Thread: Low Coolant Level Alarm

Unfortunately with Defender 200Tdi's there's no extra plug on the thermostat housing (TH) to add in any kind of low coolant level device. This means either drilling and tapping the TH, or doing something similar to the radiator.

The genuine solution of incorporating the sensor into the expansion tank (ET) still seems to be a good idea to me. I can't see how the coolant level can drop in the system without it being reflected in the ET? As Leo notes, these systems run at full pressure and are connected to the cooling system by a reasonably large hose, direct to the bottom radiator hose. This is the intake for the cooling system and the water pump pushes coolant from this hose up through the engine and out through the TH. If the coolant level was low it should show up in both the radiator and the ET, before a low level was experienced in the TH (whilst the water pump is operating). It would only be when the pump was stopped that the low coolant level would be equal in both the ET, TH and radiator. This is in fact done deliberatly by most manufacturers to ensure that the engine receives it's full level on coolant whilst in operation, even if the system is a little low. The low level is carried in the radiator, not in the engine. Only when the level is so low the it falls below the level of the water pump will the engine not be full of coolant whilst the pump is operating.

As I said above, this is the system for the majority of engines. A very few have a reverse coolant flow where the thermostat is mounted below the water pump, and the pump pushes coolant down into the bottom radiator hose, up through the radiator and into the engine. In this system coolant level is ultra critcal because any low level is carried in the engine (at head level) and the radiator will always remain full whilst the pump is in operation. The only example that comes to mind is the 12valve 2.4 Nissan engine used in the '90's in Pintaras and Ford Corsairs.

In answer to Matbor's question, yes the Rangie cap will fit V8 Disco's, all those caps are the same and have been for quite a few years. The one I picked up was off an old classic V8 Rangie.

Paul [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

Watching with interest, waiting in anticipation.

Resurecting an old thread to add some information.

My 84 rangie has a disco 300Tdi and I have fitted a low water level cap from a later rangie to the disco expansion tank. I haven't wired it in yet.

Here http://www.ep90.com/index.php?id=67 is a page, which has some information for using this cap.

Afternoon all,

Posted before on this topic, and both 300tdi's in the flock have low coolant warning alarms installed. For convenience (and not optimum), I installed the sensor in the top of the thermostat housing. This choice allows a positive seal with no leaks and the patency of the expansion tank is not compromised by having holes drilled in it to place the sensor and there are no changes to the radiator by having to install a silver soldered bush in the top tank.

Both installations have worked very well and have been in service for 4 years. On these cold mornings, Handbrake's car reacts to the contracted coolant level by a bright red 12V bezel on the auxiliary switch panel near the clock and a clearly audible shreak until the engine is started.

I sourced the kits from Flexible Drive Agencies (in every capital city except Hobart and Darwin). I used a screw-in sensor rather than a plastic bushed one, (sen 0320, I think) and drilled and tapped the brass plug in the top of the thermostat housing.

Simple installation - took about an hour. I reckon an essential piece of aftermarket kit and something LR should have done as a matter of course. Disco 2 could do with them as well, with so much plastic in the cooling system - especially the V8.

HTH

Pete

I have gone down this path in the end.... didn't want to drill holes in the expansion tank and wanted something closer to the radiator.

http://www.enginesaver.com.au

will be installing next weekend, thread here....
http://www.aulro.com/afvb/showthread.php't=27874

Matt.

Originally Posted by matbor

I have gone down this path in the end.... didn't want to drill holes in the expansion tank and wanted something closer to the radiator.

http://www.enginesaver.com.au

will be installing next weekend, thread here....
http://www.aulro.com/afvb/showthread.php't=27874

Matt.

Did you get the 10% discount he is offering ? Only a few bucks but it all helps.

I was going to order one too but I'll now wait to see how your install works out first.

Yep, got the 10%.

The TD5 cooling system is up to 20psi. That was one of my problems the dealer or previous owner had fitter a 4psi cap so it would just pump the coolant out as it got hot.