Club 80-90 Forums

Apologies if this has come up before or is commonly known, I've searched but found nothing, or mixed information at best.

I have a 1988 van with a JX and I've just realised it doesn't have an auxiliary water pump. Do some JX's not have it from the factory or is this a sign that its either had an engine change or the AWP has been removed at some point due to a fault? The wiring connector is present, I always wondered what it was for.

I only realised when researching locations to plumb in an additional coolant temperature sender and found posts referring to a JX needing to have an AWP. Brickwerks' list of available hoses supports this, but JK and Heritage list the hoses that exclude the AWP for the JX as well, so thought I'd better check.

Regardless, is it worth adding one?

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All JX had it by factory.
It switches on and runs coolant through the oil cooler when the coolant reaches ~100C° basically when you do a lot of high rpm runs like highways, mountains, offroad etc.
It is not as necessary if you have an external oil cooler.

If you switch the engine off it keeps the coolant circulating until the engine has cooled down sufficiently to avoid heat buildup. IMHO anything that helps keep a JX cool is worth having.

If you’re buying a new pump, make sure you get the one with the connector that matches your wiring, as there are two different versions - guess how I know this.

The other thing to keep an eye on at first is that the temperature switching for the AWP is working properly - there should be a relay in the engine compartment junction box that switches it on and off as required. If that isn’t working then the pump can stay on and run your battery down - again, guess how I know this.

The wiring diagram for the AWP can be found here on the syncrosport website - the aforementioned relay is marked as J151.

ZsZ wrote: ↑31 Oct 2021, 10:06 All JX had it by factory.
It switches on and runs coolant through the oil cooler when the coolant reaches ~100C° basically when you do a lot of high rpm runs like highways, mountains, offroad etc.
It is not as necessary if you have an external oil cooler.

An external oil cooler is no help in removing heat soak after switch off which is the point of the auxiliary pump.

It suddenly struck me, looking at it today, that I had always intended to look into what had been bodged here.


Now I know what's missing its obvious. The 53 relay was still in place. I need to do some more reading up as I'm not sure what rails y and b are in the diagram, and then poke at it with a mutlimeter. I understand the switch F95 is on the thermostat housing, I'll replace this just to be sure that side of it is working correctly.

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