The Stovebolt Site Forums The Shop Area Engine Shop Water pump failure - Bonneville

Jest spent a few hours trying to figure out why the heater on the Bonneville won't heat. Heater hoses were hot, heater core cold. Backflushed the core, water flowed, no junk out, new core installed last winter. Water temp 200*, but seemed to surge big time when the thermostat opened, then stopped flowing. Tonight I decided to check coolant flow through the heater, nothing. So I pulled the hose off the engine and started the engine. Still no flow. Hooked it all back up, drove to warm up engine again, and with thermostat open no coolant flow through upper radiator hose. What gets me is the engine doesn't run hot, but it's only a 15 minute drive for the kid to get to school.

In all my years of turning wrenches, I've never had a water pump fail to pump, it's always been the bearings failing first. Only thing I can figure is the impeller has broken, lost it's vanes, or something. I want to be sure before I tear it apart, it's not an easy job, the pump flange is behind the engine mount, which must be removed. I put a rebuilt pump in it two years ago, I'll be checking on a GM part tomorrow.

Anything else I should check before go any farther?

open the cap and start it up make sure you are down a little coolant start up and let warm up carefully place your hand on the upper hose. you will feel the hose get hot and watch the coolant flow thru the radiator it should stop when thermostat closes itmoves pretty good, you might have a air bubble some place I dought it

Is the serpentine belt routing messed up? there may also be right and left rotating water-pumps on similar engines.

Saw a rebuilt pump once with no impeller(fins) on back. Car ran hot, couldn't figure out why, pulled new pump & removed rear cover-nothing but shaft! Factory rebuilt part also!!! Have also seen fins eaten off by GM's Dex-Clog orange coolant.

Some water pumps have plastic impellers nowadays. It certainly is possible that yours left the scene. It is more common in marine engines. If your engine does not run hot, though, I would suspect an air pocket or a faulty valve in the system. Most modern engines have a bleed procedure to get water to the heater core, since they are usually above the water neck. My BMW has a bleed screw on the water neck.

Question: 1994 Pontiac Bonneville se 3.8 mileage: 110,000. I am in the middle of installing a new water pump on my car. In doing so it looks like the arm off the shock has to be loosened, is this true? I have all 3/8 bolts out. I am kind of at a stand still on this can you help me. Let me know what has to be removed and how to remove it.

Answer: Your should be able to remove the water pump without loosening the shocks. Check the old pump to be sure you did not miss a bolt.

-
- Found this on another repair forum.

Luke, what board was that on? On my 93 there is a bolt under the engine mount. Last time I was able to unscrew that bolt without pulling the mount, but there wasn't enough room to get the bolt past the frame part of the mount. It was easier to remove the mount.

Back to mine, I bled the air out following the instructions, the heater core and hoses are below the filler neck. I was just talking to a co-worker, and he is like me, never heard of an impeller fail completely. His suggestion was to check for a blown head gasket, which is possible since I have 190,000 miles on the engine.

Is the motor overheating? Is the radiator getting hot (coolant flow)? Any water loss? Any performance problems? If all seems normal besides heater core, check for non functional heater control valve.

And you want difficult? Try changing the water pump on a '89 caddy with V8 and FWD. Uggh.

Can you pull a heater hose off when running and see if it squirts water? (Before heater valve)

I will drive it this evening to see what the temp gauge is showing. Only coolant flow in radiator is in surges, thermostat opens an I get one rush of coolant, then no flow. Water loss? I added less than a pint, first in about 3,000 miles. Heater control is done by venting, no coolant valve on this model. No coolant flow to the heater, I plugged the return and hooked a hose to the feed, got next to nothing. Just to be sure I reversed my plug and hose, got nothing.

I either have an air lock like I've never had or a bad water pump. Don't know whether to do a compression check or pull the water pump first, one job will take as long as the other.

What happens when you rev the engine?

The engine speeds up, just like it's supposed to. But it still doesn't move any water.

Shouldn't water run out of heater hoses anyway? Even if motor not running, open the system on most cars and water runs out.... Is radiator getting hot? Then water pump is working. Can you see the rad core on this model car? Can you see flow? Cooling fans coming on? You sure you got water in this thing? Sure thermostat isn't stuck? All things being equal, the easiest explanation is the best. got me wondering.....

