That extra coolant reservoir tank thingy.

[purplechugster]

hello there... A problem I've had with my van for ages but can't seem to fix...

I've got a 1.6l diesel. It runs fine (*touch wood*) and the temperature gauge is always where it ought to be, but if I thrash (relatively speaking) the van, I get coolant leakage from the reservoir. I've seen it happen - it sprays out the reservoir where the cap is.
Now, the thing I dont understand is that the coolant doesnt overflow into the second coolant reservoir (the one behind the number plate) which is, as far as Im aware, what its there for!

Ive made sure the cap is on really tight, Ive replaced the cap, and Ive replaced the rubber tubing between the two reservoirs - but still no joy, it squirts out of the first reservoir instead of going through the valve to the second reservoir.

So... any ideas?

[Hacksawbob]

not too sure about diesel, check the bottle for tiny cracks that are caused by over tightening the cap whilst hot, mine did this looked as though it was the cap but it was comming from near neck on the body of the bottle. not aware of coolant going back into the top up tank from the header tank is that a diesel thing?

[skell]

if diesel arrangement is the same as petrol the top up tank is just that - coolant gets sucked through a one way valve into the main reservoir when needed, so there is not supposed to be a flow from main reservoir to top up tank.

[purplechugster]

Ah right, okay...

I thought that coolant went from the reservoir to the top-up tank, but if its supposed to go the other way that would explain some of it

Although, now it still spurts out but doesnt top it up from the top up tank! I need to pour in some new coolant if its boiled over.

I'll check for cracks around the cap and get back to you!

[airhead]

Maybe your coolant bottle is overfull, whioch would cause it to spray out when it gets hot enough. I think theres like a pressure popoff valve on the cap of the coolant bottle which lets water out if the pressure gets too high.

[hanloncole]

You need to bleed thr coolant system sounds like you got a lot of air in there or a dodgy pressure cap, buy a new cap and bleed the system would be my next moves cap is only £3
worth a try
Simon

[TD]

Have you had the van long?, do you know its history?
Water probs can be 'deadly ' on a diesel. But best to look for simple solutions first.
The top up tank should get the excess coolant from the system when hot and take it back when cool. therefore the expansion tank remains full - always.
Does your pipe work to the top up tank work?, has it a leak, . I replaced mine some years ago with new pipe.
Is there a crack in expansion tank?, quite common cheap to fix at around 25 (DIY).Cap unlikely to be at fault.
The thing to watch for is a pressuried system, (from cracked head of couse). If not overheating then should be ok . The top up tank has overflow hole near top any way , but should never be in use.