Water hose Delete/ Redirection?

[E30_Beau]

So I was scrolling through Instagram and found a M20 that Ireland motorsports are making with a water pump delete plate to replace with an electric water pump from Stim.Tech and a replacement thermostat plate from someone else and noticed that it completely removes the hose that goes from the thermostat over the distributor back to the water pump and I'm just wondering if all the water hoses on the front of the engine are completely necessary? would it be more efficient just to have one hose going from the radiator to the engine and one coming back, or is there a reason for the extra hoses that I'm not aware of?

[ADEN]

It seems that you are not aware of anything lol.

Water pump outlet is obvious in the picture and coolant hoses and even the radiator are not yet installed.

What are you trying to say? Where are you from?

[E30_Beau]

Right, well I'll put it in a simple question for you then, would it work if you put a pipe or hose straight from the radiators lower outlet to the water pump, and a water pipe or hose going straight from the thermostat to the radiators upper outlet?

The picture was just to show the bit that replaces the thermostat and the fact that it only has one outlet on it not three.

[hasa]

in some racing application this could work. I once ran this kind of setup, but not BMW.

[e30davie]

You still need to have the radiator cap somewhere, some of the the multitude of coolant pipes on the M20 is how they connect the remote reservoir and radiator cap, and the other pipes are for the heater pipes and the throttle body. both of which can be removed but not blocked off, especially for the heater as that is out of the back of the head so it still needs to flow back to the front somehow.

What you are describing is how i plumbed a 4age conversion in a car i did. but the radiator had its own cap (no remote resevoir). Still needed to run the heater hoses back to the front of hte engine somehow even though the heater was bypassed. i just put a steel pipe in and plumbed it back into the thermostat housing where it usually goes. <---- ignore this, makes no sense, refer post below!

[nando]

Have fun bleeding it without the expansion tank..

The M20 cooling system is already really simple. An electric pump is cool I guess, but a stock M20 pump is like $50 and lasts for tens of thousands of miles. The hoses will last for 20 years (at least).

So what's the point of deleting hoses, especially since you don't even know what they're for? Why does everyone always want to reinvent the wheel?

[E30_Beau]

Well look I really just wanted to know why both the radiator hoses go through the thermostat before one goes down to the water pump instead of the lower hose going straight to it, nothing is wrong with my M20 but looking at a few pictures just got me thinking why?

And I live in Australia I don't need to worry about cold weather stuff hahah all of the lines through the throttle body have already been removed as well as the heater core lines. But also why couldn't I just keep the expansion tank setup I have and just put a T-piece somewhere in the line between the thermostat and upper radiator outlet?

[Digitalwave]

You still need to have the radiator cap somewhere, some of the the multitude of coolant pipes on the M20 is how they connect the remote reservoir and radiator cap, and the other pipes are for the heater pipes and the throttle body. both of which can be removed but not blocked off, especially for the heater as that is out of the back of the head so it still needs to flow back to the front somehow.

When deleting the heater core and the TB heating hoses, you can block them off completely. That is what most E30 race cars have been doing for decades. Blocking off the back of the head is the same as the heater core being closed. There are no issues with blocking off the port on the back of the head (heater core) as well as the plug on the block just below the back of the header (TB heater). The corresponding port on the thermostat housing can be tapped and plugged with a large set screw and thread sealant.

[e30davie]

hmm well that is a very good point about it being the same as a heater being closed.....realising this, my post makes no sense. Best to ignore it!

[Lugnuts]

Blocking off the back of the head is the same as the heater core being closed.

With the heater core in the closed position, is it a bypass, rather than a block?

Stock late model M20B25 arrangement:

• one pipe from back of cylinder head, to heater core; returns coolant to t-stat housing + reservoir.
• barb on the back of the block (right hand side); runs via the TB, back to the t-stat housing.

At the risk of showing my ignorance, blocking both of these ... would be a Bad Idea, no? How is coolant entering the block/head making its way back out?

