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Woz
10th June 2024, 04:29 PM
Hi there,
Just wanted to share a story.
A week before our planned trip to take the van to Winton, I decided to change the fuel pump belt.
After losing my 10mm socket with the ¼ ratchet, a bolt, and the clip of the belt cover, I decided to give up. I would not recommend anyone doing this job ($400 quote to do)
To do the job you have to remove the coolant pipe that runs across the top of the engine you have to drain some coolant, so I removed the fitting as per manual, pipe that runs into the transmission cooler, to remove the pipe you pull out a thin stainless-steel clip to release the pipe, the same to reconnect it.
DON’T DO WHAT I DID, when replacing the pipe, the clip was in place, and I just pushed the pipe on thinking the clip will engage with the grooves in the transmission cooler. It did not.
Leaving the Gold Cost on the Toowoomba bypass passing trucks at 80kms, the red-light warning light came on coolant low, and the temperature gauge shot to high, fortunately there was a place to pull over straight away, the road sloped to right and I could see coolant running down the road. Time to call RACQ.
While waiting 2 hours for rescue I decided to check the coolant leak source, removed the front bash plate, and instantly spotted the pipe had come off to the transmission cooler. I secured the pipe on correctly and hoped the RACQ carried water because we had none.
Because we were considered in a dangerous position they sent a rescue unit. Fortunately, the lady had 10 litres of water on board, now that the engine had cooled, I filled it up to the level with the engine running, the red warning light low coolant was still on. We drove to Toowoomba with the warning light on and a close eye on the temperature gauge, stayed on normal.
In Toowoomba we bought more coolant. The next day the level was down so I topped it up with the coolant then checked the warning light, it was out, and I thought all was good until we drove 10 minutes down the road and the warning light came back on. (I read in a post that the float in the expansion tank that triggers the sensor will only float in coolant not in water, makes sense when the thermostat opened mixed the coolant with all the water).
Next day I bought more coolant and did a complete drain and refill in the caravan park, the next day after driving about 240 klm the level had dropped about 30mm, I topped it up again. Thinking there could have been an air lock. Next day after about the same distance the level dropped again so I took it to a radiator place, they did a pressure test and checked for a head leak, all tested good.
We are now on our way back from Winton, the temperature gauge stays on normal, and it uses about 250ml coolant every 250 to 300klms.
Will investigate further when we get back.
Lessons learned have breakdown insurance and carry water.

Woz

PerthDisco
10th June 2024, 05:48 PM
Good luck on this. Stressful situation.

I think you mean the top radiator hose which goes to the plastic coolant crossover in the valley?

A common issue after removing this radiator hose and the jiggling of reassembly (in your case extreme) is the aged plastic crossover is damaged and starts to leak. It is a common cause of engine failure. I’d be checking that immediately for your small residual leak. If it’s older than 7 years change it. It can and will catastrophically fail eventually.

Disconnecting this is not needed for the fuel pump belt. When you remove the crossover pipe at back of engine a small amount of coolant is lost. Just top off after reassembly.

You do need to get the engine electric harness out the way for good access to the hpfp belt.

DiscoJeffster
10th June 2024, 07:18 PM
It doesn’t sound like you did any effort to bleed it via the many bleed ports. This will be why you had to keep topping it up. The float works in water or coolant - it’s simply a buoyant thing - it doesn’t understand water concentrations. That said, they are known to play up in old age and lose their buoyancy.

BradC
10th June 2024, 07:21 PM
they are known to play up in old age and lose their buoyancy.

And when they do they can sink in water and float in coolant.

DiscoJeffster
10th June 2024, 08:28 PM
And when they do they can sink in water and float in coolant.

Hmmm odd. Ok well I will happily stand corrected. Thanks Brad

BradC
10th June 2024, 09:26 PM
Hmmm odd. Ok well I will happily stand corrected. Thanks Brad

No worries. Coolant is denser than water, so as the float progressively loses buoyancy it goes through a period of time where it acts a bit like a hygdrometer. It'll still float in a strong glycol, but it'll sink like a stone in pure water. It can be a bit perplexing if you are sitting there trying to figure out what the hell is going on.

