Auxiliary coolant pump?
 

Hi guys, me again. Isn't there an auxiliary pump that will pump coolant round the system with fan on after engine has been switched off? Basically I'll park up (especially now it's hot) with coolant at 90C, come back and it's gone up to 100C. Drops quickly once started but not a fan of that. :Confused:

Thought it's the one right by bulkhead on right hand side but after searching on here it seems a lot of people just unplug it once it starts getting noisy?

Engine is 2.8 APR

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There is no aux pump on the V6 or V8, only the W12. The one by the hvac is to provide faster cabin heat as the engine warms up and also cabin heat once the engine is off for a short period.

That would explain why I couldn't find any info. Why is coolant temp climbing then, and it's pushing past expansion tank cap?

The V6 is prone to airlocks. Have you opened the cooling system recently? It needs refilling with a vacuum tool.

Also worth trying a new cap - the pressure seal does fail from time to time, although usually it takes an overheating incident to trigger it in the first place.

Just had timing belt done, but airlock surely would cause overheating in traffic/idle? As for expansion tank it's new Meyle unit with brand new cap.

I tolerated a slight coolant loss through the pressure cap for close to three years after replacing my radiator, coolant bottle, coolant cap, and bleed valves.
The car never overheated, but would give low coolant warning on spirited left hand bends on occasion and I would then top it up with some G12+ (I would usually find it sitting on "min" at operating temp).

I simply blamed the aftermarket coolant bottle and lid and put up with it.
However, come timing belt time, and I drained the coolant out of the system and refilled it after installing a new pump and thermostat.
It has not needed coolant since, and sits rock steady on the max mark at running temp.

So the moral of this story is that a small amount of air in the system that can push out coolant (probably by expanding more than the coolant does), does not necessarily affect the cooling ability of the cooling system to a degree where it's a problem.


I had a V6 in my B5. It was a 12V, so I can't speak for the changes made on the 30V engines, but it had both a block bleed valve, and the high bleed point (which is the twin bleed valves on the D2).
The block blender was mounted on the engine rear coolant cross-over pipe between the heads.
You had to open both bleeders and bleed the block first before filling the rest of the system.
Even then I would still have to 'burp' the system as I ran it up to temp with the expansion cap open. Real PITA.

MJ will know if the 2.8's still have the block bleeder on them.

The D2 variant has it next to the power steering pump, but in my experience even that isn't enough to get all the air out of the V6. I've had that bleed screw out completely with the engine running and overheating, and nothing comes out - the pipe remains completely dry :rolleyes: Hence why I always use the vacuum tool on them.

The V8 burps itself just fine.

Thanks for input. I'm not bothered as such, she runs well, no overheating but just bothers me that it isn't "like it's meant to be". I'll keep an eye on it, might stop doing over time. +++

My S2 was doing similar thing. Was loosing coolant somewhere but could not see where and in hot weather would dump through the cap after parking/stopping engine but temp gauge would always be OK. Turned out to be a combination of failed electric fan making it run a bit hotter than usual and faulty/sticking valve in expansion tank cap. 1 second hand fan and a new aftermarket cap later problems were gone .