MGB V8 Conversion Cooling Pipework Layout

slinkycinqi · Post by **slinkycinqi** » Sun Sep 14, 2014 10:36 am

Hi guys,

I am sure someone here on the forum can help with this, I must have something wrong as the engine is overheating pretty quickly and water doesn't seem to be circulating around the whole system.

The car is fitted with a header tank as high as I can possibly get it in the bay, where I know other guys have them installed in these cars. The inlet manifold is an Edelbrock Performer.

On the diagram above (borrowed from another thread!) I have the following connections:

- C to H (with a small take off pipe from the top hose running up to point A on the header tank as on the drawing and I have no point B as it is a header tank with a single connection and 15psi cap)
- I have no point I as on the drawing as my rad has no cap, it is an original MGB radiator mounted 90 degrees from normal orientation.
- Dto E
- F to bottom side of my heater matrix via a copper pipe.
- The pipe from the top of my heater matrix comes out and down to the connection not shown on the drawing on the back of the inlet manifold, this is where my heater control valve is fitted. There is a bleed valve fitted in this pipe also.
- G to L

There is no stat installed inside the housing at the moment, so this is one thing out of the equation.

I hope this makes some kind of sense, if there is anything else you need to know, or isn't clear please let me know and I will do my best to clear it up.

Below are a couple of links to pictures showing the water pump housing, where you can also just see the top hose, and the second picture shows the connections to the heater matrix and rear of the inlet manifold.

Many thanks in advance for any help that can be offered.

Lenny

ChrisJC · Post by **ChrisJC** » Sun Sep 14, 2014 11:03 am

Mostly OK. The lack of a connection to 'B' concerns me. The header tank is at the highest point right?
If so, then B should go into the bottom hose.

The main connections are fine - rad top hose, bottom hose, heater circuit and thermostat bypass.

What do you mean that the rad is turned through 90 degrees? You need a bleed from the highest point in the rad back to the header tank. Small bore pipe.

Chris.

slinkycinqi · Post by **slinkycinqi** » Sun Sep 14, 2014 11:09 am

Hi Chris,

Thanks for your reply, perhaps I am getting confused with my tanks, the tank I have is the original '78 MGB tank, it only has one connection high on the side of the tank, there is then a pipe running down inside the tank to near the bottom. The tank is brass, and is fitted with a pressure cap.

The pipe that runs to the said connection on the side of the bass tank comes from the top hose (there is an aluminium joiner fitted to the top hose, drilled and tapped and fitted with a 90 degree fitting then some 8mm copper pipe running up to the connection on the brass tank).

The rad is turned 90 degrees as in if you imagine rotating a picture on your computer screen 90 degrees, it was done purely to stop the top hose coming out right in to the alternator pulley.

Many thanks again.

Lenny

ChrisJC · Post by **ChrisJC** » Sun Sep 14, 2014 1:09 pm

Ah, that is an expansion bottle rather than a header tank. It does sound like things are as expected......

Read this thread:
http://www.v8forum.co.uk/forum/viewtopi ... 86&start=0

Does that make things any clearer?

Chris.

Ian Anderson · Post by **Ian Anderson** » Sun Sep 14, 2014 3:05 pm

F to heater matrix and then back tq head?

Can you restrict this? Even with mole grips?

Then try again as I suspect you are getting a bypass flow through that so the water is avoiding the route through the rad.

Also I am not sure if running a radiator on it's side is workable.sorry cannot find any info on that

Ian

slinkycinqi · Post by **slinkycinqi** » Sun Sep 14, 2014 3:43 pm

Hi Chris,

That thread does indeed help, I am now wondering whether to fit one of those top hose joiners complete with pressure cap? Would this be suitable to feed to my expansion bottle connection? (which is also fitted with a pressure cap) I'm guessing so?

Then the small stubby outlet from my expansion bottle for any water that passes the pressure seal (where the small hose used to drop down to the ground) can still drop down to the ground for any excess?

Hi Ian, I will try restricting this hose and let you know how I get on. Hopefully get this done during the week, I need to re fit the rad to the car as it was away having a plate brazed in to the old fan switch hole (I'm using a capillary in the top rad header). I had left the old fan switch in just to plug up the hole, but the rubber grommet which held the fan switch in place developed a leak!

As for mounting a rad on its side, I have found from looking around on the internet that people have done it with success in hot rods, kit cars and the like. As long as you have the hot water going in at the top and the cooled water being sucked from the bottom then you're good. (famous last words!).

Many thanks again for all of your help so far!

Lenny

ChrisJC · Post by **ChrisJC** » Sun Sep 14, 2014 6:28 pm

We're in uncharted territory now!
I did wonder if the expansion bottle you have is supposed to be pressurised. I guess it could be, but I've never seen it done............

My money would be to switch to a system where it's not pressurised, with a top hose joiner as you say, and a suitable cap. At least you're then doing something known to work.

Yes, the overflow would work as you say.

