DAX Cobra cooling

[HDCobra]

Recently acquired a DAX Cobra and confused about the cooling pipework, hope someone can advise. The two small bore water pump ports that would have been the cabin heater matrix supply and return on the Range Rover the engine was originally fitted to, are not required on the Cobra. These have been piped together and connected to the rear port on the Edelbrook inlet manifold. I have attached a schematic, with the pipework shown in green.

Connecting the heater supply and return together doesn’t make any sense to me ?

https://ibb.co/VcC94GVN

https://ibb.co/DDCPDm6M

https://ibb.co/NgRB26pH

[SuperV8]

The two small ports on the back of the coolant pump are both inlets.
Linking them together is fine, but neater to just blank one off.
Probably a chance for air to collect in the top of that copper jointing piece.

[Ian Anderson]

For a while on my GT40 I had the pipes looped as you mention….worked ok but the engine temperatures swung quickly…basically circulating fluid without going through the radiator! Mine 3.9 with Hotwire ignition system from Morgan

I made up a connector with a restrictor therein with about a 3 mm hole in it to allow any air to bleed through but restrict the flow to very little

The wild temperature swings stopped.

A similar thing used to happen with MGB cars and they overheated in the winter as the driver called for cabin temp too much coolant flowed that way and avoided the radiator……look at the size of the pipe and check against the opening within a thermostat with all the innards reducing flow!

Ian

[SuperV8]

Yes, good point Ian, flow through these smaller pump inputs is by-passing the rad/stat, so will reduce cooling potential.
This bypass circuit is important when the stat is closed, to keep some coolant flow through the engine - but also important to limit this flow to give the rad the best chance of cooling the engine - bit of a balancing act!

I also had cooling challenges - when it was hot outside and I was in traffic my cooling was marginal and temps would start to creep up - I changed my cooling layout to position the stat at the rad output (like most later cars) rather than the input - and a benefit of this is the remote stat housing can also blank of the bypass circuit, so when the stat opens - all the flow goes through the rad. Since this change my temps are great and stable.