Nightmare-ish XM ES9J4 coolant bleeding

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Re: Nightmare-ish XM ES9J4 coolant bleeding

Post by xantia_v6 »

The XM uses a different design of header tank in a different location than the Xantia, actually the same as most other XMs (excpet the 2.5 TD). This is good because it does not suffer from the seam failure that is common on Xantia V6s, but is not ideal because the header tank is mounted a bit lower compared to the Xantia V6, and may be a bit harder to bleed.

I have heard of one case (but can't verify the actual events) where an ES9 XM was not properly bled following a coolant change, leading to a head gasket failure after a few miles. I have only drained my XM once (when replacing the timing belt) and had no problem bleeding it and no subsequent issues.
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Re: Nightmare-ish XM ES9J4 coolant bleeding

Post by white exec »

I agree with Simon's description of sensors (colours and functions are correct) and the recommendation of a 'gentle' bleeding procedure, initially filling from cold, engine not running, and using the bleed screws in succession to release trapped air. The water pump is also capable of generating suction (on its intake side), and so open bleed screws while the engine is running at speed could well ingest air.

After warming up the engine and getting some circulation and an opened thermostat, the bleed screws should be used again at idle (at least once) to further release any air that was previously trapped when the coolant was not circulating round the complete system..

Agree with Simon on the need to avoid leaving off the pressure cap with a very hot engine, because of the risk of localised (hot-spot) boiling, which could cause exactly what you are trying to eliminate - vapour and coolant overflow.

Also agree about not being able to see High speed fan operation, just Low, during the bleeding procedure, as the engine just will not get to sufficient temperature to trigger it. (High speed fan operation can be instantly tested by switching on the IGN, and pulling the plug on the Brown (fans) temp sensor, as described above.)

The use of a temporary header bottle (which equates to deliberately over-filling of the expansion tank) is the recommended Citroen procedure for XM 2.5, where the normal expansion tank is not very much higher than some other pieces of pipework and parts of the system. As such, the extra bottle generates an additional 'head' of coolant, which actively helps purge trapped air from the bleed points. It also allows expelled air to be easily monitored. The technique should be helpful on any engine where the expansion tank is not significantly higher than other parts of the system.
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Re: Nightmare-ish XM ES9J4 coolant bleeding

Post by Raatokalle »

Oh my. I need to save your messages and this whole thread just in case i happen to do something similar in future. Now there is nothing unclear about this anymore. Thanks!

Basically ive done literally everything wrong when it came to bleeding process. Im kinda suprised, i haven't blown whole engine yet. Or so i assume i haven't yet. Atleast car isn't leaking coolant anywhere nor coolant level isn't dropping in chamber at all. Or it is, but only after engine is cooled down, but that is normal.

Gotta say, i became so paranoid about air in coolant system, it didn't even come to my mind, coolant would start boil when system is unpressured, in other words, cap is open. I have always thought it's more safe to let system be unpressured rather than pressured(cap closed), if you're not sure if you have air traps in the system. So all those little bubbles were coming just because coolant was going too hot while being unpressured way too long?

OK. Now when i start up engine and don't see any bubbles coming out when idling or revin' just a bit, i know system is actually fine?
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and lots of Rovers before that: 1935 Ten, 1947 Sixteen, 1960 P5 3-litre, 1966 P6 2000, 1972 P6 2000TC, and 1975 P6B 3500S
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Re: Nightmare-ish XM ES9J4 coolant bleeding

Post by white exec »

That's sounding a whole lot better. Well done on seeing it through.
Chris
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