Help! Cold weather quickly approaching and I can't winterize. There is no flow through the block when the bypass hose is clamped closed.
The history is a rebuild late model A4 6 years ago. Raw water cooled.
This season I had some overheating and kicked myself for not doing an acid flush since rebuild, but it had been running great since rebuild. Overheating was controlled by throttling back. Flow out exhaust seemed light, but when I pulled the wet side exhaust hose there was decent flow. So I postponed flush to next Spring.
Began winterization. I ran engine with good coolant flow, drained oil, added MMO, ran to distribute, revving as water from bucket cavitated. Drained water jacket. The drain plug on manifold has been frozen in place so I skip that. (No access to drill out and retap).
When I removed the thermostat the cavity for therm was packed with scale and rust! I spooned out the scale and poked head passages to clear more scale. Then replaced therm housing (no therm), clamped off bypass, and started engine to draw antifreeze in. Nothing moved.
I then shut down, pulled the therm housing off and bumped the engine, confirming flow into therm from water pump. I then tried to blow back from outlet at rear of manifold and, with bypass closed, no flow whatsoever. With bypass open flow is fine. Opened water jacket drain and tried to blow--nothing.
Any suggestions? I figure I have to pull the manifold and clean the passage from block into manifold. I don't think acid will work as can't draw into block. Is there a diagram of flow through A4 block and head?
The history is a rebuild late model A4 6 years ago. Raw water cooled.
This season I had some overheating and kicked myself for not doing an acid flush since rebuild, but it had been running great since rebuild. Overheating was controlled by throttling back. Flow out exhaust seemed light, but when I pulled the wet side exhaust hose there was decent flow. So I postponed flush to next Spring.
Began winterization. I ran engine with good coolant flow, drained oil, added MMO, ran to distribute, revving as water from bucket cavitated. Drained water jacket. The drain plug on manifold has been frozen in place so I skip that. (No access to drill out and retap).
When I removed the thermostat the cavity for therm was packed with scale and rust! I spooned out the scale and poked head passages to clear more scale. Then replaced therm housing (no therm), clamped off bypass, and started engine to draw antifreeze in. Nothing moved.
I then shut down, pulled the therm housing off and bumped the engine, confirming flow into therm from water pump. I then tried to blow back from outlet at rear of manifold and, with bypass closed, no flow whatsoever. With bypass open flow is fine. Opened water jacket drain and tried to blow--nothing.
Any suggestions? I figure I have to pull the manifold and clean the passage from block into manifold. I don't think acid will work as can't draw into block. Is there a diagram of flow through A4 block and head?
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