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Coolant flush for changing Thermostat

1K views 8 replies 5 participants last post by  txag_530i 
#1 ·
I'm changing a thermostat on 2008 BMW 550i V8 E60 model and just wanted to know draining coolant from radiator would be enough? Is it true that 90% of the coolant would come out of radiator? Can I change thermostat without draining a coolant? Many thanks.
 

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#2 ·
If you never have replaced your coolant it's time to do it now and NO you cannot replace thermostat without draining the coolant and just draining the rad will not do since thermostat being closed will prevent all the coolant from the engine to be released and once you remove thermostat all remaining coolant will make a mess and pollute the environment as it is impossible to catch it then....
 
#4 ·
If you want to reuse what you drain from the radiator, go ahead. Note the level of the thermostat (can't remember its position on the 550). If it's high up, you're likely only going to spill from the local hoses. Low down, more will dump from the coolant jacket. Your call on how big a mop you want to use :D.

IMHO: I change the coolant whenever I have to dump most of it. Since I should be doing it every 2 years, it just saves me a trip back under the hood to do it on a short schedule.
 
#6 ·
No. You need to drain it from petcock. BTW, these petcocks need to be firmly retightened, more than finger tight -- they'll leak under pressure if you don't give it a firm tightening. But, the petcock valve is plastic (on mine, anyway) so don't be a gorilla.
 
#7 ·
There'a vacuum tool that takes all the coolant (collapses all hoses) and allows you to replace the entire amount taken out with the same amount. You don't even need to burp the system as there is no air left in the system after vacuuming. I've used the one sold by Snap On but ECS has the same setup for sale. Unfortunately, for one vehicle, the cost of the tool may not make it worth it.
 
#9 ·
You can also drain the coolant by removing the lower radiator hose.

The device that RIHI is referring to is made by UVIEW and is called UVIEW 550000 Airlift. It runs about $120. I wish I had bought the tool because I've I've ended up draining the radiator several times on this car, and others.

I don't think that the V8 has an electric water pump, so you might want to consider buying the "SpillFree Funnel" made by Lisle, which runs about $25 on amazon. I used it on my Yukon and it really works well.
 
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