7M Coolant flow

[CyFi6]

Never gave it much thought, but looking at the cooling system flow for the 7M I am a little confused. Maybe I am missing something very simple. What is the purpose of the highlighted line? What causes coolant to flow through this line? Coolant enters the line through the heater banjo at the back of the head, and exits at the water neck behind the thermostat. From my understanding both of these positions are after the water pump and before the thermostat, so therefore wouldn't the pressure at both the inlet and the outlet be nearly equal meaning not much coolant flow if any at all?

If you can't tell, the flow arrow is pointing from the rear, flowing forward to the water neck.

 

[jetjock]

You've never given it much thought? I find that very hard to believe :icon_razz

 

[CyFi6]

What you are saying could possibly be taken as a compliment so I will take it as such

 

[Nick M]

You've never given it much thought? I find that very hard to believe :icon_razz

I was thinking something similar. What, your discharge temp is 39.8, but last week it was 39.2?

 

[Grandavi]

Im afraid to answer now...

 

[CyFi6]

Lol y'all are dicks.

 

[Grandavi]

That should be a bypass hose for when the heater is turned off. The water goes into the heater, however, if your vsv is working correctly, when you have the temp turned down, it bypasses the heater and returns to behind the water pump through the thermostat housing (where it either goes back to the rad or back towards the engine/heater). Oh.. and regarding the pressure.. its only for when the heater valve is shut.

Now.. the vsv is different though.. and I dont fully have that mapped out in my head, because it shuts the water off completely I believe at lower than 65F (18C) if it functions correctly.. (it has an inlet and outlet) but I can see how it ties into the cooling system outside the firewall.. not sure what happens inside the firewall at the heatercore, because you can bypass the vsv to allow for flow if the switch fails... (which mine is).

At least.. thats how I understand it... so far

 

[IJ.]

Side note: That Baby is far too happy buy him a Mk3 toy

 

[Grandavi]

Good pic of the baby though.. looks just like I did when I found my car..

on a different note.. grandchild #4 is entering the world tonight. Im having fun with my daughter... who'd a thought you could text your daughter while she is in labor....

 

[oldsking]

What about the one that says from the head? Suppose you do not run that feed to your iac and tb and just block it off, will it create unwanted pressure in the system? I ask because the new FFIM i got has that port blocked

 

[Poodles]

Personally I'd loop em if you're going to bypass them.

 

[CyFi6]

That should be a bypass hose for when the heater is turned off. The water goes into the heater, however, if your vsv is working correctly, when you have the temp turned down, it bypasses the heater and returns to behind the water pump through the thermostat housing (where it either goes back to the rad or back towards the engine/heater). Oh.. and regarding the pressure.. its only for when the heater valve is shut.

That's just it though, have you ever looked at where the line connects up at the front? It goes to the water neck, on the engine side of the thermostat, not behind the pump. Basically the port at the back of the head and the port at the front of the head where the line connects to the water neck are both after the outlet of the pump and before the thermostat, so why would there be any flow of water from the rear toward the front?

I could understand if the front of the pipe was leading to the suction side of the pump...then yes there would be a pressure difference there, but since both ends are on the outlet side of the pump I don't really get it.

For instance, coolant flows through the throttle body/isc lines because one end of the line is on the pump outlet side and the other is on the pump inlet side, and the same thing with the heater core, radiator, and any other part that requires coolant flow...except this one section of pipe that I am not understanding.

And BTW it isn't my baby lol. It was just a really funny picture I found on the net.

 

[Dyzzyman]

Is this an extension from Mr. 7m wanting to block off the banjo bolt? I'd like to find out if there were any technical articles addressing as to what I was referring to. Takes forever for me to express all that stuff.

 

[BlackDevilSupra]

That's just it though, have you ever looked at where the line connects up at the front? It goes to the water neck, on the engine side of the thermostat, not behind the pump. Basically the port at the back of the head and the port at the front of the head where the line connects to the water neck are both after the outlet of the pump and before the thermostat, so why would there be any flow of water from the rear toward the front?

....

The highlighted coolant route goes to the water neck, prior the thermostat. Once the thermostat opens, then coolant flow begins. The other similar coolant line that wraps around the block, is the heater / TB / ISC return line which is plumbed into the water pump passage. They would be easy to identify once you take an actual look at the pipes / tubes.

 

[CyFi6]

Yeah Dyzzyman, after reading that I looked closer at the picture and I started to wonder.

BDS I understand what you are saying but it doesn't change the fact that both sides of the pipe in question are on the outlet side of the pump. The only reason water flows through the thermostat/radiator is because one side of it is on the outlet side of the pump and the other side is on the inlet side. The pump creates a pressure difference and allows flow. This isn't the case on the pipe I am talking about, both sides are on the output side of the pump. Unless there's some kind of odd pressure build up at the back of the head for some reason I don't see how the pipe does anything.

 

[Grandavi]

No, I think your seeing it a bit wrong. Both go to the heater core inlet, however one is a bypass. So I think the arrows make it look funny. Two hoses run to the inlet, one house comes from the outlet. (pretty sure I am correct on that). The water goes to the heatercore, but if the heater core is closed for no coolant, then it uses the bypass to return. All of it is "looped" in the thermostat housing, so if it cannot go past the thermostat, it has to loop back into a low pressure situation where the coolant does not flow much. However once the thermostat cracks open, then its allowed to return to the rad.
Its a closed system so I believe I have that right. However, the arrows in the drawing make it look like the water going into the heater is going backwards. ummm.. I think... not really a good drawing.. lol.

I have to go look at my 87.. its a GE... I keep trying to figure out why its different than my car.. lol (my 88 is GTE)

 

[CyFi6]

Im just not seeing it man. The way I think you are describing it is not how it is actually hooked uo. If I had a good picture in front of my of the whole engine and pipe assembly my question would be simple.

 

[jetjock]

I knew this thread would be good...

 

[CyFi6]

Hoped it would have a better ending.

 

[jetjock]

It will at some point...