The V8 Owners Forum -

Ok I’m building a rv8 that’s going into a tr7 I’ve heard that you can drill and tap the inlet manifold so you can join the two unused rear water ways on the heads, I’ve heard this can help as the coolant can become stagnent in this area ??
I was going to do this modification and was going to tee into to this pipe and connect it to my heater matrix , then conect the return pipe from the matrix to the stub on the water pump (p6 pump ) the heater is permanently flowing (temperature is controlled by flaps in the heater box)
So here are my questions
1) this a good idea and could it indeed help cooling ? It won’t take much doing and should simplify the heater pipework
2)is the fact I’ve got the heater conected in this an effective bypass
Thanks Nick

Nick, Like you I use the P6 pump and like you the flow through the heater cannot be turned off.
My return from the heater is connected to the rad top hose via a Tee. The connection at the pump is now not used and blanked off.
The by-pass hose must always be used.
When you look at the pump the return from the heater can send some of the heated coolant back round the system without going through the rad by going straight into the by-pass system yet again so no chance of cooling. By plumbing the heater return into the top rad hose ALL coolant must go through the rad, it has no choice.
To blank off the return at the pump I used a short hose with a 16mm bolt in it. It may not look pretty but it works. A stainless polished bolt improves the look a little.
Works on my car.
Mike.

Hi
I would take the new bleeds back to the header tank!
Ian

Never heard of this mod being done or needed. If you alter the water flow, you may make things worse elsewhere within the engine.

mike-b wrote: ↑

Tue Feb 06, 2018 11:04 pm

Nick, Like you I use the P6 pump and like you the flow through the heater cannot be turned off.
My return from the heater is connected to the rad top hose via a Tee. The connection at the pump is now not used and blanked off.
The by-pass hose must always be used.
When you look at the pump the return from the heater can send some of the heated coolant back round the system without going through the rad by going straight into the by-pass system yet again so no chance of cooling. By plumbing the heater return into the top rad hose ALL coolant must go through the rad, it has no choice.
To blank off the return at the pump I used a short hose with a 16mm bolt in it. It may not look pretty but it works. A stainless polished bolt improves the look a little.
Works on my car.
Mike.

Ok so let's see if I've got this right, out my heater matrix into the rad top hose ? I assume your suggesting this because if I did it "my "way the water in the matrix will still be hot and by putting it into what is effectively the bottom hose this" still" hot water will go straight back into the engine? Doing it your way it gets to go through the main radiator again to help diserpate more of the heat ?

Twinturbotr7 wrote: ↑

Wed Feb 07, 2018 10:00 am

mike-b wrote: ↑

Tue Feb 06, 2018 11:04 pm

Nick, Like you I use the P6 pump and like you the flow through the heater cannot be turned off.
My return from the heater is connected to the rad top hose via a Tee. The connection at the pump is now not used and blanked off.
The by-pass hose must always be used.
When you look at the pump the return from the heater can send some of the heated coolant back round the system without going through the rad by going straight into the by-pass system yet again so no chance of cooling. By plumbing the heater return into the top rad hose ALL coolant must go through the rad, it has no choice.
To blank off the return at the pump I used a short hose with a 16mm bolt in it. It may not look pretty but it works. A stainless polished bolt improves the look a little.
Works on my car.
Mike.

Ok so let's see if I've got this right, out my heater matrix into the rad top hose ? I assume your suggesting this because if I did it "my "way the water in the matrix will still be hot and by putting it into what is effectively the bottom hose this" still" hot water will go straight back into the engine? Doing it your way it gets to go through the main radiator again to help diserpate more of the heat ?

If you direct it into the rad...but also where water can still circulate if the stat is closed it would be ok.

I'm pretty sure the heater circuit etc is also an important feature of maintaining circulation through the block even if the stat is closed ? So whilst yes it does allow pretty hot water back in, it's a relatively small amount.

DaveEFI wrote: ↑

Wed Feb 07, 2018 9:53 am

Never heard of this mod being done or needed. If you alter the water flow, you may make things worse elsewhere within the engine.

Hi Dave here are some pictures of someone's engine I saw on Facebook it's not my engine but they must have done it for some reason




Once again this is NOT my engine but I must admit it's very trick looking

That pipe is pointless. I suspect it is there so both pieces of the inlet manifold are identical rather than being handed.