Edit : always get those two mixed up.

PerthDisco
10th June 2024, 10:40 PM
It doesn’t sound like you did any effort to bleed it via the many bleed ports. This will be why you had to keep topping it up. The float works in water or coolant - it’s simply a buoyant thing - it doesn’t understand water concentrations. That said, they are known to play up in old age and lose their buoyancy.

Bleeding is always a good thing agreed

Woz
11th June 2024, 01:49 PM
Good luck on this. Stressful situation.

I think you mean the top radiator hose which goes to the plastic coolant crossover in the valley?

A common issue after removing this radiator hose and the jiggling of reassembly (in your case extreme) is the aged plastic crossover is damaged and starts to leak. It is a common cause of engine failure. I’d be checking that immediately for your small residual leak. If it’s older than 7 years change it. It can and will catastrophically fail

No I didn’t remove the top hose, I replaced the black box that the top hose goes to about a year ago when I did the cam belt.
I removed the plastic pipe that goes to the transmission cooler and stuffed up when I put it back on.

Woz
11th June 2024, 02:01 PM
It doesn’t sound like you did any effort to bleed it via the many bleed ports. This will be why you had to keep topping it up

When I did the drain and refill in the caravan park, when refilling I turned front and rear heater to hot and cracked all 3 bleeder ports,(expansion bottle, top cross over pipe and short hose near top hose).also the radiator guy cracked all 3 bleeder ports when I showed him where they were. Before doing the pressure test. Don’t think there will be any air pockets.

loanrangie
11th June 2024, 02:07 PM
I'm struggling to picture which hose you mean and since we don't know which vehicle you have its hard to know, on a 2.7 D3 the trans cooler is in the radiator and only has fluid lines to/from the trans no coolant lines ?

Woz
10th July 2024, 02:22 PM
2012 Disco 4 3ltr
Found the coolant leak,
It had a very slow drip coming from the bleeder on the EGR pipe running across the top of the engine. the bleeder had a small crack in it, not visible until the crack got bigger and the drips more consistent.

The car was booked in for the fuel pump belt, so I purchased a new pipe (can't just by the bleeder) and asked them to fit the pipe.

Next issue was the Coolant level warning light came on intermittently, couple of minutes each time, didn't think the float would go up and down like that, so I purchased a LR sensor. Fixed the issue, all good now.

Very easy job to replace the sensor, remove the headlight, undo the 2 bolts, leave all the hoses on, pull the sensor out from the bottom of the bottle, unclip the connector and plug the new sensor in.

PerthDisco
10th July 2024, 02:30 PM
Fitting a brass plug in there with some thread sealant and deleting the plastic bleeder is a good move to never think of this part again.

DiscoJeffster
10th July 2024, 08:52 PM
2012 Disco 4 3ltr
Found the coolant leak,
It had a very slow drip coming from the bleeder on the EGR pipe running across the top of the engine. the bleeder had a small crack in it, not visible until the crack got bigger and the drips more consistent.

The car was booked in for the fuel pump belt, so I purchased a new pipe (can't just by the bleeder) and asked them to fit the pipe.

Next issue was the Coolant level warning light came on intermittently, couple of minutes each time, didn't think the float would go up and down like that, so I purchased a LR sensor. Fixed the issue, all good now.

Very easy job to replace the sensor, remove the headlight, undo the 2 bolts, leave all the hoses on, pull the sensor out from the bottom of the bottle, unclip the connector and plug the new sensor in.

Got me too

ScottLS
19th September 2025, 10:22 AM
2012 Disco 4 3ltr
....
Very easy job to replace the sensor, remove the headlight, undo the 2 bolts, leave all the hoses on, pull the sensor out from the bottom of the bottle, unclip the connector and plug the new sensor in.

Many others say that the whole coolant tank must be replaced... please confirm that the sensor can be replaced. I see the part number for the sensor is either PCJ500030 or 10D968. Which one did you use? Thanks!