myonecent
03-14-2005, 11:10 AM
Just finished the job. Best time to pass along what I learned about the water pump and bleeding the cooling system.
Under the intake manifold close to the firewall is a cooling system accumulator that links to the rear of the water pump with two aluminum pipes approximately 1 1/2 inch and 2 1/2 inch diameter. These are sealed with "O" rings. The pipes are blocked from removal by the radiator. I wanted to replace the "O" rings in the cooling system accumulator but did not want to pull the intake manifold.
Bought a second water pump because the first one gurgled loudly. The thin aluminum pipes had cut the new "O" rings on the back of the initially installed water pump. Using silicone grease on the water pump "O" rings before installing the second pump caused the pipes to slide into the water pump much easier.
Slowly replaced the coolant and started the engine. The M60 is self bleeding. The engine again had a loud gurgle. Web postings cluster in two camps - "How do you get it to bleed?" and "Just rev it a little and it will self bleed." There are a few suggestions to use cooling system pressure testing equipment to force coolant from the expansion tank on the firewall or to even blow in the expansion tank to achieve the same effect. I tried all cited bleeding methods and still had the loud gurgle.
Here is what works. A full cooling system will self bleed given two conditions - unobstructed circulation and adequate Rpm's. Unobstructed circulation requires the heater to be on and the thermostat to be fully open. Just because your cooling system temperature gauge is at the twelve o'clock position does not mean the thermostat is open. With the engine turned off, for safety, feel the lower radiator hose which should be HOT. That confirms radiator circulation.
The self bleeding takes place from the 8 mm pipe above the top radiator hose. It leads to the expansion tank on the firewall. You must have the system closed, hot, and under pressure. The hoses are "hard" when under pressure. If the hoses are not hard, the system is not hot enough yet.
A hot open system will boil coolant and you will make no, little, or adverse bleeding progress. Leave the system closed.
You need the bleeder pipe to be the path of least resistance to get any flow through it. The pipe must be clear which is easy to confirm by blowing through it from the radiator end with the expansion tank cap removed and when everything is cold. Then you need the water pump to put out so much pressure that all other coolant routes are loaded enough to make the bleeder pipe the path of least resistance. I found Rpm's in the range of between 2,000 and 3,000 will permit the bleeder pipe to become a path of least resistance.
The process requires patience. After the lower radiator hose was hard and hot, I drove three miles around the neighborhood with a gear selected that caused the engine to vary between 2,000 and 3,000 RPM for blocks. I stopped, accelerated, drove blocks, and stopped. This finally bled the air and the gurgle is gone.
Under the intake manifold close to the firewall is a cooling system accumulator that links to the rear of the water pump with two aluminum pipes approximately 1 1/2 inch and 2 1/2 inch diameter. These are sealed with "O" rings. The pipes are blocked from removal by the radiator. I wanted to replace the "O" rings in the cooling system accumulator but did not want to pull the intake manifold.
Bought a second water pump because the first one gurgled loudly. The thin aluminum pipes had cut the new "O" rings on the back of the initially installed water pump. Using silicone grease on the water pump "O" rings before installing the second pump caused the pipes to slide into the water pump much easier.
Slowly replaced the coolant and started the engine. The M60 is self bleeding. The engine again had a loud gurgle. Web postings cluster in two camps - "How do you get it to bleed?" and "Just rev it a little and it will self bleed." There are a few suggestions to use cooling system pressure testing equipment to force coolant from the expansion tank on the firewall or to even blow in the expansion tank to achieve the same effect. I tried all cited bleeding methods and still had the loud gurgle.
Here is what works. A full cooling system will self bleed given two conditions - unobstructed circulation and adequate Rpm's. Unobstructed circulation requires the heater to be on and the thermostat to be fully open. Just because your cooling system temperature gauge is at the twelve o'clock position does not mean the thermostat is open. With the engine turned off, for safety, feel the lower radiator hose which should be HOT. That confirms radiator circulation.
The self bleeding takes place from the 8 mm pipe above the top radiator hose. It leads to the expansion tank on the firewall. You must have the system closed, hot, and under pressure. The hoses are "hard" when under pressure. If the hoses are not hard, the system is not hot enough yet.
A hot open system will boil coolant and you will make no, little, or adverse bleeding progress. Leave the system closed.
You need the bleeder pipe to be the path of least resistance to get any flow through it. The pipe must be clear which is easy to confirm by blowing through it from the radiator end with the expansion tank cap removed and when everything is cold. Then you need the water pump to put out so much pressure that all other coolant routes are loaded enough to make the bleeder pipe the path of least resistance. I found Rpm's in the range of between 2,000 and 3,000 will permit the bleeder pipe to become a path of least resistance.
The process requires patience. After the lower radiator hose was hard and hot, I drove three miles around the neighborhood with a gear selected that caused the engine to vary between 2,000 and 3,000 RPM for blocks. I stopped, accelerated, drove blocks, and stopped. This finally bled the air and the gurgle is gone.