2.9 Cooling System

[phillpot]

My guess is knowhere (apart from a little down the by-pass), as the pump is not a positive displacement pump will just "paddle" the water?

[orange_dodo]

techbotics said:

where does the hot water from the bloc go with the stat closed?

Damian

I think the idea is that the tiny pipe H stops the pressure getting too high and keeps a little water flowing round the block so it doesn't boil in the heads but basically the thermostat stops the water circulating.

That would mean though that as soon as the thermostat opens the block which has nice hot water in it probably gets a big lump of cold water which the engine then has to heat up.

At the moment I can't figure out why blocking B off would give faster warm up times as has been reported. As I see it blocking B should force all the water through the radiator and make warm up take longer. It should however stop the car over heating which I think is a more common problem.


Mike sorry for getting in there ahead of you! I have wanted to put a diagram up for months but its taken me that long to find a program to draw the diagram in and actually draw it.

[phillpot]

orange_dodo said:

That would mean though that as soon as the thermostat opens the block which has nice hot water in it probably gets a big lump of cold water which the engine then has to heat up.



Mike sorry for getting in there ahead of you!

Don't think anything happens that fast!
Stat opens gradually, water begins to flow. It's not like a big valve suddenly being whacked open, If you look at a thermostat there's a fair old resistance to flow even when fully open and the pump is not a pump as such thrashing water around it would perhaps more correctly be termed a circulator (bit like a central heating "pump").


Sorry for messing up your nice tidy drawing Tom

[Griffinr]

techbotics said:

where does the hot water from the bloc go with the stat closed?

Damian

It goes through the bypass hose, into the swirl pot and to the top of the rad. It's a 16mm bore hose so shifts quite a lot of water. This is why the are slow to warm up and why I have now piped mine into the bottom hose to overcome the problem. The bypass is hose B on the diagram but the flow is shown the wrong way round on the last drawing.

Rob.

[techbotics]

Griffinr said:

It goes through the bypass hose, into the swirl pot and to the top of the rad. It's a 16mm bore hose so shifts quite a lot of water. This is why the are slow to warm up and why I have now piped mine into the bottom hose to overcome the problem. The bypass is hose B on the diagram but the flow is shown the wrong way round on the last drawing.

Rob.

aha given that I much prefer your solution to that of just restricting its flow..

cheers

D

[mep12345]

orange_dodo said:

Mike your right, had a closer look at the heater circuit and I think it is a little closer to the truth now although I don't think it is completely right. I have no idea what the flow direction is but E seems to be close to the water pump I think, its a little difficult to see. The colours for E and F are probably wrong but I'll fix them when I figure out the routing for certain.

Take 3...

I am not 100% sure but I think this diagram has only 2 errors now. I think pipe E goes into the suction side of the water pump (i.e. into pipe A) and pipe F should be red. This ties up with what I have observed putting the engine back together over the last few days, i.e. the radiator and the metal pipe that runs round the sump come into the suction side of the water pump.

However even with the engine apart it is really difficult to tell

[orange_dodo]

Hasse (sighck) has kindly constructed another diagram to correct my errors which happen to be exactly the same corrections that you just suggested Mark.

I've included mine and Hasse's diagrams for reference. Again comments welcome.





I think Hasse's diagram is neater and clearer but I'm including mine as well because it's mine

Hasse has also supplied a diagram of a modification he suggests to get the cooling system to work properly.



This involves removing 2(E) from the water pump end and plugging the hole. Removing 6(B) entirely and plugging the hole in the swirl pot. Rerouting the water pump end of 2(E) into the hole left at the water pump by removing 6(B).

I'm sure that will cause some arguments

[Griffinr]

techbotics said:

aha given that I much prefer your solution to that of just restricting its flow..

cheers

D

It's been on the car for over a year and 6000 miles and works perfectly in all weathers as well.

Rob.

[orange_dodo]

Thought I'd update things.

I put a brake hose clamp on pipe B(6) to stop water flowing through it a couple of weeks ago. The difference in temperature stability is noticeable as the temperature gauge now holds the needle horizontal no matter how I drive unless I stop in traffic. Then the needle rises until the fan comes on and it rapidly falls back to horizontal again. Compared with the needle moving around far more with B(6) unblocked and spending far more of its time above horizontal I would say that the pipe is definitely a hindrance rather than a help!