The circulation on the Rover V8 is this:
1. The water pump sucks water in from the radiator bottom hose and pushes it into each cylinder bank.
2. The water travels front to back in the block, then up at the back into the heads.
3. In the heads, it travels forwards to the front of the engine and then up into the inlet manifold.
4. From here it goes a number of ways.
4a - Into the heater matrix and back to the water pump inlet
4b - Via the thermostat bypass pipe into another water pump inlet
4c - Via the thermostat into the top of the radiator.

If you divert water from the back of the heads, you will reduce the amount of water flowing through the heads and reduce the cooling in them.

If you have the thermostat bypass circuit as described above, you can shut off the water through the heater matrix without any problems. If the heater circuit and thermostat bypass circuits are one and the same, then they must stay open.

Chris.

Thanks for your reply , maybe I've asked to may questions in one post , in Hindsite I should have asked anout the rear unused water ways in one post and I should have started another anout the bypass circuit
Ok you think it's a bad idea to mess about with the rear ports ,I get that and it does make sense and your probably right ,maybe someone else will chip in and have a opinion on that ?

Onto the second problem the bypass ,being as my matrix is a always open type (no valve on it)do I need another bypass or will just using the heater circuit be the only bypass I need ,
Thanks Nick

If your heater is always open, then you don't need to have a 2nd bypass.

Chris.

ChrisJC wrote: ↑

Wed Feb 07, 2018 9:26 pm

If your heater is always open, then you don't need to have a 2nd bypass.

Chris.

Thanks Chris one more question the return from the matrix where is the best place to fit it ??one of the reply’s said it should go into the top hoze so all water goes through the rad or should it go to the 15mm stub on the water pump (p6 pump )so it’s just keeps going round the engine , my engine is a twin turbo and it’s in tr7 so I’m expecting cooling problems hence why I’m trying to get best solution first time

TwinturboTR7 - I think you have a solution for a problem that does not exist - if the standard cooling system is in good condition the engine does not have a cooling problem. The engine has been around in various forms and power for over 50 years and if there had been a problem changes would have been made.

As mentioned - coolant in the heads comes from the back and moves forward where it then goes into the manifold and then either to the heater or top radiator hose. If you tap off at the rear of the heads like you suggest then also as suggested flow through the heads will be reduced maybe causing overheating issues there.

Just because you see a pic on Facebook does not make it right - leave it.

Garry

Odd, that engine pictured. Go to all that bother - but keeps the dizzy.

Twinturbotr7 wrote: ↑

Wed Feb 07, 2018 10:40 pm

ChrisJC wrote: ↑

Wed Feb 07, 2018 9:26 pm

If your heater is always open, then you don't need to have a 2nd bypass.

Chris.

Thanks Chris one more question the return from the matrix where is the best place to fit it ??one of the reply’s said it should go into the top hoze so all water goes through the rad or should it go to the 15mm stub on the water pump (p6 pump )so it’s just keeps going round the engine , my engine is a twin turbo and it’s in tr7 so I’m expecting cooling problems hence why I’m trying to get best solution first time

I would route it back into the water pump inlet as per Rover's design. I think if you routed it back into the top hose you may get zero circulation in the heater when the thermostat was open!

Chris.

ChrisJC wrote: ↑

Thu Feb 08, 2018 7:09 pm

Twinturbotr7 wrote: ↑

Wed Feb 07, 2018 10:40 pm

ChrisJC wrote: ↑

Wed Feb 07, 2018 9:26 pm

If your heater is always open, then you don't need to have a 2nd bypass.

Chris.

Thanks Chris one more question the return from the matrix where is the best place to fit it ??one of the reply’s said it should go into the top hoze so all water goes through the rad or should it go to the 15mm stub on the water pump (p6 pump )so it’s just keeps going round the engine , my engine is a twin turbo and it’s in tr7 so I’m expecting cooling problems hence why I’m trying to get best solution first time

I would route it back into the water pump inlet as per Rover's design. I think if you routed it back into the top hose you may get zero circulation in the heater when the thermostat was open!

Chris.

Hi Chris thanks for the reply yes it makes sense to put the matrix return back to the pump and that's what I will be doing , i think what mike -b was trying to tell me earlier in this thread was that he sends his back to the radiator but he still has another bypass so it wouldt be a problem for him , the only bypass I'm going to be able to have is the heater circuit , I've got one of John eales hybrid timing covers and the bypass is not machined into the cover so I'm going to rely on the heater circuit as my main and only bypass