Rover V8 cooling system

[AntonyJ]

Can somebody describe the direction of flow for the cooling system of an RV8.

Is it the same for pre-serp and serpentine? I presume it is , but ask due to the direction change of the water pump between the two types of front cover.

The reason for asking is because I am connecting my heater matrix to the new engine and I want to make sure I get the flow direction through the matrix( and therefore the control valve) correct.

[GreenV8S]

The flow is basically the same i.e. from the pump into both sides of the block at the front, through the block to the back, up into the heads, forwards through the heads to the water chamber in the inlet manifold and then out via the stat to the radiator. Return from the radiator goes back to the pump inlet.

Note that the bypass arrangement is very different between the two layouts so if you're changing you must make sure that you provide an adequate bypass.

Edited by GreenV8S on Tuesday 27th January 22:42

[stevieturbo]

Nearly all engines flow cold water into the lower hose, it runs through the engine, then hot comes out the top and into the radiator....cools...back into the bottom

In and out on the heater matrix isnt really that important. As long as there are no air locks, water will still flow through it

[spend]

I think the prob your talking about Ant is the heater return flow?. On pre-serp it comes out of the back of the water pump, on serps it is linked into the swan neck (rad return pipe). Seems an awful long way round past all that engine / belt / manifolds and cant see how it helps flow before the stat opens?, but thats the way they did it. I'd be tempted to tee off the hose closer to the water pump TBH Watch the inlet manifolds as well they have a couple of different arrangements in/out at the bottom, out at the bottom, out at the side (just above your old gauge temp sensor on the one that has LR casting mark IIRC)..

I've always been convinced that one of the advantages of the pre-serp arrangement vs serps (but few dare to criticize them)

[AntonyJ]

Thanks guys, clearer now.
Pete, can you expand on the bypass arrangements? what is/was on the preserp and how does the serp differ?



ETA Now understand the preserp bypass pipe, it comes from the lower front of the inlet manifold to the top of the water pump, above the matrix return pipe.

But where is the serp bypass?, I will be using a serp inlet manifold too.

Edited by AntonyJ on Wednesday 28th January 08:42

[GreenV8S]

AntonyJ said:

can you expand on the bypass arrangements? what is/was on the preserp and how does the serp differ?

Essentially, the bypass and heater feed always come from the engine outlet upstream of the stat and both return to the pump inlet.

In the pre-serp setup they are both fed from the water chamber at the front of the inlet manifold. The heater feed comes out of the back of the chamber; the bypass comes out of the front. Conventionally the heater return pipe passes back under the inlet manifold so the heater return and bypass both pop out the front and connect into corresponding spigots on the pump body.

On the serpentine setup this plumbing is separate from the pump and needs to be connected up to the bottom hose externally. That's fine as long as you do it; it's been known for people used to working with the pre-serpentine setup simply to connect the pipes they have in their pre-serpentine engine bay. This of course is a disaster for the engine as it means there is no bypass and the only flow through the engine is the flow through the radiator. This is nowhere near enough if the engine is working hard in cold conditions or when the engine is cold.

[AntonyJ]

Pete, I cant think of the bypass pipe on the serpentine, any pics?

Can this be got around by drilling the stat? Or does that not provide enough bypass flow?

[GreenV8S]

AntonyJ said:

Pete, I cant think of the bypass pipe on the serpentine, any pics?

Can this be got around by drilling the stat? Or does that not provide enough bypass flow?

Drilling the stat helps vent it and also smooths out the shock when the stat cracks open, but that doesn't flow anywhere near enough to act as an engine bypass. You need a really substantial hose, 1/2" bore is too small, 1" is ok but when you get to that sort of size you need a switch bypass rather than full time (i.e. the stat has to shut off the bypass when it opens) otherwise you lose too much flow through the rad.

[spend]

Ditch the stat and install a remote Cerbie one or a later p38 version is the best way to achieve good bypass flow IMHO. When making changes like these you are not restrained to follow a single train of development

[trackcar]

Spend mentioned this in a conversation in the workshop once with ref to just updating the cooling system on any rv8 and I said don't fix what ain't broke, but in the case of a change from pre to serps and to eliminate any potential cooling issues pre stat opening temp it's actually a great idea i reckon.

[AntonyJ]

Cerbera stat? So this would be fitted on the outfeed of the rad?

God , decisions decisions.

[spend]

Ant, the rad inlet pipe (unstatted) goes to the cerb stat. This has a loop that tees into the rad return pipe. Basically you get good flow around the system just bypassing the rad when the stat is closed, when the stat opens the rad is used... Warm up may take a little longer, but you won't cook heads and bleeding should be a lot easier. The advantages in your case are that its a lot easier to integrate the heater IMHO.

[GreenV8S]

spend said:

Warm up may take a little longer

If that's the case, you're doing it wrong!

While you're thinking about these changes keep in mind that you need to vent and degas the whole system too. The primary flow is the easy part to get right.

[AntonyJ]

Right, had a look at my car and there is a bypass before the matrix heater valve, so I presume this will also work as a bypass with the heater pipe connected either side of the pump.


Essentially this would mean there were two bypass' when the engine was preserp.

Had a good look at a serp Chimaera today and there arent any other coolant pipes to act as a bypass.

Forgive me but I cant get my head around the Cerb stat idea. Maybe I am just being blonde, or need it drawing out for me!

[spend]

just for you The Cerb stat would sit say between your swirl tank and rad. When open it diverts incoming hot coolant to the rad, when closed it sends incoming cool CoolAnt () to the rad return pipe (a hose tees into that).

[AntonyJ]

Right ,got it now !!!

What do you think about using the heater feed pipes (with there bypass) as the pump bypass , would that be ok?

Cant see how else it is done on the Serp TVR cars.

[GreenV8S]

AntonyJ said:

What do you think about using the heater feed pipes (with there bypass) as the pump bypass , would that be ok?

Doesn't sound at all promising. What diameter/length would the resulting bypass circuit be?

[AntonyJ]

Just found the info in the Griff bible, it says that the H section in the heater pipes provides the bypass function.
So it seems that is how TVR did it on the serps.

But I might just fit another H section closer to the pump...

[spend]

AntonyJ said:

Just found the info in the Griff bible, it says that the H section in the heater pipes provides the bypass function.
So it seems that is how TVR did it on the serps.

That bypass valve was on the pre-serps, but IIRC many on here have said that it was not present on the serps (just plain pipes to the heater matrix)???
Sure you read it right, your engine supplier still has my bible (does that make me an evangelist?) so I can only guess.

[AntonyJ]

Dave, was 37 yesterday but dont need glasses just yet.

Page 132 of second edition;

"With the pre-serp engines,this bypass is part of the engine pipework and with the serp engines the pipework to the heater matrix provides this function."

My car definately has one so hopefully will be ok.