Cooling system pressure warning light.

[frank rabbets]

Been paranoid after ByronJ lost his cooling water (and engine). I've been thinking of what happens in the cooling system and how to fix a low pressure warning light. When the water is subject to heat from the engine it expands and reaches a pressure equal to the pressure spring in the rad cap. When the engine is fully hot equilibrium is achieved at 88KPa (13psi). If there is even a slow leak the pressure will drop as there is no increase in water temperature to compensate. I've ordered a 0-50 psi adjustable pressure switch. My plan is to plumb this in to the cooling system and wire it to a prominent light on the door pillar, get the engine hot and adjust the switch until the light just goes off. The drawback is that the light will be on on cold start but should go off after 5 minutes or so (to be confirmed). I've done the plumbing and fitted a gauge to check the water pressure out of interest it reads about 18 psi when engine is fully hot.

Pictures to come and conclusions soon.

 

[Towpack]

Given that the pressure loss with, say, a burst hose or holed radiator, will be rapid causing the coolant to boil, a pressure warning light should come on long before the engine actually overheats. Good idea.

 

[frank rabbets]

Not finished yet. I hope it turns out to be a good idea lol.

 

[Lorin]

I used to have one of the Cartek alarms in the top hose Coolant Level Sensors | CARTEK Motorsport Electronics - [Leaving Land Cruiser Club]

To me this is the perfect solution. Alarm is immediate if coolant level drops.

Unfortunately they are no longer available and I have been unable to locate the sensor they used.

 

[frank rabbets]

Lorin, Looks like still available. Expensive though.

https://www.edfmotorsports.co.uk/product-page/coolant-level-sensor

 

[Lorin]

Lorin, Looks like still available. Expensive though.

https://www.edfmotorsports.co.uk/product-page/coolant-level-sensor

I’ve sent an email to check they’re really in stock and available! Cartek discontinued them several years ago….

 

[frank rabbets]

I put one in my basket OK but did not go to checkout. Thanks for the heads up Lorin I might buy one just in case my pressure system fails!

 

[Bat21]

Lorin, Looks like still available. Expensive though.

https://www.edfmotorsports.co.uk/product-page/coolant-level-sensor

This product couldn't be found
Looks like they are no available from there either.

 

[LandcruisingFarmer]

Reading this thread, this looks like it could be a solution. I can’t post the link to demon tweeks, but the item is called “Davies Craig low coolant level alarm kit”
Says it fits nearly any vehicle and it’s not too expensive.

 

[Bat21]

Reading this thread, this looks like it could be a solution. I can’t post the link to demon tweeks, but the item is called “Davies Craig low coolant level alarm kit”
Says it fits nearly any vehicle and it’s not too expensive.

That will be one of these.

 

[LandcruisingFarmer]

Bingo

 

[frank rabbets]

Mine is coming this week lol. Thanks.

 

[frank rabbets]

My Davies Craig warning kit came today. Trouble is it cuts down the cross section of the top hose by about 65%. Question is, under normal driving, will the thermostat open further to compensate or is it fully open when the engine is up to temperature? Very tempted to fit a bypass pipe to compensate and increase flow back to normal. Plenty of room in there to extend the top hose to fit 2 x tees, one each side of the Craig tee. Thoughts please.

 

[Towpack]

65% is too much IMO. I doubt Toyota would fit a hose that size if they could fit one 65% smaller. I'm assuming the kit just senses the presence of water, not the flow rate so it will still work in conjunction with a bypass hose.

 

[frank rabbets]

Yes the top hose will drain down together with the bypass hose so both will be dry. There is a float in the Craig so it will trigger the switch if no water is present.

 

[Shayne]

Does the sensor screw in ?

Alloy Water Temp Gauge Radiator Hose Temperature Sensor Adaptor - Silicone Hose UK

Introducing our high-performance Alloy Water Sensor Adaptor, designed to take your cooling system to the next level. This innovative accessory is a must-have for automotive enthusiasts and professionals seeking to optimize their engine's performance and efficiency.Crafted from top-quality alloy...

siliconehoseuk.co.uk

 

[frank rabbets]

No, it's all glued together.

 

[frank rabbets]

Managed to get the low pressure warning system finished. First I had to convert a brass T to take a 1/8 NPT threaded pressure switch. This T fitted into the heater pipe coming up from the block. The pressure switch was a "Longacre" 0-50 psi. I also bought a 20 mm LED warning light. I fitted later at sight level whilst driving. I had to correct my original hot pressure readings to 12 psi after taking a picture of the gauge which was clearer than line of sight. I set the cut off switch to 6 psi. First run went well initially but then the light started blinking. I stopped and removed the rad cap to equalise the pressure and set the switch to JUST turn light on. I drove home and let the engine cool overnight This a.m. went out and after 5 miles the warning light went out and stayed out.

 

[felix2566]

Is the switch an adjustable one?

I much prefer the solution you have using a heater hose.
To me creating more breaks in the cooling system by adding sections of pipe to hold the sensor is creating more weak points that could fail. I'd be more annoyed/worried that the modified part would fail first before the original system and cause the failure that I was monitoring for.....

 

[frank rabbets]

Yes the switch is adjustable 0-50 psi. It works really well. It is very solidly built. If it corrodes it will weep first rather than drop fluid. I cut the main hose up from the block which provides the heater circuit. The tee is a very tight push into the pipe and the thread fitting is a tight fit into the Tee then soldered with hard solder.