2.9 Cooling System

[magpies]

techbotics said:

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

Damian

[mk1fan]

That's some fine thread resurrection there.

[yknot]

I'm glad this has been resurrected as it needs to be sorted IMHO!

What was the solution back then? The last time this was posted by the OP (orange-dodo?) he seems to advocate blocking the flow, and others have agreed, that at least restricting the flow from the bypass hose to swirl pot improves the warm up and running temp of the engine??

I have my doubts about the direction of flow of the pump bypass hose on the final diagram, and somewhat agree with Griffinr (Rob) that the original design by Ford for the Scorpio was to send this flow via the pressurized expansion tank and back to the water pump intake (bottom hose) without going through the radiator. But what was the purpose of this as it seems a thermostat bypass already exists, albeit quite small, so was this a 'fail-safe' system to prevent the heads boiling if the thermostat was stuck shut or the flow restricted somehow??

It would be good to have a definitive answer but I suspect a lot of owners have come up with their own solution and, maybe, the problem is dependent on the model and how TVR plumbed each one!!!!

[magpies]

This is my solution. No swirl pot. Rad has bleed to head tank.

[edsj]

Blocking the by-pass (pipe B) still means that the stat by-pass H from block to swirl pot still brings "cold" water to the rad causing slow warming-up??

My S3 has stabile temp also during traffic in hot conditions, but warms up slowly with the standard (?) set-up.

[GreenV8S]

magpies said:

This is my solution. No swirl pot. Rad has bleed to head tank.

Is there another outlet from the header tank? A small/restrictive inlet from the top of the rad plus a larger/slower output to pump inlet is very effective at degassing because it uses the header tank as a settling tank. (A dead-end header tank isn't as effective at separating air because it doesn't see enough flow.) It also means you put the cap pressure directly on the pump inlet.

[magpies]

GreenV8S said:

magpies said:

This is my solution. No swirl pot. Rad has bleed to head tank.

Is there another outlet from the header tank? A small/restrictive inlet from the top of the rad plus a larger/slower output to pump inlet is very effective at degassing because it uses the header tank as a settling tank. (A dead-end header tank isn't as effective at separating air because it doesn't see enough flow.) It also means you put the cap pressure directly on the pump inlet.

Yes

There is a connection from the base of the header tank to the bottom hose (rad back to pump)

also hard to see another connection from near the thermostat to the header tank.so basically two air vents rad and engine block and water expansion from bottom hose all to the header tank (highest point)

[GreenV8S]

magpies said:

Yes

[yknot]

edsj said:

Blocking the by-pass (pipe B) still means that the stat by-pass H from block to swirl pot still brings "cold" water to the rad causing slow warming-up??

My S3 has stabile temp also during traffic in hot conditions, but warms up slowly with the standard (?) set-up.

The 'stat bypass pipe H is much smaller that the pump bypass B so, I guess, restricts the flow of coolant through the rad and prevents the circulation of cooled water until the stat opens?

Magpies solution appears to confirm the Ford plumbing (to an extent) by using a pressurized header tank to circulate coolant from the stat bypass (or pump bypass, can't really see clearly?) to the bottom hose with a small bleed off to the rad. Not sure if Ford had this connection to the rad but it obviously help to bleed air?

The issue is IMO the pump bypass which at 16mm carries quite a large unregulated flow through the rad but its not clear why this is necessary!

Would be good to find out from those with a modified plumbing system on a standard Cologne engine what they finally decided on and if any issues have arisen (such as bleeding the system after refill) but maybe they are no longer here on PH?

[Griffinr]

The small hose from the top of the thermostat housing is just an air bleed. The bypass hose from the pump to the swirl pot is the one that needs moving so that water does not go through the rad. Replumbed mine to a tee in the bottom hose about 5 years ago and had no problems since. It's up to temp within 2-3 miles and stays bang in the middle of the gauge unless in stop start traffic.