How to drain W12 engine BLOCK from coolant?
04-08-2018, 02:08 PM
#1
AudiWorld Member
Thread Starter
How to drain W12 engine BLOCK from coolant?
Any good tips, except taking engine apart?
I think I will remove thermostat tomorrow and suck out the coolant through the thermostat hole. I want to replace every single last bit of coolant to get rid of constantly glogging heater cores under kickdown.
I think I will remove thermostat tomorrow and suck out the coolant through the thermostat hole. I want to replace every single last bit of coolant to get rid of constantly glogging heater cores under kickdown.
04-09-2018, 06:21 AM
#2
AudiWorld Senior Member
A simple water flush will remove all old coolant. You are supposed to have a 50-50 mix of coolant and water so any residual water is just part of the new coolant mix. Do not try to compensate for that small amount of residual water. It isn't enough to measure.
04-09-2018, 03:41 PM
#3
AudiWorld Super User
FWIW, my drain approach is different, plus not convinced you will get at root of issue.
1. My main drain point is of course the lower main hose, but my other key one(s) are the hoses that go to the tranny + gear coolers. Those hoses sit as low or lower than anything in the whole block. I also just serially clamp one or another back together and blow low pressure air (by mouth basically) through from above to whatever remains open.
2. Consider some other ideas:
Realize there is the TSB in USA saying that the heater cores may have internal coating/erosion issues across all motors; the fix was a running parts revision circa 2007 to cores with better coatings. Moving the coolant back to a silicate type (original fill wasn't) may have helped with internal erosion issues too as far as the factory changes for later years. If failing internal passages to the heater cores is really the issue you have in the end, the flushing and all presumably wouldn't stop that longer run.
1. My main drain point is of course the lower main hose, but my other key one(s) are the hoses that go to the tranny + gear coolers. Those hoses sit as low or lower than anything in the whole block. I also just serially clamp one or another back together and blow low pressure air (by mouth basically) through from above to whatever remains open.
2. Consider some other ideas:
a. Do you have those asinine kludge floating silicate plastic cartridges in your coolant reservoir? I would fish all those out if you do, and check for deterioration. The G12++ or G13 has silicates now anyway, and ten year old + kludge cartridges are long dead.
b. Any consideration to whether your water pump impeller is deteriorating? Maybe your circulation isn't great in general as a possibility. The impeller is plastic IIRC, so could be both lower flow AND crap heading for your heater cores. I changed m water pump at one point FWIW, and impeller still looked very good.
c. Have you considered if any other plastic joints and fittings throughout cooling system are deteriorating internally and maybe putting stuff into coolant? Over the years I had plastic rot related issues at one of the two heater core elbows right at the firewall where the bleed screws are, the clamp area of the main hose just above the water pump and thermostat area, and the little Y connector near the radiator upper hose where the coolant overflow bottle plastic line finally meets back up with the main hoses.
d. What about main radiator core? They are plastic/composite stuff AFAIK. My radiator was replaced under warranty for slight weeping/leak at close to 4 years, so my radiator was not full life of my car. In general, I have found all my newer Audi radiators reliable, but on my 1985 Audi 5000 (100) that was the first one I owned with a non metal/brass radiator, it mysteriously clogged internally even with no leaks, and I had to replace to get back good cooling function. Seems far fetched, but just throwing it out there. Could be both shedding crap into coolant system, and restricting general flow. If you pull upper and lower hoses along the way of draining everything, you could try blowing thorough it to at least get a sense of whether it is free flowing or not.
b. Any consideration to whether your water pump impeller is deteriorating? Maybe your circulation isn't great in general as a possibility. The impeller is plastic IIRC, so could be both lower flow AND crap heading for your heater cores. I changed m water pump at one point FWIW, and impeller still looked very good.
c. Have you considered if any other plastic joints and fittings throughout cooling system are deteriorating internally and maybe putting stuff into coolant? Over the years I had plastic rot related issues at one of the two heater core elbows right at the firewall where the bleed screws are, the clamp area of the main hose just above the water pump and thermostat area, and the little Y connector near the radiator upper hose where the coolant overflow bottle plastic line finally meets back up with the main hoses.
