Thread: Heater core by pass

Personally I have found that deleting the 3 way stat and doing a conventional (read D1 style) top hose stat is the way to go to get dull flow when required and the best temps.

Cheers

The smart money seems to be going for the loop. So am going to do the loop. Is a cool day in Cairns today, and simply clamping one of the hoses as I have initially done seems to have increased engine temps.

What's the theory behind the smart money? Is it just the A.C. v in cabin heater core? If so I understand. If it is cooling efficiency and maximising cooling of the motor then smart money is on top hose thermostat.



Cheers

I bypassed my heater in my D1 300tdi as the was stuck on. Hose size was 3/4 tried buying a hose barb at autobahn but they didnt have it in stock. i just got a bit of 19mm stainless tube at work bead rolled the end and just hooked the 2 hoses off the firewall together works a treat.

If you cant make your own any hose joint should stock a male-male 3/4 brass hose barb to do the job

Originally Posted by ozscott

What's the theory behind the smart money? Is it just the A.C. v in cabin heater core? If so I understand. If it is cooling efficiency and maximising cooling of the motor then smart money is on top hose thermostat.



Cheers

It is about the best method to bypass your heater core, without having a negative impact on your cooling system.

The top hose thermostat is another topic entirely.

I fitted a bypass for the D1 heater core, it was a holden or ford vacuum operated unit picked up from Autobarn. I converted to a cable operation as vacuum wasn't easy to come by.

The Discovery internal heater system has the annoying controlled flaps thing which means if one breaks (like drivers footwell did in the D1) you get hot air regardless of air con and temp settings. It was pretty uncomfortable on a 10hr drive at xmas to Eyre Pen' , even with a rag stuck in the outlet near my foot.

The bypass worked awesome, I never saw it really affect engine temps.

But you really need to put a bypass not just clamp the hose on the D1/2 system as when cool the flow is head-heater-head loop, I don't think it goes anywhere else till the thermostat opens, I know the D1 and 2 differ on this, I think D2 has a small amount of flow via rad even when cool, I'd bet that was a cold weather mod to actually warm the rest of the system (including the fuel cooler).

Thankfully the D2's flaps are all functional so I've not felt the need to bypass on this one. The leave flaps at last setting when off is the main complaint I'd make about the D2 system, turning the system on to change the temp to then turn off is just annoying. Of course, I prefer manual twisty knobs rather than the whole climate control thing anyway.