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Discussion Starter · #1 ·
Hey all - took the opportunity today to replace a turbo-charger that was on it's way out. All went well, and I stitched the car back together with no problems.

Oil in. Check.

Coolant in. Check.

Crank the car up, reach over to open the coolant air-bleed valve on the thermostat housing, and... no valve. Just a blanked off spot on the housing where the bleed screw normally resides.

Car is an '88 Aero/SPG. I have another 88, a 92 and a 93 - all have the valve in this spot. Weird.

Two questions: (1) are there other locations that are commonly used to bleed air from the coolant system, and (2) how worried should I be about the whole bleeding thing anyway? I did a quick search on the forum on this topic, and someone (Jim I think) suggested that trapped air isn't normally a problem in the 900.

Any/all advice gratefully received - thanks :)
 

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No it doesn't really matter, just make sure it has enough coolant, all the air should eventually bubble into the expansion tank up the hose from the rad.
 

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Discussion Starter · #3 ·
Awesome - thanks s900t. I had visions of getting drenched in coolant whilst pulling the expansion tank to radiator hose off to let out whatever air was left in there. Couldn't think of anywhere else to bleed.... So, all good :)
 

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Find some good steep hills and drive up, have lunch, check coolant, drive down. For added reassurance operate heater at full heat for several minutes while going uphill. Also good excuse for finding some hills to drive;ol;
 

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I agree with operating the heater but what do the hills do ? :lol:
 

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I agree with operating the heater but what do the hills do ? :lol:
While level, the engine has parts that are higher than the highest part of the radiator inlet. Going up a (steep) hill changes this enough that gravity is now your friend, and assists in the bleeding of the head and heater core.
 

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While level, the engine has parts that are higher than the highest part of the radiator inlet. Going up a (steep) hill changes this enough that gravity is now your friend, and assists in the bleeding of the head and heater core.
Nice ;)
 

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You actually don't have to do a thing.
The reservoir is the highest point when completely full, except for the heater, which doesn't have a bleed screw anyway. Any little bubbles will get carried along in the stream of coolant and end up in the reservoir where they belong.

The bleed screw was more important on 8v engines because they didn't have little bleed holes in the thermostat (at the top). On rare occasions, when refilling, air could get trapped in the top hose and prevent the thermostat from getting hot enough to open.
 

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I've never bled any part of my cooling system, including heater. It all comes out naturally and ends up in the reservoir via that little hose from the top of the rad.
 

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Squeeze the upper rad hose a few times, that usually does it right away (like 99%) and you don't have to worry about checking the coolant level after.
 

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Discussion Starter · #12 ·
Thanks all for the responses; always good to get the pragmatic view from the community vs. the 'by-the-book' view in Bentley.

Drove the car ~300k yesterday. All good, apart from a minor leak on the turbo coolant intake connection. Torqued the banjo a little more to compress the washers a tad, and that seems to have sorted it. ;ol;

Thanks again!
 

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Crank the car up, reach over to open the coolant air-bleed valve on the thermostat housing, and... no valve. Just a blanked off spot on the housing where the bleed screw normally resides.
Someone has probably installed a 9000 thermostat housing in place of the 900 housing. The 9000 housing doesn't have an air bleed valve.
 
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