: Bad Waterpump???



DIXIEDOG
09-07-07, 09:01 PM
I have a 94 Eldorado that has an overheating problem. I changed my lower radiator hose because it was wet and I changed the thermostat while I was there. My question is why my coolant doesn't seem to circulate at all. After the car gets up to 200 degrees I squeeze the upper radiator hose and there is no pressure. I originally thought the pressure was just low so I pulled the upper radiator hose off and it is dry as a bone. I looked at the impeller on the water pump and it looked like it was OK all the blades are there and complete. Is there a screw to bleed the air out of the coolant system or does it just purge through the overflow? The radiator was changed approx. 1.5 yrs ago by the previous owner so I don't think it is clogged. Am I looking at head gaskets?? In the past when I had bad head gaskets there was still flow through the cooling system but I know nothing about the N*. If it makes a difference there isn't any white smoke out the exhaust.

zonie77
09-07-07, 10:19 PM
It purges through the hose that runs to the surge tank. See if there is flow at idle.

DIXIEDOG
09-08-07, 10:41 AM
There isn't any coolant coming through the bypass hose. I took an air compressor and blew air back through the hose and something did get pushed out and then there was coolant bubbling in the tank when I blew through the bypass hose so it doesn't seem blocked now. I started the car again and pulled the bypass hose but there still isn't flow, do I need to get the car up to temp so the thermostat opens or will it flow even when cold?

Ranger
09-08-07, 11:32 AM
The purge line should flow cold. Something is clogging it. Pull the fitting on the engine side and check it. Whatever you cleared with compressed air may have flowed back and clogged it again. Someone once said he found a piece of deteriorated radiator hose clogging it.

DIXIEDOG
09-08-07, 12:12 PM
Just to be sure I am looking at the correct line, the purge line is the line on top of the overflow/reservoir in the front corner on top. (not the line that just directs coolant to the ground the other line on the top.

zonie77
09-08-07, 12:26 PM
I think you have the right one. Take it off and clean it out or replace it.

The other end is near the water pump.

DIXIEDOG
09-08-07, 12:38 PM
I took it off and blew it out. The other end is on the engine right next to the throttlebody. I put the reservoir end of the bypass hose back on and blew compresser air into the fitting on the engine side and coolant came out through the bypass hose. When I use compressed air to force coolant through the engine it comes out in spurts not as a steady stream. Is this normal? Could I have a bad reservoir cap causing this?

AJxtcman
09-08-07, 03:49 PM
How are you getting the air out of the system?
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The system must be full to the fill line and NO air in the system. The water pump has a hard time pumping air. If you have an air pocket trapped the water pump will have difficulties pumping the coolant at the water pump. The air pocket will act something like a balloon. When the coolant is forced against it it will slightly compress and the push the water backwards. As like if you pushed on a balloon and released it.

I use a Vacuum fill system, but you can do it in other manors.
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I would remove the upper radiator hose at the engine side. This is the long hose that goes to the right side of the radiator.
Fill the Radiator though the hose. Pour the coolant into the hose until it if full.
With the hose still off fill the engine through the reservoir fill cap. Fill the engine until coolant comes out of the engine at the Radiator hose nipple.
Reconnect the upper radiator hose and fill the reservoir.
Run the engine for 20 minutes allowing the thermostat to open.
Let the engine cool to about 100 or less.
Now remove the fill cap and check the level.
Fill if needed.
Run the engine up to operating temp and you should have pressure

DIXIEDOG
09-08-07, 05:05 PM
I didn't purge the air. That is why I asked if there was an air bleed screw somewhere for the cooling system. (I just poured coolant into the reservoir) My system acted air locked, after I blew compressed air through the bypass hose again, I started the engine and revved it up to around 2000 in neutral and then pulled the bypass line and I started getting coolant flow. Should I still fill it using the upper radiator hose method you suggested. I drove the car for about 20 miles and it ran cool until I floored it then the temp went up to 230, I was only a mile or so from the house so I went home, put the car in park allowing the enging to idle and the temp climbed up to 238 and dropped back down to 210. Both cooling fans were running and the radiator hoses were firm. It seems like that is way too hot to me but I don't know exactly how hot the N* usually runs.

zonie77
09-08-07, 05:22 PM
Ajx's technique is a good one. It gets the system as full as possible before starting it.

I don't want to get anyone too excited but if it's been overheating (and acting like you described) get an exhaust gas test done on the coolant before you put a lot of other parts on it.

The car has to be driven with the coolant in it awhile to get an accurate test. A radiator shop is the quickest and cheapest place to have this done, or you can buy a kit at many auto parts stores. The kit will do the test multiple times.

When N*'s initially get head gasket leaks it can be difficult to confirm. Plus, at the age of the car there are a lot of other parts that could be contributing to overheating.

Do a search on HG's and read up.

Ranger
09-08-07, 05:32 PM
No bleed screw. It is self purging. If you just pour the coolant slowly into the surge tank and then rev to 3000 - 4000 RPM once or twice you should be fine. The purge line will spit coolant at idle and flow more at higher RPM. Flow is RPM related.

I agree with Zonie. Have the coolant tested.

AJxtcman
09-08-07, 05:52 PM
With the thermostat on the lower rad hose you can get an air pocket in the hose and the thermostat will not open. You said that you replaced the thermostat. Did you use GM parts? I know that most GM belts, hoses, and thermostats are Gates, but Gates sells different levels of parts. Did your thermostat have an air bleeder? I have seen some old GM Northstar thermostats that did not, but all the replacement thermostats do. If it does not have an air bleed on the thermostat you will have trpped air at the thermostat.
If it does not have one. you could losen the hose clamp at the thermostat hosing for the lower hose and bleed the air out..
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The fill proceedure on a CTS is through the upper hose. :lildevil:

DIXIEDOG
09-09-07, 03:48 PM
I used a Stant thermostat which does have the air bleeder on it. I will drive the car for awhile and have the coolant tested for exhaust byproducts to rule out the headgaskets. If I am lucky the headgaskets are OK because the headgaskets on the N* look like a real pain.

DIXIEDOG
09-11-07, 06:17 PM
How are you getting the air out of the system?
.
The system must be full to the fill line and NO air in the system. The water pump has a hard time pumping air. If you have an air pocket trapped the water pump will have difficulties pumping the coolant at the water pump. The air pocket will act something like a balloon. When the coolant is forced against it it will slightly compress and the push the water backwards. As like if you pushed on a balloon and released it.

I use a Vacuum fill system, but you can do it in other manors.
.
I would remove the upper radiator hose at the engine side. This is the long hose that goes to the right side of the radiator.
Fill the Radiator though the hose. Pour the coolant into the hose until it if full.
With the hose still off fill the engine through the reservoir fill cap. Fill the engine until coolant comes out of the engine at the Radiator hose nipple.
Reconnect the upper radiator hose and fill the reservoir.
Run the engine for 20 minutes allowing the thermostat to open.
Let the engine cool to about 100 or less.
Now remove the fill cap and check the level.
Fill if needed.
Run the engine up to operating temp and you should have pressure



I had the overheating problem occur again, coolant flow stopped acting like it was air locked again so I attempted to fill the coolant through the upper radiator hose and then fill the engine through the reservoir fill cap but the coolant never came out through the radiator hose nipple. Are you talking about the upper radiator hose nipple?