Cooling System Flush

   / Cooling System Flush #1  

gerlacr

Member
Joined
May 2, 2002
Messages
27
Location
Cal
Tractor
Yanmar 1500D
I pulled the radiator on my YM1500D to have a radiator repair shop take care of the leak. Looking up into the bottom radiator hose, I am seeing a build up of rust chunks and sludge, which means there is also crud in the block. What is the best way to flush all of this out without blocking any passages? Is there a way to remove all traces of rust so that a fresh batch of water and antifreeze will maintain the system clean and rust free?
 
   / Cooling System Flush #2  
While the radiator is off, I would run a water hose with a stiff nozzle into the upper and lower rad hoses each direction, (sealed off with shop rags), until water runs clear. Then when you get the radiator back on, flush the whole system with commercial cleaner according to instructions.
 
   / Cooling System Flush #3  
Locate the block drain plug, install a fitting, connect to a water source, and begin flushing.
Then, block off the lower radiator hose, and flush thru the top of the block.
Finally, with the block full of water, and lower radiator hose plugged, start the engine, and run for half an hour, with a slight flow of water running from the top radiator hose.
This will get most of the crud out of the block.
 
   / Cooling System Flush #4  
I don't think the 1500D has a block drain plug. The other advice is sound.

Remember that your 1500D doesn't have a water pump and therefore relies on natural convection (aka the thermosyphon effect) to circulate the coolant. Whatever you do - when you put antifreeze and water in after you are done cleaning the system, use no more than about 30% antifreeze mixed with distilled water. Mix the antifreeze with the water in a bucket before you put it into the system. Any higher antifreeze content, or poor mixing of the antifreeze and water will significantly reduce the circulation and can lead to overheating. If you live in a climate where you don't need freeze protection, the best coolant to use is just water - no antifreeze.
 
   / Cooling System Flush
  • Thread Starter
#5  
Freezing is not a concern in Southern Calif., but I thought some antifreeze in the system was needed for rust control. Is this correct?
 
   / Cooling System Flush #6  
Antifreeze does have some rust inhibitors which can help reduce rusting of the water passages in the engine block and heads. However, I would much rather have a rusty coolant jacket than an overheated engine and a cracked head - don't ask me how I know...

If you are concerned about inhibiting rust, find a cooling system additive that provides rust inhibitors without antifreeze. You may even want to consider a product which is supposed to increase heat tranfer rates (water wetter?). But I would avoid anything containing ethylene glycol or propylene glycol - the most common freezing point depressors in antifreeze. They change the thermosyphon effect of the coolant.
 
   / Cooling System Flush #7  
</font><font color="blue" class="small">( I don't think the 1500D has a block drain plug. The other advice is sound. </font><font color="blue" class="small">(

If it doesn't have a block drain, you could put flushing water in thru the port for the temp sensor/gague.
 
 
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