So fred does this GM model have to be "Burped"? Have you change the thermastat lately or done anything to the cooling system? I would pull the thermastat and drill a small hole in the flange to help "burp" the system of air. But I think the impeller has gone south on ya....

Let us know what happens

Pardon me while I utter a string of profanities.
[img]http://www.fradsplace.com/icons/icon18.gif[/img] [img]http://www.fradsplace.com/icons/icon19.gif[/img] [img]http://www.fradsplace.com/icons/icon24.gif[/img] [img]http://www.fradsplace.com/icons/icon23.gif[/img]
First, I checked the thermostat. Popped at 200*, just as I thought. Then I pulled the water pump. Impeller is steel, and is good. I'm to tired and sore to put it back together tonight. I will back flush tomorrow, and see what happens. Thursday I will have the stepson again, so we will do a compression check then.

Give me 40 sticks of dynamite and I'll blow this car to h***.

See if you get air flow through the heater core.
There should be a control valve somewhere in the system.... most likely it is up under the dash if not visible in the engine compartment :rolleyes:

A friend of mine and my self both have Bonnevilles and have had problems with air locks happening with the upper heater hose, you can try installing one of those flushing T's in the heater hose or burping the air while up on car ramps as the heater core is higher than the rad in these cars.

The real question here folks is:

Fred, have you done anything lately to miff the Chief?

Ken - there was this post, must have been my downfall. Still Smokin

Luke - I've gone into the diverter, behind the glove box. The heater core was about room temp. I put a new core in it last winter. The diverter is working like it should, seals against both the a/c and full heat side, and stops anywhere between when the heat control is adjusted.

I still have the pump out. Tonight I will backflush out through the water pump, making sure the tubes and passages are open.

Albert, I hate those tees with a passion, but I am desparate enough to try it.

My parts guy suggested a plugged radiator, which I discounted, but I'm thinking that I might have a plugged radiator and an airlock in the heater hose. More diagnostics. At least my kid is learning quite a bit about how things are supposed to work and what to do to check them.

Pull the T-stat and run the garden hose into the uppermost water inlet of the motor. Water should run out of every hose and passage you got open. If not you got calcium or scale buildup in a water jacket or hose nipple. Maybe put garden hose to heater hose and see if you can get water to flow out of water pump opening, or other opening in water jacket. That'll make sure that there isn't a blockage at heater hose nipple in block. You'd be surprised what rust/scale/lime/calcium buildup will do even with the tasty green fido killer. (antifreeze)

Next pull both upper and lower rad hoses and stick hose into upper rad hose inlet. Water should flow freely from bottom of radiator.

Check business end of water pump and inside all hoses and rad for deposit buildup or other clues to what could be going on. Don't know about this car, but have seen others that use a section of metal pipe between engine water jacket and heater core. It can contain valving or other parts you may not be able to see readily. They also rust.

good luck

chip

Thanks, Chip. That was pretty much my plan for tonight. No tubes in the lower hose, but I had put the danged orange junk in two years ago, and have had one thing after another go wrong since then.

Here's a thought,
Is there still a spring in the lower radiator hose? If not it can collapse from the suction of the pump and choke off the flow.

Years ago I was riding with a friend in his '79 Cadillac and a loud knock started and the engine boiled over.
To make a long story short, he called a tow truck and we found out that the thermostat was stuck closed, causing the overheating. I asked the guy about the loud knock and he said that the engine had some type of flap in one of the water jacket's passages that would swing closed to prevent back flow of the heated water. That flap, or whatever he called it made the knock.
Anyway, new thermostat, no more knock, engine cooled ok. I never heard of anything like that before or since and can't figure out what would be the purpose of tha "flap", or why it would make such a loud noise. Maybe this helps?
Anybody ever here of that thing that the tow truck driver/mechanic was talking about or am I just dreaming. Anyway, the knock stopped after the new T-stat was put in.

Swampcat, I think he was blowin smoke.

Update on the Bonny. I flushed the block, both directions. Got the pump back in and flushed again, this time I got some pea sized chunks out of the thermostat hole. Ran water through the radiator, it flowed as much water through it as I could get in it with a garden hose. Tonight I'll get the hoses all hooked up and give her another try.

Victory. Got it back together this evening. Put in the tee, like Albert suggested and burped it there. Also burped the thermostat housing tap. I suspect between burping and the balls of gunk that I flushed out did the trick. My thanks to all.

I told the kid I would send him a bill for my services. He ran from me.