Coolant flush help
07-04-2009, 06:18 PM
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Coolant flush help
i have a 1981 928 (automatic) and i am doing a complete coolant flush and i was wondering if there was a more direct way to pour coolant into the system rather then the reservoir also i know were the drain plug is on the radiator thats easy but were are the others on the engine located? thank you
07-04-2009, 06:35 PM
#2
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The reservoir works fine, however, the radiator won't fill until the T-stat warms up. So, to speed things up, you could pull the upper radiator hose off the water bridge and pour into that to fill the radiator first. You still need to wait until the t-stat opens and circulates water through the radiator and fully fills the return hose. Also, run the heater during filling to fill the heater core. The system self burps air, although you can loosen the temp sensor on the waterbridge during filling, a high point, if you want (really not needed). Drive the car a bit and re-check the level.
Here is a pic from the WSM of one the block drains. Notice the exhaust header and that the drain plugs are just above the gridle/block seam towards the rear of the motor.
Here is a pic from the WSM of one the block drains. Notice the exhaust header and that the drain plugs are just above the gridle/block seam towards the rear of the motor.
07-05-2009, 10:18 AM
#3
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Tony has a good writeup w/ pics at: http://members.rennlist.com/v1uhoh/coolant.htm
I could have swore Dwayne had one too---had pictures of him draining the block with a kiddie pool underneath, but I can't find it witn a search...
I could have swore Dwayne had one too---had pictures of him draining the block with a kiddie pool underneath, but I can't find it witn a search...
07-05-2009, 02:37 PM
#4
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you mean the engine wont fill until the engine warms up, right? you pour the coolant right into the reservior, and it feeds direcly into the radiator.
The reservoir works fine, however, the radiator won't fill until the T-stat warms up. So, to speed things up, you could pull the upper radiator hose off the water bridge and pour into that to fill the radiator first. You still need to wait until the t-stat opens and circulates water through the radiator and fully fills the return hose. Also, run the heater during filling to fill the heater core. The system self burps air, although you can loosen the temp sensor on the waterbridge during filling, a high point, if you want (really not needed). Drive the car a bit and re-check the level.
Here is a pic from the WSM of one the block drains. Notice the exhaust header and that the drain plugs are just above the gridle/block seam towards the rear of the motor.
Here is a pic from the WSM of one the block drains. Notice the exhaust header and that the drain plugs are just above the gridle/block seam towards the rear of the motor.
07-05-2009, 10:07 PM
#5
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No. When cold, the coolant recirculates through the engine. The circulation through the radiator is blocked off by the cold thermostat sealing off the return from the radiator and opening a bypass passage back into the block. However, yes, coolant dumped into the reservoir goes into the radiator as well as the block, despite the lack of radiator circulation until the T-stat warms up. The bleeder at the top of the radiator will allow air to escape and the fluid to fill it. Not quite as fast as dumping it staight in, but that's why I just fill and refill the reservoir while running the motor, heater on, until the fans start, signaling that the T-stat has opened. On a cool day this may not happen and may leave some air trapped in the return hose, so maybe I should have suggested filling the radiator via that hose instead of the upper hose. I don't do either but just re-check the water level the next day or so.
