Airlocked and stalling td5

A few weeks back got a fill of really cheap diesel and was running fine afterwards on the few short trips here and there,however noticed on a little longer trip engine started to stall occasionally for about a second at a time . I put this down to the cheap diesel.

We then went away on a fishing weekend to the Lakes about 80 miles away and it was then I noticed the stalling became a bit more frequent ,never when cold though. On the way home last Sunday it got quite bad and it was then I noticed the Temperature gauge dive to cold and the red light on.

I switched it off and felt top rad hoses which were quite hard and there was water in the expansion bottle and the rad was half hot. I suspected an airlock and opened the exp.cap ,squeezed on the top hoses and then I fairly soon realised I was low on water despite there being some in the bottle.

When I got home I bled the system using the bleed screw on top hose and raised the expansion bottle and it took quite a drop of water...(doesn't cost anything...only when you don't have it are you likely to have to pay big money ) and so far doesn't appear to have caused any major problems. I've taken it on a few trips (10 miles in traffic)today and it warmed up to midway and never stalled one. So I believe it may have been airlocked and is now ok.

TWO QUESTIONS I WOULD LIKE TO ASK YOU EXPERTS.

Q1.Why should it stall due to airlock/shortage of water.

and

Q2.Why did gauge go to cold instead of hot .Perhaps the sensor didn't sense any water and reports this to the ECU . However you would imagine it would go into the red instead of the blue if no water flowing through the sensor.

Any suggestions for efficient bleeding welcome ..Thanks.

Anybody any ideas on the above...my main question in brief...Should the engine of my TD5 stall due to airlocking/water shortage...

Most likely the engine water temperature sensor is telling the computer there is no water in the system, hence the stall.

U might have a problem with the ECT(engine coolant temp. sensor,
in the coolant outlet elbow on the top of the engine), u can check it with an ohm meter if u want, when the engine is on normal working temp. (around 90 degrees) stop the engine, unplug the sensor and measure it's resistance... it must be around 250 ohm(+/- max. 20) . See this>
"In the event of an ECT sensor signal failure any of the following symptoms may be observed:
l Difficult cold start.
l Difficult hot start.
l Driveability concerns.
l Instrument pack temperature warning illuminated.
l Temperature gauge reads excessively hot.
l Temperature gauge reads excessively cold.
In the event of component failure the ECM calculates coolant temperature from the fuel temperature sensor signal. If this occurs, the limit engine operation if coolant temperature is too high becomes inoperative."

But first of all make sure the thermostat is good.... for that u have to replace it with a new one(cheap and quite easy fix)

Thanks ,just got my volt/ohmmeter back this evening so will check it out. I did have an airlocking problem more than a year ago but no stalling and at that time I changed the Thermostat and bled the system and never had a problem again until last week until the coolant level dropped.The expansion bottle had always some coolant left in it despite the fact it must have been getting lower in the engine and radiator.This is what deceived me during routine level checks over the past few months I never thought I had to top up the coolant.I expect when it goes low it airlocks or have I got a problem whereby the expansion bottle I imagine should drain??

Discomite said:

Thanks ,just got my volt/ohmmeter back this evening so will check it out. I did have an airlocking problem more than a year ago but no stalling and at that time I changed the Thermostat and bled the system and never had a problem again until last week until the coolant level dropped.The expansion bottle had always some coolant left in it despite the fact it must have been getting lower in the engine and radiator.This is what deceived me during routine level checks over the past few months I never thought I had to top up the coolant.I expect when it goes low it airlocks or have I got a problem whereby the expansion bottle I imagine should drain??

Click to expand...

Seems normal to me...IMO an airlock/thermostat failure/low coolant/coolant loss will lead just to engine overheating not to driveability problems ... my guess is that u have a management issue