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[screwloose]

Hi guys, just after some suggestions with regards my 2.5 Td running hot and regularly overheating.
I have replaced the thermostat and changed and flushed the coolant but still the same issue. It tends to overheat when under sustained load for example driving up a steady incline on a motorway or prolonged acceleration. You can just watch the temp gauge climb all the way to the red and overheat.
Any ideas guys? thanks for any help.

Jonny

[MickAP]

Not experienced it myself but have heard that the rad can get so silted up on the TD causing the problems you have. Ordinary flushing may not help in this case.
Others may be along to help on this and maybe other suggestions.

Mick

[osealy]

check my recent posts

[JamesV6CDX]

How pressurised is the system when it's running hot? Is the cap blowing off at all?

[Seth]

Hmmm .... another common 'tractor' issue this!

I've experienced the same on mine, particularly when under load and/or on inclines.
I've changed the water pump, 'stat, and rad; and also done a coolant flush.
It's a lot better now, normally running around the 92 mark, but will still creep up to around 97 when worked hard, so I've got to keep an eye on it. After completing a climb, it quickly returns to 92-ish again.
This is with the viscous and rad fans running!
'The Boy' has a theory regarding the engine oil cooling jets, and I don't disagree with it - mine gets an oil/filter change every 2500 miles religiously.
My own theory is that there's simply not enough cooling for the engine full stop, ie; it really needs a bigger rad.
If you decide to change the rad; beware, as I was quoted between £150 and £330 for a replacement, so shop around. Put in 5 litres of Vx genuine antifreeze, as this gives a 50/50 mix. Leave it in permanently.

[screwloose]

How pressurised is the system when it's running hot? Is the cap blowing off at all?

The system seems fine with regards pressure and the cap hasn't blown off.

thanks for all the help so far guys.

[Seth]

With the engine running at normal temp; carefully remove the expansion tank cap. Get an assistant to rev the engine - you should see a helluva good burst of coolant entering the tank.

Mine has a tremendous flow - hence my theory regarding the need for an even bigger rad!

As an aside, certain Range Rovers are powered by this engine too, and I've also heard their owners complain about this same problem.
I've heard no complaints from BMW owners though!

[TheBoy]

The cooling system on this engine is adequate - mine gets a good ragging all the time, never beyond 97C (on gauge). That includes going up the passes in the Lakes, with back wheels rotating considerable faster than the fronts .  And my viscous fan is where it should be, in the bloody garage - what a gay pillock that came up with that idea of putting viscous on a modern saloon!

If the temp hits 100C on the gauge, reality is its over 110C, which is the safe point of the engine - beyond this, you are in head cracking territory.

Usual reasons for 2.5TD BMW lumps overheating are (in order):

Waterpump parted company with its impellors
Poor servicing (ie, ignoring the 4.5k MAX oil change intervals)
Silted rad


The TD engine relies on oil jets to cool pistons.  People who ignore the 4.5k max oil change interval end up blocking these cooling jets with sludge, result is the engine overheats quickly.  A very strong engine flush is needed to clear them, and then a few short oil changes, before back to 3-4k changes.  'Long life'/Fully synth will do bugger all to extend the ridiculous short oil change interval on this engine, whatever the dealer/factors may say.

[Omegatoy]

The cooling system on this engine is adequate - mine gets a good ragging all the time, never beyond 97C (on gauge). That includes going up the passes in the Lakes, with back wheels rotating considerable faster than the fronts .  And my viscous fan is where it should be, in the bloody garage - what a gay pillock that came up with that idea of putting viscous on a modern saloon!

If the temp hits 100C on the gauge, reality is its over 110C, which is the safe point of the engine - beyond this, you are in head cracking territory.

Usual reasons for 2.5TD BMW lumps overheating are (in order):

Waterpump parted company with its impellors
Poor servicing (ie, ignoring the 4.5k MAX oil change intervals)
Silted rad


The TD engine relies on oil jets to cool pistons.  People who ignore the 4.5k max oil change interval end up blocking these cooling jets with sludge, result is the engine overheats quickly.  A very strong engine flush is needed to clear them, and then a few short oil changes, before back to 3-4k changes.  'Long life'/Fully synth will do bugger all to extend the ridiculous short oil change interval on this engine, whatever the dealer/factors may say.

AGREED!!!!