The V8 Owners Forum -

I am thinking of blanking off the rear water outlet from the manifold - a 360 - to simplify the cooling connections. Is anyone aware of or have experience of any problems arising from blanking off this and the associated inlet to the pump.

Cheers

Andrew

it helps to circulate coolant (via the heater circuit) when the stat is shut. This helps to prevent hot spots and can generally help stabilise cooling temps. If you don't have a heater then try blanking it off but if you have odd problems then think about connecting it back into the circuit.

As the circulation will be looked after by the bypass hose on the stat housing I figure the only possible issue will be the manifiold not having a through flow - but should still be good for flow around the stat to ensure accurate operation.

As I dont have a heater in circuit the rear hose is connected to the pump inlet at present but I am concerned that this is a short circuit that will allow a fair amount of water to bypass the rad and hence not be cooled as there is no heater matrix resistance.

If there are issues with the manifold being to cold I will reduce off the rear outlet to some 8mm or 6mm bore and run this under the 360 to the pump inlet this way I can ensure circulation and still keep it all neat and tidy.

Andrew

bypass do you mean the small outlet right next to the main rad hose? if so you will have next to zero circulation there because you have just blocked off the other end of its circuit at the back of the manifold. That's on the pressure side of the pump.

I had assumed - it seems incorrectly - that both of the small connections to the pump were returns and not as you are indicating a flow and return.

In that case the outlet on the back of the manifold is the only way to get any circulation until the stat opens so I will run a reduced diameter feed under the 360 to complete the circuit.

Any sources on the net for a flow diagram of the RV8 cooling system?

Cheers

Andrew

I effectively blanked off the heater circuit when installing an SD1 into a Series 3 Landy. It had simply had a water shut-off valve as the cabin heater temperature control. With it shut the engine temp would cycle alarmingly. So for summer use I put in a bypass for the heater matrix and valve so there always some flow. Behaves itself now.

Darkspeed wrote:
Any sources on the net for a flow diagram of the RV8 cooling system?

No, but it's an often asked question!

Chris.

Went through all my Haynes and scoured the net and cant find anything - I am assuming that the pump flows are the two ports into the block and one of the 3/4" outlets at the back of the pump - the central one. The returns being the pump inlet and the other 3/4" connection - the outer one

Flow being from the block up into the heads then into the inlet manifold -

Whilst the stat is closed circulation flow is only possible via the heater circuit and on the 360 the only outlet for circulation will be the rear manifold outlet

I wonder if I blank off the rear manifold outlet - blank off the central 3/4" flow port from the rear of the pump then connect the t/stat bypass to the 3/4" - outer pump connection - by my thinking the only issue will be that the rear of the manifold will be dead legged and that circulation will be by turbulance and conduction which I dont see as much of an issue with aluminium.

Just got to make sure that the connections on the back of the pump are what I think they are.

Anyone see anything wrong with my logic?


Andrew

No idea what will happen there but personally I wouldn't try it, a bent engine is too expensive to take the risk. Its not a big job to connect it properly even if you want to put a restriction in on a short loop. If you fancy experimenting then let us know how it works out.

EDIT

Just thought if you do what you want to do then you will have to at least include a bleed valve of some kind on the back. If you don't you could end up with a big air bubble that if it moves you will be in all sorts of trouble.

I'm assuming you have the stat by-pass hose fitted from the stat housing to the pump.
If so, blanking off the rear outlet from the 360 manifold to heater the should not be a problem. It's no different from having the heater valve closed is it?

Borrowed this from another post that does a nice job of showing the by-pass hose connections - now these are in the same pump location so will both be either suctions or flows not one of each.

Now logic would say to me that they would both be suctions as I had thought originally so can anyone confirm this once and for all?

Cheers

Andrew


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as that is an EFI engine , one of those holes in the water pump will be blanked off
i found that out when i connected to the wrong one and had no flow ...doh

it's hard to see as it's just a cap of some sort half way along the pipe

Hi Lads,

Just been reading this thread as the engine that I am almost finishing is a 26D that was set up for carbs. I have dunked it into an EFi setup and almost finished the project.

Connecting the water hoses drove me nuts for ages as the two holes in the rear of the water pump are both open.

So can I clarify that ONE of them should be blocked off on an EFi setup.

I assume the reason the two are open is that it is for flow to both carbs - which I don't have - ahem - obviously.

Ta lads.

Having similar probs myself and it's nice to find i'm not the only one. From reading this and other threads I think i'm on the right track but maybe someone can offer an opinion.

Shown below is the plumbing for heater on my P6 estate on which I'm carrying out an EFI/megasquirt conversion. Waterpump is standard P6 item.
** red arrow points to a pipe from the EFI (3.9 Range) manifold to the heater (hot water feed to heater)
** blue arrow points to the pipe that takes the heater return to the back of the water pump.
** Yellow circle is the small take off from the pump bottom hose connection

My intention is to blank the yellow circled take off from the bottom hose connection . There is no thermostat bypass on the thermostat housing so I'm presuming that the engine will circulate through the heater matrix until warm and then through the main radiator once the engine is up to temperature.

Unfortunately I cannot remember what the orginal connections were on the standard car as prior to this EFI conversion I was running an edelbrock 440. However this does seem to tie up with system as removed from the donor range rover. From my photos that vehicle doesn't appear to have any take off from the pump bottom hose connection.

Ignore the crappy ignition leads and unpainted brackets etc. Just getting everything in place at the mo. It will be prettied up once it's actually working!

Any advice gratefully received as the heater has always been a little poor in this car when the edelbrock was fitted and I'm keen to get it right this time. Thanks Ben

Hey BenL,

Well it is a puzzle but essentially the key is that if it is a spare port then blanking it is fine.

Point to consider: What will happen to the circulation when you set the heater to the "cold" position? I have had no problems with circulation but my setup is different. Something to consider.

I have blanked off the spare port and have efficient ciruclation. Please note my point on another thread as I developed a small water leak and was using water. It was only found when I switched the heater to the cold position and then the back pressure created in the heater feed pipe demonstrated a jet of a leak at the flexi to metal pipe union. Fixed now but not noticeable when heater on heat.

Hope thats useful to you.

Doc