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help w/ coolant hosr layout


grahamap

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I know this is a z forum however I havent had any response from the patrol forums. Basically I have an l28 block and e30 head in an mq patrol and im wanting to hook up the heater. Basically im trying to find the best way to run the hoses so I get good heat and my engine gets suffcient cooling. I have labelled pictures of my setup but not sure how to post. Basically from the water pump cool water runa down left side of block, from a t piece a hose goes over the back of the head and connects into the right side of block. The other part of the t piece continues on around the lower part of the block and up into the manifold then at the othet end of manifold connects into thermostat housing. My current setup to involve the heaters saw me taking the longer hose from the t piece and using that for heater inlet. The heater outlet then connected to the right side of the block.. same as before just with a heater core added.. problems with this is the heat isnt that warm and ive seen a raise in temp from engine and that has me worried.. any info or pictures would be great cheers guys, if someome shows me how I can add pictures to better explain

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If you're signed in, at the bottom right of the Reply window is a "More Reply Options" button.  Click that.  You'll get a new window with a "Choose File" button below the text window.  Click that.  Should be figurable from there.

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Hot water should be pulled out of either the block port (currently labeled as "heater outlet to block") or cylinder head and then returned to the water pump.  In the US, the hot water was pulled out of the cylinder head (currently labeled "heater inlet here"), but the block port works too.

 

How yours is currently set up, it is pulling hot water out of the block, passing it through the heater core, then returning it to a tee fitting that is returning the water back to your water pump via the external bypass.  The reverse of how you have it labeled.  Switching your hoses on the heater inlet/outlet might help increase flow.

 

Coolant goes through your intake manifold to warm it up on cold days an prevent icing.  From there a line comes out the back of your intake manifold, tees with the water coming from the heater, and returns to the water pump, acting as an external bypass to help prevent cavitation before the thermostat opens.

 

If you tried to route it by pulling water out of the head, and putting it back in the block, then it would probably mostly sit stagnant.  Pulling it out of the block, or head, then letting it route back to the external bypass is the OEM way it was done and should flow pretty well.

Edited by blue72
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Thanks for the indepth reply! Yea im in australia and ive yet to see a patrol run lines off the head. However my little brothers fairlady in the backyard (where I pinched the head) did. So just to confirm, I have it currently setup correctly. Now that I know which direction it flows I can just swap inlet/outlet and be good?

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Guess that makes me wonder which on the heater core is inlet/out. For someone who has a tap that might matter but I have removed mine for winter until I can scrounge up a functioning one. So without a tap, the core should flow freely either way correct?

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Hose from block or head (Hot water supply)>heater control valve>heater core>hose back to water pump inlet.

 

If you remove the heater core, plug the lines and allow no flow. There is enough flow present through the carb preheat 8mm line and internal bypass line in the front of the block to prevent cavitation until the engine thermostat cracks open to allow more flow to the radiator.

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Hose from block or head (Hot water supply)>heater control valve>heater core>hose back to water pump inlet.

 

If you remove the heater core, plug the lines and allow no flow. There is enough flow present through the carb preheat 8mm line and internal bypass line in the front of the block to prevent cavitation until the engine thermostat cracks open to allow more flow to the radiator.

Yep.  The fitting at the back of the head and the fitting on the other side at the back of the block are, for all practical purposes, the same location.  Use one or the other as the inlet to the heater core (looks like the one on the block would be more convenient given your heater core location), and return the water to the pump inlet at the front of the block.

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Thanks heaps guys, been very help!! When you say the two (block and head ports) are the same, I envision the water flow it goes from radiator to block up to head into radiator (not including bypass system). Now having the block fittig connected (not plugged)wouldnt that take away from the water flowing into the head? Just a thought I imagine once its all full it wouldnt matter either way.

 

also no one seems to have provided a response to my lack of heater core tap. I dont think it matters but I could be wrong

 

Thanks a lot guys

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I'm not sure what you mean by the heater core "tap"-hoping it would be clarified.

 

The water pump pressurises the block front to back first, then water flows up into the head and back to the front out the thermostat.

 

The head point is hottest, and imparts flow to a relatively stagnant area. It makes for most efficient quick heater operation.

 

But the lower bock point helps with sedimentation in that area, and is used in a lot of sedans. If your plumbing is simplified by it, use that one instead.

 

 

Epithet connection takes flow from the rearmost portion of the engine, through the heater core (mini radiator) and then after being cooled goes right back to the water pump inlet. The heater core acts the same as the radiator, and this is why you don't just "loop" the two points when the heater core is removed. You plug it and divert all flow through the radiator to be cooled, instead of taking the hottest water in the engine and putting it right back into the inlet to the water pump!

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Ahhhh, it's manual outside the passenger compartment---that is what I refer to as a "Heater Control Valve"... On some cars there is what Americans refer to as a "Tap" which is a valve on the bottom fitting of the block which you can disable the heater so no matter what you do to the Heater Control Valve, no water is going to the circuit. They existed mostly outside the USA. It's a holdover from delicate Heater Cores that may not like all that pressure on them and could leak at any time...so you block the source of pressure and run 'suction pressure' from the water pump inlet on it all the time (at most 13-16 psi, whereas pressure in the block can be 40-60 psi in some cases!)

 

Now I know Ozspeak!

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