs some help, especially in very hot ambient conditions. If your fan belt slackens, or breaks, it will stop turning that fan up front that provides a nice breeze to the engine and draws air through the radiator at slow speeds. That means less efficient heat exchange, which means failure. Check your fan belt.

Anyway, this is pretty much the same for every liquid cooled auto, be it 1 year old or a 100 years old, $500 or $500,000. Modern cars have a lot of b.s. electronics on them that screw up the simplicity, e.g. electronic rather than thermal actuated thermostats; sensors and relays that kick on electric rather than constant belt driven fans. Mostly designed to heighten fuel efficiency at start up, and by eliminating unnecessary load, I guess.

If in fact your water pump failed, and not one of these other things, $250 is a great price. If the pump cracked, and your car hadn't overheated before, it would be interesting to know if there is a history of casting problems for the pump body.
 
Wow...thanks so much. That was really informative and I appreciate it very much. I'll probably print it off for future reference. Thanks a ton.
 
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