[Digitalwave]

While some amount of coolant does flow in that direction (back of head to t-stat housing) via the heater core and TB hose, it is not the primary method of coolant flow and it is not necessary to retain those. I apologize, it's been years since I researched it in depth, so I don't think I can explain it very thoroughly. Don't forget too that the head gasket has different size coolant passages; larger towards the back of the head so that coolant stays relatively equal on each cylinder.

Lots more info in this thread: https://www.r3vlimited.com/board/for...er-core-bypass
And another: https://www.r3vlimited.com/board/for...lock-off-plate

Here's a quote I found from the legendary Jim Levie, may he rest in peace:

This applies to all vechicular engines...

The cooling system is designed such that flow through the heater core occurs whether the thermostat is open or not. That is done to provide full heat regardless of ambient conditions. What that means is that the flow that goes through the heater core bypasses the radiator. If you want to eliminate the heater core the proper action is to plug each of the hoses. If you loop the hoses part of the flow that should go throgh the radiator will just circulate through the block.

The "bypass valve" on an M20 is actually a temperature/pressure relief valve. Early production cars didn't have that valve, but a recall was issued to install the valve to avoid failure of the heater core (and potential scalding) during an overheat situation.

Coolant flow diagram (shown with blocked ports):

[ADEN]

While some amount of coolant does flow in that direction (back of head to t-stat housing) via the heater core and TB hose, it is not the primary method of coolant flow and it is not necessary to retain those. I apologize, it's been years since I researched it in depth, so I don't think I can explain it very thoroughly. Don't forget too that the head gasket has different size coolant passages; larger towards the back of the head so that coolant stays relatively equal on each cylinder.

Lots more info in this thread: https://www.r3vlimited.com/board/for...er-core-bypass
And another: https://www.r3vlimited.com/board/for...lock-off-plate

Here's a quote I found from the legendary Jim Levie, may he rest in peace:



Coolant flow diagram (shown with blocked ports):

Nice info but i have a question:

If the pump can circulate the coolant, Why bmw added an outlet from the pump to the thermostat? Can that be just be blocked safely?

I always thought that the pump outlet design is the source of pressure in the system it needs to go somewhere in the system to create pressurized coolant circulation.

[Digitalwave]

I don't think I understand your question, nor can I answer for BMW on why they designed the system that way.

[TobyB]

Think of it more in terms of flow, not pressure. The mechanical pump doesn't make much pressure at all.

The stock system circulates coolant through the block continually, and then when the thermostat starts
to open, starts to meter some coolant through the radiator. If that cools the outlet flow enough, the thermostat
stays mostly closed. As the engine generates more temperature, the 'stat opens farther,
allowing more to flow through the rad. Eventually, if it's working hard enough, the
'bypass' is blocked completely and all water flows through the radiator and then back to the engine.

So if an electrical pump was speed- controlled by temperature, it could be run without a thermostat, as long as it
'idled' enough to give the outlet housing an accurate idea of head temperature. A head temp sensor would probably
be a smart thing to add, too, just for safety. Then pump speed could serve the same function as the thermostat.
As the pump now only works as hard as it needs to, you save the horsepower or 3 that the pump running at
full tilt might eat up, depending on revs.

As to the heater, blocking it's ok, but leaving a tiny bypass makes bleeding a lot easier, from experience.

I too find the stock system to be pretty effective, but that doesn't mean others can't change it.

t

[Digitalwave]

For 5 years now I have had the heater (back of head) and TB hoses (back of block) completely blocked off, and I have not had any trouble bleeding the coolant. HOWEVER, I did a neat trick that seems to have helped a lot that I read here on the forums. I drilled a 1/8" hole through the thermostat, and I fill the coolant slowly with the bleeder screw opened, until coolant flows out of the bleeder. Doing it that way, it's essentially bled before you start it. I always check anyways, but never get any bubbles out of it.

I am not sure the ramifications of the hole in the thermostat on a daily driver -- my car is track only. I'd imagine it flows a little bit of coolant through the radiator when the thermostat is fully closed, which might make the coolant take slightly longer to come up to temperature.