I wonder though if your rad is big enough......

Chris.

slinkycinqi · Post by **slinkycinqi** » Sun Sep 14, 2014 6:57 pm

Hi again Chris,

I have spoken to people who do this conversion at MGB Hive where I get a lot of my parts from, and they use the same expansion bottle as I am using, but they use the V8 rad, the only difference is where the inlet/outlet ports exit on the rad, the core is the same as the rad that I have, only mine is a standard rad turned 90 degrees to achieve the port positioning that the V8 rad has when orientated normally.

But obviously when they have the V8 rad, they connect the small pipe from the top header of the rad to the expansion tank, as the top expansion tank connection on my rad is now at the side of the rad (due to it being turned 90 degrees) it is blanked off. And I have tried to take the connection from the top hose, as I cant have it from the rad. I hope that makes sense?

Added a pic below to illustrate my ramblings!

Thanks again for all of your help people!

ChrisJC · Post by **ChrisJC** » Sun Sep 14, 2014 8:55 pm

I think I understand. Seems logical.

Therefore I can't quite see why it doesn't work......!

Chris.

slinkycinqi · Post by **slinkycinqi** » Mon Sep 15, 2014 7:44 am

Hmm, I was hoping I had completely ballsed something up and it wouldbe obvious to everyone! lol

I wonder if it is something to do with my filling technique, or lack of.

What would be the best way to fill such a system?

I filled the expansion bottle time and time again then blew it down using my mouth! I obviously have the bleed nipple that can be seen in the pictures from the top heater matrix hose, I opened this and blew until coolant was coming out of here, then closed it off and carried on fillling and blowing around, can't imagine this filled the whole system though.

I am sure this must be a flawed technique, but I am unsure what else to do to fill the system?

Many thanks again.

ChrisJC · Post by **ChrisJC** » Mon Sep 15, 2014 5:08 pm

Have you got a fill point at the highest point? That's where I'd fill it. You'll never fill it via the expansion bottle.

You could take off the top hose, and pour it into the rad, and the top hose. Depending on your stat, it might not fill that well. You could pop the stat out, and then pour water into the rad until it comes out of the 'stat hole! Then it'll be full.

Chris.

slinkycinqi · Post by **slinkycinqi** » Tue Sep 16, 2014 9:20 am

Thanks Chris,

I'll try filling this way and see how I get on.

Another stupid question if I may, when the engine is running, if I remove the expansion bottle cap, what would be expected to happen?

Thanks again!

DEVONMAN · Post by **DEVONMAN** » Tue Sep 16, 2014 9:52 am

Going back to what ChrisJC said at the start, you need to connect point B to the bottom hose. At the moment you have no proper way of filling the system as you have lost point I.

Once you are sure you have the system full, if it still runs hot then close the heater valve and see what that does.
Many guys have rearranged the heater circuit as the standard arrangement puts hot coolant back into the engine without going through the rad.

Regards Denis

slinkycinqi · Post by **slinkycinqi** » Tue Sep 16, 2014 11:15 am

Hi Denis,

Thanks for your input, sorry for any confusion I have caused at the start of the thread, I have an expansion vessel rather than a header tank. So I have no point B, my expansion vessel only has one inlet near the top of the brass tank, which has a tube that runs down inside the tank to near the bottom.

Seeing as I have no other way of filling the system I think I may have to employ the strategy suggested by Chris and fill via the top hose until water comes from the stat hole.

I wonder if this will fill the heater matrix? As the mmatrix is higher than the top hose and engine. I could make an extra long top hose (piece of pipe) for filling I guess? So that there is adequate head to push the water up and through the matrix.

I am concerned that when I remove the expansion vessel cap with the engine running I get water pouring out everywhere. Should this be so?

Many thanks again to everyone.

chodjinn · Post by **chodjinn** » Tue Sep 16, 2014 11:56 am

Turning a rad 90 degrees is not ideal, they are orientated a certain way with respect to core flow for a reason. If a standard one doesn't fit then maybe go for a custom one. Blocking off a breather is also not ideal.

Having the breather on the top hose and to your expansion bottle isn't great either, it needs to come from the highest point in the engine, i.e. somewhere on the inlet manifold. The expansion bottle won't work like an expansion bottle.

Expansion bottles are crap imo, better to have a header tank. As already stated, you can connect "B" to bottom rad hose. I my old setup, I connected the breather from the rad, with a "T" connection to the other breather from the inlet manifold, to point "A" on your drawing. Then "B" to bottom rad hose. Used a MGB V8 radiator, never had cooling issues. I also ran a Kenlow fan.

No point 'blowing' or anything like that, has no effect, and do not fill from expansion tank! You don't seem to have a radiator cap/pressure cap at all? You need a permanent breathing solution to remove air entrainment caused by cavitation that the water pump creates.

What is probably happening, is that your engine is warming up, increasing pressure from air entrainment which has no where to escape to and your engine overheats. It doesn't take long for that to happen!