Having a major cooling system headache with my late model raw-water cooled A4... Engine starts and runs fine but no cooling water is coming out the exhaust. Had water coming out the exhaust when pulling from a bucket on the hard, though the observed flow seemed a bit light. Did an acid flush last fall prior to winterizing her and installed a new impeller this spring (the 'old' impeller was intact and a year old - cheap insurance).
I verified impeller shaft is turning and verified prime by pulling from a bucket leading directly to waterpump intake.
Now for the ugly part... when I start the engine and advance the throttle, I can feel suction on the end of the hose in the bucket for a second or two, then the suction stops since the water evidently has no place to go. When I reduce the rpms, I can feel some cool water coming back into the bucket. When I STOP the engine, warm/hot water drains back through the system into the bucket. Moving my bucket to the t-fitting I use to winterize (upstream of a Groco strainer) and had hot water backing up into the strainer and into the bucket.
So... blockage. Somewhere. Since the water coming back is hot, it is making it into the the water jacket at least, correct? (Note: No thermostat, just a bypass valve). Suggested approach?
I'm thinking:
a) Verify waterpump flow by running a hose from waterpump output to a bucket and running the engine for about 15-20 seconds. Don't expect any issues here since water is coming back hot when I run the engine until about 150 degrees.
b) Try the same thing running a hose from the output of the thermostat housing. Poor flow == issue is upstream. Good flow == issue is downstream.
Assuming waterpump flow is good, test flow from bypass hose? (possible identifying a issue within water jacket?). I figure the water isn't getting too far since it draining back through the waterpump when I stop the engine.
Thoughts? What am I missing?
I verified impeller shaft is turning and verified prime by pulling from a bucket leading directly to waterpump intake.
Now for the ugly part... when I start the engine and advance the throttle, I can feel suction on the end of the hose in the bucket for a second or two, then the suction stops since the water evidently has no place to go. When I reduce the rpms, I can feel some cool water coming back into the bucket. When I STOP the engine, warm/hot water drains back through the system into the bucket. Moving my bucket to the t-fitting I use to winterize (upstream of a Groco strainer) and had hot water backing up into the strainer and into the bucket.
So... blockage. Somewhere. Since the water coming back is hot, it is making it into the the water jacket at least, correct? (Note: No thermostat, just a bypass valve). Suggested approach?
I'm thinking:
a) Verify waterpump flow by running a hose from waterpump output to a bucket and running the engine for about 15-20 seconds. Don't expect any issues here since water is coming back hot when I run the engine until about 150 degrees.
b) Try the same thing running a hose from the output of the thermostat housing. Poor flow == issue is upstream. Good flow == issue is downstream.
Assuming waterpump flow is good, test flow from bypass hose? (possible identifying a issue within water jacket?). I figure the water isn't getting too far since it draining back through the waterpump when I stop the engine.
Thoughts? What am I missing?
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