Now I just need to find an 18mm (I think thats the diameter) cap for the swirl pot and water pump....

[phillpot]

orange_dodo said:

Now I just need to find an 18mm (I think thats the diameter) cap for the swirl pot and water pump....

16mm ?

how about a bung,or maybe just a restrictor (pipe can then still act as a vent/air bleed or whatever) in the pipe?

Or even something like this, a little tail of 15mm pipe out each end with an olive soldered on to help retain rubber (silicone) pipes, totally adjustable flow

[S2Andy]

I've been using a restrictor valve just like the one above for about 12 months now situated in pipe "B" near the swirl pot. Valve very slightly cracked open to relieve pressure. Works superbly, quicker warm up and no over heating issues. Wrapped it within a split larger hose to avoid any chafing issues. Andy

[glenrobbo]

I find it amazing that it's been over 20 years to get to the bottom of this anomaly, and that there are no doubt quite a few 2.9 S's running around with the factory ( less than ideal ) set-up.
Too late for a recall I guess!

Well done to Rob, Tom et al for their efforts in sorting the problem.

[S2Andy]

ADDENDUM, slightly confused with all the letters! Mine is in the 1/2" pipe that runs from just adjacent to the water pump pulley to just below the overflow pipe on the swirl pot (second pipe down) Sorry for any confusion. Works a treat if my cooling system is the same layout as others. lol Andy

[orange_dodo]

Just bought 2 pairs (meant to buy 2 but apparently I can't read!) of these.

Hopefully they will make things look a little neater. I don't think it needs more flow than the thermostat bypass gives already. I opened the swirlpot when I started the engine and there is a pretty high flow even when the thermostat is closed.

[swimmer27]

S2Andy said:

I've been using a restrictor valve just like the one above for about 12 months now situated in pipe "B" near the swirl pot. Valve very slightly cracked open to relieve pressure. Works superbly, quicker warm up and no over heating issues. Wrapped it within a split larger hose to avoid any chafing issues. Andy

Hi Andy
Just found this topic, where did you purchase your restrictor valve from? have looked on Ebay and carbuilder with no luck.
Are you referring to the isolation valves plumbers use on 15 & 22mm copper pipe?
On a return trip from Stratford Upon Avon to Surrey I noticed my radiator cooling fan coming on whilst cruising at motorway speed, the pessure cap which is on the expansion bottle (was like this when I purchassed her) and the cap on the swirl pot both look in a poor condition so have ordered replacments hoping the hissing noise from the expansion tank might of been the cause for the fan kicking in.
Water level looked ok, can't seee any leaks plus the wire mesh is clear of leaves etc.

Thanks

Paul

Edited by swimmer27 on Thursday 11th July 14:55

Edited by swimmer27 on Friday 12th July 09:40

[techbotics]

Interested in this again shame images no longer there.

Tom could you please confirm that you have just blanked off both ends of the bypass hose ?

Cheers

Damian S3

[Top Gear TVR]

i am still planning the shift of bypass going not to the swirl pot but to the radiator bottom outlet pipe

anything here say thats wrong yet?

[techbotics]

Don't think so, it looks like a good solution.. although its just a fair bit extra work IMHO..

If I could block off the bypass then I could use the free 16mm swirlpot connection as a fill from my new header tank.. Although I don't know why I am thinking about this too much, hopefully I will be 24v powered by time it gets cold so will have a whole bunch of different issues re cooling to consider I'm sure..

Apologies for not mailing you, but it looks like you have your fan issues in hand now anyways.. a new item was always going to be a better option I reckon.

Hoping you get a speedy delivery..

Damian S3

[Griffinr]

Top Gear TVR said:

i am still planning the shift of bypass going not to the swirl pot but to the radiator bottom outlet pipe

anything here say thats wrong yet?

Worked fine for me the last 2 years even in the heat today.
Rob.
Connected mine like this..... http://thumbsnap.com/f/mT0IEmYX

Edited to add photo.

Edited by Griffinr on Sunday 14th July 18:51

[Top Gear TVR]

This may mean I need a tig welder of my own?