Rover 3.5 water system hoses. Need help!

[Callum&Doug]

Hi there,

As we approach the latter stages in our father son mgb v8 conversion, information just isn't clear on the routing of hoses. We are running an edelbrick performer intake, mgb v8 ally radiator with pressurised resevoir and an sd1 water pump. Now ill try my best to get across where I am at with my knowledge thus far. I have bottom rad hose connecting to the water pump, the top rad hose connecting to the thermostat housing. Now I'm not sure what the second smaller port on the water pump is meant to do? We aren't running a heater, do I need to run it under the manifold then into the return on the back of the manifold? Can I just block it off? My thermostat housing doesn't seem to have a slot for a thermostat, nor does the manifold, does it just sit inside? Also, where could I get a water temp sender in this system? Any help would be greatly appreciated.

Callum & Doug

[Callum&Doug]

Also, why do some thermostat housings online have a seperate small inlet port

[mgb260]

Buick used the bypass hose at thermostat housing, Rover was at front of intake. I think the Performer intake should use the Buick 215/300/340 thermostat housing with bypass.  Either one, you need the bypass or you will overheat.  It allows circulation until the thermostat opens. Also you should drill a 1/4" hole on each side of opening behind the thermostat housing.



You can use a SBF thermostat housing like this, and mount your temp sensor where the plug is. You have to drill the mounting holes a little bit to line up.

[Callum&Doug]

That looks like exactly what I need, thanks for your reply!! For the plumbing, bottom radiator to water pump, top radiator to thermostat housing, bypass on thermostat housing to the top hole on the water pump, I was just going to block the other smaller hole on the water pump facing the back of the motor, then also block the old port at the back of the manifold that I assume was heater return? Is this all correct? Thanks in advance. Callum

[mstemp]

Don't think that's right.
Back of water pump goes to bypass on thermostats housing. Back side of manifold goes to the vertical port of the water pump. Back of manifold ussualy feed heater and then the return from heater goes to the vertical water pump port.

[Callum&Doug]

Wouldn't that theoretically become another bypass of the thermostat if you're not running a heater and have no heater valve to shut it off, therefore not letting the radiator work to cool as efficiently?

[Moderator]

quote: "I was just going to block the other smaller hole on the water pump facing the back of the motor, then also block the old port at the back of the manifold that I assume was heater return? Is this all correct?"

I ran with those two ports blocked for years, without problems.

[MGBV8]

On my 215 with Buick 300 water pump, the horizontal fiiting pointing toward the engine goes to the thermostat housing, as stated.  The vertical fitting goes to the upper heater core fitting.

I agree with Curtis.  I would use a thermostat with a small bypass hole, though.

[mstemp]

Carl,

That's what I was saying.

Callum,

If you run a surge tank that rear manifold fitting makes a good point to tie into and feed back into water pump top vertical fitting.

[mgb260]

Chris Gill had overheating issues without the bypass on his 300 stroker (350) but no issues with the previous 215.

[Callum&Doug]

Thanks  guys, overwhelmed with the help on hand. Colin, did you use the verticals port for your bypass and block the horizontal? I think I'm going to opt for just blocking the others as I can't understand the difference of that and just having a heater valve closed?