Thread: Coolant level senders Tdi

I suspect that if air gathers at the high spot in the hose (in my case) it is so sensitive that it only needs some air bubbles around the sensor to activate it.

Maybe this has been the case since my vehicle was new (10 years), but it's only now that there is an audible alarm that it's noticed. There may normally be air pockets circulating in all our engines, but the condition doesn't get noticed because as soon as it is started they move on until next time.

Mine to taped into the the radiater cap ., with an alarm inside Both audible and visible. I had that done after blowing a head gasket

Originally Posted by 4bee

Wayne, I contacted David re this as I was also concerned. It was his opinion that there is still air trapped in the system from the installation. I have had a few goes at this & the test beep is much shorter now.

Even when it was beeping longer, it soon cleared.

On the V8i D1 the hose is the highest point in the system & so air can gather there.
I made up a 'tool' to help bleed this without wasting coolant. Mail me if you would like further details, although it was posted on here some time back.

Hmmm...thanks for that 4bee. I just had the water pump replaced and it was after that the beep got longer ..I'll bet they haven't bled the system properly.
On the TDi I normally just take out the black plastic plugs (or brass ones in my case )one on the radiator and one on the block and top up from therem but if you could pm me with your idea that would be great tks.

Aim of exercise is to stop motor before heat damages it. Maybe before coolant level drops.
Better solution - temperature sensitive switch fixed to flat spot on side of head with self tappers. About 20 mm diameter by 10 mm thick with two spade connectors. 105 degree ones satisfactory for Rover diesels. 95 degree ones go off too soon.
Connect wire that goes to fuel solenoid on injector pump to switch then from other terminal on switch to solenoid.
Push button for override desirable so motor can be run for short time when overheated - still below "cooking" stage eg to drive off road. Necessary for starting if oil pressure switch also incorporated into circuit , ie one that switches off, not on like oil light switch when pressure below about 10 psi (adjustable)
On older diesels with mechanical fuel shutoff a fuel solenoid can be installed in fuel line just before injector pump.
Power feed to the field in Bosch alternators can be put through oil pressure switches. Saves flattening battery if key is left on.
I installed above setup on a header (combine harvester) over 20 years ago. Several things can cause motors on them to overheat very quickly. Also more recently on tractors running unattended driving irrigation pumps.
Obtained necessary parts from Shepparton Speedo and Instrument Service ph (03) 5831 2670

1997 300 Tdi Defender 130 with tray and extended cab

Originally Posted by mox

Aim of exercise is to stop motor before heat damages it. Maybe before coolant level drops.
Better solution - temperature sensitive switch fixed to flat spot on side of head with self tappers. About 20 mm diameter by 10 mm thick with two spade connectors. 105 degree ones satisfactory for Rover diesels. 95 degree ones go off too soon.
Connect wire that goes to fuel solenoid on injector pump to switch then from other terminal on switch to solenoid.
Push button for override desirable so motor can be run for short time when overheated - still below "cooking" stage eg to drive off road. Necessary for starting if oil pressure switch also incorporated into circuit , ie one that switches off, not on like oil light switch when pressure below about 10 psi (adjustable)
On older diesels with mechanical fuel shutoff a fuel solenoid can be installed in fuel line just before injector pump.
Power feed to the field in Bosch alternators can be put through oil pressure switches. Saves flattening battery if key is left on.
I installed above setup on a header (combine harvester) over 20 years ago. Several things can cause motors on them to overheat very quickly. Also more recently on tractors running unattended driving irrigation pumps.
Obtained necessary parts from Shepparton Speedo and Instrument Service ph (03) 5831 2670

1997 300 Tdi Defender 130 with tray and extended cab

Perhaps if you have the time you could do up a basic parts list and wiring diagram and post it in the projects section. Sounds look a really good setup

Originally Posted by waynep

Hmmm...thanks for that 4bee. I just had the water pump replaced and it was after that the beep got longer ..I'll bet they haven't bled the system properly.
On the TDi I normally just take out the black plastic plugs (or brass ones in my case )one on the radiator and one on the block and top up from therem but if you could pm me with your idea that would be great tks.

How long did it take for your beeping to get back to normal?.

The radiator was flushed (and pump changed) on mine and like yours mine now beeps longer. I also assume its a bit of air in the system.

For example this morning it beeped for about 20-30 when started. So i turned the engine of and checked the coolant levels; looked good. So I drove away and it beeped continuosly for another 20-30 seconds before stopping.

How long did it take to get back to normal and did you do anything to help it along?

Thanks

I'm not worrying about it any more unless the beep doesn't stop within a short while. In my case, before it gets to our pump shed on our 300 m driveway. If it's gone by then (150m)all seems well.

I notice after driving that after stopping & restating again, it beeps for 1 second , (normal built-in self-test) if that, & to me that indicates that there is not the air at the high point of the system still & it has moved around.
It is only after standing for some hours that I get a prolonged beep, as I presume the air has gathered again in the high spot which is also where the sensor is located.

Originally Posted by 4bee

I'm not worrying about it any more unless the beep doesn't stop within a short while. In my case, before it gets to our pump shed on our 300 m driveway. If it's gone by then (150m)all seems well.

I notice after driving that after stopping & restating again, it beeps for 1 second , (normal built-in self-test) if that, & to me that indicates that there is not the air at the high point of the system still & it has moved around.
It is only after standing for some hours that I get a prolonged beep, as I presume the air has gathered again in the high spot which is also where the sensor is located.

Thanks 4bee, what you have written exactly describes mine.

How long has yours been going? Mine since radiator done mid last week.

i thought the instances of the beeping would decline day by day as the air slowed left the system.

I was particulary worried this morning as it beeped longer than I was happy with 20-30seconds. But when i opened the plug on top of the head it was full as was the over flow.

But as with you after driving for a while, stopping and restarting its back to normal beeping .

Anyone else have any hints at getting any leftover air out of the cooling system?