2.7D Coolant Change Issues

[geeegs]

Hi all,

Not sure whether anyone will be able to help me out here; I drained 10 litres of coolant from the bottom screw (measured into a bowl), took off the bleed screw and went to top up with a fresh 10 litres, but it registered max at about 6 litres full. I turned on the ignition on cold for a few minutes, then to hot for a further 5 but still no change. Then I replaced the bleed screw, put the cap back on and started her up, heating on hot but not feeling that warm. Slight dribble from he bleed screw, then I realised I hadn't tightened it up all the way. There was no change as far as I could tell in the level of coolant changing after 5 minutes (looking from the back of the coolant chamber) so I turned her off and decided to leave it for the night! The fans stayed on for about 20 seconds before turning off (she's never done this prior). My main worry is that I'll crack a cylinder head or something awful!

Have I done everything OK? And is there anything I could do tomorrow?

P.S
I loosely followed a write up on the jaguarforum.com site that was apparently copied from the workshop manual as my guide, although (I thought) it wasn't everso clear.

[J44EAG]

That sounds like an air lock to me. Most Jags of this time line suffer that issue and need careful re-filling.

You should do no harm by running the car up to temperature with the cap off the coolant tank. Squeezing the radiator hoses and adding coolant should eventually expel any trapped air. This should happen once the thermostat opens when the engine is up to full working temperature. With a full system, you should find the cooling fans should not function. Lack of fluid around the sensor will switch on the fans. At idle and after a run, the fans should not be cutting in if you have a full system.

I`ve seen this issue on a V8 4 litre and also on my current XJR 4.2 V8. I don`t see the issue you have on your 2.7D to be any different. Burp out the trapped air and you should be ok. Hope that helps.

Mike K

[rosemary]

Mike is absolutely right it's an airlock courtesy of Jaguar's superb cooling system design. The "manual" procedure is to fill as you would normally, open the heater to max heat ,put fan outlet on full through the dashboard outlets and run the engine until hot air comes out. Allow too cool and top up. It's all about when the thermostat opens and the coolant direction changes from through the engine when it's closed to through both engine and heater circuit when it opens. You may have to do this a couple of times.
Dave

[J44EAG]

Ah, yes!

Air in the heater hose circuit. I forgot about that. Agree fully with Dave. Open the heater control to full and run up until the stat opens. You should find the system gobbles the remaining coolant. Squeeze hoses whilst filling to help burp out the trapped air. Treat the car like a young baby!! Remember that just like a home central heating system, air can also get trapped at the highest point. Cracking off a hose on the engine at the highest point can often free that air...that is a last resort thing though. You should be able to evacuate all the air using the methods described previously. You will know when you have it right after a short run then an idle for a couple of minutes. The fans won`t come on.

Mike

[geeegs]

Many thanks Mike and Dave, your knowledge has proved invaluable!
I got back on it this evening and after adding about 500ml of coolant to the expansion tank (which had emptied during the night/day), ran the engine for about 10 minutes with the cap off. The coolant barely sank below the max mark during this time, but the fans were on for a lot of the time. Heating was on max with A/C on.
Switched off, fans immediately shut down. Replaced cap.I gave it ten minutes for it to cool down, although i was unsure of how long it might take for it to cool down enough for me to add yet more fluid; again in panic of if I were to crack any of the cylinder heads!
Started her up again, took her down off the ramps, removed the expansion cap carefully with a cloth covering the steam evaporation(!) The heating wasn't that warm, so I switched the A/C off whilst maintaining the 31 degrees temp setting.
I revved her for about half a minute and then let her settle for a further ten minutes by which time the fans weren't running and the cabin heater was very warm. I switched off, checked the tank which was still reading at max.
Everything seems to be ok except for the fact that I've still got just over 3L of coolant in the bottle waiting to go in! Meaning that there must be around 10L in the system as it currently stands. I left the bleed screw untouched during this whole procedure as all it seemed to do last night was bleed coolant, not air!

[J44EAG]

The car must be filled with the car on the level not with the nose in the air on ramps.

If you remove the coolant cap and leave it off, run the car up to temperature watching for the thermostat to open whilst squeezing the big radiator hoses to expel trapped air, you should then suddenly see the header tank level drop. At that point, more coolant should be added. Opening the bleed screw periodically will almost certainly help.

Mike