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No Coolant Flow?

Old 10-09-2018, 02:35 AM
  #1  
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Default No Coolant Flow?

Hi,

I'm properly stuck on this. It's not an A8 D2 but the engine (32v V8 ABZ) is from an A8. I don't appear to have any coolant flow - within the engine or coming from the engine. I've changed the WP (old one was actually OK) and the Thermostat (again, old one was fine...).
Heater hose do not get warm. Return feed to the head gets slightly warm, probably simply from conduction (no thermostat stopping heat transfer). Feed to the radiator stays stone cold.

I've bled and bled the cooling system even though this is the first time I've ever had this problem. My question is, are these engines succeptable to getting crud blocking something inside? Or an airlock within the engine that I can't get to? Bit more back ground below (might be a long post).

Thanks,

Mark.

Over the past 5 years I've had the car in bits etc and maybe fully assembled it 6-8 times. Every time I bled the cooling system and it worked fine (got to about 90 deg, radiator starts getting warm, gets to 105 and radiator fan kicks in).

Earlier this year I assembled it for the 7th-9th time and noticed the coolant issue above. As the engine has been run on varying levels of anti freeze (sometimes even none for short spells) and then stored dry for 90% of its life I just assumed the WP had corroded. But not so. Thermostat was also fine.

Only thing I noticed different this time was the oil cooler is leaking oil. I know this is common but the engine has to come out to fix it - the WP & timing belt was *tight* but the oil cooler is near impossible.
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Old 10-09-2018, 03:26 PM
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Have you checked the radiator for "basic flow" ... like, can you blow through it when drained?
As I'm sure you know, the passages in the radiator (being so much narrower) would be much more susceptible to clogging than anything in the motor block
Just a wild guess, based on what you already covered in your post.
Cheers
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Old 10-10-2018, 12:58 AM
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Cheers for the reply - no is the basic answer. It at least gets coolant from one side though as the drain plug on top of the radiator drips fluid and the coolant expansion tank drops when the drain plug is open. But as the heater hose stays cold I think there is a problem upstream to the radiator possibly being blocked.

I ran it again briefly yesterday with the fill cap off and can see that the coolant gets animated when the engine is running so obvs the water pump is doing something. Not that I have any doubt a brand new WP wasn't working.

Think I'll just have to keep running it and hope I can clear any remaining air, just a bit difficult as it gets to 100 degrees quick and I don't fancy running it over that. Also got an unrelated vacuum leak that I need to sort before running it again.

Or maybe just park it and see if sorting the oil cooler reveals any mystery coolant issue.
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Old 10-15-2018, 06:30 AM
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So not sure how many airlocks I had but after running it to about 80 deg's, switching off and squeezing all the hoses for about 20 minutes it's now flowing through both the heater element and the radiator. Turns out that I've removed a couple of bleed valves from the donor car.

Of not is that I didn't realise the thermostat in the block is actually on the return leg from the radiator so that wasted a few hours troubleshooting a none-issue.
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Old 10-15-2018, 07:09 AM
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Arg, well a good example to show the benefits of using a thermostat drilled for a bleed hole or with a jiggle valve.
Jiggly make happy.
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