d. What about main radiator core? They are plastic/composite stuff AFAIK. My radiator was replaced under warranty for slight weeping/leak at close to 4 years, so my radiator was not full life of my car. In general, I have found all my newer Audi radiators reliable, but on my 1985 Audi 5000 (100) that was the first one I owned with a non metal/brass radiator, it mysteriously clogged internally even with no leaks, and I had to replace to get back good cooling function. Seems far fetched, but just throwing it out there. Could be both shedding crap into coolant system, and restricting general flow. If you pull upper and lower hoses along the way of draining everything, you could try blowing thorough it to at least get a sense of whether it is free flowing or not.
Realize there is the TSB in USA saying that the heater cores may have internal coating/erosion issues across all motors; the fix was a running parts revision circa 2007 to cores with better coatings. Moving the coolant back to a silicate type (original fill wasn't) may have helped with internal erosion issues too as far as the factory changes for later years. If failing internal passages to the heater cores is really the issue you have in the end, the flushing and all presumably wouldn't stop that longer run.
Last edited by MP4.2+6.0; 04-09-2018 at 03:49 PM.
04-12-2018, 12:27 PM
#4
AudiWorld Member
Thread Starter
Did 4 water flushes, ONLY water by taking out lower radiator hose AND tranny cooler hose. After this i still had like 10-15% coolant (freeze point was -6celsius with optical meter). And as said I only got out 10-12L of coolant every time.
1. Taking out lower radiator hose and tranny hose only removes around 10L of coolant. Total volume 18,9L. Not a good solution. Removing lower rad hose and tranny cooler hose + nose flipping car AND purging heater cores with pressurized air gets out around 12L.
2aThe car is a 2008, as you can see from my signature, no crap in the reservoir. Coolant was swapped already 6months ago, doing another flush.
2b doubt the impeller, AFAIK W12 uses a metallic one. Otherwise i would have replaced it already 2 times (370000km on the clock)
2c Doubt the fittings are going bad, heater cores were mainly clogged with white crap, not black plastic. Almost no black particles found when doing flush nr1
2d Removed radiator 8months ago, cleaned and flushed, it's a 100% aluminium unit in all D3 A8, no plastic ends. Radiator was not in any way clogged, very clean inside and well up to it's task running 200-250km/h on italian autobahn in +35celsius for an hour 2 years ago.
Early heater cores had problems, this is a 2008 facelift car, should not apply to this.
Removed the heater cores and inspected and cleaned, very little crap came out, but i think I managed to get something off with the solution i had inside them.
Now after a couple problems inside is G13 coolant with distilled water.
1. Taking out lower radiator hose and tranny hose only removes around 10L of coolant. Total volume 18,9L. Not a good solution. Removing lower rad hose and tranny cooler hose + nose flipping car AND purging heater cores with pressurized air gets out around 12L.
2aThe car is a 2008, as you can see from my signature, no crap in the reservoir. Coolant was swapped already 6months ago, doing another flush.
2b doubt the impeller, AFAIK W12 uses a metallic one. Otherwise i would have replaced it already 2 times (370000km on the clock)
2c Doubt the fittings are going bad, heater cores were mainly clogged with white crap, not black plastic. Almost no black particles found when doing flush nr1
2d Removed radiator 8months ago, cleaned and flushed, it's a 100% aluminium unit in all D3 A8, no plastic ends. Radiator was not in any way clogged, very clean inside and well up to it's task running 200-250km/h on italian autobahn in +35celsius for an hour 2 years ago.
Early heater cores had problems, this is a 2008 facelift car, should not apply to this.
Removed the heater cores and inspected and cleaned, very little crap came out, but i think I managed to get something off with the solution i had inside them.
Now after a couple problems inside is G13 coolant with distilled water.
Last edited by volvopentaman; 04-12-2018 at 12:44 PM.
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