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Water flow around cylinders and heads.
Posted: Mon Aug 22, 2022 7:37 am
by jenko
Im pretty sure this has been covered in the past, but bear with me.
The coolant from the bottom hose on the rad gets sucked in via the pump. However, the the injection manifolds, the rear water ports in the head a blocked off......So, is there a way for the water to circulate from the rear cylinders to the front cylinders along the cylinder head. I cant help feeling that as the rear ports are blocked, and the pump and top hose feed to the rad is at the front of the engine, the water circulation in the rear most cylinders is compromised. It would make sense if the coolant could flow up into the head at the rear and then make its way back along the head to the thermostat outlet that feeds the rad.
Or, am I missing something (which is the most likely cause of my sleepless nights).
Re: Water flow around cylinders and heads.
Posted: Mon Aug 22, 2022 8:09 am
by jenko
I think I've answered my own question....
Seems coolant is pulled into the block via the pump then extracted from the block via a slot port at the rear of the cylinder heads. it then flows along the cylinder head to the front of the port in the cylinder head and out into the the inlet manifold.....
Re: Water flow around cylinders and heads.
Posted: Tue Aug 23, 2022 9:03 am
by SuperV8
Think you got there in the end:
Re: Water flow around cylinders and heads.
Posted: Tue Aug 23, 2022 6:32 pm
by ChrisJC
Yeah, you've got it.
If the rear ports on the heads were not blanked off, then the water would come up from the block straight into the inlet manifold, missing out the heads entirely!
Once in the inlet manifold, it either goes forward to the thermostat, or out of the rear to the heater (depending on manifold!)
Chris.
Re: Water flow around cylinders and heads.
Posted: Wed Aug 24, 2022 7:18 am
by jenko
Thanks Chaps......
Re: Water flow around cylinders and heads.
Posted: Mon Nov 14, 2022 8:20 am
by Feltwell
This is really helpful Gents, I think it's answered a question for me...
I've got a Rover V8 from an SD1, 3.5l carb-fed in a 7-type kit car. It has an Offenhauser dual port inlet manifold, which has coolant connections front and rear. I didn't build this car.
The rear connection goes off to the heater matrix, and then returns via a long line to a branch next to the water pump inlet. At the moment the heater matrix is permanently on, which is not great in hot weather, even in an open-topped 7 ! My legs cook!
I'd bought a solenoid flow valve, just to give me basic on and off functionality, but I was concerned that would mean no flow through the inlet manifold and was wondering if the original SD1 heater had a bypass to allow flow past if the heater control was set to cold.
If I'm reading what you are saying right though, the manifold is connected to a flow down into the block so it's fine, that rear manifold outlet can be blocked off with no problems.
I need to take the maniifold off to put a new valley gasket in anyway so I guess I'll see more then about how it works!
Re: Water flow around cylinders and heads.
Posted: Mon Nov 14, 2022 8:46 am
by SuperV8
Feltwell wrote: ↑Mon Nov 14, 2022 8:20 am
This is really helpful Gents, I think it's answered a question for me...
I've got a Rover V8 from an SD1, 3.5l carb-fed in a 7-type kit car. It has an Offenhauser dual port inlet manifold, which has coolant connections front and rear. I didn't build this car.
The rear connection goes off to the heater matrix, and then returns via a long line to a branch next to the water pump inlet. At the moment the heater matrix is permanently on, which is not great in hot weather, even in an open-topped 7 ! My legs cook!
I'd bought a solenoid flow valve, just to give me basic on and off functionality, but I was concerned that would mean no flow through the inlet manifold and was wondering if the original SD1 heater had a bypass to allow flow past if the heater control was set to cold.
If I'm reading what you are saying right though, the manifold is connected to a flow down into the block so it's fine, that rear manifold outlet can be blocked off with no problems.
I need to take the maniifold off to put a new valley gasket in anyway so I guess I'll see more then about how it works!
No.
Coolant flows from the pump into the block. From the block up into the heads, then from the heads into the inlet manifold, then from the manifold into the top of the radiator.
You need to have a small bi-pass circuit so when the thermostat is closed you still get coolant flow through the engine.
Sometimes the heater matrix IS this bi-pass circuit - in which case you can't shut this off.
If you have a separate bi-pass circuit then it's fine to shut off your heater matrix flow when not needed.
Re: Water flow around cylinders and heads.
Posted: Mon Nov 14, 2022 7:16 pm
by Feltwell
Thanks, that's really helpful.
I'm presuming this is the bypass you're referring to - from the front of the inlet manifold to the water pump housing - so I should be OK to stop the heater matrix flow?
Re: Water flow around cylinders and heads.
Posted: Mon Nov 14, 2022 8:32 pm
by ChrisJC
Yep, that's the thermostat bypass, so you can indeed shut off the heater circuit. That pipe bypasses the 'stat and the radiator, and enters the water pump at the inlet.
Chris.
Re: Water flow around cylinders and heads.
Posted: Mon Nov 14, 2022 9:17 pm
by Feltwell
Great, thanks Chris, much appreciated.